Jet Lathe Spindle

[Mike Johnson]

I have an old Jet Lathe JWL-1236 knock-off made in China that I am modifying into a variable
speed lathe using a 2-1/2HP DC motor. The spindle has an external thread of 1x8 at the head-stock
on the opposite end of the spindle there is an internal thread that goes in about and 1-1/2".

Does anyone know off hand what the thread pitch is for this internal thread? This would be where
you place your knock out rod to push the spur drive out of the morse taper in the spindle. I looked
in the parts manual for the Jet lathe and China knock-off and no thread pitch is listed.

The DC motor has a threaded motor shaft that I am wanting to mount on the opposite end of the head stock
and machine a threaded adapter that would thread into the internal spindle thread.

The China made knock-off supplier is no longer providing certain spare parts for this machine so I am wanting to do away with the reeves drive pulleys and try out a simple install of a DC direct drive motor.

Mike J.

 

[Dwight R Rutherford]

A thread pitch gauge would work to find the info you want. Know a machinist? They will have one. Short of that, you can buy a plastic one from Amazon.

 

[stu senator]

Do mean a solid coupler between the motor and shaft? This would not be a good situation as it would require perfect alignment between shafts. You would need a flexible coupler to avoid bearing problems It would be best to use a belt drive.
Stu

 

[Mike Johnson]

I found several posts on other wood turning sites and the information was questionable.
They were stating that the thread was a 1/2-12 L.H. pitch from what I can see from the end
of the spindle looking at the threads this does not seem to be correct.

Jet has a hand wheel part number 708344 that threads into this opening.
Does anyone know what the thread pitch and count per inch is on the hand wheel accessory?

 

[Bill Boehme]

The only easy solution that comes to mind is to get several metric screws to see if any of them fit. I suspect that it might be a nonstandard fine pitch. If so, you could try some smaller screws with finer pitch and basically use them like you would use a thread pitch gauge.

I had exactly the same thought that Stu did about coupling the motor shaft directly to the spindle with a threaded coupler. As Stu said, you need a precision alignment and a threaded coupler won't meet that requirement. There are various kinds of shaft couplers that will allow some angular and parallel misalignment.

Here is a link to the Lovejoy Coupling Handbook.

 

[Mike Johnson]

I have a supply of metric bolts and nuts at my work place that I can test the threads with. I plan
on machining a coupling that will incorporate a polymer segment between the motor and spindle
coupling to provide for the motor alignment issues.

With the reeves drive removed there is about 4 to 5 inches of spindle shaft that I have to work with
that I can modify or machine on my metal lathe to receive an end mount coupling. The DC motor has
a mounting flange that will readily mount to the flat metal cover that encloses the head-stock on the left
side. Several mounting holes can easily be located and drilled in the metal housing cover to attach the
motor to the left side.

With this design the only engineering required is for the motor coupling, this would simplify a DIY project
for thousands of these older machines that have the cheap reeves drives. The main supplier/distributor
is obsoleting the spindle reeves pulley from there spare parts offering for these older machines.