Levelling and Alignment - Is this run out due to bed wear?

[Richard King 2]

The other fellows have it.... the dirt gets under the saddle under the worn wipers and the bottom of the saddle gets high in the middle and rocks when you change directions like a Rocking Chair does. Unless your planning on scraping it, there is not a lot you can do. The bed ways look bad too and as you said the bed is worn near the chuck and that is why your indicator is moving plus as you stated. Is these issues causing a problem for you when your using the lathe? Many see the BIG error when using a tenths indicator and go nuts trying to figure out the problem. As Isaid, are you seeing issues when your using the lathe? If not clean, oil and put it back together.

I have twisted a end to end level/aligned bed so it will compensate for the worn spot near the chuck, so that can be done, but that will affect turning between centers and boring a hole. If you don't turn between centers or bore on the machine I can tell you how to twist the bed. It looks like your headstock is on a swivel pin? If it is you can also move the head pointing to you on the tailstock end to compensate for push away and the wear. Again as long as your not going to turn CC and bore.

If you want to learn to scrape then we can try to help you do that, but you will need to buy or borrow some tools. Rebuilding the lathe will probably cost you more then your willing to spend. Your machine is how old? 1960's? Darn near 60 years old, that's not bad for a machine that old. It like us old farts we have pain and issues after using it so long.

 

[SnakeyJ]

The other fellows have it.... the dirt gets under the saddle under the worn wipers and the bottom of the saddle gets high in the middle and rocks when you change directions like a Rocking Chair does. Unless your planning on scraping it, there is not a lot you can do. The bed ways look bad too and as you said the bed is worn near the chuck and that is why your indicator is moving plus as you stated. Is these issues causing a problem for you when your using the lathe? Many see the BIG error when using a tenths indicator and go nuts trying to figure out the problem. As Isaid, are you seeing issues when your using the lathe? If not clean, oil and put it back together.

I have twisted a end to end level/aligned bed so it will compensate for the worn spot near the chuck, so that can be done, but that will affect turning between centers and boring a hole. If you don't turn between centers or bore on the machine I can tell you how to twist the bed. It looks like your headstock is on a swivel pin? If it is you can also move the head pointing to you on the tailstock end to compensate for push away and the wear. Again as long as your not going to turn CC and bore.

If you want to learn to scrape then we can try to help you do that, but you will need to buy or borrow some tools. Rebuilding the lathe will probably cost you more then your willing to spend. Your machine is how old? 1960's? Darn near 60 years old, that's not bad for a machine that old. It like us old farts we have pain and issues after using it so long.

Thanks Richard, I have read your threads and watched some of your videos and appreciate your vast experience here. I will clean it all up and reassemble to see how it goes. The point on tenth guages is valid and I don't need to work to high tolerance as mainly playing in my garage. I think the lathe is about 72, so five years younger than me but it's definitely working better - my back is quite rough after 3-4hours in the garage this morning!

Oh yes, sorry the headstock does swivel on a pin and has an offset screw mechanism - the alignment is as good as I can currently get it at 11", but might get a few tweaks once everything is rebuilt.

 

[Richard King 2]

You can twist the bed or head so it will not turn a taper at 6" where the wear is. Your never going to turn a shaft 11" long with-out the Tail-stock center are you. That would be an accident waiting to happen. If you do get a taper between centers you can file or emery cloth it straight. Like I said and you agree, tenths indicator on a machine 72 years young is not needed. It's fun to see, but the machine probably was never .0005" when new.

 

[SnakeyJ]

You can twist the bed or head so it will not turn a taper at 6" where the wear is. Your never going to turn a shaft 11" long with-out the Tail-stock center are you. That would be an accident waiting to happen. If you do get a taper between centers you can file or emery cloth it straight. Like I said and you agree, tenths indicator on a machine 72 years young is not needed. It's fun to see, but the machine probably was never .0005" when new.

I've got a few tapered test bars from previous iterations of levelling and alignment. They are definitely getting better in both parallel and finish, but the starting point was pretty ugly.

My last job before this was putting an MT2 taper on an 20mm bar, as an alignment aid for my mill/rotary table. Turned between centres, but very decent fit and surface finish and the alignment looks great according to the dro.

