# Vise Jaw lift, is there an adjustment on PM vises?



## WobblyHand (Apr 9, 2021)

My middling vise, SKU: VISE-4in-HIGHPREC seems to have more jaw lift than I'd like.  Is there any adjustment that could be made to reduce the lift?  When I purchased my PM25 last year, PM's best vise was either out of stock, or back ordered.

I do have a 3" toolmaker's vise, which I like a lot.  The lift is significantly less than the vise above.  But it's more limited in things I can clamp.  Is there anything that came be done to "fix" the 4 inch vise?  Or should I just use it as a general purpose vise in the garage, and get a better one?


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## Lo-Fi (Apr 9, 2021)

Looks like it's just another Kurt clone that get branded all sorts. It should be like this inside:






So a quick machining job should sort your issues, all other things being equal.


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## ErichKeane (Apr 9, 2021)

So that looks a lot like the junker-ebay vise that I got (and cleaned up for my shaper, see my history for the project), I'm guessing their definition of 'high precision' is different than mine  

That is a ang-loc style vise (like the Kurts, which uses a 1/2 ball on a 45 degree angle inside the jaw to prevent jaw lift (though, it is often still POSSIBLE, but the action of clamping should force it downward).

There are two different things you can do to help out here:

Remove the jaw, there is a single set-screw in the back-center of the vise.  If you loosen it, the jaw itself should lift forward and straight up. The first way to help with jaw lift is to adjust that set-screw.  It should be tight enough to allow the jaw to not pull off, but not so tight as to prevent the jaw from moving up/down.

The second is straight polishing   There are a few surfaces you want to make sure are smooth and greased. 
1- The spot that the set-screw hits on the back of the nut.  If the set screw catches there, it can do some odd things.  This is often a raw-casting on the cheaper vises.

2- If you reach up inside the jaw (or it just fell out), you can find  the 1/2 sphere.  On Kurts, this is a precision ground part.  On the cheaper vises, this is a raw casting.  You want this to be as smooth as possible.  Also, you want the side inside the jaw (the 1/2 circle) to be smooth and without burrs, but that is harder to get to.  In my case, I was able to hit it with a carbide burr and get it more or less smooth, then covered it in grease.

3- Make sure the part of the nut that interfaces with the ball is smooth.  You want the act of tightening the vise to force this 45 degree 'wedge' 'up' so that it pulls the jaw down.  On mine, this was a super rough casting, and didn't slide on the 1/2 sphere at all.


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## WobblyHand (Apr 9, 2021)

@ErichKeane, I didn't fully follow your description, since I haven't opened it up yet.  But now I have an idea what to look for.  

@Lo-Fi, wow, quite a loquacious fellow!  It was only after he started putting things back together, that I started to understand what he was doing.

Thanks for the ideas.


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## WobblyHand (Apr 9, 2021)

Ok.  Took it apart.  First thing I found out was the set screw wasn't tight!  It was very loose.  While adjusting it, I managed to jam it too tight, oops. Screw wouldn't move, Main lead screw was now too tight!  Electrician's screw driver with hardened tip didn't fit right.  Ended up machining a Chapman screwdriver bit down in diameter just enough for the bit to fit.  (Hollow ground tip.)  Then with the little Chapman ratchet, I was able to remove the screw.  The set screw had fractured at the top edge of the slot - I was lucky to get it out.  It is an 8 x 1.25mm screw 35mm long made from low grade steel.  I'll replace it with a decent set screw.  While literally screwing around with it a bit I measured the lift, hmm, it's a little better when it's not loose!

Yes, it can use some polishing alright.  The surface the set screw hits, the bottom of the set screw, the ramp and the mate to the ramp are all pretty rough.  I will have to get some pictures.  There is no ball.  There is some sort of weird piece of flat metal pushed into a hole?  That metal isn't flat, and appears to have raised lettering on it!  I wasn't expecting a lot but this is disappointing.  

The good thing is 1) I have another vise to fix this one, 2) @Low-Fi has posted the video above so I have an idea how to fix it and 3) maybe I can make this one a little better.  Can't be a lot worse than it is now...

