# HSS Lathe Tools chipping, what might cause this?



## WobblyHand (Sep 6, 2020)

It seems that most of my lathe tools that I have ground end up chipping, or micro-fracturing.  I've had one crack not at the tip, but at 1/16" below the tip.  For the most part, I just re-hone if I can, or give it a quick touch to 100 grit ceramic belt and re-hone.  This last one seemed to crack along the cutting edge of a square cut lathe tool bit.  It is giving a ribbed, grooved finish, as opposed to a nice shiny one.  This tool bit was used on 6061, so it's not on anything hard.  The tools are kept in QCTP carriers which are in turn in Schaller boxes, so they don't hit anything.  I'm not ramming the bit into the work, the cuts aren't super deep.

Anyone have a suggestion as to why this might be happening?  The edges don't wear, they seem to chip.  Right now I'm getting significantly better surface finish with TCGT carbide than with HSS.  And the HSS isn't lasting long.  It could be something I'm doing, but I'm at a loss at what that might be.



HSS on the left, TCGT carbide on the right.

Trying to photograph the tool tip.  Here's one.  I was using WD40.  One can see a little aluminum on the tip, but behind the tip is a bright area, which is the edge breaking off.


Having trouble with getting the other view in focus.  Not possible with my phone camera.  I can see it in my stereo microscope.

Here is a view of the tool on the lathe.



Any clues I could pursue?  Thanks!


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## pontiac428 (Sep 6, 2020)

I can't quite see what you've got going on for a grind on your HSS tool, but I would recommend stoning or grinding more of a radius into the tip to achieve a better finish.  Also, aluminum likes a lot of back cut on the tool.


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## benmychree (Sep 6, 2020)

I am wondering if sharpening on the ceramic belt may be overheating the cutting edge, causing micro cracking and subsequent tool failure.


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## brino (Sep 6, 2020)

A little more info would help.
What is the work diameter, and the RPM?

The other issue that jumps out for me is lack of tailstock centre support!
With anything that is more than 3 diameters of the work long, the chuck alone is not enough support.

Even if it is not the root cause of your issue, I just worry that you could have an accident. The "lever arm" is long so a little bit of tool push at the far end could easily get the work off centre and then it could come around, catch the tool and launch the work around your shop.

Be safe!
-brino


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## extropic (Sep 6, 2020)

A few issues come to mind.
Is it good USA HSS or cheap import stuff?
100 grit ceramic belt sounds pretty course and aggressive. I read that you hone but the close-up seems to show course grind grooves.
Is the chipping happening essentially parallel with the grind marks? How about reorienting the grind on the top relief?


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## mikey (Sep 7, 2020)

In all the time I have been in this hobby I have never chipped a HSS tool except for the tip of a threading tool that didn't have a flat ground on it. Otherwise, never. You would have to catch the tip/edge on a protrusion at speed to do it and it certainly would not be likely to happen when turning aluminum.

It might help to see some detailed pics of the tool. Perhaps the clues lie there.


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## benmychree (Sep 7, 2020)

Agreed, Mikey.


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## WCraig (Sep 7, 2020)

Are you positive the tool bits are HSS?  Are they attracted to a magnet?

There are other alloys out there (Stellite, Tantung G, Blackalloy, ...) that look like HSS but need different handling.  In particular, they should not be quenched while sharpening as the metal will become brittle and may fracture.

Craig


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## erikmannie (Sep 7, 2020)

Is there a slight radius at the cutting edge? I don’t imagine that you tried to make it as sharp as possible.


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## WobblyHand (Sep 7, 2020)

Well thank you for all your observations.

@brino I'm aware of the large stickout.  This is a 2" diameter piece with about a 5" stickout.  I'm checking diameter of a 0.001" thin cut near the chuck vs the end, to check alignment.  Ordinarily I wouldn't do this without tail stock support.

@benmychree if the chip is large compared to what I can remove with honing, I just touch the tool to 100 git and I get to a sharp edge again.  It also helps restore the relief if I messed it up while honing.  I find honing by hand to be quite difficult.  Maintaining the flatness is a motor skill that I'm not as proficient as I'd like to be.  At some point I need to make a fixture for this, but my tool making skills need more development.  Under 22X magnification I see no evidence of discoloration due to over heating.  But I can see a fracture where the surface is a different color.  It could be the belt, hope not.  Alas, I have no camera attachment for my microscope.

@extropic Import steel from a company that was recommended by users on HM.  I bought 50 pieces.  This tool wasn't honed as well as I would have liked.  Looking at the photo now embarrasses me.  Usually my honing is  better.  Now that you mention it, the fractures seem to be in the direction of the grind.  I'll take a look to see if there is a different way to grind the tool on the belt sander.

@WCraig The tools behave like HSS when grinding.  They are marked HSS and they are magnetic.  They don't discolor if very hot.  Not sure if I quenched them when grinding.  I know I did it to some of them in the beginning.  Maybe this is a cause.

@mikey I don't have any idea why I'm getting all this edge failure.  To the best of my knowledge, I've followed your basic tutorial on tool grinding.  You did point out to me that the threading tool failure I had was due to not breaking the edge of the V.  So I fixed that. Haven't had issues with threading since.  I'll try to get some better photos of the tool bit.  It's rather hard with a phone camera.  Darn phone wants to focus on the wrong thing.  Wish I could take some pictures with my microscope, but I don't have a camera for it. These fractures are evident under high magnification.  To the unaided eye, they are only now visible as a tiny difference in color on the edge.  It's been frustrating that many tools I've ground have not lasted.  I don't know, might be material, or more likely my technique.

@erikmannie I tried the best I can to have sharp edges everywhere.  Under an 8x magnifying glass they look sharp save for the chip area.  Phone cameras are not distortion free.  It wouldn't surprise me if the photo looks curved.  By eye, under an 8x hand held magnifying glass and using a 22.5X stereo microscope, I don't see curvature.  Edit: I am wrong.  There is some curvature of the top face.  I find it really hard to maintain the flat.  I may have rocked the hone.

@pontiac428  I'll get better photos.

Keep your ideas coming!


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## WobblyHand (Sep 7, 2020)

Here's a few.  Gee, I didn't do a very good job on this tool.  Un-doctored photos.











Looking at the last photo, the cutting edge (as used) has damage for 2mm out of the 5mm edge.  (From the tip, then 2mm to the right.)  I don't think that damage was present when I was done honing.  

Looking at this with a critical eye, there's clearly stuff to fix.  On my part, I will try to grind a new square bit from the same lot (no quenching of any sort) and maybe from some cobalt steel (also no quenching).


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## Mitch Alsup (Sep 7, 2020)

I do not see chipping, what I see is the aluminum has welded itself to the tip of the tool.
A bit of WD-40 should eliminate this problem. {hint: machine aluminum wet}


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## WobblyHand (Sep 7, 2020)

@Mitch Alsup agreed, there is a tiny bit of aluminum on the tip.  The other stuff is a break.  I wish I could take high resolution microscope photos, but that is out of my grasp.  For what it is worth, the aluminum was wet and slinging WD40.


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## brino (Sep 7, 2020)

As you can see above, there is lots of interest in finding a solution.
What a great group!



WobblyHand said:


> This is a 2" diameter piece



so cutting aluminum with HSS I'd want to be about 110 sfpm.
For a 2" diameter, that's about 210 RPM.

Are you cutting close to 210 RPM?

I don't have any spare 3/8 square HSS tool bits in stock, but I have 5/16" (Cobalt-6 Sheffield) and 1/4" (Eclipse H5 England).
I would send you one for comparison (no charge) if you PM me your address.

