[phil burman]

An end mill holder fits directly in the mill spindle and the end mill then fits in the the holder and is held by a screw through the side of the holder. Hence the name end mill holder.

A collet holder fits directly in the mill, a collet fits in the holder and an end mill fits in the collet, which is specifically designed for that holder (for example an ER collet holder). The collet, which has an external taper, grips the end mill by being compressed by a retaining nut. the collet also has a series of radial slits that allow it to be compressed as it is pushed into the taper of the holder by the retaining nut.

An R8 or MT3 collet, which both have tapers, but different, fit directly into the mill spindle and also have a series of radial slits that allow it to be compressed and grip the end mill when the collet is drawn into the spindle taper by the draw bar.

There you go, clear as mud.

Try googling the following and then read, read, read.

"end mill holder"
"ER collet holder"
"R8 collet"
"MT3 collet"


Phil (chair)

Ok I know wearing you guys out with questions and I appreciate all answers. With a endmill holder how does this fit onto a spindel the same way a collet does?

[ZipSnipe]

Thanl you Gentlemen, Education has been achieved. I just wanted to make sure when I decide to purchase a mill that I get the right stuff to go with it. Once again thanx

[NC Cams]

Reply to Acondit:

Conversely, I've had the same cutter that cut quite accurately in a collet cut with chatter and a lousy finish in a holder.

Each (collet vs tool holder) has it's merits/demerits and you have to use each in the proper circumstances.

Based on the type of questions that were being posed by the noobie machinist in development, he seems to be looking for the proper items to buy to "get started".

In that regard, I'd recommend the purchase of the following in MY order of "getting started priority":

1. A mill fitted with an R8 collet.

2. A nice setof R8 collets (preferrably in 1/32" steps, or ultimately "god I wish I had 1/64" steps") - more accurate from position and runout standpoint.

"Import quality" is fine for getting started, with upgrade to Lyndex at some point later on (IF the mill he buys has a low spindle runout potential, otherwise, don't waste the mondy).

3. An R8 drill chuck for GENERAL purpose drilling/milling.

Due to the tolerance stacks arrising from the use of so many more pieces in a chuck, a chuck does tend to have a higher cutter runout potential than a collet. A drill chuck will come loose easier unless you know how to properly tighten a drill/cutter into position...

4. As needs require for hard core material removal, appropriate sized mill holders.

I use collets for most finish work and general purpose milling.

I save the mill holders for heavy stock removal.

I rarely use a drill chuck when the machine has R8 collet - had too many instances where I was unsatisfied with the results of using a drill chuck as a cutting tool holder.

Once the member takes the time to investigate and understands the definitions of the terms of the equipment he's asking about, the above reply should make sense....