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Atlas/Craftsman 12x36" lathe...questions

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markba633csi

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I think it requires a knife-edge style puller to remove the front cone bearing properly, although I have not done it on mine
 

wa5cab

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Until you get more familiar with it, that is probably the safest thing to do.

ISO 68 is the metric more-or-less equivalent to SAE 20. Mobile Heavy Medium Circulating Oil is what I used for several years. Last time that I needed to replenish, Tractor Supply was carrying SAE 20 ND. But someone recently said that they had discontinued it.

On the open gear grease, look for some that mentions use on open gears. Or if you can't find that, use some that is listed as graphite bearing or carrying with a temperature rating above 100C or 212F. The problem with most of your garden variety grease at the auto parts places is that it'll melt at only slightly above 100F and will quickly sling off.

FYI, the French company TOTAL bought Keystone many years ago. One of the first things that they did after taking over was to discontinue the No. 122.
 
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TonimusMaximus

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Former ASE parts guy here. Molybdenum disulfide disk brake wheel bearing grease is great for gears. Good stickiness and doesn't drop off until at least 300*F. Stuff is a bit messy to apply, but generally stays where you put it. Acid brush works good for gear applications. The disk brake wheel bearing greases are rated for much higher heat than traditional wheel bearing grease due to heat soak from brake disks.
 

wa5cab

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Thanks. That sounds like something that would be easier to find that what I described earlier. Does it usually come in tubes or cans or squeeze containers?
 

TonimusMaximus

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Comes in both tubs and grease gun tubes. You may be able to find some in a squeeze tube, but those are rare.
 

Jason280

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I've made a little progress with the lathe. I was able to get the tailstock completely disassembled, but its still a little stiff...the quill/ram really needs to be turned itself, and cleaned up with some 500-1000 grit sandpaper. I also picked up a thread dial, and mounted it in place.

I did run into an issue, but I think it is simply a lack of understanding on my part (at least I hope). I disassembled and cleaned up the 3 jaw chuck, it was pretty gunky and difficult to adjust. Got everything together, and the jaws meet perfectly in the center, except I cannot get a piece centered in the jaws. I checked runout at the side of the chuck, and its no more than .003-.004", but runout with a piece in the jaws is bad enough you can see the wobble. I can gently tap the piece and get it maybe to 10-12 thousands, but that's about it. Granted, I don't have a piece of rod stock that I know is perfectly straight, but I don't think it would make a lot of difference.

Is there a trick to getting pieces correctly centered in a 3 jaw chuck, or is it likely the chuck itself? I haven't tried the 4 jaw yet, and haven't actually tried it under power...this is with me slowly rolling the headstock via the main pulley.
 

wa5cab

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The only "trick" that I know of is that you should have one jaw at BDC (doesn't matter which one except for the practical requirement of having the chuck key on top) when you tighten the jaws. If you have one jaw at TDC, the workpiece will tend to get pinched between the two lower jaws as you tighten them. Make sure that you have all three jaws in their proper slots. Both the jaws and the slots should have 1, 2, or 3 stamped on or beside them.
 

Jason280

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Yes, I have them in their correctly numbered positions. I haven't tried with one of the jaws at 6 o'clock, I'll give it a shot. I can tell you that about the best I can get is *maybe* 15 thou, and that's with a lot of tapping....worst case is, I may end up having to grind a little off 1 or 2 of the jaws.



 

Jason280

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Another question, trying to figure out a few things with the back gear assembly that changes to direct drive/low gear. My understanding is you pull the pin on the main gear, then roll the eccentric to engage the two back gears to lower the speed. Is this correct?

The rear gear (#10-242) in the headstock, which the large gear from the back gear assembly engages, has clutch dogs (not sure that is the correct term) that mesh with the rear of the pulley assembly. The pulley assembly can be slid forward enough that it completely disengages the rear back gear....what is the point of this?


