Jet 1236P

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Randydan
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Location: California

Jet 1236P

Post by Randydan »

Hello everyone, I'm new here and I have acquired a Jet 1236P metal lathe. It's dirty but in good condition, but it's missing some parts. First off, I would like to replace the motor. I'm looking for a 1 hp 110 volt single phase. If someone has replaced theirs on this particular lathe, could you please tell me which make and frame you used? It is a belt drive and I have the motor step pulley.

I also need a tool post holder; any recommendations would be great. I would like a QC if possible.

I have found some info that the grizzly g9249 some of the parts will fit and some may still be available.

I'm in the process of cleaning it up and going to re lube and re oil, if I can get the parts I need to make it run. I will post some pictures if that would help.

Thank you
Randy
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Steggy
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Re: Jet 1236P

Post by Steggy »

Randydan wrote: I'm looking for a 1 hp 110 volt single phase.

I have a JET 1236PS and can tell you there is nothing standard about the motor that was fitted to the lathe. Physically, its size is somewhere in between a NEMA old-style (1950s-era) 145 frame and a modern NEMA 184, with a funky shaft diameter. I don't know about your machine, but mine had a 2HP, single-phase, split-capacitor motor. That type of motor is not very efficient and doesn't run very smoothly under significant loading.

I replaced the OEM motor with a three-phase, inverter-rated motor in a 145T frame. Some modification to the motor mount (drilling and tapping) was required, which was not anything difficult. You could do the same if you are willing to invest in a VFD to power the motor from your single-phase source.

The stepped JET motor sheave on your lathe likely won't fit any North American standard motor. The sheave on mine had a slightly undersized bore, which I determined was 18mm (q.v., a NEMA frame 145T motor has a 7/8" shaft diameter). Rather than bore it and redo the keyway, I Mickey-Moused a setup with two steel sheaves whose pitch diameters almost exactly matched the JET part. I also replaced the primary belt because it was ratty and glazed to the point where it would slip no matter how much tension was applied. In the near future, I will have to do something about the secondary belt, replacement of which requires extrication of the spindle.

Regarding a QC tool post, I fitted mine with a BXA. You could try an AXA, but those are meant for use with lathes having a 10" or smaller swing. The BXA post is more rigid, which will help with keeping chatter down to a dull roar. You might have to do a little rework of the post's T-nut to fit the compound's slot, but that's no big deal.
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Randydan
Posts: 9
Joined: Wed Dec 29, 2021 5:38 pm
Location: California

Re: Jet 1236P

Post by Randydan »

Thanks for the reply, the machine seems to be in decent condition. I will get it all cleaned up and go from there. I will post a few before clean up pictures here shortly. I am a newbie at machining with some experience.

Thanks again, I do appreciate your help.
pete
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Re: Jet 1236P

Post by pete »

Yep BDD is 100% correct. Fwiw, and this doesn't seem to be commonly known. My industrial supplier who sold me my VFD told me there's a separate and distinct Asian based industrial motor standard that doesn't match up with any Imperial or Metric based motor standards we have for our available off the shelf motors. Shaft sizes, key ways, slot spacing and pitch distances for foot mounted motors, bolt thread sizes and bolt pitch circle diameters for face mounted motors differ enough there's apparently no motors that are exact drop in replacements. I then asked him if the 3 phase motor on my Bridgeport clone ever died what I could do. Either source the same Asian based motor from Asia, build a new face mounted motor plate to adapt an Imperial or Metric motor to my mill, and probably a new drive pulley, or have have them rebuild what I have.

I'd also very much agree with him, 1 hp on a 12x36 lathe, not hardly enough. And if I was replacing it anyway, I'd without question go 220V 3 ph VFD and motor combination. The extra that costs and effort will be forgotten the first time you use it.
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Bill Shields
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Re: Jet 1236P

Post by Bill Shields »

Agreed on the above...been there done that..but do NOT remove the multi step pulley when you add the VFD

Bore / sleeve / key it as needed to fit a new motor. You will need the torque multiplication.
Too many things going on to bother listing them.
Randydan
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Joined: Wed Dec 29, 2021 5:38 pm
Location: California

Re: Jet 1236P

Post by Randydan »

Thanks everyone for your advice. The last owner replaced the motor with a 1 hp GE and actually mounted the original step pulley. I will take some pictures and post them but I have been busy lately. I will go the 3hp vfd route.

