School me on collets for the Atlas lathe, 3c, 3at,or both?

3MT (2MT on all 6") collets are the only ones that fit directly into the spindle nose. The 3AT, 3C and a few other rarer ones all have a closer adapter that goes into the spindle taper and then the collet goes into it.
 
Mark, 3AT collets won't fit in the 6" spindle. They, their closer adapter and their draw tube are all larger in diameter than the spindle bore.

Aside from the Atlas part number (Mt-751-n/m), I have never seen a collet name like 3AT or 3C. The largest size that they came in was 9/32".
 
Now here is a collett machine , never heard of this one before .
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http://www.lathes.co.uk/atlas/page6.html
 
westsailpat said:
OK Robert , yes as usual I didn't do the research . I think Dan has a 12" Atlas , Joel has this set up for sale https://www.mymachineshop.net/product_p/10075.htm
I think the sleeve is the way to go , that's what I believe Dan was asking .
Click to expand...

Yes I have the 12" and I have been looking at Joel's setups. With the price of the one you have linked to plus buying the milling attachment I would consider a used mini mill.
 
I was looking for a bench top mill and a lathe. The mill showed up first. Then a week or so later I found my 12x36 craftsman lathe. The lathe came with the milling attachment. I have set it up on my lathe but have never used it. The bench top mill is just easier to use and I think more versatile then the lathe milling attachment.
I went with er32 collets. I have an R8 shank chuck for the mill and a MT2 shank chuck for the lathe. I can use the MT2 chuck in either the tail stock or the head stock. I keep debating on whether to buy an er32 chuck from Beall http://www.bealltool.com/products/turning/colletchuck.php or make one. Will probably buy one.
 
Here is my collet set up it is not optimum , the best is a draw tube and a collet sleeve . The little turret (capstan lathe) pictured in my older post is set up with a lever collet closer and bar feed .
Anyhow , I went a little overboard with the draw bar . The bar is a hardened stud for a mill and the tighten up nut has a captive washer that is free to turn and the brass thumb wheel is bigger than it needs to be . The spacer is 12L14 , all this stuff I got from McMaster Carr .
I got a complete set of collets from the Bay .
IMG_0030 by mark westi, on Flickr
IMG_0033 by mark westi, on Flickr
 
S.A.E., what is your question?

The 3AT and the 3C are about the same size range. There are two differences between the two types of collets. T he threads in the draw tubes are physically the same but the 3AT threads are specified in a common fraction whereas the 3C is specified in decimal fractions. I borrowed a 3C tap and ran it into a 3AT draw tube and although it was a snug fit, I do not think that it removed any metal. Both types of collets screw into the draw tube OK. The other difference js that the closer angles are substantially different. I am not certain and don't want to look it up tonight but something like 12 degrees and 15 degrees. So they are not interchangeable. I don't know whether this is a typical problem but the 3C collets seemed usually to not want to release without bumping on the hand wheel when the draw tube was unscrewed.
 
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