Atlas Mk2 6" lathe teardown problems

[Parufus]

Hi, I am new to machining generally, having started out with watchmaking lathes. I recently acquired a well used but more or less complete Atlas 6" Mk 2 lathe.

My main concern is the spindle does not turn very freely. A am assuming this is due to grotty bearings and was expecting to replace them in this process. I am not sure what a really free spindle in one of these feels like, but given how light it is, I would imagine it would spin somewhat freely as opposed to requiring firm pressure to move it. If this amount of resistance is not an issue, I'd be tempted to forego any more messing with it... it certainly moves under power.

I have managed to disassemble the majority of it, but there is one area that is stuck and I am unable to free it.

The innermost gear on the spindle shaft (that engages with the back gear mechanism) and the spacing/clamping collar to the left of it are not moving. I took out the grub screws in the collar, and it has 1-2mm of rotational play and along the shaft, but will not slide off. I understand there is a Woodruf key for the gear, but it does not engage on the collar, as I have enough clearance to see the shaft and have cleaned up the old grease. I put long screws in the collar's grub screw holes and tried applying a bit more force/torque, but it only rocks a bit and slides axially even less. If the grub screws bit into the spindle, like they seem to on the left end, then it might have pushed up a bur that is limiting movement, but this seems like more than something like that. Even if it does, this shouldn't keep the ring from sliding off the shaft. I tried blocking it up and beating the spindle out (relatively gently) from the back with a deadblow hammer and it did nothing, same play, no movement in the spindle or front bearing. If I were to use a jack to press out the spindle at this point would the gear and ring get forced off, or would I just break everything? I was also thinking a gear puller would be useful, but I am worried about the zamak cast gears, as I am told they are fragile.

Having watched a couple of other atlas bearing replacements (for other lathes) on youtube, I am a little surprised at how firmly this seems to be put together... I am assuming I will need a press of some sort to manage this? I was thinking a bottle jack?

Anyhow, if anyone has experience tearing down and putting new bearings in one of these, or more generally, I would appreciate hearing about it.

Thanks!

 

[markba633csi]

My first thought would be to leave it alone since you are most likely to break something if you don't have a proper press and tooling.
I have a MK2 also but I have never pulled the spindle. If the spindle turns smoothly without roughness then I would say it's normal.

Some resistance is fine, it just means there is a good firm preload on the bearings. On a machine like this with a short spindle with closely spaced bearings it's a good thing. I would focus on other areas of the machine to improve. You'll find them.
There are both ball and roller bearing headstocks- do you know which type you have?
Atlas or Craftsman branded machine? Model number?
-M

 

[MYoverI]

Parufus,

I am currently disassembling a Halifax lathe (a direct clone of an Atlas 10"), it should all slide apart but if you have a roller-bearing model as I do , be prepared for some sticker shock if your model requires stepped outer shell bearings. The ones I can find are all around the $200 mark...

 

[markba633csi]

MYoverl: The MK2 headstock is a completely different beast than the other Atlas models- another reason for my "leave well enough alone" comment

 

[Parufus]

Not sure RE model/serial #, can't check right now.

Thanks for the heads up... frankly the bearing replacement felt like a big stretch of my limited capabilities in any case. It doesn't grind when it moves, and doesn't have any runout or anything, it just feels like old lube... a little bit of tackiness in the end feel of the motion.

I will let sleeping dogs lie.

All that said, I am still curious about the collar... from the manual it looks like it should just slide on/off but it is really not moving.

 

[markba633csi]

You are making the right decision, believe me. You don't need the heartache of having to buy a new headstock (although they aren't too expensive used)
You'll probably find the drive belt idler pulley chatters like crazy unless constantly lubed. You might try some heavy grease on the shaft. My final solution was to install a needle bearing but that's an advanced project- You could probably dispense with the idler altogether I think, if you don't change the belt position too often. Just move the motor.
If you are planning on making a lot of small parts you might consider buying a set of MT2 collets and making a drawbar for them. Much better than a 3-jaw chuck for repetitive operations. But you need both 3 and 4 jaw chucks also.
Also, try to stick with HSS tooling rather than carbide. Get a small bench grinder and practice grinding your own. It's a valuable and satisfying skill.

 

[Aaron_W]

I've been cleaning up a prior generation 6" Craftsman that I bought last year. Without the belt the spindle turns easily, but the belt adds a fair bit of drag. I wonder how much of what you describe is simply caused by the belt and related bits rather than actually being the spindle being tight.

The other thing I've encountered is the one I have is in very nice shape, but it sat unused for quite some time. It was covered in a solid layer of dirt / dust and much of the lubrication oil has dried into a glue like consistency. The lead screw, feed lever and threading dial were completely frozen solid, until I was able to disassemble them and clean out all the old oil. Many hours of repeated soaking in WD40 and PB Blaster helped me get them apart. Now cleaned up and lubed with fresh oil they are turning very smoothly as they should. The spindle was also a little tight at first, but I filled the oil cups with WD40 and kept turning by hand, and eventually got it turning easily. WD40 isn't a good lubricant but it does a nice job of dissolving old oil and grease.

 

[Parufus]

You are making the right decision, believe me. You don't need the heartache of having to buy a new headstock (although they aren't too expensive used)
You'll probably find the drive belt idler pulley chatters like crazy unless constantly lubed. You might try some heavy grease on the shaft. My final solution was to install a needle bearing but that's an advanced project- You could probably dispense with the idler altogether I think, if you don't change the belt position too often. Just move the motor.
If you are planning on making a lot of small parts you might consider buying a set of MT2 collets and making a drawbar for them. Much better than a 3-jaw chuck for repetitive operations. But you need both 3 and 4 jaw chucks also.
Also, try to stick with HSS tooling rather than carbide. Get a small bench grinder and practice grinding your own. It's a valuable and satisfying skill.

Thanks for the advice. I have a lot of positive experience with collets coming from watchmaking lathes, so I will start shopping for those. I've been learning how to grind tools, and it is indeed fun, and one of these days I might actually make something usable. I only got a 3 jaw with it, but would really like to find a 4 jaw. I am assuming nobody uses the lantern tool posts?

I've been cleaning up a prior generation 6" Craftsman that I bought last year. Without the belt the spindle turns easily, but the belt adds a fair bit of drag. I wonder how much of what you describe is simply caused by the belt and related bits rather than actually being the spindle being tight.

The other thing I've encountered is the one I have is in very nice shape, but it sat unused for quite some time. It was covered in a solid layer of dirt / dust and much of the lubrication oil has dried into a glue like consistency. The lead screw, feed lever and threading dial were completely frozen solid, until I was able to disassemble them and clean out all the old oil. Many hours of repeated soaking in WD40 and PB Blaster helped me get them apart. Now cleaned up and lubed with fresh oil they are turning very smoothly as they should. The spindle was also a little tight at first, but I filled the oil cups with WD40 and kept turning by hand, and eventually got it turning easily. WD40 isn't a good lubricant but it does a nice job of dissolving old oil and grease.

I had the same experience with the lead screw... When I got it home I thought I was screwed, but after a lot of coaxing and oil it freed up well... The worst part for me was the screws holding the headstock to the ways... they were rusty and kind of abused Philip's head, and I had to turn the screwdriver with my biggest vicegrips while putting a lot of weight on it, so I think they are going to get swapped out for hex-socket screws. The drag I was discussing was on just the spindle, with no belt or gearing on it. Like I said, it ran with the motor hooked up, but it is stiff to hand turn.

 

[markba633csi]

I used a little tool post from my Unimat lathe for a while till I made this Norton style post:
Most folks buy the QCTP from China but I wanted a challenge- works good