# End mills.. need help.



## negatronix (Aug 24, 2014)

Hi,

I'm new to machining, and have a question regarding end mills.

I am looking at purchasing a Grizzly go755, which comes with a spindle adapter R-8 x MT#3.

My question is this. Do I purchase a set or R-8 collets or R-8 endmill holders to hold the endmill, and ball endmill tools. If not the collets, what are collets used for?

Sorry for the total newbie question, I am just getting started with all of this and have zero experience.

Thanks, -Kory


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## chuckorlando (Aug 24, 2014)

If it has a r8 spindle I would just buy r8 collets. Any adapter is going to take up some of your work height. Yes collets are for holding tools on a mill and they hold stock on a lathe


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## Rbeckett (Aug 24, 2014)

If you can afford it I would also buy both styles of end mill because I prefer to hog out material with the ball ends and the finish the surface with a flat once I get close to the finished measurement.  I seem to have better luck clearing large quantities of chips with the ball nosed than I do with the flats.  The flat and Ball nosed sets are available at HF for about 80 bucks each for a pretty complete set and if you have coupons you can have a pretty decent set of both for around a hundred and twenty bucks easily.  That's what I did and those bits are good enough for a beginner to figure out what they are doing without ruining a high dollar bit making a newby mistake.  Welcome to our little gang and I hope you find everything you are looking for and the knowledge you need to get going.  If you ever need help or have an issue all you need to do is start a thread or ask a Mod.  We are here to help and provide assistance when and where we can.

Bob


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## george wilson (Aug 24, 2014)

I have only ever used the R8 collets for my work.  The only end mill holders I have are for end mills whose shanks are too large to fit any of the R8 collets. 

I don't like the extra length of unsupported end mill sticking out of the spindle that you have when using end mill holders. It reduces rigidity,and it does,as mentioned,take up your vertical space.

Keep your collets free of oil,and also the shanks of the end mills you are putting into them. Tighten the draw bar well. I have never had an end mill suck out of an R8 collet. But,my journeyman did once. I think he must not have tightened the draw bar enough.


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## negatronix (Aug 24, 2014)

Thanks everyone! I will be purchasing a set of R-8 collets, a set of 2 and 4 flute end mills, and a sets of small and large ball cut end mills with 7/8" shanks. I believe the tools that I selected are all HSS-TiN.

Thanks,
-Kory


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## ScrapMetal (Aug 24, 2014)

George,

What brand of R8 collets are you using?  The reason I ask is that I have nothing but trouble when trying to use the collets on my mill.  The end mills either try to pull out, on "regular" operations, and push in if I'm plunging.  I use a Kurt automatic draw bar which snugs them in as good as can be.  I keep oil away from the collets as well as end mills but still haven't been able to rely on the setup.  The only place I can see maybe being a problem is that I've got some cheap Chicom collets.

For this reason I prefer to use end mill holders instead of collets.  Combined with a Weldon shank end mill they are rock-solid.  My mill has enough head room where the extra extension of the holders isn't much of an issue though.

JMHO

-Ron


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## chips&more (Aug 24, 2014)

Well I might as well add two more cents. I have a Bridgeport mill and use R8 collets and for the last 45 years or so. Can’t recall ever having a problem with using collets, and that goes for in lathes and collets used anywhere else in the shop. The draw bar is used with a standard wrench. I do not gorilla the torque went tightening the collet. The threads on the draw bar look great. I dislike using the end mill holder type because of the extra length as others have noted. But it’s a necessity above 7/8”. Because many other folks share my R8 collet experience as with no problems. I suspect that any issues using collet type holders is unique to that machine and not a general wide spread common reoccurrence...Good Luck.


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## chuckorlando (Aug 24, 2014)

I have sucked the work out the vice before but never the tool out the collet. I have one end mill holder for my big old end mill but thats all.


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## george wilson (Aug 24, 2014)

I am just using cheap Chinese collets. The only one I have found to be faulty is a 3/16" one which is way off center on the 3/16" hole. I have not found any trouble with these collets. I actually have used 3 separate sets. I had 2 vertical mills at work,and mine at home. All outfitted with the same collets.

