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reversing a Jet lathe

I

Ira

Joined
Sep 5, 2004
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Location
New Boston, NH
I have a Jet 12-36 lathe and would like to wire a switch to run the lathe in reverse. I have purchased the appropriate size double pole-double throw switch but do not have a schematic to go by. If anyone can give me instructions or better yet a schematic to go by it would be greatly appreciated. Thanks in advance!

Ira Gray
 
Ira........ many motors cannot be run backwards. Most U.S. motors will have the wiring diagram either on the motor cover plate or under it. I'm not sure about the Jet with its off shore motor. There should be a wiring diagram in your manual.
 
Ira said:
I have a Jet 12-36 lathe and would like to wire a switch to run the lathe in reverse. I have purchased the appropriate size double pole-double throw switch but do not have a schematic to go by. If anyone can give me instructions or better yet a schematic to go by it would be greatly appreciated. Thanks in advance!

Ira Gray
Click to expand...

Ira,

Took Jake's lead and pulled the schematic from JET's website. Does not show alternate wiring for reversing the motor. Suggest that before you do something you'll regret that you contact JET tech service out in Redmond directly with your question. They were always very knowledgable and helpful to me.
 
Hey, Ira

Make any headway with a reversing switch on your JET?

Mentioned it to the guy I sold my 1236 to and he'd like to know as well.

M
 
Jake and Mark,
Thanks for the input. I suspected that I may have some trouble reversing this motor. My next step is to check directly with Jet as Mark suggested, I will let you know what they have to say. Thanks again!

Ira
 
I think that OSHA may have made it more difficult to reverse an application specific motor since they all seem to be wired these days with only three wires coming out from the motor windings. The trick to reversing the motor is to reverse the leads on either the start or run windings -- but not both. With only three leads available, you can't do it unless you are brave enough to dig further into the motor to find where the start and run windings are connected together and brought out as a single wire. They would need to be separated so that you could reverse the power to one set of windings. A word of warning: you can't reverse a single phase induction motor while it is running -- you need to let it come to a stop first or it will just continue running in the same direction.
Bill
 
Hi Bill,
Thank you for the input. I don't think I will go to that extent to reverse it; with my luck I would probably blow the thing up or melt it. I have a call and an e-mail in to Jet tech support and I will let you know what they say.

Ira
 
ira,

i had been considering the same thing with my jet mini, the motors jet uses just are not convertable, but there are numerous motors out there that can be had (sometimes ) for cheap.. i picked up an older delta 3/4 hp motor, thats not only reversable, its dual shafted and can work 110/220v ,, and the best part i got it for 20$.. runs like a champ.. i know i'll pay at least the same amount for the double pole switch.. but when its all said and done you get what you pay for..

best of luck..

pete
 
I admit that this is an unorthodox solution, but.... I once had a lathe that didn't reverse and since I only wanted to reverse to sand, I found a small motor and pulley, and mounted it so that I could loop the belt from the original motor to the external motor and shazzam! I had a lathe that reversed! Could you flip down the rear door to the Jet mini, fish the belt up and loop it over another motor?
Just a thought.
B
 
Bruceyp said:
I admit that this is an unorthodox solution, but.... I once had a lathe that didn't reverse and since I only wanted to reverse to sand, I found a small motor and pulley, and mounted it so that I could loop the belt from the original motor to the external motor and shazzam! I had a lathe that reversed! Could you flip down the rear door to the Jet mini, fish the belt up and loop it over another motor?
Just a thought.
B
Click to expand...

Bruce,

Ira's talking about reversing a JET 1236 that runs on a reeves drive. What you're talking about is a jack shaft motor that will work with stepped pulley drives but may be a different situation with an adjustable pulley system. Neat solution for a Mini though! 😀

M
 
Possibility?

Ira, Mark,

A small motor + belt could be used if connected to the outboard end of the spindle. You would have to slip the belt on and off as needed. 😱
 
Thanks Jake,
that is something I had not thought of and because I will only need to reverse the lathe for sanding it might just work. I have not heard back from Jet yet but when I do I'll let you know what they have to say.

Ira
 
Jake Debski said:
Ira, Mark,

A small motor + belt could be used if connected to the outboard end of the spindle. You would have to slip the belt on and off as needed. 😱
Click to expand...

Voilaz! 😉 A double-use handwheel for the 1236! I'll pass that good idea along, Jake. Now we gotta find a bolt to fit that weird thread in the outboard spindle . .

M
 
That is a great idea!

Jake, that should work. The way I see it, sanding requires much less power because the weight has already been considerably reduced.

The outboard thread in most lathes is left handed. Fitting a handwheel or pulley directly on the thread will require using a left handed tap also. I don't think there is much room on the threaded end to fit a pulley and a handwheel. The outside of the handwheel can be machined to accept a belt. It probably would be wiser to buy a handwheel from a machinist supply house. They can be had unbored and untapped, and tap and machine the pulley right on it.

One question: what speed do you intend to sand at? The ratio of pulleys has to be considered. I think a machinist friend of mine could do it.
 
Mark Mandell said:
Voilaz! 😉 A double-use handwheel for the 1236! I'll pass that good idea along, Jake. Now we gotta find a bolt to fit that weird thread in the outboard spindle . .

M
Click to expand...

Jet has a hand wheel available for the Jet 1236, I have one on mine. The shaft of the hand wheel could easily hold a belt for reverse sanding. The outside diameter of the shaft is 7/8", if you could find a pulley with an inside diameter of the same size you could reduce the speed even more.
 
Fred in NC said:
Pulleys can be bored and/or tapped easily. A 3/4" pulley can be bored to 7/8", if you don't find the correct size.
Click to expand...

You know. . . if someone had a wood lathe. . . they could turn a wood pulley to fit that shaft 🙄 😉
 
Ira,
I don't think that Jet is going to help you in figuring out how to reverse the motor. Reason: Product liability. If they gave you instructions on how to do it, then they are not only sactioning your modification, but participating in it. They don't know what your workmanship skill level is and if they OK your modification, they would be liable if you injure yourself on the lathe even if it has nothing to do with the mod.
Bill
 
Bill pretty much explained the reversing question above. A single phase, squirrel induction motor is reversed by reversing the two starting winding leads (traditionally marked as T7 and T8 in the motor terminal box), only when the motor is stopped.

However, the point no one has made yet is this: Most lathes (including every Jet model I've seen) use a right hand thread for attaching chucks, faceplates, etc. The standard rotation of the lathe causes the force against the wood to create a constant tightening of the chuck on the head stock. Turning the lathe in reverse causes a loosening effect on the chuck. Therefore, the chuck and piece could come flying off the spindle if you're not very careful 😱 . I would only reverse one of these lathes after having drilled and tapped the chuck or faceplate perpendicular to the shaft and filed a flat on the spindle such that you could install a locking setscrew to assure the chuck will not rotate off the spindle.

Ya'll be careful now, ya heah! 🙂
 
Thank you for the advice Fred. That is the one thing that I have already done, though I did not use the method you mentioned. What I do is simply spin a thin 1"-8LH nut onto the spindle first and then the chuck or faceplate. The nut and the chuck or faceplate are tightened against each other and together form a kind of lock-nut, much simpler than drilling tapping and filing and quite secure. I have to say it did take me some time to find a 1"-8LH nut. I do appreciate the advice, I have learned a lot from the people responding to my question.

Ira
 
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