Lead screw question.

timmeh

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Spacer- OD: 1 1/16" +0.000"
-0.020"
ID : 3/4" +0.010"
-0.000"
Length: 1/2"+0.010"
-0.010"
That's what I mean when I say dimensions aren't that critical, for example, my spacer is 0.520" long, haven't had any problems.
The gear box is by no means close alignment wise, but it is a LOT better than it was. Zamac is not very ductile, and low melt point. Easy on the heat, light on force. It took me nearly a week, to do mine. A bit here and a bit there. The half journal was bent nearly .125" from where it should have been, within .020" now. IMG_20200317_080449.jpg IMG_20200317_080622.jpg
 

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timmeh

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Here's the set up you're looking at; 64t on the leadscrew, 20t/64t with the 64t adjacent to the spacer. Well worn zamac gears are meshed closer than they should be, 3d printed 64t has .012" clearance on the spacer.
If you get the bore of the spacer close(within .005), you could even go + .020" on the OD.
If you don't have a spacer at all, that will get you going. I would hesitate to try filing a double keyway spacer, doable but difficult. IMG_20200317_102802.jpg IMG_20200317_103124.jpg IMG_20200317_103056.jpg IMG_20200317_111557.jpg
 
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Exuptoy

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A bit of bad news, I finally removed the gearbox and aside from the hailine crack in the top left hand corner of the reversing gearbox (the inclination of the stub was indeed off, even noticeable by eye) the lower support for the right hand reverse gear has a cracked finger support. My only choice now is to get a reverse gearbox casting made. I could make a half moon support and bracket it from inside the casing as a stop gap but it’ll need repairing.

Does anyone have a dimensional drawing for this box so I can get one made?
I have contacted Clausing but am waiting for a reply. Obviously if they supply one I’ll post it in here.

Looking at the break there is evidence of discolouration on the break which I would assume happen some time ago. Irrespective of when it happened I am going to try and get one manufactured!

I was also surprised by the wear in the stub gear collar as the brass bearing doesn’t look too bad!


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wa5cab

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That's strange, though. The center of the 24T and 12T gears are the same. And there would be roughly four times as much material in a 24T as in a 12T. ???
 

wa5cab

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On the gear case, we don't have any sort of drawing. I would first call Clausing and see whether or not they still have it, and if so, price. If they do, then buy it or don't. If not, ask them for a copy of the drawing. And send me a copy.
 

Exuptoy

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I may not need to go down that route Robert. I posted pics of my original spares on the welding forum I frequent when I purchased it, including a homemade gearbox......I was pointed back in their direction today......

can you spot it?? I didn’t!!! :D

B07D0A62-2498-4763-A4FF-17F5BA41A48A.jpeg
 

Exuptoy

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@timmeh, could I ask you a favour? Any chance you can measure that collar OD and I’ll turn down my 24 to fit.
 

timmeh

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1 1/16" or 27mm.
Unless you have extra 24t gears or that one is damaged, as the "set" only has one.
If you make a spacer, the keyway doesn't have to be close, its not under load.
 
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Exuptoy

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1 1/16" or 27mm.
Unless you have extra 24t gears or that one is damaged, as the "set" only has one.
If you make a spacer, the keyway doesn't have to be close, its not under load.
The 24 I was referring to looks like a 24T which has had its teeth tuned off. I wouldn’t destroy an original gear but I’ll happily turn down my existing spacer.

Thank you by the way.
 

Exuptoy

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Removed my spare case, gears in good order, case is perfect. Stripped off the paint, gave it a first coat of direct to metal Rustoleum.

208AD588-6D32-4EEF-847D-BF01F517B22C.jpeg 898A8643-0CEA-4FCE-8C99-42F7A112E3FF.jpeg 83ABFF2A-C1EA-4016-AFDD-DA73315B26B7.jpeg 903FC44A-6DB3-4F5D-A880-8C11535744DA.jpeg FAA90BDD-CF3A-40F3-A5F1-FD2CC4A10222.jpeg
 

wa5cab

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Exuptoy,

(set up your signature)
I still don't have a drawing for the gear spacer but if you measure the diameter of a 20T gear at the root of the teeth and subtract about 0.020", that should work safely.
 