I'm inclined to think your Kurt draw bar isn't tightening your collets tight enough. That's the only conclusion I can reach,based on my experience,and those of others here. Is your draw bar tightener adjustable to make it tighten more? Do you need higher air pressure? I have never used one myself,so can only pose these few questions.

I tighten mine with a standard draw bar hammer. The one with a brass head on 1 end and the hex wrench on the other end of the head. I hold the brake lever while tightening. The handle of the standard hammer is not really long,but I get good,secure collet tightening with it. I am a large guy,but am 73,so I doubt I'm tightening unusually tight.


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## chuckorlando (Aug 24, 2014)

Now that you mention it, I have seen some issues on the air draws at school. Both holding and releasing. It would slip so they turn up the psi, then turn it back down and cant get it to un screw.


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## Pat of TN (Aug 24, 2014)

My rule of thumb for tightening a drawbar is finger tight, followed by between a half- and two-thirds of a turn with the vise or drawbar wrench, while holding the brake of course. Usually I just do about a half turn. Over-tightening, of course, can break drawbars or strip threads.

But as to the OP - a set of collets will do you just fine. If you were to get a roughing end mill - then I would consider a solid holder. But even then, I wouldn't worry too much about it. 

For types of end mills - square or flat end mills are for standard work. They are what you need most of. Ball-nose end mills create a whole radius - a 1/2" ball end mill will make a 1/4" radius or half of a 1/2" diameter. Not really too useful unless you need radii, or in 3D contour milling on a CNC... neither here nor there.

But a _bull_ nose end mill, or a corner radius/chamfer end mill, can be useful. These are flat end mills with a small radius or chamfer on the edge. This results in a stronger edge, allowing higher feed rates without chipping. Then again, on a smaller machine, it can also induce chatter.

If I was you starting out, I would buy one of the common sets of 2 and 4 flute end mills you see on Enco all the time - they go from 3/16 to 3/4 diameter. Buy a set of collets that accompany that set of end mills - the shanks are 3/8, 1/2, 5/8, and 3/4. That'd be somewhere around $120. That would get you started in terms of milling cutting tools and holders.


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## Walsheng (Aug 24, 2014)

Every tool shop I have worked in had a set of end mill holders and they all had a hefty layer of dust on them from lack of use! And all used the R8 collets except for one 1947 South Bend mill, now in my possession, that used a pain in the neck mongrel collet system.
We did use a holder once because for some reason, and I can't remember why because it was probably 40 years ago, we needed the extra reach.

The biggest problem I encountered was apprentices over tightening collets to the point you needed a hammer to loosen them.  We had one kid who couldn't have weighed 120 pounds soaking wet but he could tighten a draw bar so tight it would make your eyes bleed trying to loosen it.  A couple of good raps on the knuckles helped considerably (probably not an acceptable cure these days!)

John


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## stupoty (Aug 24, 2014)

I origionaly used mt3 collets when i got my bench mill, i would change to a chuck for any drilling, that changed the height a lot and required putting the head up to give room for chuck and drill bit, now i hold everything in an er32 collet holder that goes in the mt3 spindle.

holdes from 2mm to 20mm with no gaps.  I havent had anything come lose on me yet.

Stuart


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## Cobra (Aug 24, 2014)

I have the same mill. I use an R8 chuck holder for ER32 collets. 
Work great, have never had a problem. 
Jim


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## negatronix (Aug 28, 2014)

So my finalized starter tool list is as follows. PLEASE chime in if there is something really important missing.

1Set of 2&4 flute Endmills HSS-TiN

1 set of small and one set of large ball tip endmills. The large set has 7/8" shanks.

1 3/4" chamfer tool. I assume it can chamfer from 3/4" max size and down (smaller chamfers). If I am wrong please let me know!

1 set of fly cutters with 3/4"  shanks... and a piece of tool steel.

I'll be using R-8 collets.

I have a milling book with a project for making a boring head, so I plan to make that and save the money.

With any luck, I should be ordering the machine and all the other goodies Monday or Tuesday.


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## kd4gij (Aug 28, 2014)

Sounds like a plan. Good luck.


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## Smudgemo (Aug 29, 2014)

Did I miss seeing a call out for a work-holding device?  You'll either need a vise (4" or 5" most likely) or a clamping set of some sort.  

