Mill cutter vs R8 collet size

[chucketn]

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?
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

 

[Davyboy]

Hi Chuck. If you are going to get a 1/2" collet, for sure get a 3/8" collet too. It's one that I use often. I don't know about */64 size collets. ???
IMHO, I don't think I would jam an odd size shank into a R8 collet. They grip pretty much full contact on diameter split 3 places. = fairly rigid. You want good contact for accuracy and positive holding power.
Hope this helps.
DB

 

[ksouers]

Chuck,
The shank on the end mills should be a standard nominal size: 3/16, 3/8, 1/2 etc.
It would be used in the appropriately sized collet or an end mill holder. The marked sizes are the cutter diameter, something irrelevent to the collet.

As you've already found out, measuring across the flutes can be difficult. You have to be EXACTLY across the cutting edges of the flutes, off even slightly and your measurement is wrong because of the clearance behind the cutting edge.

The other markings are manufacturer labels and logos.

Try measuring the shanks, that should give you what you need.

Hope that's what you were looking for.

 

[joeby]

Most milling cutters will have a shank size in increments of 1/16", as in 1/8, 3/16, 1/4, 5/16 etc.
Some of what you have could be reground, as in the .312 marked as 3/8. At any rate, the cutter size across the cutting edges is irrelevant to collet size, as you will be holding the shank in the collet.

End mills can be purchased with a larger shank, 1/4" cutter with a 3/8" shank, for example. Not so common with carbide, except in smaller sizes. The 25/64 that you mention would likely have a 7/16" or 1/2" shank size, unless it's a custom or oddball tool.

Looks like you have most of a set of collets, the few that are missing can be purchased as needed.

Kevin


Dangit, one of the other Kevin's beat me to it!

 

[chucketn]

I have a 3/8" R8 Collet. I will purchase a 1/2" one, maybe today.
The one really odball size is 25/64 , stamped on the shank. I has not been reground and the cutter is the same diameter throughout its length.
Anyone know what the logo W&B in a sideways diamond represents?
As 25/64 is 1/64 larger than 3/8, would it fit/work in a 3/8" collet?

Chuck in E. TN

 

[ksouers]

Chuck,
The tolerance on the collets is only +/- a couple thou. I doubt you'll even be able to insert it into the 3/8. Personally I would forget about it and just stick to the more common sizes, but that's just me. It may be carbide and you really want to use it or have a need for it. MSC should carry the 25/64, or be able to order it for you.

Good luck.

 

[doc1955]

If it were me I would just go to the lathe and turn up a step down spacer to allow you to use the next size larger collet. But thats just me I try to make do with what I have on hand and if I had some cutters that were of od size and they still had life in them (still sharp and not dinged up) that would be my way of using them up.

 

[chucketn]

That adaptor sleeve sounds like an idea! Thanks for your input.

Chuck in E. TN.

 

[shred]

I have some old, odd-size end mills. I use them in an R8 ER collet set-- with the full set you can hold any size shank or material.

I'll poke around and see if I have boxes with logos and names on them-- I remember at least one or two diamonds-and-initials logos.