Gear slipping on my 10k

[Webb Wyman]

Hi There,

I'm not sure what your problem is (especially
with no pictures to go by) but I'll offer an out-
side possibility.

What type of nut(s) are you using to hold the
gear onto the leadscrew? Early 9 inch Workshop
lathes used two jam nuts and later, they switched
to a nylon insert type lock nut. I'm not sure when
the change occurred (before or after the 10K came
out). But seeing the 10K uses the same gearbox,
it could have either (but most likely, the insert
lock nut).

If you are using a "standard" nut, it might be self
tightening as the leadscrew turns. The nut should
be tight enough to remove all "play" but not interfere
with free rotation of the leadscrew. A lock nut or a
pair of jam nuts can accomplish this but a plain nut
cannot.

Just a thought.
Good Luck!
-Blue Chips-
Webb

[jasono]

Hi Webb
im using a lock nut and it was tight i thought it might have been 2 tight but i will pull down again and take pics i have just come so far and am wanting to finish and be able to use my lathe
Jasono

[The Energy Rebel]

Originally Posted by jasono

the energy rebel
i answered the pm but you have them turned off
Jason

Sorry about that, it was off for a few days.

Originally Posted by jasono

ok so i cleaned the gearbox pulled it down put it back up fond a bit of damaage on the selector shaft in the oil ways filed it down the gearbox is running perfect then i put it back up
ran it perfect no problems put back on the leadscrew and it locks up again i am @ a loss
any more ideas would be really appreciated im a newbie and just want to use this wonderful lathe

You're almost there.
Mine isn't exactly the same, but close. I'd say you still have a bind in the leadscrew or carriage.
Lots of oil, move by hand and look for that bevel gear in the carriage hat engages with the leadscrew.
I can't see your machine from here, but that was the last thing that unbound on mine.

[jasono]

OK So i have been in the gearbox 3 times now and its fine .I have noticed when running the carriage down to the headstock end as i get about 8-12 inches away from the headstock
the sound of the machine changes and it all slows down. When i bring it right up it locks up .
So what now? Any thoughts? I have pulled off the apron, cleaned it and no difference .
This is driving me mental! Gearbox?Apron ?Could the leadscrew be bent? Please bear in mind this is a frankenlathe and the parts are from Ebay. I removed the v belt pulleys as I thought that I might have been running the lathe too fast, I just dont know. What I put on the lathe since I rebuilt it is -a leadscrew ,an apron ,and vbelt pulleys .Im just frustrated here HELP!! I have also run the lathe with the apron @ the tailstock end through the whole gear range and it ran perfectly for about 3 hours without moving the crossslide ,so im stuck again!
Jason o

[SBLatheman]

Originally Posted by jasono

OK So i have been in the gearbox 3 times now and its fine .I have noticed when running the carriage down to the headstock end as i get about 8-12 inches away from the headstock
the sound of the machine changes and it all slows down. When i bring it right up it locks up .
So what now? Any thoughts? I have pulled off the apron, cleaned it and no difference .
This is driving me mental! Gearbox?Apron ?Could the leadscrew be bent? Please bear in mind this is a frankenlathe and the parts are from Ebay. I removed the v belt pulleys as I thought that I might have been running the lathe too fast, I just dont know. What I put on the lathe since I rebuilt it is -a leadscrew ,an apron ,and vbelt pulleys .Im just frustrated here HELP!! I have also run the lathe with the apron @ the tailstock end through the whole gear range and it ran perfectly for about 3 hours without moving the crossslide ,so im stuck again!
Jason o

Sounds like the alinement of the gearbox, apron, and/or bed is incorrect.
Disengage the right hand tumbler on the gearbox, move the carriage to different positions on the bed and rotate the leadscrew with your fingers. It should rotate easily in all positions. If it is tight at the headstock end, deturmine which direction it is off(up, down, front, back) and shim the gearbox to correct.
Ted

[jasono]

Hi Ted
thanks for the advice i shall definately try this and let you know how it goes
thanks
Jason

[tentacles]

Is there a lot of wear in the bed? Was it remachined? You may need to shim the gearbox down, or check if the apron needs to come down (very unlikely). There's clearly something binding the leadscrew as the apron comes closer to the gearbox. A good way to check would be to measure the distance from the top of the ways to the bottom the leadscrew at each end. Or to measure from the bottom of the ways to the top of the leadscrew.