I got the 10 piece 2/4 flute cutter set from Grizzly when I bought my prior mill, and it's been fine.  Enco right now has a 20%+free shipping sale until Sunday night in case you can't get it all from Grizzly or HF. Way oil and cutting oil would be good investments.

Are you doing Harold Hall's boring head project?  That's the one I did, but I don't see it saving you much money (if that's your goal.)  I probably spent $80 in materials (which included the R-8 arbor), and you can buy a MIC set for that much. However, mine works really well, I'm proud of it and it was a terrific project.  You can see the results in this thread: http://www.hobby-machinist.com/showthread.php?t=22120 

-Ryan


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## 6530 (Aug 29, 2014)

Smudgemo said:


> Enco right now has a 20%+free shipping sale until Sunday night in case you can't get it all from Grizzly or HF.
> 
> -Ryan



Can you share the Enco codes?


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## 6530 (Aug 29, 2014)

Pat of TN said:


> But a _bull_ nose end mill, or a corner radius/chamfer end mill, can be useful. These are flat end mills with a small radius or chamfer on the edge. This results in a stronger edge, allowing higher feed rates without chipping. Then again, on a smaller machine, it can also induce chatter.
> 
> If I was you starting out, I would buy one of the common sets of 2 and 4 flute end mills you see on Enco all the time - they go from 3/16 to 3/4 diameter. Buy a set of collets that accompany that set of end mills - the shanks are 3/8, 1/2, 5/8, and 3/4. That'd be somewhere around $120. That would get you started in terms of milling cutting tools and holders.



Which Enco set would you recommend?  I can't find anything in their catalog with a bull nose other than lathe tooling.

Thanks!


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## 6530 (Aug 29, 2014)

6530 said:


> Can you share the Enco codes?



Edit: nevermind, found the code thread.


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## Smudgemo (Aug 29, 2014)

6530 said:


> Which Enco set would you recommend?  I can't find anything in their catalog with a bull nose other than lathe tooling.
> 
> Thanks!



Something like #321-0001 would work, but in reality, just having a nice 1/4" or 3/8" and 5/8" in both 2 and 4 flutes would be a fine start unless you need to cut smaller for an upcoming project.  The Hertel cutters Enco carries are nice and not overly expensive.  I don't own any ball-cutters and can't comment on owning one.  I also don't care if they are coated as I haven't noticed any difference, but then I'm just a hobbyist.

Enco has sales all the time, so hold out when you don't need something right away and watch for them.

-Ryan


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## rpmMan (Aug 29, 2014)

don't have a mill yet but found the comments about holding tools in collets interesting , especially since I just stumbled across this tormach report on preventing collet slip.. 

perhaps the mods can post the pdf if ok with tormach .. for now I will just post the link..

http://www.google.com/url?sa=t&rct=...T_e9BF7rYsn6x5nDQ&sig2=HEKLUItEL0kdl8suBE-4jw


rich


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## mattthemuppet2 (Aug 29, 2014)

I don't have a lot of milling experience, but I have found that I _love_ roughing end mills. You can take off a lot of material very quickly, then finish with the appropriate 2 or 4 flute. They seem to work especially well for side milling pockets as they make and spit out lots of small chips instead of clogging up with the long fine slivers you get with a finishing end mill. Grizzly sells a neat looking set (1/4 to 1in I think) for around $50, which isn't a whole lot of money. I'd buy those over round nose end mills, which seem more specific to creating radii at the bottom of pockets (or an exaggerated "milled" finished on CNC'd parts).

Also, don't overlook the various bundles of used/ new end mills that you find on eBay. I have just over $60 in my 50 or so end mills from 3/64 to 1/2in and have a huge variety of flute no./ length/ diameter to choose from.


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## ScrapMetal (Aug 29, 2014)

rpmMan said:


> don't have a mill yet but found the comments about holding tools in collets interesting , especially since I just stumbled across this tormach report on preventing collet slip..
> 
> perhaps the mods can post the pdf if ok with tormach .. for now I will just post the link..
> 
> ...



Very informative.  Thanks Rich!

-Ron


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