Repairing Atlas 10" lathe

Hi Ross,

If it was feasible, having a swap over babbit head would be the ideal solution, then you could use whichever one was perfect for the job.

On your first pic, the one with the drill, if you go to the top right, you will see the vertical and horizontal joint lines between the apron and saddle. If you slacken off the apron bolts on the top, you should be able to insert a shim at either end of the vertical joint. I would use a couple of coke can shims, and by doing that, the apron should be moved away from the rack.

If that didn't work, as far as I can remember, the troublesome gear is just held on the shaft by rough peening over. By the marks shown, it looks like the gear isn't square on to the shaft. There would be no harm done if you just took a file to the gear and reduced the high spot until you got no fouling. Maybe try this before shimming.

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not pretty but hopfully functional

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Ross, paint doesn't cut metal, so just being a bit scruffy means nothing, you can slap a bit of paint on anytime.

John

Thanks John

my descriptive skills seem to be lacking.......it isn't the drive cog and the rack that are binding but the face of the cog and the bed.

If it is the rough peening then how much can I remove before it becomes weak?

thanks for the encouragement for less than beautiful machine. personally I agree with you but there is a trend for perfect shiny machinery.......

What John was suggesting was shimming the vertical split between the outer and inner parts of the apron (see arrow in pic). this would have the effect of moving the gear out away from the bed.

However, judging by the position of the marks on the bed the binding isnt the gear itself but the end of the shaft on which it is located. I'd have thought taking a light grind off the end of the shaft/gear face (a few thou) would resolve that without compromising the peening/fitting...

Attachment 2319

Thanks irving and John.

Yes the bind is the end of the shaft but the apron is non movable

Ross,

I'm sorry, I should have said that I realised it wasn't a gear/rack problem.

Irving has said it all.

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but the apron is non movable

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Almost everything on that lathe is moveable, you just need to know how to move it.

The peening, as far as I can remember was a real rough job, and I think I ground down mine to be level with the face of the gear, then centre popped around the edges of the shaft joint to keep the gear in place.

Things like this really are a 'suck it and see' exercise, and you just do what is required to get the machine running correctly. The clones were never meant to be a super high accuracy machine, but with a little work, they can easily be turned into one.

John

I suppose I had better qualify my statement in the last post where I stated that everything is moveable.

My Atlas didn't have a dowel pinned apron, but from your comment, I suspect yours is.

If that is the case, you shim up in a slightly different way to achieve the very tiny movement that is required.

Slacken off the top apron bolts to give you a tiny gap on the horizontal joint. Then you insert a narrow shim into either end of the joint, but very close to the vertical join. When you retighten the joint, you will find the apron has kicked out slightly, maybe with just one coke can shim, enough to cure your interferrance problem.
This will move the apron out by a tiny amount, but I wouldn't go more than a couple of shims as you will be putting a lot of stress on the dowel pins and castings. If you can't get the required clearance by shimming, remove the shims, then resort to grinding or filing a little off the peened area.

John

John,

Without cutting up a coke can to measure (surprisingly I dont have one to hand) how thick is a 'coke can shim'?

Irving,

We only have Pepsi Max in our house (no sugar content), and they usually measure up at between 0.0025" to 0.003" (somewhere around 0.06mm).

Being made of soft ali, if used in between iron or steel parts, they should compress down to about 0.002" (0.05mm) with a little excess pressure.

It really is a very cheap and acceptable material for shimming. Proper stainless shim material can be a little on the expensive side, a small range pack of 6"x4" sheets can easily cost £20

I also use a fair amount of it as protectors between the part and the chuck jaws when turning, it prevents a lot of the bruising you normally get on fine finished surfaces.

So stuff recycling bins, recycle the cans yourself.


John

Ah... dont touch the stuff myself, but my wife is addicted to Coke Zero (if a couple of cans a day is an addiction), but as I put the recycling out yesterday there are none to cut up... I'll acquire a couple in the next day or two...

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My Atlas didn't have a dowel pinned apron, but from your comment, I suspect yours is.

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yes the apron is dowel pined but I suppose I could remove them? Haven't had chance to look at it today but I think you have covered all the options :smile: cheers.

I like the idea of using cans as shims and workpeice protectors, I do have some proper shim steel but I didn't buy it and if its as expensive as you say then when it runs out I'll be using the cans.

I don't drink coke or fizzy drinks much but I'm rather partial to the alcoholic variety and they are bigger cans too.

Just need a rainy evening to get in the workshop.

Well what can I say but thanks again John, Irving :beer::beer::beer:

Grinding the end of the shaft down worked a treat and was far quicker and easier than my suggestions.:rolleyes:

The offending article
Attachment 2332

And after a diet.....
Attachment 2333

In hind sight it was the obvious solution but having some say "yeah I've done that and it was fine" just gives you the confidence before you potentially turn a working bit into scrap.

