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Author Topic: Mill cutter vs R8 collet size  (Read 6997 times)

Offline Chuck in E. TN

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Mill cutter vs R8 collet size
« on: February 06, 2010, 08:07:15 AM »
I inherited a few milling cutters from my Dad. I would like to use them on my mill, just because…  I am confused as to the R8 collet that will properly secure them. One is marked 25/64 with a diamond logo Containing the marking M&B. It measures .385” on my HF Digital calipers. 25/64” divides out to .3905.
I have a couple more that measure .312, one has the sideways diamond with M&B, one is a Weldon, marked 3/8.
And another that measures .385 and is a 5 flute mill cutter with 7/16 stamped in one of the flutes. 7/16 divides out to .4375.
What am I missing? I have a set of R8 collets that came with my 2nd hand HF X2 mill, in 1/8, ¼, 5/16, 9/16, 5/8, 11/16, and ¾. The ½ is missing. I hope to pick p a ½ today at the local MSC store.
I guess my question is can I use these cutters with the collets I have? What is the clamping tolerance of an R8 collet without damaging it?
Do I need a 25/64 R8 collet? Is there such a beastie?

Chuck in E. TN
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Offline Bernd

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Re: Mill cutter vs R8 collet size
« Reply #1 on: February 06, 2010, 01:27:52 PM »
Hi Chuck,

I did a quick parusal of the MSC catalog. Looks like the smallest number from one collet to the next is in 1/32" increments. So no 1/64's. Although you can get collets and make your own sized hole in them.

As far as the holding tolerance I couldn't find any specs. I'm sure there are some somewhere. I just don't know were to look right now.

Hope this will help clear some of your questions.

Bernd
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Offline 75Plus

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Re: Mill cutter vs R8 collet size
« Reply #2 on: February 06, 2010, 01:46:31 PM »
The shank size is not always the same as the cutting size. Could this be part of the problem?

Joe
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Offline Chuck in E. TN

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Re: Mill cutter vs R8 collet size
« Reply #3 on: February 06, 2010, 02:37:41 PM »
Admittedly, I'm a noob at milling, but the mill cutter apears as a quality drill would. The cutter shows no change in diameter from shank to tip. Stamped with size , company logo, and USA as a #, letter, or Silver and Deming drill set would.The flutes are the same diameter as the shank, .385".

Chuck in E. TN.
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Offline Bernd

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Re: Mill cutter vs R8 collet size
« Reply #4 on: February 06, 2010, 07:26:03 PM »
Chuck,

I'm a bit confused here. Are you trying to figure out what collet the 25/64" mill will fit in or are you asking if this is a standard type everyday mill cutter?

Looking at a decimal conversion chart it looks like you would need to squeeze a 7/16" collet down about .025" a side to hold the cutter. A 3/8 collet might also work but the cutter would fit in a bit tight. Since I don't know the torlerances of collets I'm not going to suggest that you could use either one. But if they were mine I'd use the 3/8".

My other thought is if you are going to buy a collet in the 1/32" range go for a 13/32" collet to hold the 25/64 cutter. Now your talking about .005" per side squeeze.

Ya I know clear as mud, right?  :scratch:  :)

Bernd
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Offline Darren

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Re: Mill cutter vs R8 collet size
« Reply #5 on: February 06, 2010, 07:42:39 PM »
Use a 10mm collet  :thumbup:
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Offline andyf

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Re: Mill cutter vs R8 collet size
« Reply #6 on: February 06, 2010, 07:48:35 PM »
Chuck,

Though I realise you probably want to use it because you inherited it from your Dad, it probably isn't going to be economic to locate and buy a collet to fit one rather unusual size tool. Could you perhaps make a sleeve bored out to 0.385" and with an OD to suit one of your larger collets, and either Loctite the tool into the sleeve, or slit the sleeve down one side so that tightening up the oversize collet squeezes the sleeve on the tool?

Andy

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Offline Chuck in E. TN

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Re: Mill cutter vs R8 collet size
« Reply #7 on: February 07, 2010, 06:42:32 AM »
The sleeve suggestion is doable. I purchased a 1/2" R8 collet from an e-bay seller at a price with shipping that was cheaper than I could get it from the local MSC outlet, if they actually had one in stock. I inquired about a collet for 25/64, and he also suggested a 10mm. A 10mm would only be .009 off and could probably clamp it. For less than $9 delivered to use Dad's mill is affordable, I think.
Thanks for the input folks. At least I didn't get told I was "crazy", "ain't no 25/64 mills", "you ain't measuring right", etc.

Chuck in E. TN
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Offline Bernd

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Re: Mill cutter vs R8 collet size
« Reply #8 on: February 07, 2010, 09:20:32 AM »
Hey Chuck,

We'll ask all the questions first and then tell you your crazy or it can't be done.  :lol: (just kidding of course)

Glad we get that straightened out for you. I also like the solution Andy gave. Very doable. Matter of fact I did than on one of my mills.

Bernd
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Offline Chuck in E. TN

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Re: Mill cutter vs R8 collet size
« Reply #9 on: February 07, 2010, 09:29:00 AM »
I will also try Andy's suggestion. I used that mill in my lathe chuck with a sleeve also, just can't remember the od of the sleeve. I'll go check, and if it fits a collet I have I will try it.
Thanks again, folks.

Chuck in E. TN.
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MicroMark 7x14, HF X2 mill, Green 4x6 saw. Harbor Freight 170A mig
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