-brino


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## WobblyHand (Sep 7, 2020)

So I ground two new square tools, one from the same lot of HSS and a second from piece of 5% cobalt steel.  Haven't got to honing them yet.  My belt grinder needs more modification to better make these tools.  After I put on a finer grit belt, I found I had difficulty touching up the top relief cut.  The reason for this is the belt grinder structure is in the way of where the tool needs to go.  Basically, this particular belt grinder is being asked to to things it never was designed for.  So maybe I have to grind my grinder...

Here are all 3 tools.  The new ones have not been honed yet.  You can see the on the top relief where the belt only partially hit the surface.  On the other faces, the fine belt did remove the gouges of the coarser belt.  A few more photos.


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## WobblyHand (Sep 7, 2020)

brino said:


> As you can see above, there is lots of interest in finding a solution.
> What a great group!
> 
> so cutting aluminum with HSS I'd want to be about 110 sfpm.
> ...


Yes, lots of good insightful responses.  There's a lot of helpful folks here.

I was cutting faster than 210.  Maybe 800, mmm, 900?  Sooooo, that's something I can fix!

As you can see, I do have some cobalt, and at least 20 more pieces of HSS from that lot.  I have one weird piece of Mo-max, but that has an odd grind on it, so that one's a last resort.  So for the moment, I'm all set, but thank you very much for the offer!

Really need to make a settable articulated holder for honing these guys.  Keeping the hone flat is a problem for me.  My forum name is Wobblyhand and let's just say it's apt.


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## mikey (Sep 7, 2020)

Let me say that you have ground some really nice tools! I'm not sure if I could have done them better and that's the truth.

I honestly don't know how you're managing to chip an edge unless that edge is not sharp. It is NOT your tool grinding but it may be your tool honing. Each plane on the tool tip - side and end cutting edges and the rake angles - must intersect precisely. You cannot get this from grinding; it must be honed that way. Try honing and looking at it under your scope.

Otherwise, I got nothing.


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## markba633csi (Sep 7, 2020)

Hi Wobbly: One problem with your grind is shown here in your pic:  The face of your tool should be flat or slightly concave, not convex. Looks like the tool would be rubbing too much.  Normally we would use the face (as opposed to the side) of the grinding wheel to do this.  Hard to do properly with a belt. Also, I don't see sharp knife-like edges there, I see dull, roundy edges. Small things, but they make a big difference
Your geometry looks fine, you just need to finesse it a bit more
-Mark


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## WobblyHand (Sep 7, 2020)

@markba633csi some of what is seen in the photo is an illusion.  I had a tough time getting the right lighting on all three tools.  That said, I think there's some problem on the top edge, as you say.  You are seeing incomplete tools.  No honing or prep was done, just raw off the belt sander.  I can see a burr on the cobalt tool.  I need to do better on the belt.  I have an aluminum table and sometimes the tool digs in rather than sliding.  Perhaps that's causing some of the rotation.  Maybe I'll replace the surface with steel.  Since I have a mill now it won't be that hard to do.


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## WobblyHand (Sep 7, 2020)

@mikey, flattery will get you nowhere
I think I am messing up the edge with my grind, and hosing the edges with honing.  I really do have a devil  of a time doing the honing.  So much so that I've been looking at diamond disks today.


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## markba633csi (Sep 7, 2020)

OK understood.  Try then to get as flat as possible on those tool faces,  then hone carefully without rounding over the edge.  Your bits should be dangerous when you are done 
Personally, I don't even hone mine. I just use 'em right off the wheel.  ("Free Bird" begins playing)


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## Flyinfool (Sep 7, 2020)

Granted phones do not take great pics. BUT in all the pics the "chipped" edges look a lot more like built up aluminum than chips.

It could be the pics and the lighting but the ground surfaces look awfully rough. I see almost no evidence of honing which should almost look polished. What grit is your stone?
I have found that the direction of the grind also has an effect on the performance of the cutting edge. When the grind is parallel to the cutting edge the chip has to flow across all that roughness rather than flowing with the "grain".

When you are honing the edges, are you holding the stone in your hand?  Are you holding the tool in your hand?
If holding both it is nearly impossible to get a good edge. Best result will be with the stone on a hard steady surface. hold the tool lightly with just thumb and a finger. This will allow the tool to follow the ground edge and not try to change the angles.


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## WobblyHand (Sep 7, 2020)

There was aluminum on the tip, I can't deny that.  Maybe what I thought was a chip is aluminum.  Under a microscope those two areas look very different.  One day I'll figure out how to get photographs through my microscope.  

@Flyinfool the new bits _are_ rough.  They were sanded with 100 grit ceramic belts.  No honing on the new bits.  As for the first bit, guilty as charged. Got lazy.  I'm working on the new bits now.  They take forever to hone.  I think I need to get a decent 220 or 320 grit belt so I don't have to work so hard getting the grooves out.

The stone or the tool is on my desk.  I usually try to draw the tool across the stone.  Unfortunately, after a couple of minutes I sort of relax and the angle shifts.  It's hard for me to hold the tool in the in the correct complex angle relative to the stone.  My hand wants to twist as it's uncomfortable for me.  I'll keep trying.  At one point I rubber cemented some silicon carbide sandpaper to a machined surface to use it as a longer hone.  To be honest, it worked pretty well to get rid of most of the gouges on the big long surface.


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## Flyinfool (Sep 7, 2020)

It might be cheaper and easier to just get a cheap 6 inch bench grinder. It dont take up much space and is specifically made for the job at hand. A 100 grit grinding wheel leave a much smoother surface that a 100 git belt.

If you are trying to hold the bit at the angle you are trying to hard, let the bit float in your fingers and it will follow the angle that the grinder made. Your fingers are not to hold the bit, just to move it back and forth and give a bit of down force. When you get it right it will just click, till then it is maddening.


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## WobblyHand (Sep 7, 2020)

Definitely will look into both getting a grinder and more likely just putting on a finer belt.  Issue with a grinder is making a decent tool rest.  Most grinders these days come with sheet metal rests.  Those rests are utter junk.  That's one of the reasons I went with a belt sander.  Still, I'll look at my 8" and see if there is some way to rig up a better tool rest.  

Polishing the long face of the tool is easy.  Don't have a problem with that.  The face is roughly an inch long and 3/8 wide.  As you say, just guide it along and it does it's thing.  It's the smaller faces that are hard, because the size of the face(s) isn't really big enough to plop down and stay, especially with gravity.  The small faces are roughly 0.3 x 0.35 and 0.25 x 0.35.  It's just harder for me to keep it flat, especially the top relief face.  The bit tail is facing downward so I need to support it, and the back side my fingers are split between the two faces.  If I press on the edge between the two faces, it becomes uncomfortable after a short while.  Gravity wants to make the tool move away from the surface.  It's not impossible, just difficult.  I need a better way to do this, just haven't found something that works for me yet.  

Don't know, maybe your set up is totally different.  So far, mine leaves a lot to be desired.


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## mikey (Sep 7, 2020)

WobblyHand said:


> @mikey, flattery will get you nowhere
> I think I am messing up the edge with my grind, and hosing the edges with honing.  I really do have a devil  of a time doing the honing.  So much so that I've been looking at diamond disks today.



I wasn't trying to flatter you; just being honest. There are a lot of guys on this site who cannot do what you did.

Honing comes with practice and time. It helps to get the face you're sharpening flat on the stone and lock your wrists, then make a single stroke pulling towards you. Then go back and re-orient the face on the stone and repeat. It doesn't take a lot to hone a face if you do it that way. Try not to put a lot of pressure on the stone; let it do the cutting. When the tool is sharp, the cutting edges will not reflect light; let that be your guide. I hold the stone and tool in my hands; I don't put them on a surface because I cannot feel the tool that way.

