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dnalot

dnalot

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A friend of mine's dad passed away and left me his old atlas 10" lathe. Its had very little use and was kept in a dry shop and sprayed with oil from time to time. For a 55 year old lathe it looks really good. Everything works and it runs smooth.
The real score though was the tool post grinder it came with. Also included were milling attachment and several unused chucks and 50 pounds of cutter bits from 1/8" to 1/2". I was thrilled to see it had the quick change gears and the 54" bed (36" between centers).

Here is the question, it is cutting a slight taper( .003" in 4", is there a way to align the power head to the bed on this lathe? I have the machine leveled and bolted to the floor and i found no twist to the bed or humps in the bed.

Atlas 10F.jpg
 
nice score!

first you would have to ascertain where the taper is coming from.

the bed might be low and the tool bit moves vertically.

the headstock might be misaligned as you said.

the carriage might be moving to one of the sides.

once that is determined should be an easy fix. the headstock can definitely be re-aligned, even if it takes some shimming.
 
If your talking about the piece sticking out of the chuck cutting at a taper, you might want to just chock it up as the metal deflecting. Try turning between centers.
Also check the headstock bushings for play.
 
Good suggestions. The part in the chuck was to give me a handle to shake the chuck while checking for a lose fit on the spindle bearing. There was a lot of play so i tightened it snug plus 1/16 turn as per specks. My test cut was on a piece of 1-1/2" stock chucked close. I have the carriage and cross feed adjusted up snug and there is very little play there. There is a noticeable amount of play up and down on the carriage to bed but that is not adjustable.
 
Check your tailstock alignment first. In the Atlas lathe book: "Manual of Lathe Operation", this is discussed in a section titled:" Realigning the tailstock after taper turning". The technique is also in "How to Run a Lathe", by South Bend Lathe.

Check out mrpete222 on Youtube. He shows different ways to do this in his videos 78,79.95, and 96.

Tom
 
Another way to test the run out is chuck a piece of straight ground drill rod that will go up the spindle , face off and centre then move it so that only an inch is held in the chuck , bring the tail stock with a centre up close lock off , and watch when you touch the centre in for deflection of the rod , that will tell you which adjustments are needed .
 
Removed the head and cleaned up the mating surfaces and re installed. The fit is just a littttle sloppy so I pushed it tight to one side and tightened it. Test cut showed a noticeable improvement so I will do some shimming. After that I will work on aligning the tail-stock. I think will a little work this old machine will work just fine.
 
If the photo you posted is the setup you used to turn the work. Your issue is likely deflection, you have what look like 6" of stock sticking out of the chuck, deflection is huge.
 
dnalot said:
There is a noticeable amount of play up and down on the carriage to bed but that is not adjustable.
Click to expand...
First of all, congratulations of your inheritance, and with the QC gearbox too!. That alone is worth the price of admission. The carriage sliding clearance IS adjustable and is done by changing the long brass shims (#711-007,008,009,010) between the carriage slides and the bearing plates. This may or may not help the situation because there may be localized bed wear in which case it may slide well in one area of the bed and bind in another. My experience (with several older Atlas lathes) is that it's not unusual for an older Atlas to face from .001" to .003" in 6" concave when facing. The owners I knew (including myself) tended to work around this, which was fairly easy because we all did smaller diameter hobby work and rarely fully faced anything that approached a continuous 6" diameter.
In working this out, I would investigate all possible culprits before I resorted to messing around with the headstock fit.

CARRIAGE.jpg
 
Last edited:
When checking the headstock for alignment the test cuts should be done without the tailstock. If the tailstock is out of centre then this will introduce a taper, by not using it you remove the risk of introducing errors. On our large Colchester the official test is a 2" diameter steel bar, sticking unsupported 6" out of the chuck. Using this size removes the risk of deflection.

If you cannot adjust the headstock, the taper can be removed by adjusting the right hand forward leg support. If after the test cut the stock is larger at the end furthest from the headstock then the right forward leg needs to be raised. If the end furthest from the headstock is smaller, then the leg needs to be lowered. (Think of the bed twisting as you adjust the pressure on the foot, moving the tool into, or away from the stock) When adjusting the foot, the slightest turn will make a difference to the test cut so i would recommend setting up a DTI in the tool holder and setting it up against the stock at the point furthest from the headstock. Have a friend watch the DTI whilst you adjust the foot so you know when you have it right.

Only when you are satisfied the headstock and bed are in alignment should you centre the tailstock.