Going back to the bearings I have put the preload on them and it is still smooth but there is a definite bind/rub on one point of the rotation, does this sound like a problem?

I have read on John Stevenson site that the bearings are hand marked with the precision and the high spot so they can be matched. Before i strip it all down again dose this sound like the solution?

Thanks again and thanks in advance

Ross,

Glad things turned out well. There is always more than one way to skin a cat.

If you can still have easy access to the ground off part, I would go around the square joint with a centre punch, just to make the gear a little more secure.

Don't go having nightmares about the unequal pull off pressures just yet. I would wait until you can run the spindle up before taking any rash measures.

Plenty of oil for lube, then let the spindle run for ten to fifteen minutes, checking on the bearing caps to make sure that things aren't overheating, warm is OK, hot is not.

After that time, let it cool down for an hour or so, then recheck to see if it has the uneven drag.

You have done so much work on it, it could be something as simple as a bit of oil varnish in either the races or on the rollers that is causing the problem. It only takes microns of thickness to show up as uneven.

If it is still at fault, then investigate.


John

yes I will centre punch the shaft now i know it clears OK, I've only got to undo the two screws and the apron is off again.

I think I have also cured the problem with the binding. I just slackened of the preload and bearing caps, few light taps with a nylon hammer and tightened it all back up and it seems to be fine.

I will still wait till i can power it up and give a good run before ultimately deciding if they are OK. If the preload is there to allow for the shaft expanding, would it not be better to adjust it when its hot and then slacken it off again when finished?or is it possible to over tighten and damage the bearings?

Progress is extremely slow at the moment as i can only grab the odd 10-15mins here and there. Still praying for rain so I have an excuse to stay in the workshop all evening:wink:

Ross,

The preload is put on whilst cold, and after the spindle has warmed up, the pressure on the bearings should have been taken off, and you end up with no end float on the spindle.

If you attempt to put the preload on whilst warm, you run the risk of the bearings being too tight when the spindle contract due to cooling, and that might set up a brinelling situation.

John

The rain has arrived....... 3 hours of workshop time and the lathe is running. well sort of. I'm having a mare setting up the belt tension and alignment on the counter shaft. I fitted the metal atlas pulleys and shaft because it also has roller bearings but the end pulley is damaged and out of balance causing a vibration. I put the complete Halifax counter shaft on but now there is a nasty/annoying clanging noise coming for the spindle shaft. It seems to be the small amount of play where the final drive gear locks to the pulley assembly for normal speed. if i reduce the belt tension it helps a bit but i don't think then it would then be tight enough in use :eek:

I have run it for quite a while and kept the oil topped up and the spindle spins freely but there is still a small amount of binding at one point. Is it likely that it is this slowing up that is causing the pulley to bang against the locating pin?

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If you attempt to put the preload on whilst warm, you run the risk of the bearings being too tight when the spindle contract due to cooling, and that might set up a brinelling situation.

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OK wont do that then :smile:

Thanks in advance

Solved the binding, the idler on the end of the spindle for the lead screw drive was loose :rolleyes:

Finally got the lead screw and reverse gear box working nicely, had to resort to using the Halifax gearbox with the atlas gears, 1st drive shaft and selector nob and plenty of grease.

I tried machining the small pieces of ball screw that Gary gave me but not much luck :thumbdown:

I thought the tool post I had was very sturdy but seeing it move out of the way instead of cutting the screw proves otherwise.

Attachment 2421

So I'm going to put the tee slot table on, get a QCT and some new carbide tooling

Attachment 2422

The only problem is that I didnt get the gib. So my question is how can I get around this? will a small strip of brass be ok? something in the back of my mind tells me that only precision ground steel will do :eek:

On my Atlas, they started off as ptfe gib strips (which I now think is standard issue), but they can be almost of anything, brass, bronze (recommended) or mild steel, and yes, they will need to be a nice constant thickness along the length. Nothing too exotic, but you do need to angle the narrow edges so that they sit in their position nice and snug, with only about 0.25mm (0.010") adjustment gap.
Also put countersinks into the wide side for the grub screws to sit into and hold the strip in position even if the gib is slack.

John

Thanks John, forgot about this little problem. I got sidetracked with the newest edition to the CNC family.

Ptfe? I'm only familiar with the plumbers tape, can you get it as solid as well then? Any one with a surface grinder that could Knock me up a new gib strip? (not you John I know your not well,:thumbdown:)

Before I get too ahead of myself I also need to check headstock and tail stock alignment and carriage alignment, Ive seen various methods for each element but is there an order to which they should be checked and which is the best method given that I have completely striped and rebuilt it, Any pointers would be good (the bed was leveled with a precision level, not sure of the spec but moved at lot even when a rizzla paper was put underneath)