My tools will slice paper like a sharp knife. There is no magic to honing, just technique. A coarse diamond stone will take all the grind marks off. A fine stone will flatten the faces quickly. An extra-fine stone will put a near mirror finish on the face. Take your time and learn to do it and it will pay off.


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## WCraig (Sep 8, 2020)

WobblyHand said:


> On my part, I will try to grind a new square bit from the same lot (no quenching of any sort) and maybe from some cobalt steel (also no quenching).


It is fine to quench HSS.  The cast alloy tools are pretty uncommon and on the order of 10X more expensive than HSS.  I thought that perhaps you got a bunch of unknown tool bits with the machine and might be unknowingly dealing with an odd duck.

What are you using for honing?  Oil stones, water stones, diamond, ...?  How coarse or fine?  How big are your hones?

For honing tool bits, I like the folding style diamond hones.  Like these:



			https://www.leevalley.com/en-ca/shop/tools/sharpening/files-and-hones/102437-folding-diamond-hones?item=70M0701
		


It usually only takes a few swipes with the fine hone to form the bright, polished, sharp edge.  Repeat for the three surfaces that form the cutting corner and polish the nose radius.  Only the cutting corner needs honing but the polished portions must go right to the edge.  Apply some black marker before polishing to make it easier to check your progress.  As you say, it is really difficult to photograph this intersection but pretty easy to check with magnification.

HTH

Craig


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## WobblyHand (Sep 8, 2020)

mikey said:


> Try not to put a lot of pressure on the stone


This, is in fact, what I am struggling with.  To have the face flat to the stone (actually diamond coated 2" x 3.25" steel) I seem to need too much pressure.  And more pressure makes it hard to pull and maintain contact.  If I relax, it works a little better, but then the tool sort of slips from my fingers.  If the slip is during a draw stroke, that puts a defect on the surface, (usually rounds an edge) which takes a lot of honing to take it out.


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## WobblyHand (Sep 8, 2020)

WCraig said:


> It is fine to quench HSS.  The cast alloy tools are pretty uncommon and on the order of 10X more expensive than HSS.  I thought that perhaps you got a bunch of unknown tool bits with the machine and might be unknowingly dealing with an odd duck.
> 
> What are you using for honing?  Oil stones, water stones, diamond, ...?  How coarse or fine?  How big are your hones?
> 
> ...


@WCraig yes, this helps.  Great idea on the marker.  I'm using diamond hones.  Have two different hone sets.  One is an Eze-Lap which is easy to hold but has a smaller active area and the other are 2x3 steel cards coated with diamond.  The coarsest grit is on the Eze-Lap which is allegedly 150.  On the bigger cards the coarsest grip is 325.

Altogether, I have grits ranging from 150, 250, 325, 400, 600, 1200

I need to use a finer belt grit before using the diamonds.  The diamond hone's material removal rate is really slow, especially compared to a belt sander.  Like well over 1000:1 ratio.  It's taken me over 6 hours of honing just to get to what you see below. There are still remnants of the coarse grooves in the tools.  First pic is HSS, second Co.  Can't get decent lighting on both bits at the same time.  You can see the groove near the tip on the HSS bit.  On the cobalt, I'd just use finer grits as the defects are away from the cutting edge.




Once the grooves are gone, going to finer grit is relatively smooth sailing.

Edit:  One thing I am finding is that the stones that I do have aren't really flat.  Not potato chipped, but not really flat either.  I can tell because the material being removed is from different places depending on what stone I use.


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## ttabbal (Sep 8, 2020)

Holding things at weird and uncomfortable angles is certainly an acquired skill. I find that the key is not to be in a hury. Honing can be a bit zen if you let it. 

Try a few different ways of holding the bit and the hone. Find what works best for you. I started with putting the hone on the grinder table. Then it's already at 15 degrees. I also rest my hand on the table while honing. My whole hand and arm move the bit. Then I'm using my hand to position and arm to move. It helps me to keep a reference and feels more natural. The smaller faces are definitely the most difficult to keep aligned.

Maybe hold the bit in a vise and use both hands to position the hone? I've never tried that, but it might work for you. 

Switching belts didn't work as well for me. I ended up creating facets most of the time. I found it best to grind with 36 grit and just hone out the grinding marks. But maybe it will work better for you. 

I'm not sure what would cause the chipping. I have done it, but it was me crashing into steel. I was learning and got the direction wrong. I have some steel that will dull them fast, at least the import M2.


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## WobblyHand (Sep 8, 2020)

erikmannie said:


> Is there a slight radius at the cutting edge? I don’t imagine that you tried to make it as sharp as possible.


I think this really is my issue.  The tool bit must be rocking a tiny bit as I'm pressing it in.  Kind of need a press down action and push action at the same time while keeping your hands away from the belt.  The aluminum surface I have on the grinder tool rest isn't helping me.  

I marked the face and then partially honed it with a coarse grit.  The black parts  are near the edges.


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## WobblyHand (Sep 8, 2020)

ttabbal said:


> Switching belts didn't work as well for me. I ended up creating facets most of the time.


It's extremely difficult to not create facets without a fixture.  That's what's happening!  36 grit makes for some monumental grooves.  But facets are even worse.


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## mikey (Sep 8, 2020)

Just take your time, don't get in a rush. Practice. It will come. 

Most edge rounding happens on a push stroke.


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## WobblyHand (Sep 8, 2020)

_Gee, take your time!_  It's been a day and 1/2...  Getting impatient!  I barely have the big long faces done.  All I have to get are the very tips.  I find when I pull the tool back on the stone too far, I lift.  That messes up the edges.  Back to hogging off the face to get back to an edge.  What a strange cycle.  I feel like Sisyphus.  Too far of a pull is anything greater than about 1.5 inches.

Confession time.  I think the diamonds are prematurely coming off the stones I have.  This may be due to excess pressure on my part, although I didn't think I was pressing down that hard.  But, a lot of dark grit came off, and some of my stones don't cut very well any more.  And yes, there are some bare spots (after cleaning) on the hones.  My apologies for tool abuse.  Still learning, I guess.

How did I come to this conclusion?  I found this 20 year old cheap diamond stone with 1mm perforations in it.  Apparently came from Gander Mountain, a now defunct outdoors supplier.  Thought to myself, what the heck, why don't I try it?  Hey, this seems to cut pretty well - I can tell it is removing material.  Is the removal fast?  No, but stuff is coming off, as I can see the different scratch pattern.  The holes seem to reduce the loading of the stone.  Is it really flat?  Not really, it's mounted to a little 1/4" thick block of wood.  But it's cutting at speeds far exceeding what I had before!  And rounding edges and tips at breakneck speed.

At least I've identified some of what's messing up.  Take my time, yes, I'll try.


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## pontiac428 (Sep 8, 2020)

I really don't mean to ruffle feathers, but I need to point out that the grinding wheel leaves a flat, mirror-like surface, whereas the belt grinder flaps and jumps around a lot, leaving a heavily ribboned surface that is clearly making more work at the hone.  I do my grinding with stones, so from the wheel to the hone there is very little sweat work.  I gotta say, as cool as belt grinders are for knifemaking, they are not a good tool for lathe bits.  A simple Delta carbide grinder would run circles around a belt grinder on lathe tools.  A fixtured grinder, like the Deckel, will outperform the carbide grinder, stretching the gap between the belt grinder and tool grinders even further.  Like I said, not out to cause any anger, but one tool in this lot has limited performance when it comes to grinding flats.


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## WobblyHand (Sep 8, 2020)

Not ruffling my feathers.  The honing is proving to be more work than ever anticipated.  That's because the finish from a belt grinder is not only rough, but perhaps rounded.  The slight rounding might just be due to my technique.  However, the rounding causes a lot more material to have to be removed (to get back to flat).  If I could fix this, perhaps the honing won't be so tedious.

