Atlas 10 questions regarding chuck and runout

The 5" chuck that you have probably was bought from Atlas with the lathe. If it is like the 6" Union chuck that came with my Atlas 3996, it does not have a backing plate. The rear of the chuck body is threaded 1-1/2"-8. If you found the #2 and #3 inside jaws, the #1 is probably there somewhere. If not at your house, it would be worth a trip back to where you bought the lathe to look for that one jaw.

If all that you wanted to do with a collet set was to hold milling cutters, the least expensive choice would be a full set of 3MT and a 3/8"-16 draw bar. These would directly fit the spindle nose taper. However, if what you want to do is hold 3/4" or smaller work, the 3MT wouldn't be a good choice as they only come in 1/16" increments and you can't pass the work through them because of the draw bar and 3MT arbor. I have a 3MT set, a 3AT set and a 5C set, the latter two of which can pass stock or work through the spindle. However, the last two would be pretty expensive to acquire a full set of today. I would suggest either ER25 or ER32, and only with a 1-1/2"-8 threaded collet chuck so that you can pass stock through the spindle. But do not buy a collet chuck with either straight shank or 3MT mount. Neither of these types will allow you to pass work through the spindle. Plus the 3MT requires a draw bar to be safe and the straight shank requires a 3-jaw or a 4-jaw chuck to hold it. Otherwise, the only drawback to the ER collets with threaded chuck is that of all of the types of collets, they are the slowest to load and unload. However, unless you have a job to make a bunch of parts, that isn't a major problem.
 
A number of us have made our own ER collet chucks that screw onto the 1-1/2 x 8 spindle. I made one for ER40 and am very happy with it. There are several tutorials on how to make them. It is a good learning experience.

By thew way, the runout on my 3-jaw is about .014 peak-to-peak. It is a 5" Atlas chuck I assume came with the lathe when new, as Robert said. The chuck has a date stamp of 1951 but is in nice condition. So I assume that even when new the stock Atlas chuck's runout was not great.
 
AFAIK, Atlas never published the expected runout figures for their stock chucks. However, 0.014" isn't very good. And you didn't say at what diameter you got the figure. A well-used chuck may have some flat spots on the scroll. I would suggest that it should be checked at about 1/8" increments say from 1/8" to 2" or larger. And check the actual spindle runout first as it will either add to or subtract from the chuck figures..
 
It was a few years ago that I made that measurement - I don't remember the details at this point. I have work on the lathe, which I don't want to disturb, or I would check now. The socket on the 3-jaw chuck does not seem to be a precise fit onto the spindle registry. But the socket doesn't look damaged or worn. The runout on the spindle registry is good - around .001 or maybe better.

I seldom use the 3-jaw anymore. If the workpiece is under 1" I use the the collets, otherwise the 4-jaw.
 
I found and purchased another chuck with the correct jaws, its an original Atlas 5" chuck and in good condition. Now I need to consider the collet chuck option as well. I am familiar with collets, but not entirely are they only usable when inserted into a collet chuck? Or can the collets be used in the normal 3 jaw chuck? Sorry, I guess I just don't understand the limitations. I also need a Jacobs chuck, is there a size and model that would be most usefulfor the Atlas 10?
 
Here is my thread on making an ER40 collet chuck for my Atlas 12". I pretty much copied the work of others.

www.hobby-machinist.com

Yet another ER40 collet chuck for an Atlas

Just completed an ER40 collet chuck for my Craftsman (Atlas) 12-inch lathe. I followed the excellent drawing by Ronald Crowell, Harold Hall's website, and the many YouTube tutorials. This was a real nice learning experience with a variety of operations... boring a precise diameter, internal...
www.hobby-machinist.com www.hobby-machinist.com

I'd like to have a Jacob's chuck with a through hole that mounts to the spindle, but they sell used for over $100 used and many of them look well worn. I don't think anyone makes new ones currently. The ER40 collet chuck does almost everything a Jacobs would do.
 
First, for what is available that would easily fit the Atlas 10, there are basically three types of collets. The 3MT collets fit the taper in the spindle directly and only require a 3/8"-16 drawbar to operate them. If what you want to do is to hold milling cutters, they will be the least expensive option. However, they only come in 1/16" increments and do not allow you to hold work pieces that are much longer than the collets nor are of a diameter in between 1/16" increments as the gripping range isn't continuous from 1/16" to 3/4".