 

jwmay

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The bull gear has a set screw and is keyed to the spindle shaft. When in back gear, that pulley drives the small gear on the left through those “clutch dogs, which drives the back gear assembly, which drives the bull gear, which drives the spindle. Slide the pulley back into engagement with the small gear on the left, and tighten the set screw in the bull gear that is on an angle after it’s all together and your two spindle gears are in line with your two back gears. Before you tighten it, it may behoove you to remove the set screw and drop a small piece of brass or copper wire into the hole, to avoid upsetting the spindle where the set screw bears. But before you do any of that, wait for Wa5cab to reply, just in case I’ve missed something.
 

wa5cab

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Another question, trying to figure out a few things with the back gear assembly that changes to direct drive/low gear. My understanding is you pull the pin on the main gear, then roll the eccentric to engage the two back gears to lower the speed. Is this correct?
Yes, that is correct. When in back gear, the pulley will make about six revolutions while the bull gear and spindle are making one.
 

wa5cab

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There is a shoulder on the spindle against which the collar to the left of the small spindle gear should sit. Loosen the set screws in the collar and push the collar toward the tailstock without rotating it and re-tighten the set screws. Pull out the direct drive pin and confirm that the pulley is free to spin on the spindle.

There is an oil plug at the bottom of one of the pulley grooves. There have been a few reported cases where a PO has somehow forced the set screw/oil plug on down and against the spindle, which locks the pulley to the spindle. If you pull out the direct drive pin, engage back gear, and try to start the motor, either the motor stalls, the belts slip, or the pulley slips and the screw damages the spindle. If this has been done to your machine, back the oil plug out three or four turns, and find a short (3/16" or 1/4" set screw to put down in the hole and lock the oil plug. But hopefully this hasn't happened to yours. If it has, there is nothing to do about it at this point but if you ever pull the spindle, you will almost certainly have some difficulty in getting the spindle through the pulley. And you will need to replace the damaged pulley bushing that results when you pull the spindle through it.

At this point, since odds are that it hasn't been done in years, oil the pulley bushings. Pull out the direct drive pin and slacken the belts. Remove the oil plug from the pulley groove. Put about three squirts of SAE 20 ND through the hole and reinstall and tighten the plug. Tighten the belts, start the motor and let it run for 10 or 15 seconds. If you haven't done this in the past month, repeat twice.

Slacken the belts, pull out the direct drive pin, and check the end float of the pulley. The books don't give a figure but there should be definite movement, maybe 0.003" to 0.010". The only adjustment would be to move the bull gear, which might take it out of alignment with the small back gear.
 

markba633csi

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My personal rule of thumb is to chuck the chuck. Well, I mean that many older lathes are sold with chucks that are so worn they have done their best work and need to be retired. You might be able to improve it a bit but I wouldn't spend a lot of time and effort. Use your 4 jaw for accuracy until you can afford a decent 3 jaw
Mark
 

Jason280

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Most of that makes sense, but its still a little confusing!!
 

wa5cab

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Part of what Mark is alluding to is that the scroll disk wears both in the threads and in the spigot and hole that it runs on. The common way of re-grinding the jaws using a pre-loading jig plate is not really satisfactory in my opinion as the gripping surfaces end up with a radius ground on them instead of the original flat. There is a way around this as all of the Atlas lathes have a 60-hole index in the bull gear but it still doesn't do anything about the scroll.

So he is saying that if the chuck is worn out, it is just worn out.
 

Jason280

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Any suggestions on a decent 3 jaw replacement? Shars lists a 6" 3 jaw for 1.5x8 spindles for $150, and I'm sure prices go up from there.

Actually, now that I think about it, doesn't a South Bend B9 have the same spindle thread? If so, I could always try the 3 jaw chuck from the one I have...

Also, and I assume this is pretty straightforward, any special technique for removing the spindle adapter?
 

wa5cab

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Yes, the SB 9A, B and C all have 1-1/2" - 8 spindle nose threads. So anything that will screw onto an SB 9" spindle should also fit the Craftsman 12".
 