The Delta carbide grinder looks well made with the nice cast iron table.  Wish I could find a relatively intact one.  The Deckel grinder is in a totally different league, the eBay prices prove it.  The Deckel is not in the cards, unless some kind soul donates it to me.  I'd love to learn to use all its capabilities.

Somehow, I'll muddle through this.  Probably have to modify stuff that I have to work better, rather than buy my way to nirvana.  That's how it is in my current circumstances.


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## pontiac428 (Sep 8, 2020)

Do you have a miter slot in the rest on your belt grinder?  I'm assuming you are using some type of guide, since your angles look consistent.  Can you feed the bit left-right or right-left across the belt with a guide?  Your included angles might be harder to achieve, but for your outside angles feeding across the belt may help get a flatter result.






The Delta carbide grinders are ideal for lathe bits.  I'd still like to get one someday.   I use a Deckel clone with lathe bit attachment, and my lathe tools come out like knives.


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## WobblyHand (Sep 8, 2020)

pontiac428 said:


> Do you have a miter slot in the rest on your belt grinder?  I'm assuming you are using some type of guide, since your angles look consistent.  Can you feed the bit left-right or right-left across the belt with a guide?  Your included angles might be harder to achieve, but for your outside angles feeding across the belt may help get a flatter result.
> 
> 
> 
> ...


Gee, I wish.  Nope, they are done by hand, almost free hand.  I did scribe some lines in the table, so I line up the tool to the line or parallel to the line.  I have lines at 10 and 15 degrees, and at 100 and 105 degrees.  I try to line up the pusher to the perpendicular line.

This picture gives me an idea.  Maybe I can make something like it.  It won't be ground, but it could be machined.  Probably could find some sort of miter gauge to buy.  It would be a lot better than effectively freehand.


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## pontiac428 (Sep 8, 2020)

Yeah, trying to perfect total freehand grinding while learning how to make good lathe bits at the same time is really tough!  I'm a fan of fixtures.

There are a few schemes for fixture blocks for lathe bits.  If you make a tool holder that is 4-sided and can accept a bit in each side, then set up the groves so they hold different side rake angles, you can use a miter guide to guide your block while making a compound facet... clear as mud.

Here's one:


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## WobblyHand (Sep 8, 2020)

@pontiac428 That's pretty cool.  Just a dumb question, whats the advantage of this vs just setting the miter to the correct angle?  The fact that the block is bigger and easier to control?


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## pontiac428 (Sep 8, 2020)

The block is easier to grip, and most miter slots are far enough away from the grinder face to benefit from a block.  The key part of the block is the ability to dial in two angles, the tilt and the face angle.  Harder to hold a 7 degree tilt for edge relief in your bare hands than it is to seat in a block with a 7 degree groove.  When doing your back cut, you'll end up hanging the block and bit over the edge of your grinder's table, the block provides enough of a rest to do this.


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## WobblyHand (Sep 8, 2020)

Ok.  I can tilt the table and lock it in position.  For these tools I had set the table to 15 degrees.  So I "only" had to worry about keeping the tool flat against the table and parallel to the scribe mark.  That was plenty hard enough for me...


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## mikey (Sep 8, 2020)

pontiac428 said:


> I really don't mean to ruffle feathers, but I need to point out that the grinding wheel leaves a flat, mirror-like surface, whereas the belt grinder flaps and jumps around a lot, leaving a heavily ribboned surface that is clearly making more work at the hone.  I do my grinding with stones, so from the wheel to the hone there is very little sweat work.  I gotta say, as cool as belt grinders are for knifemaking, they are not a good tool for lathe bits.  A simple Delta carbide grinder would run circles around a belt grinder on lathe tools.  A fixtured grinder, like the Deckel, will outperform the carbide grinder, stretching the gap between the belt grinder and tool grinders even further.  Like I said, not out to cause any anger, but one tool in this lot has limited performance when it comes to grinding flats.



You know I am saying this will all due respect but I have to disagree, Pontiac. A belt sander with a Pyroceram platen will grind totally flat faces with speed and control. It is far faster and cooler than a grinding wheel, even on a flat faced wheel. It comes down to the operator. Grinding tools is a skill and while some may feel that fixtures are necessary, I am not one of them. I alter tool angles often and I am more accurate and far faster doing it freehand, using only the table angle as a fixed parameter. I will  grant that if you must have a given angle ground into a tool every single time then fixtures and dials work better for that but for lathe tools they are not necessary. More to the point, geometry can vary with material and application; there is no perfect geometry for everything and quite honestly, what is often accepted as a standard may not be optimal. If it were, I would still be taking 0.020" deep cuts on my little Sherline instead of the 0.050 - 0.060" I can actually take.

Lathe tool grinding is not hard but it does take some time to learn to move your hands. I assure you that some of us can produce perfectly serviceable lathe tools right off the belt sander and hone them with maybe only a few minutes with diamond stones. I can, freehand, remove the coarse grinding marks from a lathe tool in under a minute, smooth the faces in another minute and form the nose radius and polish the faces in under another minute with an extra-fine stone because I've done it hundreds of times and have paid my dues. And I am not alone. 

I know you already understand this; anything that involves skill takes time to master. 

I am suggesting to the OP to take that time.


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## pdentrem (Sep 8, 2020)

Might try building a few jigs! There are many styles and types out there. Here is one


			Lathe Bit Sharpening


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## erikmannie (Sep 8, 2020)

OP, what is your intended nose radius, generally speaking? Are you intending to make the cutting point as sharp as possible or do you intend to grind (or hone) a small nose radius?

I don’t know very much about grinding HSS cutting tools (I usually use inserts), but my understanding is that it should have a small radius. You probably are well aware of this.


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## WobblyHand (Sep 8, 2020)

I've learned the hard way (previously) that no radius is an invitation for breakage.  For this tool I'm looking at putting in a radius of about 0.020-0.025" or so.  Much bigger than that then cutting forces get high.  Much smaller than that then the nose breaks.  Mini-lathes don't have that much oomph, so I don't want to go to a large radius.


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## WobblyHand (Sep 9, 2020)

@mikey My take away from your reply to pontiac428 is that I'm messing up the grind.  Consequently, the hone is taking forever.  It is an art to hold the tool correctly for honing.  I'm using a death grip due to fear of messing up, but that's counter productive.  If I relax some, it surprisingly seems better.

The real problem is the grinder.  It needs to be modified to work better.  Whether it can be altered sufficiently to generate crisp edges without rocking remains to be seen.  The current aluminum top plate is soft and catches the edges of the tool bit.  I also need to increase the notch on the right side of the grinder to get a better top relief.  The far end of the tool is hitting the housing and belt guard, limiting the top relief cut.

Don't want to blame the grinder, but this unit wasn't designed to do tool grinding.  There are definitely compromises.  Hopefully, enough of the compromises can be overcome to generate decent grinds.  Got to think about a new table surface that offers enough support where it's needed.  And a better more controllable way to hog out the notch.


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## WCraig (Sep 9, 2020)

WobblyHand said:


> I think this really is my issue.  The tool bit must be rocking a tiny bit as I'm pressing it in.  Kind of need a press down action and push action at the same time while keeping your hands away from the belt.  The aluminum surface I have on the grinder tool rest isn't helping me.
> 
> I marked the face and then partially honed it with a coarse grit.  The black parts  are near the edges.
> 
> ...


I think you know, but just to be clear I've cropped just the cutting tip from the above picture:



There appears to be far too much rounding to be honed away (see arrow).  Unlike Mikey, I can't freehand grind.  I think your 100 grit belt is making things worse.  It is pretty aggressive and may be 'grabbing' the tool bit as you make contact with the abrasive.  That could tend to roll the tool bit and result in the problems above.  I use a moderately worn 120 grit Blue Zirconia belt but most of my tool bits were ground on a 6" bench grinder before I got the sander.  The convex surfaces left by the round grinding wheel make it easier to register the tool bit on the honing stick.  

