Lathe disassembly question, take carriage off?

[tornitore45]

On the left side (headstock) the location of leadscrew and feed bar is established without uncertainty.
At the tailstock end the bar and screw can wiggle, flex and move in their drive sockets, that is the reason I suggested to define their position at the tailstock end by engaging the 1/2 nut wit the carriage at the tailstock end.
Once the two ends are in the proper place inserting the roll pin is no problem.
By the way I have replaced the nearly indestructible steel roll pin with a Home-Depot sourced screw (made of Chinesium) weakened to the point it will break in case of a crash.

[rmac]

You're probably right but I don't know yet. Last night I took the setscrew out and tugged on the black collar that the screw is in. It needed a bit of heat-gun to come off; either a light press fit or maybe gummed up like with dried coolant. But it slid right off and then it wasn't obvious what to do next so I went to bed. Today I was looking at my documentation, which is poor and hard to read but the parts list calls out a taper pin in about that location, so I'll look again. Dunno why they'd have a taper pin and a collar with a setscrew (belt and suspenders?)

Oops. I was wrong when I said the setscrew was securing the leadscrew to the gearbox shaft. As you've discovered, the black collar is just a cover of some sort, and it does in fact hide a tapered pin. Mine slid right off when I undid the setscrew just now, so it's a good bet that yours was just stuck on with gunk. Chances are you'll find the taper pin when you take a second look.

Re: poor documentation. One trick that's helped me in this regard is to download the manuals for Grizzly machines similar to (more or less) the ones I have. Of course there's no guarantee of an exact match, but these machines are all similar enough that the Grizzly manuals are definitely helpful. At the very least, they're legible and written in understandable English. At the time, the manual for the Grizzly G9249 was the closest I could find for my lathe.

-- Russell Mac

[bulgie]

Oops. I was wrong when I said the setscrew was securing the leadscrew to the gearbox shaft. As you've discovered, the black collar is just a cover of some sort, and it does in fact hide a tapered pin. Mine slid right off when I undid the setscrew just now, so it's a good bet that yours was just stuck on with gunk. Chances are you'll find the taper pin when you take a second look.

Update 1: as Russell pointed out, the leadscrew has a taper pin to disconnect from the shaft in the gearbox (see attachment).
The black collar appears to be a shield for the thrust bearing, as well as keeping the taper pin from falling out I guess, though it would be really bad if it got loose enough to need the collar to hold it in. That taper pin should be rammed home good'n'snug.

I tightened up those jam-nuts, that I loosened previously when I thought I was going to take the shaft out. Everything's smooth in there so I'll just do a light cleanup without disassembling the gearbox. The jam nuts adjust the end-play on the leadscrew shaft. I put a little preload on the thrust bearings, whataya think, bad idea? I tightened it to zero play, then just a little more. Still smooth turning, but with a little "feel". I figure a slight preload is better than allowing any slop, which could cause bad surfaces on cut threads. Just a theory.

Update 2: started removing the main spindle but I don't know how! Should I start a new thread for that, since this thread is titled "take carriage off"?

Thanks,
Mark

[bulgie]

[I'm new here, what's the ettiquette — should this be a new thread?]

Here's where I'm at with the main spindle removal (see attachment). I took off the two locking nuts on the left end of the spindle, took out two setscrews on the collar inside the headstock, and removed the four screws holding the main bearing cap on the right side of the spindle.

I pounded on the left end of the spindle with a big soft mallet and got the spindle to shift to the right a few mm, which knocked the bearing cap off the right side. Inspected the main bearing, it is clean and oily, looks perfect.

But I can't just keep pounding, because the large helical gear on the right, that's keyed to the spindle, is also moving right, and will soon hit on the inside of the headstock casting. And not hitting in a good way; it'll hit on one tooth on its outer rim only, where there's a bulge in the inside of the headstock casting for the oil guage/reservoir. So this can't be the way to remove the spindle.

What's the trick, guys?

While I'm asking stupid questions, how do you get the tumbler off? I removed the one obvious nut and the tumbler "fixing screw", but it sure doesn't slide right off. Gear puller?

I know you guys will straighten me out but in the meanwhile I'll try to find a youtube, there's gotta be one covering this type of lathe. Everything on youtube is the gospel truth, right? Totally trustworthy?

Thanks,
Mark

[NP317]

Personally, I would never remove A functioning spindle unless there was an obvious problem with bearings.
RussN

[rmac]

Here's where I'm at with the main spindle removal (see attachment).

<big snip>

What's the trick, guys?

I don't know. At the time, I kind of felt the same as RussN on that . "If it ain't broke ..." and I just left the spindle and the back gears alone.

If you do decide to go ahead and remove the spindle, consider installing new drive belt while you have it apart.

While I'm asking stupid questions, how do you get the tumbler off? I removed the one obvious nut and the tumbler "fixing screw", but it sure doesn't slide right off. Gear puller?

I did disassemble that part on my lathe because the bushing in one of the reverse gears was shot. (Probably hadn't been greased properly.) I don't remember it being difficult, but I also don't remember the details. Unfortunately, I can't find any of the pictures I took at the time, either.

-- Russell Mac

[bulgie]

Personally, I would never remove A functioning spindle unless there was an obvious problem with bearings.
RussN

Yeah, unless I find someone showing me "it's easy", I think I'm going to button it back up and just clean it "half-fast" without disassembly. It's a bit hard to clean the sludge out of the bottom of the headstock cavity, but that sludge isn't really hurting anything.

Thanks everyone for floating some sanity my way.

-Mark

[NP317]

" It's a bit hard to clean the sludge out of the bottom of the headstock cavity."

Pour in solvent, stir, drain, repeat until clean enough.
RussN

[Harold_V]

" It's a bit hard to clean the sludge out of the bottom of the headstock cavity."

Pour in solvent, stir, drain, repeat until clean enough.
RussN

Yep! What Russ said. If you're not familiar with solvent, it's commonly known as Stoddard Solvent. You can use mineral spirits (paint thinner) as well, and it may be easier to find.

Some folks like to use diesel fuel for cleaning. I don't. I don't like its smell, and it's an oil, not a solvent (although it does dissolve hydrocarbons).

I suspect you're smart enough to NOT use gasoline.

H

[LIALLEGHENY]

A good friend of mine who has spent many years servicing , repairing and rebuilding machines told me to use white gas, also known as camping stove gas to clean the internals on gearboxes, bearings etc. He said it is the cleanest solvent, better than mineral spirits, and no residue.

Nyle

[John Hasler]

"White gas" is gasoline. I use it, but only outdoors, working on the ground.

Acetone works well (keep it away from paint and plastics) but it is nearly as dangerous as gasoline.

[Steggy]

Dunno why they'd have a taper pin and a collar with a setscrew (belt and suspenders?)

Perhaps the tapered pin was used to guarantee that there is no backlash between the lead screw and the gearbox's output shaft.

Yeah I can see the need for a taper pin. What I'm confused about is the collar with the setscrew, what does it do? That tiny setscrew can't take much torque, so it's looking more like a cover, to keep swarf out of the thrust bearing. It seems too thick and heavy to be just a bearing shield though, those are usually real light duty.

But I probably don't need to understand its function as long as I get it reassembled correctly. Famous last words?

-Mark

On some lathes, that collar also acts as a carriage stop—that is the case with my lathe. If it's acting as a stop it needs to have some substance to it.