Lead screw question.

Exuptoy

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After recently purchasing my 10F TV36 I’m not really au fait with what should or shouldn’t happen when in use.

I’ve noticed even without the drive selected on the left hand lever, my lead screw is still turning and sometimes moving the carriage if it’s locked with the half nuts. I’m thinking it may be due to the banjo/gear meshing? What’s wrong with my set up? I’m sure it didn’t do this when it was collected and after removing a few of the gears I never set the mesh with paper. Could this be my problem?
 

brino

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My advice:

1) Pick a version of the Atlas "Manual of Machine Operation" (aka "MoLO") and/or Southbend "How to Run a Lathe" and get to know them intimately.
There are several version in our downloads section.
Southbend, How to Run a Lathe
Atlas, Manual of Machine Operation (MOLO)

2) With the manual go over your machine carefully to understand _ALL_ the knobs and levers. It's also a great time to become familiar with all lubrication points.

3) Start small and slow. With my 1916 Cincinnati Mill I had NO manuals. Once cleaned-up, I started learning it without the motor by turning the flywheel by hand. That let me engage spindle and feeds without any worry of "crashes". Once I knew how to disengage everything and it was all lubed I carefully tried it with the motor. Things like how to switch between the built-in X/Y/Z power feed were NOT initially obvious.

Be careful and have fun!

-brino
 

brino

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Is it possible that while you were exploring the gearing that it didn't quite get put back together properly?
Is it perhaps in the reverse position not off position?

On my 1937 9-inch Southbend, the power-feed level has three positions; forward reverse and centre-off.
(see manual page below)

-brino


1584104387171.png
 

T Bredehoft

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sometimes moving the carriage if it’s locked with the half nuts.
Its normal for the lead screw to be turning all the time. If the half nuts are closed, the carriage will move. Yes, the lead screw may be put in neutral, but most of us don't do that. We just let it turn so when we want it it will be there.
 

pontiac428

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If your carriage moves with the half nuts disengaged, it might be worth your time to remove the skirt and clean/inspect the half nut assembly. Also, if your carriage is creeping on a disengaged half nut, your gibs might be a little on the loose side in addition to whatever is causing the lead screw to drag.
Edit: Also check your reversing gear assembly. Something may be loose/dirty in there.
 

wa5cab

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First off, the Atlas 9" and all of the 10" except the QC and Pic-O-Matic have a FWD-OFF-REV gearbox on the front of the bed below the head stock. And do not have a tumbler. So studying the left end drawing of the South Bend lathe above will only confuse the issue. And most people probably disengage the gear box when the lead screw is not being used. But I guess that's just personal preference. However, if your lead screw continues to turn with the gearbox in OFF, and especially if the carriage moves when you engage the half-nuts, the problem is in the gearbox. Something is dragging or the drive dogs are not disengaging,
 

Exuptoy

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Cheers Robert. I’ll look into it. Even without the half nuts engaged and the Fwd-Rev in neutral it’s turning. If I lock the carriage with it in N it still tries to drive and there is a noticeable change in sound like it’s under load. Once my bench is finished and the lathe is in position I’ll start looking at it.
Thanks for the other info guys.
 

Exuptoy

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Whilst I’m at it I think I’ll set up the gears for metric threading (1.5mm pitch) as I probably will never use it for imperial.
I notice from the threading chart that the spindle stud gear needs to be 16 tooth.
I have a number of spare 16/32 compound gears, is this 16t stud gear the same gear? I assume it’s the 32/16 compound thats the under the gear at the end of the spindle which starts the gear train down the end to the lead screw? Do I turn the compound gear around or just use the 16t to drive gear A?

Sorry for the basic questions? This really is new to me.

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054FD3AD-5149-4745-8A8C-746A8B836118.jpeg
 
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wa5cab

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If you spend some time studying the threading chart, it would answer your question, but the 16T/32T compound spindle stud gear always goes on the machine the same way, with the 32T gear closest to the headstock. The 32T spindle gear is so wide for historical reasons. The Atlas 9 and the 10 through 10E did not have the stud gear.