I think the tool bit above needs to be reshaped on the belt sander or bench grinder.  Use black marker and go back and forth between the machine and your medium hone.  That should show visually whether the new-ground surface is getting rounded over or not.  (HSS is really pretty cheap!)

Also, I don't think you've said what kind of belt grinder you are using?  A 1 or 2 inch?  Hopefully not something like a 6X48.

Craig
BTW, your photos are pretty darn good.  It is very difficult to photograph reflective metal and smartphone cameras generally get thoroughly confused about what to focus on.


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## WobblyHand (Sep 9, 2020)

Yes, there's too much rounding to take off honing.  I have to both modify my technique and the table surface.  It's an 1/8" aluminum plate screwed to the underlying table.  The aluminum tends to grab when sliding the bit on the surface.  Been caught by it before. Going to remake the surface out of a piece of scrap 1/4" plate steel.  While I'm at it, I'll extend the right side so I can get more support especially when grinding the critical top face.

This is a 2 x 48 belt sander with no disk sander.  The platen is cast steel and an integral part of the unit.  It makes it tough to modify. Like I said previously, it was never designed to grind lathe tools.  So I have made some minor mods to enable this.  It seems there is still room for improvement.  

Thanks for your comments on the photos.  It is tough to take these photos.  Spend a lot of time setting up the pictures.  If one puts a a new surface close to the desired surface the camera will then tend to focus on the correct object.  (The close stuff, not the background.)  Have to fool the autofocus algorithm.


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## mikey (Sep 9, 2020)

WobblyHand said:


> @mikey My take away from your reply to pontiac428 is that I'm messing up the grind.  Consequently, the hone is taking forever.  It is an art to hold the tool correctly for honing.  I'm using a death grip due to fear of messing up, but that's counter productive.  If I relax some, it surprisingly seems better.
> 
> The real problem is the grinder.  It needs to be modified to work better.  Whether it can be altered sufficiently to generate crisp edges without rocking remains to be seen.  The current aluminum top plate is soft and catches the edges of the tool bit.  I also need to increase the notch on the right side of the grinder to get a better top relief.  The far end of the tool is hitting the housing and belt guard, limiting the top relief cut.
> 
> Don't want to blame the grinder, but this unit wasn't designed to do tool grinding.  There are definitely compromises.  Hopefully, enough of the compromises can be overcome to generate decent grinds.  Got to think about a new table surface that offers enough support where it's needed.  And a better more controllable way to hog out the notch.



No, the point I was trying to make in my response to John/Pontiac428 was that a belt sander is, in my opinion, almost ideally suited to grinding lathe tools. I've used bench grinders for years for that purpose and it won't come close to a belt sander that is properly set up. I've tried Baldor tool grinders, too; they work but are very slow compared to a belt. For drill and end mill grinding, I won't even get into a thread where Pontiac or C-bag are discussing stuff because I'm an idiot when it comes to that but lathe tools, that I have some experience with. John already knows I have a great deal of respect for him and his opinions. Its just that I disagreed on this one point. 

As for your belt sander, there are two things a good belt sander needs to grind lathe tools. One, an adjustable tool rest to grind the angles you require; it is best to make this tool rest from steel to prevent sticking and dragging (as you've discovered). It must also provide adequate support on the right side of the sander to allow you to grind your rake angles. Two, it needs to have a flat platen so you don't grind curves into your tool. The best fix for this is a ceramic glass platen commonly known as Pyroceram. Trying to grind tools on a steel platen that is even slightly dished is an exercise in frustration.

Honing is something you have to do to get better at. It is actually harder to learn to hone a tool than to grind it, or at least it was for me. If you think about it, you ground three flats on your tool with your belt sander. Now you simply need to hone those flats with your stones. The key is to understand that you are trying to keep those flats *flat* while also trying to remove grind marks. 

I will concede that if the tool face is not flat then it is harder to make it flat but I assure you that it is possible because I used to do it all the time when I was learning to grind and hone lathe tools. The trick to it, if there is one, is to work at making each face flat because it is the intersection of those flats that does the cutting. If the faces are not flat then they will not precisely intersect and the tool will not cut. That really is all there is to it, intersecting flats at angles that you choose to grind.

As for technique, keep your hands soft and your wrists locked. Do most of your cutting on the pull stroke; if you push, you will be more likely to roll an edge. Use gentle pressure and let the stone cut; excess pressure causes your hand angles to change. Use the coarse stone to flatten the face and once it is flat, do all you can to keep it flat. The goal when stepping up through the grits is to simply remove the grinding marks left by the media before the current one while maintaining the flat surface your working on. Concentrate as you move so you don't rock the tool; when I hone, nothing else exists except the flat on that face.


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## pontiac428 (Sep 9, 2020)

Mikey has contributed more to this site on the subject of grinding HSS lathe bits for beginners on up than anybody else here.  There is a megathread here where you can read several "a-ha!" moments per page from a number of folks new to grinding the hard stuff.  

There is quite a difference between different belt sanders, and belt grinders deserve a category of their own.  Belt grinders have 4-pulley systems that eliminate belt hop and wander, and they are always equipped with a glass platen or better.  They are usually a prized tool by those who build them.  All I have to work with is a 2x48 belt sander, same as WobblyHand.  The Jet that I've had since the 1980s runs pretty smooth, but the pop-pop-pop from the belt seam (Norton or USA zircon belts only) is enough to discourage me from grinding lathe bits with it.  I guess it's different from free-handing a drill bit in that with the drill you only need to make the correct sweeping movement once or twice per side.  That's like a blind hog finding some acorns compared to grinding a perfect plane on lathe bit, which would take much more practice.

The reason I advocate fixtures is they give practically perfect results.  Machine work is done in a fixture because the work gets located and held precisely, so I look at lathe bits as a machining process rather than an artistic one and seek a way to hold the work while removing metal.

I always welcome discussion, even if it means I have to modify my opinions (oh, darn!).  I'm here to learn, and I don't mind a little back and forth when it comes to growing my understanding of it all.


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## WobblyHand (Sep 9, 2020)

I must of read all 35 pages in one sitting.  (Now there's more!)  Quite the storehouse of knowledge which @mikey and others have shared.  Quite the amazing thread.

@pontiac428 , there's nothing wrong with fixtures or jigs.  In my case, the simple fixture will be a better, more stable table for the grinder.  I'll fly cut the surface to make it smooth.  As mentioned previously, I have a some 1/4" plate that I thought I'd start with.  Not sure if it should be thicker, but that's what is in the shop junk pile.

Went out to the garage to get my plasma cutter to carve off a piece of plate.  No arc.  Air solenoid cuts off in 5-6 seconds.  Drat.  Yet another thing to fix...  Put in new consumables, but that didn't make it better.   Idiot lights all ok.  Pounds head against wall.  Guess there's tomorrow to sort it all out.


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## mikey (Sep 9, 2020)

pontiac428 said:


> Mikey has contributed more to this site on the subject of grinding HSS lathe bits for beginners on up than anybody else here.  There is a megathread here where you can read several "a-ha!" moments per page from a number of folks new to grinding the hard stuff.
> 
> There is quite a difference between different belt sanders, and belt grinders deserve a category of their own.  Belt grinders have 4-pulley systems that eliminate belt hop and wander, and they are always equipped with a glass platen or better.  They are usually a prized tool by those who build them.  All I have to work with is a 2x48 belt sander, same as WobblyHand.  The Jet that I've had since the 1980s runs pretty smooth, but the pop-pop-pop from the belt seam (Norton or USA zircon belts only) is enough to discourage me from grinding lathe bits with it.  I guess it's different from free-handing a drill bit in that with the drill you only need to make the correct sweeping movement once or twice per side.  That's like a blind hog finding some acorns compared to grinding a perfect plane on lathe bit, which would take much more practice.
> 
> ...



