# Milling advice wanted - new to milling



## cederholm (Jan 30, 2015)

Hello everyone,

I'm new to milling and I'm trying to learn on my Maximat Compact lathe with vertical mill. One of my early projects is to remove .150 off of some Chinese made quick change tool holders for the lathe. I'm using a 1/2" four fluke endmill and I'm removing .050 in each pass. My problem is that I keep chipping of the cutting tips of the endmill.  The first dovetail pass goes pretty well (see Fig. 1 and note the arrow indicated the bed travel direction) the second dovetail pass is a little more choppy and by the time I've finished removing the whole .150 my tool is pretty chipped up. 

I'm feeding ad a very slow rate (because I'm scared) and I'm using oil. 

Any advice would be greatly appreciated. 
~ Carl

Fig. 1




Fig. 2




My machine


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## Jim2 (Jan 30, 2015)

A couple of comments.  It looks like you're climb milling.  That's probably not a good idea on a home-shop machine unless on a very light finishing pass.  See http://www.cnccookbook.com/CCCNCMillFeedsSpeedsClimbConventional.htm  to see difference between climb milling and conventional milling.

That setup looks pretty shaky.  It would be a good idea to support the work closer to the spindle by lowering the head, or using a riser block or such.  I've never used a 3 n 1 machine, so not sure how much flexibility you've got with that.  Then shorten up the distance between your spindle bearings and where you're cutting.  A smaller endmill probably wouldn't hurt either.  

Toolholders are probably made w/ a hardened steel, so not easy to cut in any case.

Jim


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## T Bredehoft (Jan 30, 2015)

Feed in the opposite direction.

You are climb milling, a big *NO-NO* for manual machinery.  the cutter pulls the work into itself, taking far larger bits of metal than it was designed for.  By feeding from the other end, you will be pushing against the rotation of the cutter, and there is no slack in the feedscrew. 

One drop of cutting fluid per pass is sufficient, don't flood the work, it just makes a mess. 

Climb milling gives a far better finish, and that is desirable, but almost no manual machines can do it well, and for a person in a learning situation, it is not a good choice, as you have found out.


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## herbet999 (Jan 30, 2015)

Agreed on the climb milling. Just reverse your spindle motor and see if that helps. Feed in the same direction.


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## cederholm (Jan 30, 2015)

Wow! Thanks for the advice all. Very helpful. 

~ Carl


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## herbet999 (Jan 30, 2015)

By the way.. love your carriage stop


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## cederholm (Jan 30, 2015)

Thanks Herbert,

Since I have nothing to compare it too, can you explain what you like about it? ...I really have a LOT to learn. 

~ Carl



herbet999 said:


> By the way.. love your carriage stop


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## herbet999 (Jan 30, 2015)

Sorry, I was being facetious. looks like it does the job and it's bare bones.


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## cederholm (Jan 30, 2015)

LOL!! Yes, that's my next project is to make a proper stop. 

~ Carl



herbet999 said:


> Sorry, I was being facetious. looks like it does the job and it's bare bones.
> 
> View attachment 93717


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## cederholm (Jan 30, 2015)

Jim, how would I best achieve this? Unless I'm missing something the majority of the space is due to my tool holder. Should I look into collets? 

Thanks you,
Carl



Jim2 said:


> That setup looks pretty shaky.  It would be a good idea to support the work closer to the spindle by lowering the head, or using a riser block or such.  I've never used a 3 n 1 machine, so not sure how much flexibility you've got with that.  Then shorten up the distance between your spindle bearings and where you're cutting.  A smaller endmill probably wouldn't hurt either.


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## Billh50 (Jan 30, 2015)

collets that fit the head will allow you to have a much more rigid setup. The further out your tool is the more it will have a tendency to start shaking and cause all kinds of problems. Collets allow the tool to stay close to the head.


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## cederholm (Jan 30, 2015)

Got it! Thank you!!!



Billh50 said:


> collets that fit the head will allow you to have a much more rigid setup. The further out your tool is the more it will have a tendency to start shaking and cause all kinds of problems. Collets allow the tool to stay close to the head.


