Repairing Atlas 10" lathe

[Ross77]

Thanks but I don't think I need another one.......3 lathes is enough for me:heehee:

Or are you tempted??? I think I had a good deal with the Halifax tho..as that is just the lathe for £100+ (they didn't do a 46" either!)

[Ross77]

Yet another cry for help :wave:

I've finally got around to looking at this again, welded up a frame, bolted it all down and leveled it up so its now rock solid, but I'm stuck on removing the spindle from the Atlas fixed headstock to rob the metal pulleys. The split caps on the Halifax were a doddle compared to this.

Ive looked at the 'atlas press' guide online and it makes it sound so easy... I just cant get enough clearance between the main pulley and the bearing housing to remove the woodruff key so the main shaft can slide out.

And I'm completely lost with disassembling the backgear from the eccentric cam...Anyway I'm sure there is some clever person on here that knows :whistling:

[bogstandard]

I'm sorry I haven't been available recently, health and bereavement issues reared their ugly heads.

I have done the spindle removal many times, and there is a definite knack to it.

It is very tight indeed, and the first thing you need to to is get the bull gear back towards the change gear end as much as possible, and the spindle as far forwards as it will go.

Then a slight tap on the top of the key in the position shown on the sketch should rotate the key in it's half round slot. As long as where you hit is further back than the centre position of the key, this should work.





Bogs

[Ross77]

Thanks Bogs. sorry to hear you are not well again.

Unfortunately I couldn't get that to work as I could only see about half of the key. I have no idea how this was assembled in the first place...... I had to resort to the rather drastic solution of filling the key down so it would slide out through the oil seal/collar.

That turned out to be the easy bit as once the shafts were out it was apparent that they are different. the Atlas spindle (top) has only one step in it whereas the Halifax spindle has 3 steps



So rather than just putting the metal Atlas pulleys and gears on the Halifax spindle I had to use the Atlas spindle as well, but due to the different oil seals that meant changing the bearings as well (although its probably a good idea to keep the rollers and shells together anyway.)

The back gear was another pain, I had to use the Halifax mounts, shaft and eccentric cams with just the Atlas gears. I probably didn't need to change it but the Atlas gears are definitely stronger and they also had the spring washers to stop it sloping around.

I think its fair to say that the Halifax isn't a direct copy of the Atlas and not all parts are interchangeable, even the bolts have a finer thread.

[bogstandard]

Ross,

You can make it a lot easier for future events, the dust cover nearest the key can have a small close fitting cutout filed into it, that will allow the shaft to come out with the key still in position. As long as you keep the cutout at the top when you fit the cover into the casting, it will still do it's job of retaining oil in the bearing for as long as possible.

That would also help in getting the outer dust cover off, as the key would push on the inner bearing race and knock the outer cover out when it moves the bearing.

If the bearings have been pre-loaded for any length of time without being run, you will find they may have 'brinelled', they feel ratchety, and as such are of no further use.
The Atlas bearings have a specially shaped outer race and as far as I know, are special order only from Clausing (the genuine US Atlas spares company) themselves, and worthy of a second mortgage.
The inner race is a standard Timken part. I had a friend regrind the inner faces of the old outer races, and then I fitted new Timken inners. That came to a fraction of the cost of new bearings all round. I now have my own facilities to do that sort of regrind if you need it.

John

[Ross77]

You can make it a lot easier for future events, the dust cover nearest the key can have a small close fitting cutout filed into it, that will allow the shaft to come out with the key still in position. As long as you keep the cutout at the top when you fit the cover into the casting, it will still do it's job of retaining oil in the bearing for as long as possible.

Thanks. Thats a good idea and makes perfect sense now I know how the oil system works. Hopefully I wont have to do it very often as I will be using the removable clamp headstock of the halifax.

Not so sure on the the bearings tho. they seemed a bit ratchety when I was cleaning them and rotating by hand but now they are back in the head stock they seem nice and smooth. Which is the best way to tell?

Do you have supplier details and specs for inner timkin bearings? and how much would you charge for the regrind? (rubber cheque book at the ready...lol)

At the moment I'm just rebuilding to make sure every thing works and fits correctly. I will then tear it down to repaint and fine tune. I presume that damaged bearings would give poor surface finnish and could be corrected later?

just out of interest to anyone repairing a halifax with atlas parts. the cross slide screw is the same size and overal length, but the halifax has a longer treaded section and therefore extra travel. I opted for the shorter atlas one as IMO it is a better set up with the adjusting nuts to take out all the slop in the system.

[bogstandard]

Ross,

You need to preload the bearings before checking anything.

With all taper bearings, they need to be overtightened slightly, and when the machine is started after a non working period of say 1 hour or longer, it needs to be run without any cutting being done for about ten minutes.

During this time, the bearings will generate heat, and the lathe spindle will then heat extend by anything up to about 0.005". This then cancels out the preload and you end up with perfect running bearings with no end float. If you don't do this warm up period, and use the lathe straight away from cold, anything you machine, until the spindle has warmed up, will tend to have bad surface finishes and tolerances.