The next job was to face and machine the register on a D1-3 camlock backplate for a trugrip 5C collet chuck. I was trying to tighten up the alignment to get this as accurate as possible. I'll probably drill and tap the bolt holes on the mill/rotary table, as my toolpost drill is still a WIP and lathe headstock dividing is just at the thought stage until I can turn up a decent worm and gear!

As a correction, the lathe is circa 1972, so 48 rather than 72 years old and I'm staring down 52 in the coming month - though with my back in spasm I'm feeling at least 77 ;-)

I have posted the manufacturers standard accuracy chart for this lathe in another thread before, it's not actually my serial number but is the right age, model and metric spec. From memory the only measurement in microns was the spindle nose run out 0.005mm with correct bearing preload adjustment (to allow for thermal expansion of shaft/bearings?). I'll post my new figures once I get everything cleaned and reassembled, but will allow a couple of days rest before to allow my back to recover.

 

[Richard King 2]

I have a copy of the Lathe spec's from Testing Machine Tools written by DR. George Schlesinger. At the top of the reconditioning forum page, Nelson the founder of this forum posted links to 3 of the greatest rebuilding books, The TMT book is there too. The Moore book, The Foundations of Mechanical Accuracy and the Connelly Book Machine Tool Reconditioning.

 

[SnakeyJ]

I have a copy of the Lathe spec's from Testing Machine Tools written by DR. George Schlesinger. At the top of the reconditioning forum page, Nelson the founder of this forum posted links to 3 of the greatest rebuilding books, The TMT book is there too. The Moore book, The Foundations of Mechanical Accuracy and the Connelly Book Machine Tool Reconditioning.

Thanks Richard, really useful pointer. I hadn't looked at these before, but just reading through now - a little light sofa surfing while resting my back

 

[eeler1]

I've spent an incredible amount of time with test bars and tenths indicators trying to get my old beaters into level and alignment. My conclusion is that while the testing is not a total waste of time, it's best just to do the two collar thing and get it accurate where you do most of your work. Actually, I'd be curious to see, after all the level/align using the test bar, how it actually cuts, i.e., does the cut follow the same pattern as the test bar.

 

[Richard King 2]

That question is obvious to me. The test cut is the true tell. Testbar in spindle hole is closer to the head and after you mount the chuck on and take cuts your what 4" out from the spindle taper? Most lathe owners can't afford a ground test bar. and the 2 collar or turn test is so much easier. On small lathes there is no reason to level it for that matter, just be sure the bed doesn't have a twist. Like the old saying. "How do you level a lathe on a ship?"

 

[SnakeyJ]

Like the old saying. "How do you level a lathe on a ship?"

Oddly enough, my grandad was a naval engineer officer during the WW2 mostly on destroyers. He made almost everything in his tiny workshop at the stern using Admiralty Drummond/Myford Lathe(s) like this.... The days of superheated steam, though he later worked on incorporating and commissioning some of the first marine gas turbines in the RN.



http://www.lathes.co.uk/drummond-m-type-post-1924/

He served on Maltese and arctic convoys and, during D Day on HMS Swift and was sunk twice by mine and torpedo, his life saved on both occasions by being a smoker! Sadly not here now, but told some fantastic stories, like winding the Russians up with fake radar arrays made from bed springs and hub caps at Murmansk. He also made and repaired clocks and watches as a hobby - 100x the engineer I shall ever be and wish I could have him teach me a little in my workshop now.

 

[SnakeyJ]

Okay, all back together after a long week. The carriage cleaned up and went back on very quickly, but the apron itself was filthy and took a good while to strip, clean and rebuild. Nice little project for a day under normal circumstance, but my back has been pretty rough all week.

The carriage movement is much improved and I'm definitely getting better, more repeatable readings on the dial indicator and less variation when changing direction of the rack, though I still see a couple of thousandths of an inch variation as indicate along the length ground test bar.

I need to find some more/beefier mild steel stock for test bars and will try and get some 1" mild steel. I've got some decent silver steel, stainless and brass billet, but don't want to waste good stock!



I turned this up from 7" of 3/4". The centre relief is fairly rough and ugly, but the ends were machined free with light cuts and slow feed. The black sharpie marks are 5" apart and I have 0.7175" on the left and 0.721" at the right - a taper of + 4/1000" (0.0458 degrees or 2mins and 45seconds of an arc). Not sure how much of this is deflection, but not too dire and should be able to improve on this.

Just found an old weight bar that's 1" diameter so will cut a couple of 8" lengths, but will have to hold in my three jaw.