View Full Version : Jet 12x36 backgear problem

Mike Gibson
11-05-2006, 09:19 AM
Yesterday, while I was threading on my Jet 12x36 the backgear mechanism on the spindle locked up like I had never disengaged the pin in the spindle.
I was able to free it up by turning the spindle in reverse but I am sure it will bite me again. Does anyone have advice on this before I disassemble the spindle to see what caused the problem ?

11-05-2006, 09:57 AM
The 12x36 headstock is very similar to the 10x24's. It's pretty easy for chips to get in through the back of the headstock where the belt goes. In case you don't have one, there's a manual here:

Too bad it doesn't have a parts illustration.

A chip probably found its way into the opening between the pulley and the gear on the spindle, or into the meshing gears. It wouldn't take much in either place to bind things up.

I took a look at mine, it's definitely time to clean it up. :D


Mike W
11-05-2006, 12:59 PM
Winchman, do you have the page that shows the metric thread cutting chart? I have a 10 by 24 that is very similiar. The main difference that I see is the position of the carriage hand wheel, mine is on the left side, thanks.

11-05-2006, 03:30 PM
I have 1975 Jet 1024 that I bought used in 1981. It would seize up in backgear very quickly from heat expanding the spindle. It was intolerable, so I dismantled the spindle assembly to open up the bore in the step pulley just a bit. Once it was apart, I decided to bore out the pulley and left end gear and press in an oilite bushing. I broached an oil groove to line up with the existing oiler. I don't remeber how much clearance I gave it, but I should have left 1/2 or 1 thou more, because it will still sieze, but it takes much longer now. I also get 1 or 2 seconds audible warning, and if I give it a shot of oil before a long back gear operation I rarely have a problem now. For your problem, perhaps more frequent oiling would help enough to avoid the rebuild I did, assuming your problem is similar to mine. Keep us posted.

Mike Gibson
11-05-2006, 05:47 PM
My problem sounds a lot like yours. I'll try the oiling first and see if that helps. Thanks.

I wish I had the original manual but Jet was only able to send me a xerox copy of the manual. If I have to disassemble the spindle I am going to take pictures and hopefully help me and others who may have experienced the same or similar problem. This problem is a real pain when threading 1 5/8 x 4tpi acme. Thanks for the look at your manual.

11-06-2006, 07:07 AM
Sorry, that's all there is to the manual. There's nothing on the machine labels, either.