r8 collets for solid carbide endmills?

[wooleybooger]

a friend just gave me 60 SC re-sharps he picked up for $8.00 most of the EMs i use have 3/8 or 1/2" shanks and i have EM holders for these but with these SC end mills the shank is the same as the cutter diameter so Ill have to buy something just use them. will the SC spin in a collet?

[KiddZimaHater]

Endmills usually don't spin in collets, unless you don't tighten them very good.
Tighten the willies outta them, and let 'er rip.

[beanbag]

a friend just gave me 60 SC re-sharps he picked up for $8.00 most of the EMs i use have 3/8 or 1/2" shanks and i have EM holders for these but with these SC end mills the shank is the same as the cutter diameter so Ill have to buy something just use them. will the SC spin in a collet?

I've never heard of that. When endmills are resharpened, they leave the shank alone.

[Black_Moons]

They will do fine in collets, Just tighten them a little extra, I have heard carbide is harder to get a good grip on.

[lazlo]

I've never heard of that. When endmills are resharpened, they leave the shank alone.

Agreed -- that sounds odd. The shanks should not be undersized -- there's no way to hold them otherwise.

R8 collets have very little clamping range -- I wouldn't try to clamp an undersized tool!

[Arthur.Marks]

If they truly are undersized & you don't have an r8 to fit... my vote is for holding them in an ER adapter. One reason ER collets are very handy---big clamping range.

[lazlo]

If they truly are undersized & you don't have an r8 to fit... my vote is for holding them in an ER adapter. One reason ER collets are very handy---big clamping range.

That's good advice -- an ER-32 or ER-40 set will clamp any arbitrary diameter, but that's a lot of money to spend to hold a resharpened carbide endmill...

[SDL]

Agreed -- that sounds odd. The shanks should not be undersized -- there's no way to hold them otherwise.

R8 collets have very little clamping range -- I wouldn't try to clamp an undersized tool!

Maybee they sharpen between centres? is there a centre both ends?

wouldn't matter to those using ERs etc

Steve Larner

[Arthur.Marks]

I don't know... depends how nice an ER set you want to get into. Doesn't have to be new, either---or for that matter a full set (i.e. one holder, two collets). From what I see, if the end-mills are a non-standard diameter from being improperly sharpened across the full shank, your only other option is an R8 blank arbor to hold them. Bore it out to the correct size and add a set screw. At least the ER's could be used for a host of other things.

As for collets and carbide endmills... for diameters below 1/2" or so they rarely are found with a Weldon flat in my experience. That would suggest to me that small diameter carbide end-mills are used more often in collets than a true Weldon-shank, end-mill holder.

[PaulT]

If you plan on doing heavy and high RPM cutting, carbide endmills and R8 collets are unfortunately not a good match, even if you tighten them hard, they will be prone to slip and pull down.

I had to move to ER32 collets to avoid this problem on my BP clone CNC machine, and even with those you have to tighten them to at least 65 ft-lbs or so. I had to fab up a vise mounted fixture to be able to tighten them as that much torque is too much for the index pin in the R8 spindle (yes, I learned that the hard way).

Good luck-

Paul T.
www.power-t.com