Best Collets For A Round Column Mill Drill?

Tozguy said:

So you got 4 R8 collets then. Not only were they less expensive than a set of ER collets but they are superior to the ER system in my books for holding end mills. I have a set of ER 32 collets for work holding but use a Sheldon holder or MT3 collet for tool holding.

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Interesting, I havn't used r8 but the morse collets are not very good for holding tools from my experience and the tightening torque is a bit rediculus, and they still like to slip. I'm only using MT3 for holding mandrils in my dividing head these days.

I would say I have never had a tool come lose in my er chuck (except when somones distracted me half way through tightening ahhhh. User error )

Stuart

Stuart, your experience is interesting. Thanks for sharing it.

My opinion about R8 and MT3 collets being superior to ER collets is specific to holding end mills and is not based on slippage.
The reason I like them better is because they don't require a chuck but mount directly in the spindle taper and hold closer to the spindle bearings.

Also, my ER32 chuck has to fit in the spindle taper and then the ER collet has to fit in the ER taper. I would prefer to have only one source of run out instead of two. Published run out tolerances for the ER collets seem to be a bit broad and they also have limits as to RPM.

I have only used Sheldon holders for end mills so my opinion here is strictly intuitive. Although MT collets seem to me like a suitable alternative for holding end mills, my experience with MT collets is limited to work holding on a lathe and is very limited at that, so I may be dead wrong!

With respect, Mike

HBilly1022 said:

Well the decision turned out to be an easy one. When I picked up the mill today I also bought some tooling and mill supplies. The 20 piece end mill set I got only required 4 different sized collets and the end mills ranged from 3/16" to 3/4". So do I get the 15 piece ER 40 set for $250 or 4 drawbar collets for $32. That was an easy choice to make.

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You will find that your 4 R8 collets will hold 95+% of the tooling you will be using, and you can add others as you need them or as you find them available used and/or cheap.

Bob Korves said:

You will find that your 4 R8 collets will hold 95+% of the tooling you will be using, and you can add others as you need them or as you find them available used and/or cheap.

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Bob - good point. I have 1/8" through 3/4" R8 collets and have never used the 1/" and 1/4" ones. Still have the packing grease on them from when I bought them ten years ago. I use the 3/8", 1/2" and 3/4" quite a bit and the 5/8" occasionally.

Tom S.

TomS said:

Bob - good point. I have 1/8" through 3/4" R8 collets and have never used the 1/" and 1/4" ones. Still have the packing grease on them from when I bought them ten years ago. I use the 3/8", 1/2" and 3/4" quite a bit and the 5/8" occasionally.

Tom S.

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Those are the sizes I got, except for the 1/2". They didn't have one in stock in any of their stores, so I will be ordering that one from a competitor. They got my money anyways because I spent the $220 savings on other tools.

I have a set 1/8-7/8" set by sixteenths. The 13/16 and the 7/8" collets have a step in them. Those two sizes only go in about an inch deep to the step. I think I have only used the 3/16, 1/4, 5/16, 3/8, 1/2", 5/8, and 3/4" collets so far, but I actually have NOS and used end mills with shanks in all the sizes of my collets, never needed to use the odd ones yet. I have never wished for 32nd or 64th collets so far, or for metric or square or hex bore collets. They are mostly for workholding in my world, not tool holding.

Tozguy said:

Stuart, your experience is interesting. Thanks for sharing it.

My opinion about R8 and MT3 collets being superior to ER collets is specific to holding end mills and is not based on slippage.
The reason I like them better is because they don't require a chuck but mount directly in the spindle taper and hold closer to the spindle bearings.

Also, my ER32 chuck has to fit in the spindle taper and then the ER collet has to fit in the ER taper. I would prefer to have only one source of run out instead of two. Published run out tolerances for the ER collets seem to be a bit broad and they also have limits as to RPM.

I have only used Sheldon holders for end mills so my opinion here is strictly intuitive. Although MT collets seem to me like a suitable alternative for holding end mills, my experience with MT collets is limited to work holding on a lathe and is very limited at that, so I may be dead wrong!

With respect, Mike

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The run out could easily add up it's true , I was curious so I just popped into the cold brrrr. I messured 0.02mm (0.0008") direct on a shank of an end mill (0.375" dia end mill) and strangely 0.025mm (0.001) on the taper of the er chuck, although the head was down low and I didn't have a mirror handy to check for dirt etc. and it was cold so I came back in didn't get a chance to check the MT3 runout too cold.

When ever I see a video of some one using R8 collets they look like they release far far easier than the morse taper one's, might be todo with the area of the taper and the angle. When I used the mt collets directly I had to use a large dead blow hammer to release them and I didn't like doing that much. My lathe has MT3 tail stock and the ejector works very well for them their though (not collets but other things like chucks and taper shank drills etc.).

I also have a lot of imperial or odd sized end mills kicking about that I couldn't hold in the fixed size collets (not without a full imperial and metric set any how) so that swayed my decision towards the broad clamping range of the er collets.

I made a draw bar for my old lathe for MT3 collet use, that worked but I never had the right collet for the stock or was using hot rolld steel and it was too bumpy so I havn't realy used them much for work holding. I made up some arbors to use with my dividing head and they work quite well for that so far.

Always interesting to hear other peoples opinions and experiences.

Stuart

For those not familiar with the R8 and ER collets, here is a video that might be useful.


Here's one that compares the various ER size collets.

Tozguy said:

Published run out tolerances for the ER collets seem to be a bit broad and they also have limits as to RPM.

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Forgot to mention, took me ages of looking to find a set of er collets at a reasonable price that quoted a run out spec that was good (a lot didn't list their spec at all), my mill only goes to 2400rpm so I hadn't given the rpm limit's much thought.

Stuart

Regarding the concentricity specs for ER collets, Hardinge publishes theirs on page 12 of this document:
http://hardingeus.com/usr/pdf/2351.pdf
There is a short but interesting 'Frequently asked questions ' chapter at the end of the document.

Now Hardinge is a reputable manufacturer so I don't expect my budget no-name ER collets to match Hardinge collets for concentricity.

Had I done my homework better, I would have opted for a smaller ER chuck to turn small stuff with more precision.

Releasing MT3 tools or holders is not always easy for me but I take it as a good sign that they would not slip easily in use. My tailstock ejector works well but sometimes it needs a heavy hand with the TS locked down. An MT5 arbor pops out of the lather spindle with a light tap but then it can be especially tricky to get the MT3 arbor out of the MT5 adapter. Somehow it seemed to me that MT3 collets should pop out more easily but they don't.