Help with a lathe problem

[Denver]

My Sears/Atlas lathe decided to quit on me in the middle of making some sizing dies for my Star luber.
It appears to be in the QC gear box. I had just chucked a piece of 7/8 W1 in the four jaw and started to make a cut when it bound up and started slipping the belt. I shut it off to check things out and narrowed the problem down to the gear box. When I disengage the lead screw, I can turn the spindle by hand or it will turn normally when I start the motor. I want to take the gear box off to see if I can find what's going on in there.
There's allen head cap screws holding the housing on plus the leadscrew enters it also. There's 2 collars where the leadscrew enters the box that look like they have to come off before the box can be removed. The inside collar looks like it has a set screw holding it in place. The outer one has a smaller hole for a pin maybe? Just need to know the proper steps to get it apart without fouling something up.
Any help appreciated.

Denver :castmine:

[R.M.]

Is it possible that you sheared a shear-pin? I'm not familiar with that particular lathe, but it sounds like you twisted a pin off. A lot of machines use a tapered pin, which have to be removed from the proper side.
Just a thought. Something for you to look for.

R.M.

[ARKANSAS PACKRAT]

Denver;.........Look at the half nuts very carefully, my craftsman 12" qc tore up the box because the nuts tried to climb over the threads and bound up the shaft. The final cure for mine was to replace the nuts, guide bracket and the snail. It took all 3 parts to get the nuts to work in correct alignment.
The quickchange comes off easily with the two allen screws and the banjo retainer bolts on the end of the spindle head, it slips off the leadscrew, no retainer, just a slot..
With the lead disengaged, qc in gear, does the gearbox turn freely? If it does, the box is probably not hurt, the leadscrew can be removed from the box by removing the bearing at the tailstock end and winding the carriage away with the halfnuts engaged. With the gearbox and the halfnuts separated, both systems can be checked.
The gearbox is a "project" to tear down, (pictures are great help) there are lots of gears and retainer collars that have to be in exact spots for everything to mesh correctly. I replaced 3 gears and cleaned up 2 others plus streightend a shaft to get mine to turn freely, had it apart 3-4 times.
Good news is Sears has the parts new[smilie=1: ...........Bad news....sit down when you price them, order everything you need at once, they'll kill you with shipping charges otherwise.
Just some advice from someone who know lots more about a qc box than he'd like to!!!!!!!!!!!!:mrgreen:
Good luck, Nick

[Denver]

Still don't know what the problem is/was, but I got her back operating for now. Played with turning the lead screw by hand and was able to shift the carriage to reverse. I was able to turn the spindle by hand, so kicked on the motor and Yahoo! there she goes. Shifted it back to forward and it now seems OK. I still might take the gearbox off to clean and check it, Some of the other gears are getting a bit noisy.

Also,FWIW, Clausing Industrial Inc bought Atlas years ago and they still have parts for the Atlas lathes. They have a toll free number on they're website,

www.clausing-industrial.com

Thanks All for your help,

Denver :drinks:

[Bret4207]

With an Atlas the gearing is made of a zinc alloy called Zamack. It's decent stuff, but any looseness will result in very accelerated wear compared to steel. A loose nut or key can cause this and the lockup you got

[Denver]

With an Atlas the gearing is made of a zinc alloy called Zamack. It's decent stuff, but any looseness will result in very accelerated wear compared to steel. A loose nut or key can cause this and the lockup you got

Thanks. Good to know. The gears are getting a little sloppy and they are the ones you can see when you open the side door. Can't tell about the ones in the gearbox without taking it off or taking the lathe off the stand.

[gzig5]

The gears in the quick change box should be steel. The gears that are used to drive the QC box off the rear of the spindle ( that you see when you open the side door ) are usually Zamak. A bit of slop won't really hurt anything and you can adjust most of it out. Use one or two strips of typing paper and feed it between the gears to set the clearance between the gears. Keep the gears lubes with open gear lube. I found that replacing the two small gears on the reversing yoke with new nylon gears make the lathe ten times quieter. I got the gears from MSC and cut the hubs and bored them to what I needed. The change gears on these lathes are 16DP 14 1/2 PA. Used ones which may be no better than what you have are on ebay all the time, or you can get new steel or nylon gears from MSC.
Greg

[Bret4207]

Blue Ridge Machinery offers gears for the Atlas and there are specialist places you can get them too. Try Googling Atlas lathe clubs and you should come up with 2 or 3 anyway.

[Denver]

[QUOTE=gzig5;203451]The gears in the quick change box should be steel. The gears that are used to drive the QC box off the rear of the spindle ( that you see when you open the side door ) are usually Zamak. A bit of slop won't really hurt anything and you can adjust most of it out. Use one or two strips of typing paper and feed it between the gears to set the clearance between the gears. Keep the gears lubes with open gear lube. I found that replacing the two small gears on the reversing yoke with new nylon gears make the lathe ten times quieter. I got the gears from MSC and cut the hubs and bored them to what I needed. The change gears on these lathes are 16DP 14 1/2 PA. Used ones which may be no better than what you have are on ebay all the time, or you can get new steel or nylon gears from MSC.
Greg[/QUOTE

Greg,

Thanks for the info. I don't recognize MSC. What's the company name?
I'm still having the same problem with the lathe locking up in forward gear. I can run it in reverse all day with no problem.:confused:

[Nueces]

Hi, Denver

Since I'm tuned in, I'll answer - MSC is short for Manhattan Supply, a major US tool distributor. Go to mscdirect.com.

The paper catalog is 3 inches of thin paper.

Mark