Hope this makes sense and helps you out

Regards Dom
 
you need to very precise (0.0001 or better) indicators. Tram a tram bar to the spindle. True the spindle to the way using the tram bar. Then check the tailstock.

That's over simplified but excluding the time involved it's really that easy :p
 
Starting at the beginning, I notice your lathe is bolted to a wooden bench top. If this is'nt all square you could be torqueing the lathe bed.
Loosen the tailstock end bolts [which in imo should'nt be tight anyway] & check again.
If no change get onto some of the ideas already given.
 
Nice inheritance. good luck . and like aone pointed out that part stick out is too long unsupported. rule of thumb is about 3 times diameter.
Tin
 
I have that same lathe of about the same age, but not in such nice shape. I had a taper issue as well. It is very unlikely that taper is caused by a mis-aligned headstock. The headstock on the atlas is bored while on the lathe bed, and is not adjustable. If you have the proper pre-load on the bearings, and they aren't worn, then the problem is somewhere else.

First issue is lathe bed alignment. Level the bed as accurately as you can, preferrably with a machinist's level. There can still be a taper from wear in the lathe bed or other components. When you have chased down all the other problems, if there is still a taper, you can correct for it by shimming a litle twist into the lathe bed, but you want to eliminate all other possible causes first. To eliminate worn chuck problems, use a 3MT collet in the spindle and a 3/4" test bar when testing for taper. Use a dial test idicator. Checking in this way will eliminate deflection from cutting pressure. Slop in the carriage cross-slide or compound gibs can be a problem. Also, mis-alignment of the lead screw and half nuts can pull the cross slide out of alignment and induce a taper.
 
Thanks everyone. Free lathe, free advice, now all I need is some free metal.

Our local professional machinist is coming over this weekend with some tools that I don't have. He laughed when I told him my problem and asked what I expected from an Atlas. With that said he told me he could make it right in an hour or two if the machine is not too worn. Between listening to you guys and watching what he does I think this is going to be a very good learning experience. Bartering for the service with some CNC sign carving. My time is free my wallet is empty.

Mark T
 
You are fortunate to have a pro to help you. If you haven't been through the process before, it can feel like chasing your tail. If you have, you get a sense of how to test and adjust accurately. As to what to expect from an Atlas, I don't think there is any reason that you can't get your Atlas to cut within .001" of cylindrical over, say, 4 or more inches, with a good chuck, the proper adjustment and possibly the replacement of some easily available wear parts. If you need better than that, you can always set up the part between centers, and adjust the tailstock to get it cutting closer to a true cylinder. I just recently turned a 3/4" piece of drill rod down to 9/16" over 3 inches, using an E32 collet chuck that screws onto the spindle, and miked each end with my brand new Mitutoyo digital mike, and it was within .0005 difference at the two ends. And my lathe is a lot more worn and beat up than yours appears to be. A better machinst than me could doubtlessly do better, but that was more accurate than I needed for the part. When you are that close, things like the type and geometry of the cutting tool, the type of material you are cutting and the depth of cut affect deflection and therefore taper.
 
There could be one of a half of a dozen things wrong. First off is deflection of the material. Second is the lathe is bolted to a wooden table, third is that it is bolted to the floor, fourth is that do you know whether the floor is level or not, five is that you have everything bolted down tight causing twist, sixth is the grind on the tool bit you are using.

First off, i would loosen the bolts on the floor and see if you can slide shims under any of the four legs. Then I would chuck up a piece of steel short, and put a center in it. Then I would turn the piece between centers or at least a center in the tailstock. For your final pass, you only want to take a couple of thou.
 
Problem solved

My guy checked my leveling and found it to be good for the level I used but made a few minor adjustments using his precision level. Some of you had mentioned the wood table top, that really wasn't an issue as there is a steel bushing that passes trough it connecting the lathe directly to the steel legs. There is a very small gap (now a little larger due to shimming) My floor is crappy so the legs were leveled and then the lathe to legs. The real problem was the chuck. Once it was removed you could see six screws that hold the back plate to the chuck. These were a little lose. Snugged those up and the machine is now cutting very well. The Pro said it was the nicest Atlas he had seen in years and didn't know they ran that quiet when they were new. I was tempted to paint it but as the paint is original I think I will just buff it down with some compound and let it be.

Mark T

Thanks again for all the suggestions
 
Nice be thought of when things wind down. Hope you treat the memory well.
 
I should have asked what type of level you used. I was fortunate when I purchase my south bend I worked in a machine shop. we did precision grinding and was allowed to borrow a very nice precision level. I now own a precision level. It is an import.
tin
 
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