John, we've just had a difference of opinion, that's all, and it was based on our personal experiences. I respect that and I hope I didn't upset you; I did worry about it. 

To be honest, I think that most guys in our hobby would rather use a fixture to make grinding lathe tools easier and more reproducible. Heck, I was one of them in the beginning because I was sooo horrible at freehand grinding back then. The reason I took the plunge to grind them freehand is because I discovered that altering the angles found in grinding tables made for a better cutting tool, so much so that no jig or fixture really worked well. Now I know that the key to a lathe tool is its geometry and you must be able to grind that tool so it does what you need it to do. Can't do that with fixtures until you finalize a design; maybe then it might work. 

I only have a simple Sears 2 X 42 belt sander BUT I have used a Wilton Square Wheel and a Burr King belt grinder and those are beasts of a different sort. With that said, my sander will grind tools just as well on my humble machine, albeit slower. I only use it with coarse belts to shape nowadays and my go up to an 80 grit belt to take coarse marks off but I don't go much finer anymore so I don't deal with the hump thing much. What my grinder does have is a really good tool rest and a glass platen and those things make all the difference. 

I was going to relate a funny story. I bought a new smartphone a few years ago and my son helped me. We were trying to register my fingerprints to turn on the phone but we couldn't do it with my right hand; had to use the left. That right hand has honed so many lathe tools and has been cut and ground down so much that I have no fingerprints left on my fingers - true story! I have learned to turn the phone on with my left hand but only two fingers have any prints left on them; the rest are gone. When I said I paid my dues honing lathe tools, I wasn't joking!


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## brino (Sep 10, 2020)

WobblyHand said:


> Went out to the garage to get my plasma cutter to carve off a piece of plate. No arc. Air solenoid cuts off in 5-6 seconds. Drat. Yet another thing to fix... Put in new consumables, but that didn't make it better. Idiot lights all ok. Pounds head against wall. Guess there's tomorrow to sort it all out.



The last time I saw that on mine, I had neglected to fully tighten the new electrode.
Pleasantly surprised by the quick fix.....once I found it.
-brino


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## WobblyHand (Sep 10, 2020)

Wish it was as quick fix as you experienced.  Swirl ring is broken in 3 pieces.  That surprised me.  Guess what part I don't have spares of?  Off to order one. No make that a couple of them.  If I have 3, I'll never need one again!  I'll buy the parts.  To be honest, I don't even know if this will fix the problem, but it is a step in the right direction.

Save for the tiny holes, it doesn't look that hard to make...  My original is ceramic.  Replacements seem to be made out of a different material.  Almost phenolic looking.  Those tiny holes allow a wire that's 0.024" in diameter to pass.  So the hole is a little larger.  Found a carbide machinable ceramic material called Macor on McMaster, but at the diameter I need,  about 5/8", the expense for the raw stock is far more than buying multiples of the finished product.  On evilBay, machinable 15mm diameter ceramic isn't cheap either.  ($65)  Can buy a lifetime supply of swirl rings for that price.   And avoid breaking a lot of #73 drills!  So the wait begins.  A swirl ring from eBay might show next week.  I also ordered a bunch of consumables from Aliexpress.  If they show up by the end of October, it would be good.  That eBay swirl ring should get me going.


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## WobblyHand (Sep 14, 2020)

Been busy.  Can't say productive, but you will find out why.  So the idea was to make a new steel table surface for the belt sander. Had a piece of scrap for the table that needed trimming.  But just couldn't get the plasma cutter working.  After 2 days of this, I gave up on it (for now).  It doesn't seem like the pilot arc is igniting.  (New consumables, etc.)  So, found a 14 tpi hacksaw blade and went after the plate.  After what seemed like forever, the plate was cut.  Stuck in my mill and squared up the edges and fly cut the surface.  Came out ok, well, except the holes (in the plate) were in awkward places.  Turns out it didn't matter.  Made a cardboard template and cut it away in places to fit it to my belt sander.

Milled out the notch for the belt.  Then thought to myself, it would be nice if the edge was cut away beneath the table so it could be snugged up close to the belt.  Found an angle vise that I had tucked away and mounted it to the mill table.  Attempted to tram it.  Let's just say it was pseudo-trammed.  Aka not very well trammed.  Proceeded to cut a 15 degree cut off the edge.  Surprisingly worked ok. 

Today made some 8-32 transfer screws to locate the plate to the belt sander table.  I made them from SHCS's that I chucked in my hand drill and ran against the belt sander.  In no time I had four transfer screws.  It was simple to transfer the hole locations to the plate.  Back to the mill.  Drilled out the 4 holes and made my fatal error.  Yes, the counter-bores for the SHCS's are on the wrong side.  Yes, there is insufficient material to flip it over to counter-bore.  I'm unhappy with this result.  Guess I need to chalk it up as a practice run...  Slaps the side of his head, just why didn't I see that?  

So, next time, I'll use a thicker 3/8" piece (no holes!) and try again.  I have a metal template now (save for the counter-bores).  Can't say I'm that sad.  This plate was pretty rough and the holes didn't help much...



So I just chalk this attempt as a practice run?  Hope the second one is a lot nicer!


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## Flyinfool (Sep 14, 2020)

Or instead of using SHCS use flat head screws so you only need a c"sink?


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## WobblyHand (Sep 14, 2020)

Flyinfool said:


> Or instead of using SHCS use flat head screws so you only need a c"sink?


Can try that.  The piece is 0.240 thick.  I counter-bored 0.170.  At this point there's not much to lose.  To be honest, I do want a redo. Just think those holes and points on the corners are an accident waiting to happen.  I can file them, but not sure how to make them look nice.  Will try the countersink and see how I like the basic design.  If it's ok, might leave well enough alone.  If not, there's always version 2.


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## brino (Sep 14, 2020)

.......or can you fill 'em full of weld, grind/machine flat and re-drill the holes.

-brino


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## WobblyHand (Sep 14, 2020)

@brino, think I like that idea.  Gives me a chance to fire up the welder.  Haven't done that in a while.  MIG ok?  How do I avoid plug welding to the table?  Copper strip?


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## Flyinfool (Sep 14, 2020)

A clearance hole for a #8 screw can be easily closed with the mig and no backing needed. I have filled much bigger holes with the mig. Either way you will have to machine and/or grind both sides.


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## brino (Sep 15, 2020)

I would MIG, but only because I'm still terrible at TIG.

Yes, just a copper sheet underneath will peel right off. You may have to flip it and fill a small divot that was originally against the copper.
Once both sides are machine/ground it's like the mistake didn't happen.

-brino


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## WobblyHand (Sep 16, 2020)

Unlike my plasma cutter, my MIG welder did work!  (Hobart 187, C25 gas, 0.023 wire)  Didn't quite fill the holes perfectly, but good enough!  I actually practiced it ahead of time, by making some similar holes  1/8" through and 5/16" counterbore in some scrap. Welded it directly to my table.  Just gave each weld a tap and it broke of the tiny piece that was stuck to the table.  Gee, this is almost like an eraser!     Interesting HAZ zone, just a circular zone about 1/2 in diameter.  Just machined off the big lumps on the weld side.  Next is to flip it over and get the little bumps off.


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## WobblyHand (Sep 20, 2020)

Since honing was so onerous, I found some honing plates on e B a y.  They are 75x170x1mm.  I made a flat plate from some 3/8 aluminum to put the plate on.  Much better surface to use rather than my old swaybacked desktop.  


