Why end mill holders?

[Sleazey]

Newbie question:

Why are there end mill holders? Do they offer some advantage over sticking in an endmill into the properly sized R-8 collet? Is using an endmill in an R-8 collet a no-no?

Or, is that smaller ones in the collet are OK, but when you get up to the larger endmills, you need a dedicated end mill holder?

Help me Ani-wan, you're my only hope!

[mechanicalmagic]

This is a common topic, rarely agreed upon. But, since I'm first, I'll offer MY opinion.

R8 collets hold tooling fairly well.
Advantages close coupling to the spindle, reducing chatter.
Dis-advantage: The tool must be reset in the Z axis on every change.
Warning: Collets CAN be loose, and the cutter will extend in use.
Comment: A bell mouthed collet will not hold a cutter true.

R8 holders:
Advantage: Repeatable Z axis position.
Dis-advantage: Tool sticks out a bit farther. A loose holder will allow the tool to be off center.
Comment: Bell mouthing WILL happen with use.

In both cases, the holder IS GOING to WEAR, if used over a long time, in a production environment. (Or, if bought from such a place.)

DJ

[gda]

The 2 reasons I use holders:
1) large end mill shank like 1 or 1 1/4 that is too big for a standard R8 collet.
2) to hold the end mill further than the fat quill to get into deeper areas.

[strokersix]

I've never had an endmill walk out of a holder. Can't say that about collets. For this reason my first choice is a holder.

[medwards]

I use both. I have a 1/16" set of collets and 3/8",1/2",5/8",3/4" and 7/8" endmill holders. I keep the endmill holders fitted up with my most commonly used endmills and almost never change them out. The collets allow quick tool changes (with a power drawbar) and accept a fair range of drill sizes. I use the endmill holders when I'm doing heavy milling. I have no worries about the endmill slipping out of the holders and they seem to chatter less.

[bborr01]

The main advantage to holders is their set screw clamps the the end mill into the holder and does not allow it to pull out on deep cuts. The helix (spiral) on an end mill has a tendency to pull the end mill out of the holder when taking deep cuts with large end mills. I also have found it helpful to use the quill stop to keep the quill from pulling down on deep cuts with larger end mills.

Brian

[zipzit]

Hmm... cutter can walk out of collet. Does that mean it not possible to use the lathe as a small mill (with the workpiece mounted to the compound rest?) Obviously the length of any milling cut is reduced to the length of compound rest travel. Obvious too, occasional use only.

I keep thinking of these projects DIY Milling Attachments for the Lathel

and in particular DIY Stacked Plate T-Slot Milling Attachment as a great way to make a lathe do a little bit more work.

Anybody been there, done that?
thanks, zip.

[Randyinaloha]

I have used the holders only for deep heavy cuts and have confidence that the set screw will not let the tool spin. Also for large dia. shanks that will not fit into a regular collet. Taking a 1.5" dia. tool @ .5" depth feed 20" min. was fun and scared all the folks in the shop. Chips welded themselves to the tile floor.
I wanted the strongest thing available to do that.
Was not a standard knee mill. Very solid. Forgot the name.
Normal shop work I like 5C and do not like "Power" tighteners.
Do not trust them.
Randy

[Randyinaloha]

Zips, have had to use a mill as a lathe. Things turning or tool turning is the same. Whatever is easiest or available. Worked at one place we had to make 10-32 screws into 8-32 to get a job done. Folks there were too lazy or stupid to go to the store. Or maybe the fact that the store was several hours away and it was midnite. Anyway to get-er-done.
Randy