Some pictures a little later...


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## ErichKeane (Apr 9, 2021)

WobblyHand said:


> Ok.  Took it apart.  First thing I found out was the set screw wasn't tight!  It was very loose.  While adjusting it, I managed to jam it too tight, oops. Screw wouldn't move, Main lead screw was now too tight!  Electrician's screw driver with hardened tip didn't fit right.  Ended up machining a Chapman screwdriver bit down in diameter just enough for the bit to fit.  (Hollow ground tip.)  Then with the little Chapman ratchet, I was able to remove the screw.  The set screw had fractured at the top edge of the slot - I was lucky to get it out.  It is an 8 x 1.25mm screw 35mm long made from low grade steel.  I'll replace it with a decent set screw.  While literally screwing around with it a bit I measured the lift, hmm, it's a little better when it's not loose!
> 
> Yes, it can use some polishing alright.  The surface the set screw hits, the bottom of the set screw, the ramp and the mate to the ramp are all pretty rough.  I will have to get some pictures.  There is no ball.  There is some sort of weird piece of flat metal pushed into a hole?  That metal isn't flat, and appears to have raised lettering on it!  I wasn't expecting a lot but this is disappointing.
> 
> ...


I look forward to the pictures... The joint between the 45 angle on the nut and the inside of the jaw is supposed to have a half sphere, if it doesnt, I wonder if that is the problem!


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## ErichKeane (Apr 9, 2021)

Actually... I guess it isn't necessary that there be a half ball, if the two surfaces could slide, it would probably be ok.  That said, on mine I also found that there was a part of the casting on top of the nut that kept it from staying down all the way, which caused some lift. I managed to machine a bit off the top to help. That said, I had machines/ground the bed, so I blamed that.


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## WobblyHand (Apr 9, 2021)

Well maybe it is a half sphere?  Which side touches the ramp?  The flat?
Some pictures...  The new collet I used to machine the hexagonal bits.  The set screw which fractured at the tip.








You can see the X on the surface of the half sphere?  Reject?  Why would someone do that?  Can I just take it out and polish it on a diamond stone?  I took the last picture through the set screw hole...


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## ErichKeane (Apr 9, 2021)

Yep, that is the 1/2 sphere!  No idea why someone would put an X on it, but you can polish it up on whatever you have handy, and grease it up so it slides nicely.  You also want it to pivot smoothly, so polishing the other side is a good idea as well.  The ball is just kept in there by grease, so it'll pop out easy.  The 'flat' touches the 45 spot on the nut, the other side is round so it 'pivots' inside the jaw a little.

You can also polish the inside of the nut (picture 4!) to make it slide easier.  It looks like someone started on that, but forgot to finish! If that ball gets caught on that machined bits, it'll cause jaw-lift.


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## WobblyHand (Apr 9, 2021)

Picture of some of the Chapman screwdriver bits.  Top one is unaltered.  Middle one I did today to take out the set screw.  Reduced the diameter to 7mm to fit inside the 8mm screw hole.  Bottom one is a JIS#1 bit I did.  It fits the screws in my laptop perfectly!  Replacement bits are all under $3.


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## WobblyHand (Apr 9, 2021)

@ErichKeane thanks so much!  Think I'm going to see if I can set up my mill to do the inside of the nut.  It looks pretty rough there.  Seems I have acquired yet another project!


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## T Bredehoft (Apr 9, 2021)

Thanks to this thread, I've begun to "fix" my el cheapo PM 4" vise. It has several problems, lack of sphere only one. The hole through the frame for the screw is not exactly on center, When you pull the jaw back it binds, also, the other end of the hole is apt (has) to get chips in it (packed so tight the screw won't go through.)
I'm going to
1) sleeve the hole for the shaft, after I center it and 
2) fabricate some PVC  tubes to cover the screw to keep chips off. 

I've been looking for a project, think I've found one.


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## WobblyHand (Apr 10, 2021)

Had some time to look at this.  If I understand correctly, the fixed jaw has to come off to allow the nut to slide out.  Once the nut comes off, then, if desired, the screw can be removed.  I moved the screw some and found there was a bearing unit in the housing.

