Jet 1236P

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spro
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Re: Jet 1236P

Post by spro »

Thanks Rex. That is a keeper as are You btw!
jcarmon
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Re: Jet 1236P

Post by jcarmon »

Well, I found something bewildering. The chuck wont screw on. Ive completely disassembled the chuck, cleaned, re-oiled it, and it just wont screw back on. The still rusted face plate and drive plate screwed on, and cleaned right up. But the one piece I expected to have the least problems with , just throw me for a loop. Yesterday It fit like a glove, today I must have been holding my mouth wrong. Chuck itself works like a charm. Scroll, pinions, and jaws turn with one finger, just as smooth as a new ball bearing. But I must have done something wrong when I remounted it. Oh well, thirds time seems to be the charm.
spro
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Re: Jet 1236P

Post by spro »

Well for starters, a section of 2X6 with plywood atop to center the chuck to the spindle. It makes it easier and believe me, untold thousands do that. We are all pretty strong but those chucks are heavy that you can't get the "feel" of the thread engagement. The other thing with mine; the spindle end and thread are slightly tapered, so it is easy for it to start wrong. I was frankly appalled, at the loose fit of those threads but as it cinches up closer, gets much better. The main thing is the register of two parts. The "neck" past the threads is pretty dead on and the back plate is total flush against the thrust surface. I never removed that back plate from that chuck for it could not be any better than it is.
Our dear Harold often advises avoiding threaded spindles, for that and other reasons (like rapid reverse) but we are stuck with what we got at a particular time.
jcarmon
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Re: Jet 1236P

Post by jcarmon »

It seems its easier to thread the plate on first, and then bolt the chuck to it. Once I did that, it went on and off with ease. Guess I just had to play with it for a while. Ive about decided the designers of this lathe did everything they could to confuses new users. One full turn of the saddle hand wheel is .580". Makes measuring a pain. Three turns should be 1.5 inches, not 1.74 inches. Never thought I'd say this, but I miss metric. And whoever decided not to put some form of chuck stop on this thing is an idiot. Sucker spun itself off threading today. Even my little Harbor Freight tool didn't do that.
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Rex
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Re: Jet 1236P

Post by Rex »

The G9249 had a simple chuck lock. The collar of the backing plate was drilled for two clamps that hooked the plate to the spindle. Probably could be retrofit pretty easily if there is room in there.
spro
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Re: Jet 1236P

Post by spro »

I was trying to put together how this would happen but I see now. Our Encos were capable of metric as well as inch by the included gears but only one thread dial. Unlike inch, I found that only one spot of the dial could reliably enter the thread. This leads to reversing motor because it is more dependable that way but yeah not with a 20lb.+ chuck.
jcarmon
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Re: Jet 1236P

Post by jcarmon »

My HF 5980 3n1 had a set screw in the cluck plate collar that you could just tighten the crap out of and held the chuck to the spindle when in reverse. Ive got a set of metric taps, so I guess I could drill and tap this one too. How big a set screw would you think I should use? Couple of 8mm should do it I'd think.
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SteveHGraham
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Re: Jet 1236P

Post by SteveHGraham »

This sounds pretty cheesy. I would be concerned about accuracy issues if I had to reattach a chuck to a mounting plate all the time.
Every hard-fried egg began life sunny-side up.
spro
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Re: Jet 1236P

Post by spro »

If you use 3 screws spaced 120* apart, you can further adjust the accuracy while locking it.
ccfl
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Re: Jet 1236P

Post by ccfl »

Spindle nose threads are supposed to be loose, right? They should only provide clamping force and let the register behind the threads handle alignment. Otherwise the threads will be influencing things and making threads accurate enough for that task is not easy to do.
"Never trust a man who puts a witty quote in his sig line." -Mark Twain
spro
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Re: Jet 1236P

Post by spro »

Exactly ! I cannot say how far a spindle is threaded from here nor what aftermarket back plate- but- there is a tiny bit of give in the neck register/radial clearance. Now the problem is; driving bolts atop precise threads and what damage that can do. Mine has a fair amount of unthreaded neck register, so 8mm could be set in but that still disturbs the original surface. (sure brass or plastic insert)
I would investigate Rex's earlier information about the clamps.
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Rex
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Re: Jet 1236P

Post by Rex »

The clamp deal depends on a groove cut in the OD of the register. I looked at the Logan and. South Bend today and neither had enough material to do this.

But honestly, I cannot recall the last time I needed a lathe to run in reverse. I do remember once I hit reverse by accident and got hurt. I no longer make my lathes reversible unless they come to me that way. Drum switches mostly go to eBay. YMMV
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