Confused About Collets For A 10f

great white

great white

Active User
Registered
Joined
Jan 25, 2015
Messages
2,558
I've been reading and googling about collets for my 10f.

Seems the original ones are a 3AT, which I take to mean taper to fit the spindle/headstock. Those seem to be very expensive though.

But it seems people use all different types. I've seen 3c, er11, er32, er42 and all other sorts of numbers.

I'm just looking for something that will bolt up to my 10f, hold end mills for my (new to me) milling attachment and further down the road allow me to explore the other uses collets are good for (still learning very basic stuff).

I'd also like to not spend the bank on them. I see sets on eBay anywhere from 35 bucks and up, but I don't want to buy crap. The buy it now auctions with cheap or free shipping are also very attractive as shipping to Canada usually cost as much (or more) than the item.

I'm also not adverse to building some parts of a collet system myself as long as its not too complex (still new to machining) and it would be good practice.

So, can anyone clear up which of those collet numbers would work in my atlas with the least amount of trouble?

I'm also not clear on the whole drawbar thing. I think I understand the basic principle, which is a bar that pulls the collet into a taper in order to clamp the work. I would prefer not to use a drawbar (because of the atlas change gear cover) unless that's a more reliable system than a chuck with a ring.

Any help appreciated. I'm pretty turned around in my head from all the info.

Oh yeah, please keep it simple. I'm on info overload right now....
:headache:
 
The original set for Atlas was 3AT. There was an spindle sleeve/adapter that converted the spindle from MT3 to the external dimensions of the collet. These dimensions are available in many references, for example Machinery's Handbook. Along with the spindle sleeve there is a draw tube that is fed from the far left end of the spindle and is hand closed by threading onto the external threads of the collet. There was an option for a lever closer version as well.

Collets will not hold an end mill to well. Been there, done that. It can not clamp down enough to stop the end mill from spinning in the collet under load. You will really need a end mill holder that fits the MT3 socket of the spindle. They usually have set screw to prevent spinning the end mill. The ones I have are set up for 3/8 threaded closer rod.

An option would be to get a 5C set up, with a collet chuck that threads on the spindle. Check out Little Machine Shop for pictures. 5C are fairly cheap collets to find, but the quality of the chuck is up for debate, as they can vary quite a bit. $300 to $1k is a wide swing in price that is for sure!
Pierre
 
What Pierre said. Plus I will add for emphasis that a draw bar is solid, with male threads. Commonly used in MT and R8 collet, which have female threads on the back end. For most other older design collets, like 3AT, 3C and 5C, the collet has male threads on the left end, is hollow all the way through, and the draw TUBE is hollow through and has female threads.

End mill holders with set screws require end mills of the Weldon style. These have a flat across the shank for the set screw to bottom on.

ER style collets are like Dremel collets. They require a collet chuck that usually fits the 3MT (2 MT for 6") spindle nose, and are retained by a draw bar. They have two advantages over the traditional style - greater clamping diameter range in a single collet because both ends are squeezed. And usually longer clamping length. They also have four disadvantages. The clamping part of the chuck consists of a hollow tapered region in the chuck body and a removable hollow tapered nut. The nut screws on, squeezing the collet, and requires an external removable wrench. The nut is slower to unscrew and must come completely off to change collets, and can be dropped whereupon it will immediately roll under the nearest large heavy object and become the subject of a job stopping search. You cannot work parts being made from long pieces of feed stock. And you cannot change work pieces without stopping the spindle (which is also true of the MT and R8 collets).
 
Last edited:
Ah, so I need to look for an MT3 end mill holder for milling on the atlas?

I thought it was collets that people hold end mills with.

Learn something new every day!

:)
 
great white said:
Ah, so I need to look for an MT3 end mill holder for milling on the atlas?

I thought it was collets that people hold end mills with.

Learn something new every day!

:)
Click to expand...
I use MT3 collets to hold end mills. They work fine for me.
 
pdentrem said:
Something like this one.
Pierre
Click to expand...
Interesting. Busy bee is local and I can pick it up on a trip to town.

Oddly enough, after taxes, its the same cost as ordering one off eBay and the eBay one lists accuracy of .0004 and busy bee lists .0006

And we all know where the busy bee comes from, same place as eBay: China.

I like to buy local but sheesh, they're not making it easy....
 
I'm with Pierre in that MT collets don't hold a cutter very securely. I was trying to notch thin-wall 4130 tubing with a hole saw and the collet just wouldn't hold the arbor well enough to avoid spinning. That being said, the ER collets seem to hold things just fine in my mill, and making an ER collet chuck would be a fun project that wouldn't be very tough. Harold Hall outlines his version of the project here: http://www.homews.co.uk/page130.html
It was also a featured project a few months ago in the one of the machinist magazines I believe we are not supposed to link to here, and a number of other examples can be found if you google "er collet lathe chuck". The only difficult operations are the internal threads and cutting metric threads for the nut (unless you make your own.)

I haven't made one, but it's on my list. I'll probably do an ER25 since I have the collets, but I'd go ER40 if I got a do-over because it handles larger sizes and I sold the smaller mills I originally bought the ER25 set for. ER 32 might be suitable for your needs, too.
-Ryan
 
I totally agree that the proper milling cutter holder on a 3MT (or 2MT or R8 depending upon your machine) and the proper milling cutter shank is the better way to go. The first problems is that the cutter holders seem to be much more common in the Tang type instead of drawbar type shank. Do not even think of using the Tang type in your spindle as you are unlikely to finish a part before one of them comes loose. Atlas also sold a drawbar type holder for 1/2" dia. shanks plus reducing bushings for 1/4", 5/16", 3/8" and 7/16". The second problem is that Weldon style cutter shanks are less common and usually more expensive than ones with no set screw flat. However, a Dremel or similar tool post grinder can turn non-Weldon into Weldon if you would rather spend the time than the money.
 
Last edited:
You must log in or register to reply here.
Back
Top