# Lathe repair



## Larry42 (Jan 14, 2020)

The cross slide on my lathe had started moving erratically when under power. It finally stopped. Took the taper attachment off the back of it, then the rest of the cross slide off of the carriage. Found the problem. The set screw that held the key in the gear shaft (hand wheel shaft) that slides onto the threaded shaft had fallen out. That released the key and it also fell into the apron gear box. The parts book listed the screw as a 3mm x 5mm panhead. I tried a 3mm in the hole but it didn't even touch the sides. A 4mm went in very loosely. Threads looked stripped. I had never had this part of the lathe apart before so it was made that way. A very bad design as there were only 2 -3 threads engaged to start with. The shaft was very thin because of the keyway at that point. Using my gage pin set I found that a pin .010 larger that the 4mm threads would go right through. Only choice now was to drill & tap for a 5mm set screw. I used a gage pin to align the hole to the chuck on the mill. Then tapped using a tap follower. Made a new 5mm key. Thought about Leaving the key & set screw in the apron gear case but decided not.

The feed shaft slides through, so I will have to take the block off the end of the lathe and see if I can get the 3 shafts out far enough to clear the gear case. 
I've decided to clean every thing and while putting it back together try and figure out how to take some of the slack out of the taper attachment. I had wondered how they managed to get both the front cross slide hand wheel and the taper attachment to move the slide. It is the concentric shafts & key way. Don't know if that is designed into the lathe or parts have to be replaced to make it that way when you want to add a taper attachment. 
The Chinese method of scraping the cross slide was to put some course grinder marks in the surface. Sort of looks like scraping and may fulfill the function of keeping an oil film between the parts.       To be continued!


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## markba633csi (Jan 14, 2020)

The Chinese method of scraping is often no scraping at all   Just milled and assembled


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