How does the fixed jaw come off?  I've tried tapping it with a small machinist hammer (brass faced) but it isn't moving at all.  Is it just a tight fit on the rectangular key?  No hidden fasteners?  Just a much bigger hammer?


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## ErichKeane (Apr 10, 2021)

WobblyHand said:


> Had some time to look at this.  If I understand correctly, the fixed jaw has to come off to allow the nut to slide out.  Once the nut comes off, then, if desired, the screw can be removed.  I moved the screw some and found there was a bearing unit in the housing.
> 
> How does the fixed jaw come off?  I've tried tapping it with a small machinist hammer (brass faced) but it isn't moving at all.  Is it just a tight fit on the rectangular key?  No hidden fasteners?  Just a much bigger hammer?


There should be a pair of socket head cap screws from the bottom holding it down.


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## WobblyHand (Apr 10, 2021)

Oh, I feel so embarrassed. Of course!  

Ok, it's all apart.  My half sphere isn't smooth on the sphere, or the flat.  For that matter, the cavity is pretty rough as well.  I was imagining it would be something a lot nicer.  The cavity is not machined, it is rough cast.  

No idea how one would polish the spherical part.  Glue it to the end of a rod?  It has turning ridges.  It isn't smooth.  Seems to be, surprisingly, 0.500" in diameter.  After a little surface cleanup and some honing one can still see the big scratches in the flat surface.  Looks like a crack that will continue to grow.





Is it possible to cut a ball bearing in half?  How would one hold it?  

The nut isn't that bad, considering.  Part of it is unfinished.  I will need to fit it together to see if that part actually needs finishing.  Maybe it never hits there.


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## ErichKeane (Apr 10, 2021)

For the ball, it doesn't seem all that bad.  Definitely better than my ebay one was.  You likely would want to grind a ball bearing in half on a sander, and I'd hold it by drilling a hole in the end of stock and hot-gluing it in while you grind. 

What I did on mine that was pretty bad was take an abrasive paste (auto part stores have it I think for prepping for paint), and just moving the hemisphere in there until it felt smooth.  Then, I cleaned both and tossed a ton of moly grease in there.

I got most of my lift problems fixed by messing with the nut and making sure the front is smooth, the top doesn't hit the underside of the jaw, and that the angle was about a 45, on mine it was not quite right, so it was putting more force 'forward' than down.  If anything, you might want the opposite.  Also, the 'tip' of the 45 on the nut should never hit the inside of the jaw either, so you may wish to blunt that too.


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## WobblyHand (Apr 10, 2021)

I will get some ball bearings.  Might use one ball and some valve grinding compound and rotate it about to make the pocket a little smoother.  Somehow or another, I'll grind a ball in half.  Thought I would use some steel tubing that is just under 0.500 ID.  That way the ball would nestle in the tube.  If I have to, I could either glue it or solder it to the tube.

My 3" toolmakers vise doesn't hold the nut very well.  (And that's the only operative vise I have.)  I need to mill some additional flats on the nut so I can clean up (mill) the 45 degree ramp.  I think if I hold up the nut on some 123 blocks I can get the flats in.  

Three weeks ago, I never would have imagined I'd be rebuilding my vise.  Interesting hobby, never know where it will take me...


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## Larry$ (Apr 10, 2021)

WobblyHand said:


> Is it possible to cut a ball bearing in half? How would one hold it?


Given how hard ball bearings are, I think you may need to grind it. 
Use a close match ball mill on the end of a ?brass? rod. Make the pocket a little deep so you can crimp it around the ball after you glue the ball in with epoxy or permanent Loctite. Dress your abrasive wheel so it is sharp. Since heat can release the glue you will need to keep dunking it in water. Use the side of the wheel to make a flat. Yes, & no you shouldn't use the side but light pressure and just enough grinding to clean it up should work. Duck if it disintegrates!


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## mikey (Apr 11, 2021)

A belt sander makes short work grinding ball bearings if you can find a good way to hold it. I wonder if a neodynium magnet buried in a tube would work?

