NEWLY-ACQUIRED JET 1236PS

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pete
Posts: 2518
Joined: Tue Feb 10, 2009 6:04 am

Re: NEWLY-ACQUIRED JET 1236PS

Post by pete »

Odd why they would use a North American belt standard that they would have to know was incorrect. Not unusual though, there electrical motor frame size designations also don't match anything for North American or even metric frame designations. It's a separate set of Asian specific standards that don't cross reference to anything off the shelf here.

Are you using a VFD? If so then there should be a soft start or motor ramp up parameters you can adjust for that starting torque issue. My mills 5 hp VFD with a 3 hp motor would sometimes fault out at the highest pulley rpm ratios due to the torque load, but once I changed it's ramp up time to a few seconds longer everything was ok.
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Steggy
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Re: NEWLY-ACQUIRED JET 1236PS

Post by Steggy »

pete wrote: Fri Oct 23, 2020 2:56 am Odd why they would use a North American belt standard that they would have to know was incorrect. Not unusual though, there electrical motor frame size designations also don't match anything for North American or even metric frame designations. It's a separate set of Asian specific standards that don't cross reference to anything off the shelf here.
Yep! The old motor was sort of a NEMA 145T but with a funky-sized shaft and a mounting bolt pattern that was completely different.
Are you using a VFD?
Not yet.
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Charlie W.
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Joined: Mon Feb 02, 2009 6:18 pm
Location: Concord, CA.

Re: NEWLY-ACQUIRED JET 1236PS

Post by Charlie W. »

I've been away from the Forum for some time. All I can say is life got in the way.

I use to have a Jet 12 36 P(Y) about 10 years ago. Mine was a 1981 but don't remember for sure what year. OK I know it is messy.

Lathe-1236_w.jpg
I have the original manual so maybe I can clear up a few things. The next picture is of page 1 of the manual. Notice that the spindle thread is 60mm x 8TPI. Yeah, it is odd but that is what it is. Just slightly larger than 2-1/4 x 8TPI

JetManual_pg1a.jpg

I made the following backing plate from a barbell weight.

Backing-Plate-weight.jpg

I made the 2 test plugs to assist me in threading several backing plates I made. One plug is undersize. I cut threads fairly aggressively until it screwed in. This let me know I was close to the finished size. I took small cuts until the full size plug screwed in. Once it did, I was finished. I made the full size plug by gauging it with thread wires until I matched the spindle measurement.

4.jpg

I bought a hand-wheel collet closer on Ebay which had a threaded backing plate 2-1/4 x 8 TPI . I increased the thread diameter until the Finished plug fit properly.


I had owned an Atlas 10" before the Jet that had a milling attachment. I kept it for the Jet and used it by making an adapter that fit where the compound mounted. It worked well and I still have it and the other accessories pictured in this post.

1.jpg

For the most part I liked the Jet. It had plenty of power 2HP motor. More capacity with the 12" swing. Large Tapered roller bearings, Helical back gears were quiet, a 1-3/8 spindle hole, hardened Ways, thread dial, steady rest, 3 jaw chuck. Though it was a good bit heavier than the Logan and Atlas lathes it was lighter than the 11" Sheldon I use to own. I was for the most part happy with it.

I sold it because I found a 1983, 3300 LB, 1440 Goodway gearhead lathe that was a significant step up. I am super happy with it.
Charlie W.
rbertalotto
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Joined: Sat Aug 16, 2008 11:38 am
Location: Dartmouth, MA

Re: NEWLY-ACQUIRED JET 1236PS

Post by rbertalotto »

I have that same lather, although heavily modified...New tinkham bearings, 90v DC motor variable speed motor, School bus windshield wiper motor to power lead screw, tachometer.........All on my website wwwrvbprecision.com

It's a fantastic lathe for gunsmithing in that it has a short headstock and a relative large bore.

Good luck with it!
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