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## Wreck™Wreck (Jan 30, 2015)

That is about 10X too much tool hanging out of the spindle, the tool block is likely fairly hard as well.

Also, climb milling with 1/2 or more of the tool diameter step over will not walk until the tool breaks through the end of the material. If you reverse the spindle bad things will happen, you wouldn't run a RH drill bit left handed would you?


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## T Bredehoft (Jan 30, 2015)

There are tool holders (hold the end mil lwith a set screw) that go in where your collet is, eliminating the vast majority of your tool length.


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## rgray (Jan 30, 2015)

I'll second that those holders are hardened and unfriendly to end mills. Looks like a job for a grinder. Might be less trouble to build you're own holders, and much more fun.


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## JimDawson (Jan 30, 2015)

herbet999 said:


> Agreed on the climb milling. Just reverse your spindle motor and see if that helps. Feed in the same direction.




Normally running the end mill in reverse will destroy it instantly.  Just feed from the other direction, against the rotation of the cutter (Conventional milling) as opposed to cutting in the same direction of rotation. (Climb Milling)


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## Wreck™Wreck (Jan 30, 2015)

JimDawson said:


> Normally running the end mill in reverse will destroy it instantly.  Just feed from the other direction, against the rotation of the cutter (Conventional milling) as opposed to cutting in the same direction of rotation. (Climb Milling)



Ran a 100+ part lathe job several months ago requiring 4 manual tool changes (QCTP), turn and face, plunge straight in with a 9/16 endmill because the job required a bore with a flat bottom, bore to finished diameter and depth and part off. The only sharp endmill that I could find in the shop was Left handed, this requires a spindle direction change from all of the other tools. I failed to change direction after 20 or so parts, it cracked all four corners off of the tool before I could blink. The material is 6061 aluminum.

Keep in mind that this is a CNC lathe so I ran the tool into the work very rapidly, and BOOM over.


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## janvanruth (Jan 30, 2015)

herbet999 said:


> Agreed on the climb milling. Just reverse your spindle motor and see if that helps. Feed in the same direction.



reverse spindle motor???????????????:nono:


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## cederholm (Jan 31, 2015)

T Bredehoft,

I am using one of those holders, am I not? I understand that my tool might be set to low but is it okay to use the holder shown?




T Bredehoft said:


> There are tool holders (hold the end mil lwith a set screw) that go in where your collet is, eliminating the vast majority of your tool length.


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## JimDawson (Jan 31, 2015)

cederholm said:


> T Bredehoft,
> 
> I am using one of those holders, am I not? I understand that my tool might be set to low but is it okay to use the holder shown?



There is a lot of tool/holder sticking out from the spindle, if you have a collet that will hold the endmill in the spindle then that would help the setup.  It's OK to use it that way, but it is less ridged than having a shorter setup.  You just have to compensate by taking lighter cuts.

It looks like the width of the cut is greater than 1/2 the diameter of the end mill, that can tend to pull the tool into the work.  This may be why the endmill is chipping.  I would make that cut in 2 passes on the width with a springy setup, maybe 1/4 the diameter of the endmill.


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## cederholm (Jan 31, 2015)

Thank you - that makes sense.
My spindle is 2mt. While digging through the tools left to me I found two Bridgeport (so labeled) 2mt collets. They seem to fit the machine and draw bar, but they won't bite down and hold the tool. Any thoughts?




JimDawson said:


> There is a lot of tool/holder sticking out from the spindle, if you have a collet that will hold the endmill in the spindle then that would help the setup.  It's OK to use it that way, but it is less ridged than having a shorter setup.  You just have to compensate by taking lighter cuts.
> 
> It looks like the width of the cut is greater than 1/2 the diameter of the end mill, that can tend to pull the tool into the work.  This may be why the endmill is chipping.  I would make that cut in 2 passes on the width with a springy setup, maybe 1/4 the diameter of the endmill.


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## Jim2 (Jan 31, 2015)

cederholm said:


> I am using one of those holders, am I not? I understand that my tool might be set to low but is it okay to use the holder shown?



