9x20 Rack Alignment Issue

[spanish249]

Hello everyone, first time posting here. I recently purchased a 9x20 Chester lathe, as near as i can tell its an exact copy of the Grizzly, Jet and HF lathes.
It is in pretty decent shape apart from an issue with the apron gear that meshes with the rack.

As i move the carriage towards the headstock the gear starts to 'slip'. Upon closer inspection it seems the gap between the gear and the rack increases as it approaches the headstock.

There is a noticeable difference in the gap between the top of the rack and bottom of the ways. I measured the distance from the top of the ways to the bottom of the rack at each retaining screw that holds the rack. At the leftmost screw the distance is 31.3mm (1.232 inch) and the rightmost screw is 32.1mm (1.263 inch)

Im wondering if anyone else has came across this particular issue and might be able to offer some advice.

 

[Eddyde]

Hum .031" difference, certainly enough to cause noticeable slop, Most likely was made that way, I doubt the ways wore out that much. I would remount it, maybe replace it as well, that one looks pretty worn.

 

[markba633csi]

Yes the factory mounted it incorrectly, one of those "Friday" jobs. You can approach it a couple ways. Probably I would remove the rack then spray out the holes with brake cleaner. Epoxy screws into holes. Cut off flush with the bed. Redrill one mounting hole on each end, intersecting the repaired holes. Tap holes. Re-mount rack and mark and drill remaining holes. Tap remaining holes and reassemble.
-Mark

 

[spanish249]

I took off the rack and inspected it. Cant see any obvious wear, measured it and theres only 0.1mm (0.003") difference in the size top to bottom.
However the tapped holes that the rack screws go into seem to be misaligned, higher up on the spindle side, lower down on the tailstock end

 

[C-Bag]

Welcome to the wonderful mystery world of the Chinese made 9x20 lathe where anything can be wrong. Those of us who have them have decided they are a “kit” and as such it’s up to us to find and cure the problems. And an opportunity for creative repair I sometimes find things that were originally a design flaw, but often just a one off “made on Friday/Monday” kinda thing.

I would bet either the rack was drilled wrong for the locating pin or the lathe frame was drilled wrong. I would pull the rack and check it for wear and distortion. You might be able to turn it around if it’s worn. It might also be possible to shim it up and reinstall.

 

[spanish249]

Yes the factory mounted it incorrectly, one of those "Friday" jobs. You can approach it a couple ways. Probably I would remove the rack then spray out the holes with brake cleaner. Epoxy screws into holes. Cut off flush with the bed. Redrill one mounting hole on each end, intersecting the repaired holes. Tap holes. Re-mount rack and mark and drill remaining holes. Tap remaining holes and reassemble.
-Mark

Ya i think that might be the way to go mate, im not sure if the rack is supposed to be flush with the bottom of the ways or that there is a certain gap that should be allowed

 

[DavidR8]

These is just a random thought...
Could you shift the rack toward the headstock maybe .5" or so to allow you to drill and tap all new holes?

 

[spanish249]

These is just a random thought...
Could you shift the rack toward the headstock maybe .5" or so to allow you to drill and tap all new holes?

Ya thats a good idea, id probably shift it towards the tailstock end though so im not losing any travel with the apron

 

[Cadillac]

Maybe mount a scribe on the carriage run it back and forth to give yourself a reference. Pull the rack off file and oblong the mounting and locating holes. Then when in the proper position drill some new holes to hold in its new place.

 

[spanish249]

Maybe mount a scribe on the carriage run it back and forth to give yourself a reference. Pull the rack off file and oblong the mounting and locating holes. Then when in the proper position drill some new holes to hold in its new place.

I may do that, unless anyone who owns one of these lathes knows what the gap between the apron gear and rack is supposed to be?