I hope you can grind or lap the pocket for the ball well enough to house the ball without too much slop.


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## Lo-Fi (Apr 11, 2021)

I'd probably clamp the BB in the edge of a vise and run a slitting disc through gently. It doesn't need cutting right through the centreline. If you can find a carbide burr or spherical stone the right size you should be able to get the dimple sorted well enough without much fuss too.


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## WobblyHand (Apr 11, 2021)

After 2 seconds of observation, I realized I could use the toolmakers vise to hold the nut upside down.  I then milled flats on the top side so I could hold the nut at 90 degrees.  I ran a mill just kissing  the flat at the end to smooth that end.  Just shaved off 0.001" enough to take off the tool marks. Prior to that I checked that the "flat" was perpendicular to the table.  Surprisingly it was pretty good.

Roughly measured the ramp angle, it is very close to 45 degrees, but it is not square to the vertical axis.  There's about a 0.04 gap at the top relative to the bottom, as measured with a square referenced to the fixed jaw top.  I'd bet in practice this doesn't matter, as the ball takes up the error, but it's annoying.

Next step is to tram the toolmakers vise to 45 degrees so I can take a cut on the ramp to clean it up.  I have a 45 degree angle block so that won't be too hard.  The milling cutters I have aren't long enough to cut the ramp in one pass.  I need almost 1.5" LOC to do it in a single pass.

A bit apprehensive about lapping the pocket.  It will be tedious at best.  Maybe a single cut spherical burr would be better and faster.  As I understand it a single cut is slower and more precise.


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## ErichKeane (Apr 11, 2021)

WobblyHand said:


> After 2 seconds of observation, I realized I could use the toolmakers vise to hold the nut upside down.  I then milled flats on the top side so I could hold the nut at 90 degrees.  I ran a mill just kissing  the flat at the end to smooth that end.  Just shaved off 0.001" enough to take off the tool marks. Prior to that I checked that the "flat" was perpendicular to the table.  Surprisingly it was pretty good.
> 
> Roughly measured the ramp angle, it is very close to 45 degrees, but it is not square to the vertical axis.  There's about a 0.04 gap at the top relative to the bottom, as measured with a square referenced to the fixed jaw top.  I'd bet in practice this doesn't matter, as the ball takes up the error, but it's annoying.
> 
> ...


so, I was thinking about the lapping...  If you are going to get a steel ball to cut in half, buy 2.  Attach the 2nd to a bar in some way (welding?  Soldering? etc?), put some abrasive compound on it, and fire up your drill and use that instead.  A burr might take too much material and not leave it smooth enough.  You don't care if it is perfectly flat, just that the ball can tip side to side/up/down with a minimum amount of force.  You also don't want to take too much material off, because if the half-ball sits too deep in it, your nut will hit the jaw instead of staying in the ball.


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## WobblyHand (Apr 11, 2021)

Oh, I had to buy a bunch of ball bearings...  Didn't have much of a choice, and shipping was practically the same anyways.  So I'll have 50 to play with.    So when some of the balls go flying off when grinding, I won't have to search for them with the same sense of urgency if I only had one.   Power lapping (with additional random motion) is a possibility if I can somehow attach a rod to the bearing.  The vise is trammed to 45 degrees, which wasn't that hard.  I'm less than 0.001 off over a few inches of travel.  That's way better than how the ramp was machined.  

This beginner doesn't have the full complement of tooling to attack the problem at hand.  So I'll wait for stuff to dribble in.  It will take less than a week.  There's no shortage of other projects here to keep me occupied.  Have to say this project has been fascinating for me.  I did order a single cut burr, which is for slow removal and better surface finish.  I'll just kiss it to the surface by hand and see what it looks like.  Can't be a lot worse than what is there now.  (It looks more like a dimple than a spherical surface)


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## WobblyHand (Apr 13, 2021)

Have the ball bearings, the burr, and some steel tubing.  As well as an end mill with 1.5" LOC.  Cut off a piece of tubing and lightly bored it out so the ball diameter just fits below the surface.  Was getting a little late, so didn't press my luck with grinding the ball.  Have to change out the belt to ceramic anyways.  Tomorrow should be an interesting day.  Probably take a couple of tries to get sufficient grip on the ball.