But 0.5 mm pitch is going to give you a pretty rough looking finish if you always set up the lathe for threading it. 0.5 mm is almost 20 thousandths in real numbers. It is more than twice the coarsest feed shown on the chart, which is 8.7 thou. Which would generally only be used for roughing cuts.
 

timmeh

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Check fwd/rev gear box. Mine also turned the leadscrew when in neutral, not enough to drive the carriage. The gear box housing had been damaged in a crash. Will try to find the thread I posted the info to.
"Atlas 10F V42" is thread title, bottom of first page.
Pics not very clear, can take more. Need more info? By all means, ask.
 
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Exuptoy

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Cheers @wa5cab that makes sense. Now I sort of have my head around the gear selection process I’ll set it up for turning but maybe I’ll keep the gears for threading marked up somehow and set it up for slow feed turning. Makes perfect sense now you mention it!

@timmeh funny you should mention this as I was up the garage till gone midnight last night, initially to try and change out the gears then I got a little annoyed with the minor amount of backlash in the saddle so took the saddle off for inspection and when I removed the lead screw I noticed the gearbox had an issue. There is a hairline crack along the top alongside the banjo but it is still in serviceable condition, however, I found the yoke which selects forward /reverse doesn’t hold the transfer gear in the central position. I found one of the little fingers which push the transfer gear was missing!
I made one up from a piece of 3mm wall steel box section with a 3mm pin.

You can see in the straight up (N) position that the yoke doesn’t hold the transfer gear perfectly central.

50A7C728-EE83-4E50-8B35-920C330AACB8.jpeg

988BA9E9-5CFC-4440-82BB-0A52DB7D86F2.jpeg

This item was missing its pair!

53B3C6AF-E520-4DCE-8023-D3610ED2C446.jpeg

CB1E2100-74A9-4691-85F8-B84ECE90680C.jpeg

I have made and fitted the finger follower but have not yet reassembled things. If it cures my ills I’ll post a full thread explaining the repair for others if required.
 

Exuptoy

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Well, the repair made no difference but since changing gears to 32tpi gearing it’s certainly running sweeter and slower. Need to make a spacer for the lead screw stub shaft as the one behind the screw gear is marked 24 and is too large for me to run 64 of the screw and a compound 20/64 above it to get it REAL slow. Anyone know its actual size?
Also I found some contact details of a lovely guy by the name of Michael Kurn who has agreed to send me the actual parts to repair my reversing box.
I’m amazed no-one spotted that my sliding gear yoke is home made from my previous pics unless mine is an earlier version.

Anyone spot the difference? :D

maybe @wa5cab may be able to use the drawing behind the part for the drawing repository in here? It could easily be redrawn.

7ACD0736-DCC0-47F3-AE8B-88BEC5675EBF.jpeg
E771B614-04FE-454C-B329-B31C065C315F.jpeg
 

wa5cab

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Drawings are always welcome.

We do not have the drawing for the 9-116A spacer because last time that I checked, it was still available from Clausing. But if you look at your 9-101-20A 20T gear and visualize it with all of it's teeth cut off, you would be pretty close. As I mentioned a day or three ago, anyone with any gears that are scrap because of broken or worn-out teeth should not throw them away as the 9-116A is often among the MIA's when someone buys one of these lathes.
 

Exuptoy

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I have quite a few 20’s and could use one but I think I’ll just turn one and get my mate to spark erode the keyway. The 24 does indeed look like the 24 without its teeth but as it didn’t look like Zamak I dismissed it.
 

wa5cab

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OK. I don't know whether 9-116A is cast or machined. I had always assumed that it was cast.
 

Exuptoy

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By the way you mentioned the other day that in back gear the torque should have been greater......

it was my fault, I assumed that backgear was just removing the bull gear pin, until I removed the upper cast covers I found the free wheeling gears with the lever in the end!! It does indeed have plenty of torque! Where’s the embarrassed icon :D
 

wa5cab

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One other thing:

If you engage the back gears without pulling out the direct drive pin, you lock up the spindle. The MOLO says to do this for routine chuck removal. Just don't forget and leave the spindle locked afterwards and start the motor. However, I would NOT use this method to lock the spindle if you are trying to remove a stuck chuck. For example on a new to you machine that may not have had the chuck removed for eons.
 

Exuptoy

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I’ve had the chuck off this since purchasing. Changed it for the Burnerd 4 jaw, clocked a Kawasaki rear hub and dressed the faces. First time ever so was pretty pleased with myself.
 

wa5cab

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OK. Sounds as though you've already gotten some useful work out of it.
 

