Make end mill holder- bore or ream?

stoneaxe · Apr 24, 2019

I want to make a endmill holder-7/16". This is for an old machine, so holding tenths is not necessary. I can make the arbor ok, but have a question on the hole- should I bore the hole to final size, or drill it and ream it, or bore it and ream it? And to what size? .001 over?

Seems like a drill would not center as good as a boring bar, and since the reamer is really a sizing tool, not a centering tool, that would not help.

I know you folks have made these- what say you?

BTW, I am going to use 1144 , I am not going to harden this as it will be occasional use only.

Hazzert · Apr 24, 2019

Do you have a 1/2” holder? You can usually buy various size endmills on one shank in HSS.

If your pilot hole for the reamer is straight the reamer should follow it well so perhaps bore it undersize and ream to size. But if you already have the holder setup, I would probably just take it to size with the boring bar.

Terry Keeley · Apr 24, 2019

If it was me I'd bore it since I'm pretty confident I'd be able to hit the size within a couple tenths or so.

If you can't be sure to hit the size you want you could drill, bore to make sure the hole is on center then ream to size.

I wouldn't want more than a half thou or so over...

Cole2534 · Apr 24, 2019

Drill out the bulk of the material, bore the hole straight and .015 - .020" U/S, ream to size.

Jim S. · Apr 25, 2019

Make the basic holder in a lathe, including the rough endmill hole. Then mount in the mill and final bore in-situ with a small boring bar held in a vise. Reduces the sources of runout error to the maximum extent possible.

M.B. Naegle · Apr 25, 2019

I'd bore it so it's located exactly where you want it. Reaming could help clean it up if you're not happy with your boring's surface finish.

Is this a tool holder that has a locating key so it will always go in the spindle clocked the same (and are you happy with your spindle bearings/run-out)? If yes then having the final hole size concentric to the spindle will help, but if not, I'd make it concentric to the holder.

Search

Largest Manufacturing Technology Community on the Web

Search

Make end mill holder- bore or ream?

stoneaxe

Stainless

Hazzert

Stainless

Terry Keeley

Titanium

Cole2534

Diamond

Jim S.

Hot Rolled

M.B. Naegle

Diamond

Similar threads