The hand wheel and drive train that operates the rack drive is sloppy and not a pleasure at all.
I remade the original bushing that mounts the handwheel. This improved things a little, but the rack drive train is still sloppy, and far from silky smooth.
I removed the apron and gear box to investigate. Here are some photos.
If I get time I will redo all the gears, shafts and bushings on this drive train.
↓ Here is a view of the grrrbox.
The small gear at the bottom of the picture runs on the rack.
↓ Part of the problem is the state of the gears and the meshing.
↓ I took it apart to investigate further.
↓ This is the shaft that the handwheel is attached to.
Look closely at the gear teeth, they're awful.
I remade the bush that carries this shaft.
I think that if this shaft and gear was remade, extended, and supported at two points then an improvement will be made.
↓ I remember reading somewhere that the shafts in these Chinese machines are a standard bearing size.
I tried some washing machine motor bearings.
Well, they were a surprisingly good slip fit on the shafts, but not a press fit.
I reckon they could improve the feel of the drive. The grrrbox casting would have to be bored out for this.
↓ As an experiment, I temporarily increased the radius of the handwheel to see what it felt like.
The hand wheel was mildly easier to turn, but the drive was still sloppy.
Up until now, I have not been able to do anything to this drive, because I needed a second lathe to make the parts on.
I was lucky enough to get an ML7, so I may get down to redoing this drive sometime.
I think I will make new shafts and maybe use bearings instead of bushes. I could bore out the
castings and make 'never go back' changes, but I am always reluctant to do this.
Instead, I will probably bolt some bearing housings to the castings to take the new shafts.