The other two common types of collets are typified by the 3AT (what Atlas normally sold back in the day) and the European ER. . The former requires a closer-adapter that directly fits the 3MT spindle on a 10" or 12" Atlas (and other makes of similar sized machines such as Logan/Wards, Clausing and South Bend) and a draw tube inserted through the spindle from the left end that screws onto the collet after it is inserted into the adapter. The 3C collet is similar enough to the 3AT that it is easy to get confused with them if you have a pile of both. Both are available in diameters from 1/64" to 1/2". These have the ability to pass the stock through the spindle if you are making a lot of identical small parts. from the same stock. If you had a bed or tailstock turret, you would have a stop set up in one of the turret positions. And part off the previous completed part, index the stop to the active position, slide the stock piece forward against the stop, close the collet, and proceed to make the next part.

The draw tube came as part of two types of closers, The simpler and cheaper type had a hand wheel on the left end that you used to tighten the collet onto the stock. Most of the more expensive types had a lever with stops that you used to tighten or release the collet with. Theoretically you did not have to stop the lathe after parting off the previous part in order to advance the stock for the next one. But I have never tried it.

The much more common 5C collet looks like the 3AT and 3C but about twice the diameter. And the draw tube is about twice the diameter. So to use either the hand wheel or lever operated closer requires a larger lathe with larger spindle taper. However, the Chinese make several brands of collet chucks that will fit the Atlas 10" and both 12". Plus Royal once made a front-mounted lever operated closer that screwed onto the spindle threads and could handle stock up to 3/4" diameter through the spindle. And short parts up to 1-1/16" diameter.

The ER collets are made similar to the collet used by Dremel except larger. They are identified as ER11 through ER50 (AFAIK). Of possible interest to you would be ER25 (.047" to .625"), ER32 ( .109" to .781") and ER40 (.125" to 1.000"). Their closers are often referred to as collet chucks and can be bought or made to mount with a straight arbor, a tapered arbor or with female threads to screw onto the spindle nose threads. Most people who make them buy the closer nut. Whether you buy or make, I would recommend one with 1-1/2-8 threads unless you have a special need that favors either of the others. If you do opt for one with a 3MT tapered arbor, it must be threaded for draw bar and you must use a draw bar or sooner or later you will live to regret it.
 
oldschoolcane said:
I found and purchased another chuck with the correct jaws, its an original Atlas 5" chuck and in good condition. Now I need to consider the collet chuck option as well. I am familiar with collets, but not entirely are they only usable when inserted into a collet chuck? Or can the collets be used in the normal 3 jaw chuck? Sorry, I guess I just don't understand the limitations. I also need a Jacobs chuck, is there a size and model that would be most usefulfor the Atlas 10?
Click to expand...
Ans. 1) Collets fit a tapered receptical in the collet chuck. That taper varies depending on the style of collet. "ER" is the most well known currently, but there are many including an MT-3. But hang on to your wallet when you go looking for one. The collet alone should not be used in a 3 jaw.

Ans. 2) I have, and occasionally use, a Jacobs chuck that fits the 1-1/2X8 spindle nose. But I suspect what you are asking after is a tailstock chuck. The tailstock is MT-2, which is a fairly common size for smaller (<1") drill presses as well as lathes. As with most machine tools, the cheaper the tool the higher the runout. That is a "rule of thumb" and you may stumble into a zero runout chuck for $10 bux. But don't expect it. . .

Most chucks have a "Jacob's Taper" mount, with MT-2 to Jacob's adapter. That combination is readily available with a wide price range. Just remember and heed the rule-of-thumb above. The Jacob's taper has several sizes. If bought separately, be sure of the sizes. Also available from some Sears stores is a 1/2 chuck with 1/2-20 threads and the corresopnding MT-2 to 1/2-20 adapter. They are getting rare but still can be found.

.
 
As Bill wrote earlier, the tail stock arbor has a 2MT taper. So don't buy any drill bits with 3MT tapers. And you probably don't want to pay the extra money for a 5/8" or 3/4" maximum capacity drill chuck as except for Silver & Demming, the majority of drill bits over 1/2" capacity will be MT. .

When picking the tailstock drill chuck arbor, the shorter JT (Jacobs Taper) end must match the drill chuck taper. The longer MT end should be 2MT. If the 2MT end has a narrow flat tang on it, cut it off and carefully grind the cut surface flat. The Atlas tailstock had a feature whereby as you retract the ram, the 2MT arbor runs into the end of the 5/16" ram screw and ejects the arbor from the ta[er in the ram. Using a tanged arbor will cost you about 1/2" of usable ram travel. The most accurate way to do it is to fasten a short piece of half inch round stock in the drill chuck. Use the loose end of the round stock to mount the drill chuck in your 3-jaw spindle chuck. Put the lathe in the slowest back gear speed. If you don't have a tool post grinder, jury-rig whatever you do have to the compound and with the lathe running, grind the small end of the arbor flat.
 
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