Exuptoy

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@wa5cab Had a reply from Clausing, they list the reverse gearbox casting with bearing at £148 so would not supply a drawing. Thankfully I don’t need one any longer.
 

timmeh

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Exuptoy

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It’ll never come to anything though @timmeh as it’s not complete and I have no interest or idea what’s needed to finish it. Just pleased that I had the reversing box and gears etc spare.
 

wa5cab

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We have I think instructions for building two QCGB"s for the 618, 101.07301 and 101.21400 in Downloads. It would probably be worthwhile to look at those, compare them to the partial one that you have, and see whether or not it matches one of them. Other pieces may turn up or someone may decide that they want to buy what you have and make the missing pieces.
 

Exuptoy

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Fitted my gearbox, then took an ally bar, turned it down as a press fit, took one of my spare 20T gears and knocked off the teeth to make a spare spacer then the existing 24 spacer I turned down to 27mm then parted it off to make a 5mm spacer as I wanted to align the transfer gears correctly, then when I went to fit the screw gear I found my stub shaft had been turned down to fit the homemade gearbox!! Not a problem, I managed to swap the stubs over but kept the unmarked bevel gear as it was just roll pinned.

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Following repairing the gearbox I fitted the bull gear pin and detent / spring but first I managed to drop the spring inside down the back of the bull gear into the pulley, which caused me some consternation, so I made the decision to remove the head and retrieve the spring.
Whilst off I decided to use Mike Kurns’ original new old stock bull gear pin with detent feature as it was longer than my one which seems to have been made to fit. I’ve told Mike he can have the spare pin as it does work and when spares dry up he will at least have another spare for someone who is desperate.

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Next up was the saddle, I removed the apron and immediately found the gear housing was snapped but still sat in the same position it should be due to its dowel pins. I replaced the gears and shaft as I had intended but also managed to stick the 2 parts together with my Tig . I say stick it together as it was clearly not welded! (I can tell you that it’s either cast or Zamak and it didn’t like being welded! It was fizzing and giving off a white residue on my torch). I have dropped Mike a line as he has a spare gear case for £32.
I will at least have piece of mind then that all is well inside.

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Anyway, all in all I now have a lathe which is in rude health and does all it should with no backlash in the carriage and runs fairly quiet, but that’s not to say I won’t buy more parts to refine it even further and get rid of any evidence of it having seen much work in the past.

[media]
 
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wa5cab

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Looks promising, anyway! Yes, the carriage traverse gear case is cast in Zamak. So is the lead screw right bearing and FWD-OFF-REV gear box casing, most of the gears and AFAIK, all of the cranks and hand wheels and the two tailstock ram locking cylinders.
 

Exuptoy

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Cheers @wa5cab
I have a spare lead screw and carrier bearing and plenty of gears. If I can find my low temperature alloy welding rods I might try to repair the reversing box. Tig is too much for Zamak, even with the amps right down it didn’t like it. For the thickness I should have been up around 60-80 amps but even at 30 amps it was turning to gloop! I had to turn off the up slope and try tacking then added a little filler once I stopped meting it!
 
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wa5cab

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Yeah, aside from the consequences of the factory having been supplied with a bad batch of Zinc, the main problem with Zamak is that parts made from it are seldom repairable.
 

Exuptoy

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@wa5cab is it worthwhile using moly grease on the side transfer gears down to the lead screw or must they be left dry?
 

wa5cab

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If you are referring to the change gears on the left end of the headstock (that you assemble in various configuration to change the traverse power feed to the lead screw for various feeds or thread pitches), short answer is that they as well as the back gears in the headstock should be lubricated frequently. For the details see the lubrication charts in various vintage editions of the MOLO.