Finished the table and mounted it on the belt grinder.  Ground two edges of a new 3/8 blank on it.  The long first cut is no good.  I'm rocking the tool on the grinder.  The hone is flat, the tool isn't.


I notice a couple of things are wrong.  1) There's too much gap between the table and the platen.  That's fixable.  2) The belt seems to have stretched.  Hope there is enough adjustment range in the belt adjuster.  3) With a 120 ceramic grit belt, the tool gets kind of hot.  Hot enough that it's hard to hold down flat to the table.  I tried 120 rather than the 40 grit, reasoning that it might be easier to hold flat.  Of course it takes longer to grind, but the gouges are finer, so the honing might not take as long.

So, I'm making a holder for the lathe tool bit.  (A fixture.) This helps in two ways.  The first is it's 1" wide rather than 3/8".  This should make it easier to keep flat.  Also it's longer than a lathe tool bit, so it's easier to hold.  2) The increased mass of the holder will allow a little more grinding before having to cool down.  The holder is modeled after a QCTP bit holder.  Milled out a slot in a piece of 5/8 x 1" stock.  Will add in some 6mm set screws to lock the tool bit in place.  Still figuring out how I'm going to hold the piece so I can cut a slot in the corner so the lathe tool bit will go flush to the corner.  Will use a slitting saw to make the cut.  This is what I have so far.


Cut needs to go in the corner like the figure below.


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## turnitupper (Sep 21, 2020)

WobblyHand said:


> Still figuring out how I'm going to hold the piece so I can cut a slot in the corner so the lathe tool bit will go flush to the corner. Will use a slitting saw to make the cut. This is what I have so far.


Had some lathe tool holders with internal corners rounded. Hit them with a Dremel with an abrasive blade hand held at about 45 degrees.worked well.
John.


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## Larry$ (Sep 21, 2020)

My diamond hones are considerably larger. Makes it easier for me to maintain a uniform stroke. I made a simple holder for the hones that attaches to a counter. I have a tube that drips water on the hone. Once I have got the surface to be honed positioned flat on the hone I lock both elbows against my body and only move my entire body in an effort to not change the angle of the tool. I'm not a fan of belt grinders for sharpening. I've got an 8" bench grinder with two of the relatively soft white wheels. I use a star type dresser to keep the faces sharp & flat. I try to use two hands and not rest the tool on the machine, only my hands touch the tool rest. The resulting grind is concave making it very quick to get the cutting edge honed. I think it also reduces the likelihood of doing a rounded edge. 

I've never had HSS chip. I get a better finish with HSS than with carbide inserts. I gave up on the import inserts after I finally bit the bullet and paid a kings ransom for a box of name brand ones. I buy the ones with a larger nose radius. I keep one inserted tool that I use re-ground inserts in. Fairly esy to do the regrind on a diamond wheel.  They get used on rusty, scaly steel. Crappy finish but saves the good tools for the finishing pass.


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## WobblyHand (Sep 21, 2020)

So finished mounting the "scrap" table to the grinder.  You can see the HAZ affected area from my welding.  Adjusted the table closer to the belt.  Not quite sure how to increase the tension on the belt, save for inserting a shim under the spring.  Have to think about that.


Finished the machining of the tool holder.  First use of my slitting saw!  Boy that was a big scary setting up for the first time.  Got things lined up, was ready to go and heard this strange thumping.  What's that?  Oh!  It's the saw spindle nut whacking the vise. Some quick thinking, and figured out a solution.  Kind of weird doing this, but this angle vise isn't that great anyways...  Machined off 0.125" off the back of the angle vise, using a roughing mill.  Gave the clearance needed without compromising the vise much. Why is such a huge long nut on the saw arbor necessary?  The thing feels like it is half a mile long.


Finally was able to make the cut with the saw.  Apparently I was too lazy to flick off that little chip before taking the picture.  Whoops!


Fits much better now.  Holes are drilled and tapped for 6mm.  Still need to cut down the set screws.  Have 16mm long set screws, but 10mm long would allow the set screws to just be flush with the surface.


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## WobblyHand (Sep 21, 2020)

Larry$ said:


> My diamond hones are considerably larger.


Larger than 3" x 6.625"?  Where did you get them?  Gee, thought these were huge!


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## WobblyHand (Oct 1, 2020)

An update.  Even using the fixture rested against a clamped guide on the table resulted in a grind that was not good.  I removed the belt and ran a straight edge against the platen.  The steel platen is worn out.  So I am going to have to try to inset a glass platen into the cast steel platen.  In the past, (Before Mill) it wasn't conceivable to do this mod myself.  Now that I do have a mill, I have been pondering how I would do it.  I just received a 2"x8" piece of pyroceram.  Guess I have to take the belt grinder apart and have at it.

The L shaped platen is an odd shape, it's about 18" long, 3" wide (give or take, depending where you measure from), and about 7 inches deep.  Item #28 in the figure below.  Since I'd be milling out a pocket, (on the top face) I'd like to support it pretty well.  I was thinking of using 246 and 123 blocks to hold the platen on the mill table.  I don't have any 246 blocks at the moment, but that's fixable.


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## ttabbal (Oct 1, 2020)

It looks like the platen location in relation to the belt is adjustable. I would just glue the glass to the steel and move the platen back a little to compensate for the thickness. I used JB Weld to glue mine on, and it isn't going anywhere.


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## WobblyHand (Oct 1, 2020)

ttabbal said:


> It looks like the platen location in relation to the belt is adjustable. I would just glue the glass to the steel and move the platen back a little to compensate for the thickness. I used JB Weld to glue mine on, and it isn't going anywhere.


How do you deduce that?  Where's the adjustment?  The motor location and the drive pulley are fixed relative to the platen.  

Ah, yes, the top pulley can be adjusted a little away from the platen and also go up and down.  

When I have it all apart, I'll check to see if I can get away with a simple JB Weld job.  And a stop for the glass.  Otherwise I have to mill it.  Might mill it flat anyways, that is, if I can figure out where there is a true reference surface.  (Flat or perpendicular to what?)


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## pontiac428 (Oct 1, 2020)

Does anybody have a good source for pyroceram?


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## mikey (Oct 1, 2020)

pontiac428 said:


> Does anybody have a good source for pyroceram?



Here you go.


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## WobblyHand (Oct 1, 2020)

Evil bay.  $13.50 for a 2*8 piece.  That's including shipping.

Search for 2 X 8” High Temperature Pyroceram Robax Glass Knife Grinding Wood stove Ceramic


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## ttabbal (Oct 1, 2020)

It looked like it might be adjusted by loosening some screws like #59 in the image. Hard to be sure from the photo though. My homemade one has slots you can use to slide the platen. That part on mine is a steel angle, commercial setups may be different.


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## WobblyHand (Oct 1, 2020)

@ttabbal Nice grinder.  I need to make one.  Maybe this winter...  First, will try to patch what I have.

#59 is the screw to hold the table to the platen.  The drive wheel #53 is fixed relative to the bottom of the platen.  Tomorrow will look at all the pieces and figure out some sort of idea.  No clue right now.


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## WobblyHand (Oct 2, 2020)

Well, uncovered a couple of things.  There's not much of a curve to these rollers.  Both are not flat, but the curve is very minimal, say 0.5mm.  And apparently this set up wasn't adjusted to track well, as the belt sort of sat against the "L" and slowly ground it away.  The belt ground through some sheet metal, and a some of the "L" behind it.






You can see the cut in the casting.  It actually cut two screw heads as well as making a semi circle cut.  

Here's the platen wear.  It's uneven and varies between 5-20 thousandths.