I'm not sure what you've got there.  It may have it's uses, but I don't think it's a very good tool in this application.  I don't have anything similar myself.  I rely upon r8 collets primarily when milling, though I have added a couple of the end mill holders like





See how much shorter the stickout is here?  Maybe you're running a different taper (not r8)?  A smaller endmill would reduce chatter, and likely have less stickout. . . .  It may help by reducing sfpm also--something is wrong when you're losing the corners off the endmill that fast.

Jim


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## cederholm (Jan 31, 2015)

Thanks Jim, I'll do more research. You're photo is very helpful.

- Carl




Jim2 said:


> I'm not sure what you've got there.  It may have it's uses, but I don't think it's a very good tool in this application.  I don't have anything similar myself.  I rely upon r8 collets primarily when milling, though I have added a couple of the end mill holders like
> 
> 
> 
> ...


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## JimDawson (Jan 31, 2015)

cederholm said:


> Thank you - that makes sense.
> My spindle is 2mt. While digging through the tools left to me I found two Bridgeport (so labeled) 2mt collets. They seem to fit the machine and draw bar, but they won't bite down and hold the tool. Any thoughts?




The only thing I can think of is the collets are not the correct size for the shank of the end mill.  The fit should be a tight slip fit with the collet in your hand, if the shank of the endmill is loose in the bore of the collet, then the collet is the wrong size.  The other possibility is that the collet is not drawing up tight, try it without the end mill in it and see if it will draw up more.  You may have to shorten the collet a bit on the back end.


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## John Hasler (Jan 31, 2015)

cederholm said:


> T Bredehoft,
> 
> I am using one of those holders, am I not? I understand that my tool might be set to low but is it okay to use the holder shown?



I'm not very knowledgeable about mills but that looks like an extension holder for reaching down into deep holes where the spindle won't fit.  It appears to me to be at least four times as long as it needs to be to do your job.  When milling as when turning length is your enemy.

Also, could you change your setup to cut with the side of the tool?   I find that gives better results and doesn't use up the tool as fast.  Cutting with the end makes the tips do almost all the work.


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## cederholm (Jan 31, 2015)

That makes sense John. I'm not sure if I understand about cutting with the side. Are suggesting a deeper cut with less width? Of course cutting in the correct direction as noted above.

Btw - using the advice above I did finish my tool holders, now I'm taking notes to learn and inprove. I'm very gratefull to everyone for their insight and advice.



John Hasler said:


> I'm not very knowledgeable about mills but that looks like an extension holder for reaching down into deep holes where the spindle won't fit.  It appears to me to be at least four times as long as it needs to be to do your job.  When milling as when turning length is your enemy.
> 
> Also, could you change your setup to cut with the side of the tool?   I find that gives better results and doesn't use up the tool as fast.  Cutting with the end makes the tips do almost all the work.


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## John Hasler (Jan 31, 2015)

cederholm said:


> That makes sense John. I'm not sure if I understand about cutting with the side. Are suggesting a deeper cut with less width? Of course cutting in the correct direction as noted above.
> 
> Btw - using the advice above I did finish my tool holders, now I'm taking notes to learn and inprove. I'm very gratefull to everyone for their insight and advice.



I'm suggesting rotating the workpiece 90 degrees so that the dovetail is horizontal and cutting with the side of the mill instead of with the end.  You'd lock the quill and the knee and feed only with the table so that the flutes do the cutting.

Again, I'm not an expert at this.  My milling experience is with my own rather odd machine.


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## mikey (Jan 31, 2015)

I agree with all the above, especially the climb milling and the need to choke up on the end mill to reduce extension beyond the holder. It does look like that holder is a bit long for this job. I did not see any mention of cutting speed but in carbon steel cutting at the full diameter of the cutter your SFM will only be about 35. That gives you a speed of only about 280 rpm with a 1/2" dia. cutter. If you cannot get down this low then take the width in multiple passes at the lowest speed your machine can manage.


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## herbet999 (Jan 31, 2015)

janvanruth said:


> reverse spindle motor?



