Collets, Tapers - So many Questions

[dsquire]

Everyday I read somewhere a question regarding collets or tapers with regards to lathes or mills. It even spills over into chucks sometimes. Does anyone have a good document that covers all these questions? Below are listed a few of the terms that I have came across. If there is not a single document then perhaps the members can help to create one answer to many of the questions that are asked about collets and tapers and chucks.


MT4 spindle
MT4 collet chuck
ER collets are a good choice but don't instantly dismiss C5 collets
ER11, ER16, ER32, ER40 etc
Emergency collets
pot chucks
collet chuck
a draw bar
R8
5C
MT3

I appreciate all answers, even the technical ones as to why it has that name or how it came to be developed as that is all part of learning.

Cheers 

Don

[Lew_Merrick_PE]

Everyday I read somewhere a question regarding collets or tapers with regards to lathes or mills. It even spills over into chucks sometimes. Does anyone have a good document that covers all these questions? Below are listed a few of the terms that I have came across. If there is not a single document then perhaps the members can help to create one answer to many of the questions that are asked about collets and tapers and chucks.


MT4 spindle
MT4 collet chuck
ER collets are a good choice but don't instantly dismiss C5 collets
ER11, ER16, ER32, ER40 etc
Emergency collets
pot chucks
collet chuck
a draw bar
R8
5C
MT3

I appreciate all answers, even the technical ones as to why it has that name or how it came to be developed as that is all part of learning.

Cheers 

Don

Don,

MT = Morse Taper (see Machinery's Handbook for more information than you ever wanted to know).
ER collets are double-taper collets introduced by Rego-Fix in 1973 where you will have a collet holder that adapts to your spindle and (generally) very accurate collapsing collets that grab whatever it is you want to hold.
C-5 (and C-3 -- though generally quite hard to find) are collets similar in design to the (Bridgeport) R8 collet, but are self releasing once the retention force is removed.
R8 is a self-locking collet designed by Bridgeport (I believe) during WWII to reduce material usage.  It is "self locking" in that you will need to rap the end of the drawbar to get it to release.
A drawbar is the threaded rod that applies pressure from the aft end of a collet to retain it.
A collet-chuck may either be a collet holder and collet set or a part that holds a collet holder while a collet and tool or part is clamped (the second usage is generally found with Caterpillar "CAT" toolholder systems).
An "emergency collet" is an unhardened collet, most commonly associated with C-5 collets, that can be bored or broached for an unforeseen application.

I have no idea what a "pot chuck" is unless it relates to the now obsolete practice of locking a part into a fixture (or tool holder) by casting it in place with zinc (i.e. pot metal).

You will also run into: Jacobs Taper (JT), Jarno Taper, and (1/4 inch per foot) pin tapers.

[andyf]

I have no idea what a "pot chuck" is unless it relates to the now obsolete practice of locking a part into a fixture (or tool holder) by casting it in place with zinc (i.e. pot metal).

My understanding of a pot chuck (gained from here: http://www.gadgetbuilder.com/MiniMods.html#PotChuck ) is a shallow collet with one slit, and a shouldered bore so that it will grip a thin disc and support it from behind.

No idea how it got its name, though.

Andy

[D_Harris]

Everyday I read somewhere a question regarding collets or tapers with regards to lathes or mills. It even spills over into chucks sometimes. Does anyone have a good document that covers all these questions? Below are listed a few of the terms that I have came across. If there is not a single document then perhaps the members can help to create one answer to many of the questions that are asked about collets and tapers and chucks.


MT4 spindle
MT4 collet chuck
ER collets are a good choice but don't instantly dismiss C5 collets
ER11, ER16, ER32, ER40 etc
Emergency collets
pot chucks
collet chuck
a draw bar
R8
5C
MT3

I appreciate all answers, even the technical ones as to why it has that name or how it came to be developed as that is all part of learning.

Cheers 

Don

I think you may be going about this the hard way.

What kind of lathe and/or mill do you have? That is where you should start.(I guarantee you'll think up many times more questions than the few you asked here. And they will be more in line with what you really need to know. The peripheral knowledge will come as you research what tools you'll need for the machines you own.

That said, I'll give the definitions a shot. (Disclaimer: Those here more experienced than me, which is probably everyone, can make whatever corrections that are warranted.)

MT0, MT1, MT2, MT3, MT4, MT5, MT6, MT7 are designations for the male/female tapers of a spindle, bore ,or whatever is supposed to go in them.

ERxx is a system of collets that seat into your spindle or a special chuck, and they hold the metal you are going to work on.

A Pot chuck basically does what a collet or conventional chuck does as far as holding what you are going to work on. Specifically thin work pieces. (And they are usually machined to fit the specific work pieces).

Emergency collets are "soft"(not hardened) collets that can be easily machined to the size of the work piece/s.

A collet chuck is for holding collets.

Like the MTx series 5C and R8 are work and tool holding standards.

A draw bar is basically a bolt that is used to secure(draw) a collet into a spindle.

And a spindle is the motor driven cylinder/rod that serves as the axis for other parts and work pieces that need to rotate.

Darren Harris
Staten Island, New York.

[Dean W]

Just a little more for "pot chuck".
It's like an emergency collet, but has an over sized end on it.  The end is made to be machined for the job at hand.
I guess it's called a pot chuck because the end, on the larger ones, looks like a pot.  It's made for flat pieces, like gear
blanks, & etc. 
Since the end is kind of oversized, both in diameter and thickness, it can be used over and over by facing off the end
that was previously made for one job, and cutting a new face into the jaws for the next job.

This is a very small one for a WW spindle, but you can get the idea.  A WW collet is normally just the size of the silver
part of this one;






Dean