[jasono]

[QUOTE=tentacles;1234512]Is there a lot of wear in the bed? Was it remachined? You may need to shim the gearbox down, or check if the apron needs to come down (very unlikely). There's clearly something binding the leadscrew as the apron comes closer to the gearbox. A good way to check would be to measure the distance from the top of the ways to the bottom the leadscrew at each end. Or to measure from the bottom of the ways to the top of the leadscrew.[/QUOTE
Tenticles
there does not seem to be that much wear on the bed, it was not remachined i can see the original casting marks ,when i remove the right hand tumbler the leadscrew is still tight when i remove both i still cant turn it. When i remove the apron the leadscrew will turn but with a slight bind if i slacken the locknut anymore the leadscrew will move back and foward(headstock to tailstock)also discovered that if i lift the apron when its moving down the bed the speed does not go down and it will go right to the headstock. it just gets more complicated !

[Webb Wyman]

Hi There,

What is the serial number on the bed? Could this be
a model B or C that someone added a gearbox to?

Anyway, it definitely sounds like you have a leadscrew
alignment problem. Pretty unusual for a SBL with a
factory equipped QC gearbox to have this issue unless
the saddle and/or apron have been changed. A lathe
that has had its bed resurfaced could throw the carriage
assembly out of alignment but a proper rebuilder would
have relocated the QC gearbox and rack to compensate.

I hope you don't have a "Frankenlathe."

Good Luck!
-Blue Chips-
Webb

[jasono]

Hi Webb
the serial number is 7410kar8 im just at a loss here
maybe you can shed some light on the situation
regards
Jason

[Webb Wyman]

Hi There,

According to the serial number, you have a
10K made in 1960. It came with a QC gear-
box and friction clutch apron. And equipped
with a horizontal drive.

So, it appears your lathe did come with the
QC gearbox originally. But something is off
with your leadscrew. Was your lathe assembled
when you got it?

-Blue Chips-
Webb

[jasono]

Hi Webb
when i got my lathe it was a pile of parts i got the army manual and put it together
i got the leadscrew foma guy in nova scotia the apron from e bay and v belt pullies from ebay along with the motor mount i have built it from scratch basically.
Jason

[Webb Wyman]

Hi There,

Okay, that explains a lot. SBL tried to keep things
interchangeable but one will find problems when
compiling parts into a lathe. When possible, try to
obtain parts from lathes made in the same general
time period.

How much of your lathe is original? What is the catalog
number on the gearbox id tag?

I guess the first thing to find out is whether the leadscrew
is too high or too low. Tell me, if you remove the right-
hand leadscrew support and crank your carriage towards
the headstock, and measure down from the lathe bed
to the leadscrew at the either end, what do you come
up with?

If the right-hand end of the leadscrew is closer to the bed
than the other end, I would think this indicates the gearbox
is too low (in relation to the apron). The reverse would
indicate the opposite situation.

Good Luck!
-Blue Chips-
Webb

[jasono]

Hi Webb
I also bought the gearbox from ebay i forgot to put that in as well the cat number is cl644a
i have some pics here as well im going to post now as well i will go back to the lathe this evening or tomorrow and check the leadscrew height as well

[jimwallis]

Hi,
I often see on the forums people referring to "the original machining/scraping marks are still visible" - and I wonder how it is possible to tell that such marks are the original ones and not evidence that a bed has been re-worked?

Certainly your V-ways don't seem to have a ridge so appear not to be worn but your symptoms do possibly suggest that the ways could be worn close to the headstock so the apron dips as it gets there (as another option to the leadscrew alignment being out). Have you ignored appearances and actually measured for wear?

So assuming it's not wear but a leadscrew alignment issue, the screw must be too high at the headstock end, which means you need shims between the gearbox and the underside of the bed to bring it down level with the tailstock bushing (you say the apron feeds Ok at the tailstock). I reckon you should be able to check this without power. The leadscrew runs through a worm in the apron which it drives by a keyway so the only way it can bind is if it is out of alignment and pushing against the leadscrew (up or down I'd guess from your description, but possibly sideways although you should have some set crews to align the gearbox that way) - it may be possible to visibly see the leadscrew deflect, and if not I reckon if you set a DI on it and move the apron you will register a change.

If it's not leadscrew alignment, then it must be the gears inside the apron - given the amount of gunk that collects in there, and the routing of the oil wicks it is quite feasible that one of the gears could pick something up randomly and get jammed. It's awkward fishing around in the apron casting (and mine is a 13") but a good cleaning and check up is well worthwhile - you'll probably want to replace some or all the oil felts whilst you are in there.

Er, one other thing from the photos - is the cross feed bushing meant to stick out that far? Maybe the feed gear is not meshing properly because the feed screw is in the wrong place?

Jim