You use grease on the gear teeth and SAE 20 ND on the bushings that they turn on. That being said, the grease usually recommended is a lithium base grease rated for use on open gears. To keep from being quickly slung off, it should have a fairly high melting temperature and be tacky. The common greases found in the auto-parts stores usually lack both properties. Unfortunately, the company that made the grease that Atlas recommended (whose name escapes me at the moment) was bought out by the French company Total who very quickly ceased the production of that grease.
 

Exuptoy

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I went with motorcycle chain lube in the end. Nice and quiet. The only issue I have now is the back gear lever creeps off until disengaged. Any ideas?

[media]
 
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wa5cab

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Back Gears: If you study the Headstock page of any 10F illustrated parts list dated from 1946 up to the final one in 1966, they are all the same as there were no changes to that part of the headstock. The back gears are engaged and disengaged through the actions of two eccentrics, 10-251 and 10-252. For the back gears to remain disengaged or engaged when subjected to vibration and when engaged to torque reaction while driving the spindle, the two 10-167 Wave Washers must be present and slightly compressed and the eccentrics must be on one side of their peak when engaged and the other side when disengaged. If the eccentrics don't cross over their peaks while being engaged, torque forces and vibration will combine to make the lever slowly move back to the disengage position.

With the motor off, watch the motion of the back gears as you move the lever to engage them. They should move toward the spindle and then back away from the spindle slightly, indicating that the eccentrics are rotating past their peak when going from disengaged to engaged. If this is the case, all that I can suggest it to loosen the set screws in either or both collars and move them slightly on the shaft in the direction to squeeze the wave washers a little more. If the gears move toward the spindle but bottom out and stop before breaking over center, you need to increase the thickness of the 10-261shim pack. If the 10-254 Handle hits the headstock before the eccentrics cross over their peaks, the only solution that I see is to make sure that the handle is tight, mark the headstock side of it, remove and and bend the handle away from the headstock.

As an aside, given that the lathe has obviously been repainted, it would not surprise me any to find that there are no 10-261 shims present.
 

Exuptoy

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Thank you Robert. Clear and concise. ;)
 

Exuptoy

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I removed the motor earlier today to check bearings as it was noisy.

[media]

The motor I found had no roller bearings but instead had soft bearings with helix cut for grease retention!

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So I greased the shaft on both sides and reassembled then refixed the motor after aligning it correctly and shimming the motor as it was twisted in relation to the head pulley. I filled both main bearing cups with 10W40 as it was all I had handy and it sounds far better. Little improvements all the time. I should have a nice lathe once I’m finished.

[media]
 
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Exuptoy

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One thing I just realised is when I removed the head it had 2 piece split white metal bearings which were set in the body of the casting & caps (which I assume are Babbit bearings?) and were maybe 20mm thick! I wish I'd taken a pic now! The model plate deffo states TV36 but I never noticed Timken roller bearings in there.
Could it have been modified if the PO couldn't source the correct timken bearings or just incorrectly badged?
Maybe the previous owner sourced a different bed for this lathe (which is where the name plate and serial number came from) as there are so many different parts with it like the spare lead screw, spare reversing box making up the home made QCGB, the extra gears etc. I'd assume the Babbit bearings would be normal for an earlier lathe although this one does have the power cross feed? Confusing. Maybe not all is as it seems?
 
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wa5cab

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Glad that you noticed that. I would guess more likely that the PO swapped the bed but didn't bother to swap the nameplate. When I look at some of your photos, it is obviously a babbit bearing headstock. Which would make the actual model number V36 assuming that the bed length is correct.

However, both Timken and babbit bearings were available on the 10" as far back as about 1935. Which was well before the 10F appeared. And as late as 1945. The headstock castings, although physically interchangeable and containing some of the same parts, are not themselves interchangable. Different spindle and the babbit one is a little bit longer because of the ball thrust bearing. My guess is that he changed the bed and happened to get one off of a TV36. But in any case, it is a 10F because it has power crossfeed and a 2-piece carriage. The actual model number would be V36.
 

yendor

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I see you have some 3D Printed Gears, I wonder if that Gear Box could be 3D printed?
 
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