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## WobblyHand (Apr 14, 2021)

So far the ball grinding is going surprisingly well.  Must be beginner's luck!  Right now the ball measures 0.330" from the truncation flat to the spherical part.  How close to 0.250" do I need to be?  The original (which I did polish) is very close to 0.251" but I'm not sure I trust that dimension - after all, the vise isn't a showcase...  I've dykemed the tube to make a mark on it so I have some reference mark.  Not sure if I should remove 0.060, 0.070 or 0.080.

It's pretty easy to grind as I have the ball inset in a tube.  The tube makes a great handle.  No adhesive, no solder, just a light press fit.  I use a punch to remove the ball from the tube.  I just apply light pressure to the tube against a ceramic belt with a pyroceram platen.  With the ceramic belt there's no heat issues, it cuts very nicely.  Initially started grinding with a 60 grit belt and later switched to a 80 grit belt.  I'll clean up the grinding marks later with diamond stones.  I found if I slowly rotate the tube, it seems to clean up the grinding marks a little.  Unfortunately for the picture below, I reverted to straight "push it in" mode as I needed to remove more material.


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## ErichKeane (Apr 14, 2021)

I don't think it being a half-ball is particularly important, just that it sits proud of the cutout in the jaw when in place, and has a smooth flat for the nut's 45 to run on.


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## WobblyHand (Apr 14, 2021)

Great.  I just checked the ball in the "dent", it's definitely proud to be there   It moves in the socket pretty nicely, even without grease.  Already an improvement.  Not grinding off too much gives me a little more latitude in cleaning up the pocket to make it smoother.  The smooth face is already 0.470" in diameter, so the area is only 13% less, than if it was ground to half diameter.  Guess I will hone the flat and move on to cleaning up the ramp. 

Not really sure if the nut is square in the vise.  I am using the "square" cut as the reference side and have placed it against the fixed jaw.  On the movable jaw I have a piece of aluminum TIG rod to be a little squishy.  Dead blow hammer set the nut into the vise.  It seems the square cut may not truly be square.  Have any suggestions?  (Picture was taken before adding the wire.)


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## ErichKeane (Apr 14, 2021)

Thats almost exactly how I held mine, I used the vertical 'rail' as my indexing surface for that, which is the only one that matters.  If the angle is less/greater than 45, it doesn't particularly matter.  45 is the 'magic' number because it produces an equal amount of force down and closed, but if you were 'smaller' than that (in reference to the top surface) you'd get less clamping force, but more 'down' force (and vice-versa).

So in your case, the only meaningful 'index' is that you're square to the vise 'horizontally', that is, parallel to the table.  The rails aren't perfect for indexing, but are as close as you have (as you REALLY care about parallel to the lead screw).


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## macardoso (Apr 14, 2021)

Looking good. The ball on my shars vise was much more polished than yours, but the socket was in poor shape. I figure the ball is there to account for variations in both surfaces, so I'm not sure how critical it is to have the surfaces exactly at 45 degrees.






Compared to the accuracy issues in the grind of the vise and the fit of the jaw to the body of the vise, I doubt the ball on mine has any impact on accuracy. Scraping resolved my fit issues.


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## ErichKeane (Apr 14, 2021)

macardoso said:


> Looking good. The ball on my shars vise was much more polished than yours, but the socket was in poor shape. I figure the ball is there to account for variations in both surfaces, so I'm not sure how critical it is to have the surfaces exactly at 45 degrees.
> 
> View attachment 362638
> 
> ...



Right, the ball is simply so that the 'interface' between the jaw and the nut is flexible.  The angle just controls the 'vector' of the force applied by the nut.  The inside of the jaw is simply clearance so there is enough wiggle room between the two to not bind.