What was I thinking... I'll keep my mouth shut


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## barrydc1 (Feb 3, 2015)

A couple things that haven't been mentioned.  I stilll new at this too, and have learned a lot here and now by experience too.  If you are cutting a hardened steel.  You'll go through endmill pretty fast if they are HSS (high speed steel).  They don't chip as easily as Carbide endmills do, so I assume you are using carbide.  A formula to use to find the RPM to use is this.  Look up in a Feed/Speed Chart the Square Feet per Minute (SFM) chart the kind of steel you have and it's hardness (the hardness you may have to guess at if you don't know).  Do a little research if you know where you bought the QCTP holder. When you know that SFM value, multiply it by 4 and divide by the endmill (or other cutting tool/part on the lathe) diameter you are using.  This will give you a ball park RPM to start from.  When I was new at milling, I was afraid to hurt things, so I typically went way too slow or sometimes way too fast feeding the part, and often too shallow a cut. Also if you are using carbide, then double that SFM value before you multiply by 4 and divide by the diameter. Once you get this ball park RPM listen to the cut and make sure there is no chatter, or other "BAD" sounds.  This is part of experience, as there will be rattling and shaking of a sort. You will have to know what is okay for your machine.  The rigidity of the set-up is important, and less leverage is the idea, so no long stick-outs when you don't absolutely need it. I would watch a bunch of Tom Techniques videos and then go try things and that has helped me a great deal.  Good luck as you learn and have fun with this new and expensive addiction!


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## digiex_chris (Feb 3, 2015)

Just need a few more MT2 collets like these to fit the cutters you're using. They're pretty much one collet per cutter size. You'll be happier with that. The end of the collet will be pretty much flush with the end of your spindle and be much more rigid. Rigidity is something to always be striving for in machining. Might look like a big solid piece of metal you've got there, but it'll flex a surprising amount and cause more leverage to flex your machine. 


Two of the most important things to learn is keep the cutter as close to the spindle as possible, and keep the area of cut as close to the vise top as possible (while still being able to make successive cuts and finish the job without unclamping it). Though the work holding part of it tends to be more of a "oh crap, it moved and screwed up the cut/cutter" instead of a "it's not cutting well" kind of thing.

This should also help. Feeding slower is no big deal, but try to get in the ballpark for the rpm/sfpm caluclation. http://www.custompartnet.com/calculator/milling-speed-and-feed
Here's a chart of common materials to get the SFPM from to feed into that formula: http://www.vm68.com/stuff/sfpm.html

The fundamentals are feed, speed, and depth of cut. Feed, handcranks. Speed, spindle rpm. Depth of cut, depends on the rigidity of your setup and the strength of the cutter, and will take some experience with your machine and setup to determine. Nothing wrong with smaller DoC as you're learning too, it'll just take more passes to get the job done. It'll take some practice to get a good feel for it.

I agree, the tool holders are probably reasonably hard, and that makes the challenge go up a few levels. I'd start with maybe 35 SFPM, so if I was using a 1/2" endmill, it would go something like this:  (35 x 3.8) / .5 = 266 rpm for a high speed steel endmill. And then RPM figures into feed rate meaning the slower the cutter is turning, the slower you'll need to feed it. Making more tool holders from mild steel would be fantastic practice and a greater likelihood of first time success than trying to tackle an unknown steel in an unknown state.


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## caster (Feb 3, 2015)

cederholm, you have received good guidance; conventional milling, correct speed & feed and a stiffer shorter setup.  If you can here is another suggestion; anneal the part, make it softer, take your cuts then harden it again. Not everyone is able to do this but if you can it would be a great help.  Its difficult to mill hard metal, you need every advantage you can muster when doing this on a small machine.

For my curiosity why are you doing this?  Is the holder too high to center the cutter?

Caster


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## cederholm (Feb 3, 2015)

Fantastic advice everyone and I am taking it all to heart. 

Being the genius that I am, I posted this while halfway through my last tool holder and was only able to apply it to the final cuts. Things turned out well, but I did destroy two endmills in the process. I will be taking everything mentioned about into account as I improve my setup and make a few things to better my skills. On the short list is a carriage stop and some other small tools for the shop. Making other tool holders also sounds like a great project. 