Jason280

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My plan was to try my SB 3 jaw chuck this morning, except it seems to be stuck pretty firmly in place. I didn't have time to try and muscle it off, so I'll have to try again tomorrow. Hopefully the runout on the SB chuck is much better, it would definitely make things easier.
 

wa5cab

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Well, good luck.
 

Jason280

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No luck on the SB chuck, it must have a different thread pattern....it will barely start threading on, and then stops.



 

wa5cab

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They are both nominally the same 1-1/2"-8 threads. The difference has to be in the details. Carefully measure the diameter of the registry and major diameter of the threads on the two spindles.
 

jwmay

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I’ve read something about them not being compatible, but wasn’t sure enough to say so. Unfortunately, I cannot remember exactly why.
 

Jason280

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I'll mic them once I get a chance, but a little surprised it wouldn't work.
 

TonimusMaximus

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I'd be willing to bet the major diameter is different. Ran into the same issue when I re-barreled my Savage rifle. Only went about 1/4 turn then bound up. I ended up knocking down the major diameter on the barrel. Doubt I'd try that on the lathe spindle, though...
 

wa5cab

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Most likely. If the chuck had to be usable on the Atlas, you would need tp chase the threads in the back plate. An possibly adjust the register bore. But that would make it unusable on the SB. So best bet is go buy another chuck.
 

Jason280

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Interesting thing I noticed earlier today with the lathe. I've been going through the gears in the quick change GB (while rotating the spindle by hand), but cannot get the left lever into the "E" detent. I can get it close, but not quite all the way. I've also noticed that with some settings on the QCGB, it becomes difficult enough to rotate the spindle that it causes the belt to slip. Now, I haven't actually tried it under power, wanted to make sure all the bugs were worked out first.

I assume I will probably need to pull the QCGB and check it, anything else I should be looking at?

eta: Also, how do I correctly "size" the belt running from the electric motor to the main pulley? I know the length isn't too much of an issue, but how thick should it be and should I use a cog/notch style or standard V pulley?
 
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jwmay

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. I've also noticed that with some settings on the QCGB, it becomes difficult enough to rotate the spindle that it causes the belt to slip.
There will be different levels of resistance between different settings on the QCGB, depending on how many gears are being used to get that feed rate. But I've already lost confidence to continue with this train of thought. I don't have a gearbox on mine, so maybe that idea is all wet. I do agree that you're gonna have to at least get down and look up in there, to see what's stopping your E selector. Maybe it's just full of chips and gunk. Oil gets pretty hard after a few decades of sitting around. It may just be that. Maybe just spray brake parts cleaner up in there, and see if anything changes. The standard application is one full can according to Mr. Lyle Peterson. My Youtube shop teacher.

should I use a cog/notch style or standard V pulley?
Standard V pulley, or link belt. It's been suggested not to be cheap when selecting the link belt. I've got enough faith in the recommendation to agree. While any brand new V belt of proper size will probably do the job equally well. As I've been putting mine back together, I've already realized that once all the extra hardware is on the headstock, I'm not going to want to take it back apart to get the spindle out and change the v belt. So, I'll more than likely be buying a link belt whenever the need for replacement is apparent.
 

wa5cab

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The Atlas 10F and Craftsman 12" made prior to 1957 use Fractional Horse Power (FHP) V-belts with part numbers beginning with 4L plus a 3-digit number which is the belt length in tenths of an inch. The single digit before the "L" is the nominal outside belt width in eighths of an inch.

There is no good reason to use a link belt for the motor belt unless you already have enough new and good quality links to make one up. Otherwise, you are just spending more money.
 

jwmay

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Agreed. I wasn’t paying attention to which belt the OP was asking about. What about the gearbox problem Wa5cab? Any historical problems he should be informed of? Are those gears zamak too?
 
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