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## WobblyHand (Apr 14, 2021)

Oh, foo, minor disaster.  I was taking off 0.005" at a time, everything went well until the mill hit a hard spot or something.  I had taken off 0.035", 0.005" at a time, without a problem.  The surface was ok.  When the mill hit the hard spot, it dove in and pulled the piece up from the vise about 0.100".  Exciting in a bad way. There's plenty of meat left to take out the somewhat cylindrical divot, but it is disappointing nonetheless.  Coming in that way should not be climb milling right?  Normal rotation, workpiece to the left and cutting from back to front?  I wasn't even near the end, where I would slow the feed rate.  My feed rate was really slow, by the way, like about 0.5" per minute.  I really was taking it easy.  Once I slow my heart down, I'll go at it again.  



Ball came out nice, first pass.  I have 49 extra of them, but only 1 nut, so I have to rescue the nut.  

Obviously did something wrong, what was it?  Not eager to make the same mistake.  Milling 0.005" but with 1.5" LOC?


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## ErichKeane (Apr 14, 2021)

Based on the previous image, you need to cut from the 'inside' out to not be climb milling.  That is too bad, but it seems you have enough material to make it happen.  _IF_ it gets too bad, you can always loctitle/glue on a shim of some sort to space it out, so as long as you don't go TOO far you're ok.


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## WobblyHand (Apr 14, 2021)

The way it grabbed would seem to be climb milling, but the picture I have, would indicate it wasn't.  I'm confused...  
The mill was talking to me - it was kind of squeaking at times, even though I had put cutting oil on the mill and the workpiece.


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## ErichKeane (Apr 14, 2021)

That diagram is awkwardly configured, at least to me.  The arrow is the direction of the workpiece in relation to the mill.  So you would have to start your cut from the 'bottom' in that picture (near the operator) and pull the material/table toward you to get a standard cut.


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## WobblyHand (Apr 14, 2021)

I should say so.  I apparently have been doing it wrong from the beginning, due to that drawing.  This is the first time, I've been burned, which, if I think about it, is pretty amazing.

I found a better picture on Harvey Tools that describes normal and climb milling. 
Normal:
	

		
			
		

		
	






Climb:




I still find these pictures confusing, since my mill rotates CW, not CCW.  Why draw it as a mirror image?  

But I have now learned I have done everything backwards   I need to make my own picture, that even I can follow.  

Climb is fat to skinny.  Standard is skinny to fat...  *That was a tough lesson*.  Ok, back to work...


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## jwmelvin (Apr 14, 2021)

I like to think of whether the cutter is pulling itself into the uncut region (climb) or pushing back from the uncut region (conventional). Then think about a full-width slot and it’s neither.


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## ErichKeane (Apr 14, 2021)

Yeah, that harvey pictures is odd, I don't know why they would do a 'bottom' view!

I always considered it like the flutes were 'swimmers' arms.  When they are trying to pull the material with them, like a swimmer, that is 'climb' milling. When they are trying to swim 'against' your feed,that is conventional milling.

So on a normal clockwise (from the top) spindle, clockwise around the material is 'climb', counter clockwise around the material is conventional.


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## Lo-Fi (Apr 14, 2021)

I always think of it as "am I traveling with the flute, or against it?". Which has been pretty foolproof.


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## WobblyHand (Apr 14, 2021)

Well, it's done.  More or less recovered from the climb gash.  Tiny divot on the edge, nowhere near the ball.  Tried setting up the movable vise jaw in my toolmaker's vise, but it wouldn't fit the way I wanted to hold it.  My toolmakers vise needed about 0.100 more travel.  Kind of gave up on that.  Tried some grit in the pocket to smooth things out but the throwaway ball bearing was too slick for me to rotate it all that much.  After a while, I just cleaned out the pocket about 4 times, then decided I was going to put the vise iall back together.  Greased the half sphere and the ramp surface.  The lift is slightly lower than before, but I was getting a little tired at that point and sloppy with the measurement.  I have to go back and look at my notes on my initial measurements, to see if there was any improvement.

The good thing - learned a (hard) lesson about climb milling.  I also have a working vise again.  Here's a picture of the mostly recovered nut.  


I'm going to say, I'm not going to knowingly set up milling that way again.  It was like working blind because my vision was obstructed.  I had to go by sound and feel - which is good, I guess, but I sure wasn't comfortable machining that way.


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