Exuptoy

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Yeah, I need to make some spacers up next to fit the Z650 wheels to the ER-5. Pretty much the reason I got it.

D8AD92BC-E618-429F-91C5-27156B7D4E20.jpeg 2D67FD05-8E68-4B57-93A3-DC7D53007D81.jpeg
 

timmeh

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My gearbox had the same crack, left hand side, running from the "inside" corner of the g/box where it mates up to the bed(top face) to approx. halfway to the front. That led me to check alignment of the journals at either end. Couldn't see any bend/misalignment until I tried the input shaft in the full journal backwards, around 3mm/.120" off centre at the half journal. Prior to repair, very difficult to switch from one direction to other. Now, smooth as silk. A fairly agricultural repair to say the least, only measured by a rule, maybe got it under .5mm/.020".
Made a huge improvement to operation.
 

timmeh

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I have quite a few 20’s and could use one but I think I’ll just turn one and get my mate to spark erode the keyway. The 24 does indeed look like the 24 without its teeth but as it didn’t look like Zamak I dismissed it.
You could file the keyway, it only needs clearance. Only critical dimension for the spacer is length and if it's on the leadscrew input shaft, only one keyway required.
 
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Exuptoy

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You could file the keyway, it only needs clearance. Only critical dimension for the spacer is length and if it's on the leadscrew input shaft, only one keyway required.
Not quite correct. The spacer circumference is critical too as there is no room to use a 20/64 in the final position at the 64t screw gear as the spacer behind it fouls on the rearmost 64 compound by a few mm. I need to either make a new spacer for the end of the Screw or turn down my 24 spacer to allow clearance. I’ll try and take a pic later.

Couldn't see any bend/misalignment until I tried the input shaft in the full journal backwards, around 3mm/.120" off centre at the half journal. Prior to repair, very difficult to switch from one direction to other. Now, smooth as silk. A fairly agricultural repair to say the least, only measured by a rule, maybe got it under .5mm/.020".
Made a huge improvement to operation.
Very interesting @timmeh I’ll be sure to remove it when I replace my sliding collar yoke and check it for runout. I take it you are describing the LH side stub shaft which carries the screw (item 9-52A Stub below?)

9E96AA67-52E8-4835-934B-8D746F08BAC8.jpeg
 

timmeh

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Not quite correct. The spacer circumference is critical too as there is no room to use a 20/64 in the final position at the 64t screw gear as the spacer behind it fouls on the rearmost 64 compound by a few mm. I need to either make a new spacer for the end of the Screw or turn down my 24 spacer to allow clearance. I’ll try and take a pic later.



Very interesting @timmeh I’ll be sure to remove it when I replace my sliding collar yoke and check it for runout. I take it you are describing the LH side stub shaft which carries the screw (item 9-52A Stub below?)

View attachment 316900
Yes, insert backwards, eyeball from r/h end.
I'll measure the spacer, as long as it is small enough on the OD to clear the adjacent gear is all that matters, not necessary to be within .001".
 

Exuptoy

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Spinning it in the chuck to find the throw then using a press to ‘tweak’ any run out would be as effective Id suggest?
 

wa5cab

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I'll add that there is a 1/4" x 7/8" roll pin holding the gear 9-48B to the stub 9-52A that was missing from the exploded view drawing in all versions of the 10F parts list. The version in Downloads has it added. Look for:
Atlas Lathe 10F-Series Parts 10L-6 Rev11.pdf 2019-07-13
 

Exuptoy

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Cheers Robert.
Just had an email from Clausing.....they have actually quoted for a number of items that they still carry in stock. The bull gear pin and detent items, saddle gears and shafts to get rid of the backlash along with sliding collar and yoke from the reversing gearbox, Not THAT cheap but reasonable and if you wanted to bring a tired lathe back to life not too bad.
 

wa5cab

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That's good news. I had heard from someone that Clausing had reduced the prices on a lot of Atlas parts. I just hope that they are not having a Fire Sale and that when current stock is sold, there will be no more.
 

Exuptoy

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Well, the two 9-102-12s gears in the saddle are £103 so no fire sale BUT the 9-102-24t gear in the saddle is only £18. As I say not cheap but reasonable. £200 to get mine back in VERY good condition.
 
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