Then, only after this warm up period, can your check the bearings for brinelling. They should feel as smooth as silk, if not, they either need to be replaced or have the races reground.

I wouldn't charge for any work done, just you pay the postage charges. Unfortunately, I am in no fit condition to get into my shop at this time.

If you take the bearings to any bearing factor, they will recommend what is available to you.

For preloading, you should really get the friction figures for the bearing, and using a spring balance and an arm in the chuck, you check the 'pull off' pressure, that is the figure required to get the spindle to turn from a standstill position before spindle warmup, and adjust the end nut until the correct reading is obtained.
If the figures for the bearing are not available, I usually tighten up the spindle until you either start to feel friction against turning or there is no end float, then turn the nut between 1/16th to 1/12th further. This will give a general setting that will work in most cases.

Most the people who have tapered bearings don't do this preload setup, and start to complain when they get rough finishes, then they blame either the bearings or machine, rather than themselves for not setting the bearings up correctly in the first place.

If you are not going to be using the machine for say a fortnight or more, I would recommend you release the preload on the spindle, and preload again when you next come to use the machine. The bearings should then last a lifetime.

I can't work in my shop at this time, but I still go in once a week and spin the lathe up for quarter of an hour. This ensures that the bearings don't 'settle' in a fixed position and they get a bit of lubrication.


John

[Ross77]

OK thanks I'll get it preloaded before testing then. Atlas recommends 1/16" turn (equivalent to two spindle gear teeth). so i will try that.

Its interesting that you recommend to remove the preload if its not being used, being able to look after and set up the machine correctly seems to be more important than knowing how to use it!!!


Thanks for the offer to regrind for free, maybe when your well enough and have finished all your over projects that have been stacking up eh...

With regard to the brinelling is it the rollers that deform or the races? (or both?)

If you don't mind me pestering you (or anyone else in the know) I also have another problem that I'm not sure of the best way to resolve. on the Halifax lathe the apron drive cog and reducing bracket was broken and there is a small groove under the rack were the cog had been rubbing the bed. I have replaced it with the atlas one but when the gibbs are tightened the same thing happens and the drive goes tight and binds.

The easy solution that I can see is to put a thin piece of shim steel on the side of the way to push it over a bit,(not sure how to secure it tho). Or the better but harder option is to pocket the mounts and sink the assembly in a bit. I did think of milling the bracket down but as its made of ZAMAK I didn't want to weaken it.

Do any of those options sound feasible? or have a missed a blindingly simple alternative:heehee:

[bogstandard]

Usually Ross, it is both races that get socketted. Hence my suggestion to get a new inner, and regrind the old special profile outer.

I changed my Atlas from a plain bearing head to a taper bearing one, and the second hand head must have stood preloaded for a few years. It was like trying to turn over a ball bearing detent fixture, it jumped out of one impression and clicked into the next one, hence that is when I found out about grinding and costs of bearings for the head.
BTW, if you used a plain bronze bearing head, you would find that the surface finishes on components are far superior to a tapered bearing head. The taper bearings were introduced to up production rates as they could have a faster running spindle, what you gain in quantity, you lose in quality. I noticed a definite quality reduction when I swapped over.

Another thing worthy of note, the bearings should be oil fed only. If you try to pack a taper bearing with grease more than half full, you run the risk of 'hydraulicing' on the rollers which can lead to roller damage, little and often for oil lubrication, if necessary, fit drip feed oilers if you can.

I can't really understand about what you are saying about the saddle gear and rack, but there is an adjustment cage on the back of the apron that allows for slacker or tighter engagement of the gear. There is an adjustment bolt for it just to the rear of the handwheel. that allows you to move the cage up and down. Also, you will find that if you slacken the two top apron screws, you can shim in the joint to 'kick' the apron in whatever direction is required, but you must ensure you realign the leadscrew afterwards, so that it doesn't deflect when the half nuts are engaged. That is done at both ends of the leadscrew, by shimming up and moving about the reversing box where it bolts to the bed, and the same again at the other end at the break away sacrificial support for the leadscrew.
BTW, don't ever be tempted to replace that break away bearing with anything else more solid, that is a safety feature to protect your very expensive gear castings and apron area plus leadscrew in case you ever have a massive jam up, where the saddle stops and the head carries on turning. That piece is designed to break under such circumstances, when the leadscrew tries to carry on turning, and screws itself backwards thru the half nuts. You should see that it is cast with weakening cut out 'wedges', to control how and when it is to break.
I have seen these lathes where people have made massive bearing block replacements or had a broken one welded up. A very bad idea.

John

[Ross77]

thanks John, concise as ever, so should i upgrade to babbit bearing then?????

Sorry im not very good at explaining things. I meant the adjustment cage you talked about that mounts on the apron and drives the rack but it is rubing on the side of the main bed below the rack.(see pic)



So when I adust the gibbs on the saddle it pulls the saddle over even more.hope that helps.

heres some pics of the lathe as it stands, not pretty but hopfully functional