Unfortunately, I think I have to mill this flat(ter).  With the 7/32" platen, the belt won't be in a good place.  When I put everything in place, along with the belt guard and the drive wheel, the geometry didn't look good.  I am going to try to take off about 0.100" off the surface.  That way the platen will only stick up 0.118" rather than 0.218.  Probably make a pocket for the glass, with little cutouts for the corners.  The pocket will act as a stop for the glass, should it come loose.

Since nothing on this piece is really flat, or for that matter smooth, I'm not going to bother getting 246 blocks.  Have two 2x3x6 blocks of 6061 that can be used as spacers instead.  The blocks were fly cut together to 'match' them and make them smooth and flat.  I'll use the blocks to hold up the "L".  Somehow I'll clamp the whole mess down and reference it to the table.

Here are the roller wheels.  


The top wheel has a rocking adjustment, to sort of track the belt.  It also has a spring to maintain tension on the belt.  The bottom drive wheel is 5" OD with a 16 mm keyed shaft.  The top wheel has a bearing, but I haven't looked at it yet.  Have to say, grinding dust is terribly messy, and just gets everywhere.


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## WobblyHand (Oct 3, 2020)

Had to make a Frankenstein set up but it's almost done.  Used a combination of aluminum blocks, 123 blocks and normal tie downs.  Used my longest studs for this.  Lining it all up was pretty hard.  At one time, nearly everything fell over.  Was not happy about retrieving a 123 block up off the dusty concrete floor.  Eventually stuff was nearly level and in sort of tram.  Here is the set up.



Used a little Sherline fly cutter to hog out most of the pocket.  It took a while, mostly since I was afraid to load the machine and hold downs by taking too deep of a cut.  After a few passes I had:


Then I took a 1/4" Niagara carbide tool to chase out the corners and slightly increase the size.  It turns out the pyroceram was a little oversize at 2.05", not 2.00.  That's why we test fit.  Here is the pyroceram, now fitting in the slot.  The slot is 0.100 deep, or about 1/2 the total thickness of the glass.  I made the slot a little oversize in case the thermal expansion of the table or glass is a problem.



Last photo is the lower part of the pocket.  I stopped for a little bit to post, and to figure out how I was to machine out the corners.  Had to clean up, just so I could draw a couple of sketches to convince myself where to make the clearance pockets.  I figured the work has turned out pretty nice so far, so I'd stop and check what my next step would be - before I ruin the whole piece.  It was slightly different than what I thought, so it was good to stop for that sanity check.  

While it's still up on the table, will cut a relief on the other (left) side, so it's possible to grind left hand tools.  At the moment, it's not possible to grind left hand HSS tools on this grinder, especially the top relief.  This belt grinder most definitely was not designed to grind lathe tooling.  Hopefully these modifications will make lathe tool grinding a little better.


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## ttabbal (Oct 4, 2020)

Nice job! I think that will work nicely for you. I think it will help if you can get clearance for the top rake in there. That can be tricky if you don't have good clearance.


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## WobblyHand (Oct 4, 2020)

@ttabbal Thanks!

Put in the mouse ears to better register the glass in the bottom.  (Round holes at the corners.) Then milled a notch for left hand tool grinding.  Whether all this work will result in better lathe tool grinding, that we will find out after it's all together.  I'm really pleased with having a mill. It made this kind of repair/modification possible.  And it was an interesting puzzle to solve.


The right side notch was ground out using caveman methods, before I had a mill, you can see it is slightly undercut under the glass.  (Using a 7 inch hand grinder in situ.  That grinder was really heavy and gyroscopic.  Amazed that it came out as well as it did as both the grinder and I really were out of control.  )  

The left hand side was done with a mill.  In this picture it looks kind of crude, but it's reasonably machined.  (The phone has problems focusing at much less than 6 inches.)  I can get nearly a 45 degree grind angle if needed from the face.  That's more than enough.


The extended pocket really was a blunder, but hey, that happens.  One can think of it as a feature, so the angle to apply leverage on the glass is a little less, should it have to be removed.  Going to JB Weld it.  Plan to clean everything up with acetone and maybe scuff the machined surface for a little better adhesion.  (Kind of seems heretical to scuff it up after machining it flat!)  Then a thin layer of epoxy in the cavity and place the glass.  I've heard people use duct tape to hold the glass in place rather than clamping.  Guess it reduces pressure points on the glass which reduces the stress on it.  Will try the duct tape although I'd like something better. 

Unless I can think of something in the next few minutes, I'm going to break down the set up.  It was a first for me, never milled anything that didn't fit in a vise before.  Learned a lot and will be able to do similar set ups better and faster the next time.


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## ttabbal (Oct 4, 2020)

That looks good to me. I think it will be a good setup for you. Having a mill and a lathe open all sorts of options. Being able to do odd setups on them opens still more.

I think the machined surface will have enough bite for jb weld. Particularly when you have that ridge for downward force on the glass to push on. 

I used masking tape to hold it together for the epoxy to cure. It doesn't take much. You just want it to stay put, the amount of pressure isn't a big deal.


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## WobblyHand (Oct 5, 2020)

Epoxied the pyroceram to the platen.  Waiting for it to cure.  Tomorrow morning should be 24 hours.


Totally messed up the welding on the sheet metal guard for the bottom wheel.  Not going to show the picture.  Too embarrassing.  Sort of a combination of bird poop and blow through.  Never attempted to do something this thin.  Kind of disappointed, but guess I shouldn't be surprised.  (Yeah, should have practiced on something first!)  Maybe it can be saved, but it sure is rough now.


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## pontiac428 (Oct 5, 2020)

Got my piece of Pyroceram today!  Looking forward to modifying my belt sander.  Guess I should get some fresher belts, too...


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## Shiseiji (Dec 3, 2020)

There are advantages and disadvantages to any jig, and cost is always a legitimate constant in the |Good|Quick|Cheap| balance. The advantage of the South Bend style jig is that the angles are adjustable. Disadvantages are cost and the size of the jig requires a fair amount of overhang. Here is a link to the South Bend reproduction by the Alisam Company.


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## mikey (Dec 3, 2020)

Shiseiji said:


> There are advantages and disadvantages to any jig, and cost is always a legitimate constant in the |Good|Quick|Cheap| balance. The advantage of the South Bend style jig is that the angles are adjustable. Disadvantages are cost and the size of the jig requires a fair amount of overhang. Here is a link to the South Bend reproduction by the Alisam Company.



Do you own this jig? If so, how do you like it?


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## Shiseiji (Dec 4, 2020)

mikey said:


> Do you own this jig? If so, how do you like it?


I do, and like the results. My grinder rest is a piece of crap I haven't yet replaced, so I tend to blame small errors on it and my inexperienced hand rather than the jig. The graduations are large, but all in all I don't regret the purchase.  I have, uh, kissed the wheel a couple of times hence the caution on needing the tool over hang. 
As I mentioned in another thread, I also use a tangential tool holder for a lot of my work, so the jig doesn't see constant use.  Also once ground, honing can minimize the need to regrind a tool.

For what's it worth, I tend to do my honing on the vice anvil as it's steady and provides plenty of clearance around the stone. 

I also use their bull's eye for tool centering and really like it. I've made a simple height gauge but find the tool quicker and eliminates any doubt I may have that I've managed to knock the gauge.


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## mikey (Dec 4, 2020)

I remember searching for an original SB jig over 30 years ago and could not find one in nice condition so I learned to grind tools without it. Glad I did but I always thought that design was pretty cool.


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## Shiseiji (Dec 4, 2020)

mikey said:


> I remember searching for an original SB jig over 30 years ago and could not find one in nice condition so I learned to grind tools without it. Glad I did but I always thought that design was pretty cool.


I think I looked around after spotting this and decided on the purchase for the same reason.


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