Caster, yes, that's the reason exactly. By removing .150 from the bottom corner I now have the adjustment I need and using my lathe has just become more enjoyable. 

~ Carl




caster said:


> cederholm, you have received good guidance; conventional milling, correct speed & feed and a stiffer shorter setup.  If you can here is another suggestion; anneal the part, make it softer, take your cuts then harden it again. Not everyone is able to do this but if you can it would be a great help.  Its difficult to mill hard metal, you need every advantage you can muster when doing this on a small machine.
> 
> For my curiosity why are you doing this?  Is the holder too high to center the cutter?
> 
> Caster


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## caster (Feb 3, 2015)

I just finished making QCTP Holders and documenting the process.  Follow the link it might help.

http://www.hobby-machinist.com/showthread.php/31648-QCTP-Tool-Holders

Caster


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## cederholm (Feb 3, 2015)

Yes, I've seen your post. Very inspiring and beautifully crafted.

~ Carl



caster said:


> I just finished making QCTP Holders and documenting the process.  Follow the link it might help.
> 
> http://www.hobby-machinist.com/showthread.php/31648-QCTP-Tool-Holders
> 
> Caster


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## mr bill (Feb 5, 2015)

I didn't notice anyone mention to lock the "Y" axis while milling in the "X" axis direction and visa versus. This will help tighten up your set up and keep the table from creeping off location. Of course, locking the spindle too.


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## digiex_chris (Feb 5, 2015)

mr bill said:


> I didn't notice anyone mention to lock the "Y" axis while milling in the "X" axis direction and visa versus. This will help tighten up your set up and keep the table from creeping off location. Of course, locking the spindle too.


Oh yeah, big time! I just broke my favorite endmill by forgetting that. Lock all axes that you're not moving.


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## dracozny (Feb 5, 2015)

I often adjust depth of cut and then lock that axis. Doing things manually I try to have only one axis moving and the others locked down tight. without locking them down they tend to drift and create some nasty chatter. Good way to destroy Carbide!


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## Andre (Feb 5, 2015)

T Bredehoft said:


> Feed in the opposite direction.
> 
> You are climb milling, a big *NO-NO* for manual machinery.  the cutter pulls the work into itself, taking far larger bits of metal than it was designed for.  By feeding from the other end, you will be pushing against the rotation of the cutter, and there is no slack in the feedscrew.



Not to contradict you; I'm certainly not an expert and you have your opinion, I can't argue with that. 

If you tighten your gibs or engage the table lock a little (adding a little drag to the table) you can sometimes climb mill on a manual mill. It might not be a good idea to do it on a combo machine or small mills, but is possible on manual machinery that is stout enough. (Larger benchtop and up) but if you only have a small mill save your climb milling for the last finishing pass, only removing a few thou.


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## cederholm (Feb 6, 2015)

Thanks Mr. Bill, I learned that lesson fast on my own. 

~ Carl



mr bill said:


> I didn't notice anyone mention to lock the "Y" axis while milling in the "X" axis direction and visa versus. This will help tighten up your set up and keep the table from creeping off location. Of course, locking the spindle too.


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## cederholm (Feb 6, 2015)

For those loosing sleep over my progress, rest easy.  

I finished the tool holders and applied all your advice to some new projects which are moving along pretty well. This has been a great learning experience and I'm feeling more comfortable with my mill. 

Thanks all!
~ Carl


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## robertw78368 (Feb 16, 2015)

JimDawson said:


> There is a lot of tool/holder sticking out from the spindle, if you have a collet that will hold the endmill in the spindle then that would help the setup.  It's OK to use it that way, but it is less ridged than having a shorter setup.  You just have to compensate by taking lighter cuts.
> 
> It looks like the width of the cut is greater than 1/2 the diameter of the end mill, that can tend to pull the tool into the work.  This may be why the endmill is chipping.  I would make that cut in 2 passes on the width with a springy setup, maybe 1/4 the diameter of the endmill.


Also I found that using a 1 or 2 flute end mill works better than a 4 flute end mill, but each to his own.


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