Thanks again for everyone's help.
Randydan
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Joined: Wed Dec 29, 2021 5:38 pm
Location: California

Re: Jet 1236P

Post by Randydan »

The wires on the contactor on the top go to the motor and wires on the bottom go to a F/S/R switch on the apron. The 2 wires on the left at the top row are 110 volt Line in.

I want to change it to 3HP vfd. I will search the net for models that have been converted, so I know what components to buy. If anyone here has done the change over maybe you could steer me in the right direction. I have the original belt sieves. The motor that is on there is a GE 110v 1 phase reversible motor.

Thanks
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Bill Shields
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Re: Jet 1236P

Post by Bill Shields »

wiring all goes in the trash.

on / off switch is now the VFD push button setup, which will use non of what you see.

3 phase wiring goes from VFD straight to motor, no switches.

you can use your drum switch if you like, but it will connect to the control strip of the VFD -> not to the motor directly.
Too many things going on to bother listing them.
pete
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Re: Jet 1236P

Post by pete »

100% on what Bill just said. As a safety, I like having a good industrial rated on/off before the VFD. That of course switches the power off to the VFD when making machine adjustments, tool changes on the mill etc. I can do it at the sub panel in my shop, but breakers aren't really made for that. Any VFD I know of uses a method of storing and not loosing any of the parameters you've programmed in. So switching to no power at all to the VFD isn't an issue. For lathes with a motor control lever for forward, neutral, reverse on the carriage and if yours has one, you'd have to ask someone much more electrically qualified since I've never done that yet. I know it can be done, I'm just not exactly sure how to do it.
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Bill Shields
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Re: Jet 1236P

Post by Bill Shields »

When my machines are not used, all the VFDs are disconnected from the main power supply.

Safety, power surges and power consumption are major contributor. All my VFDs are the same make model and size...even if a couple are much larger than they need to be..I only need one spare for the all the shop machines, coal furnace, water well, etc...the possibility that I would lose two at once is low. (Water well and furnace are critical ..lathes and mill are hobby use so a day or three off line is no matter)

Considering what I see of your wiring...it is all ready for the trash can anyway
.
I can help with concept for components, but if you are not comfortable with doing the wiring and switching, strongly suggest you find someone who is.

Before you do anything...look around your shop / house and plan for the future...which is coming faster than many of us are willing to admit..

Putting a VFD on my furnace circulating fan paid for itself in a season...and gave me better control over noise and temperature as I zoned things more carefully.

I spent as much $ on the disconnect and control switches and boxes as I did on the VFD..already had the motors.
Too many things going on to bother listing them.
pete
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Joined: Tue Feb 10, 2009 6:04 am

Re: Jet 1236P

Post by pete »

Yep same for mine Bill. If I'm not going to be using the machine in the next few days I unplug the VFD or throw the breakers if I'm gone for awhile, even with the inline power shut off switches, as well as the dro etc just for the safety and those power surges that aren't exactly unknown around here. Plus more than a few possible lightening strikes in the summer. Also highly agree about good quality switches, boxes etc. Imo electrical just isn't the place to pinch pennies. Interesting detail about a VFD on the furnace fan, I don't recall seeing that mentioned anywhere else. I'd say it makes pretty good logical sense.
Randydan
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Joined: Wed Dec 29, 2021 5:38 pm
Location: California

Re: Jet 1236P

Post by Randydan »

Thanks everyone, for the words of encouragement about switching over to VFD. I'm actually pretty excited to get things going. I have no problem with electrical and wiring my own, but advice is always welcome. Since I don't have 3 phase in my shop, I'm going to use 1 phase 220 volt to run to the VFD. So, I will finish cleaning up the lathe and start investigating the make model of components and motor I will need. So I will need to get a 3hp 3phase motor. I do have the original pulley sieves. Which I believe are 18mm ID and keyed, on the motor side.

Anyway, I will finally get around and take some before pictures, and progress pictures.

Also, I just wanted to say thank all of you for your time and help, it is very much appreciated.
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