H-M Supporter - Gold Member
H-M Supporter - Gold Member ($25)
- Apr 27, 2014
I recently got a Harbor Freight Mini Mill (branded Speedway, but it looks like a Sieg X2D) fairly cheaply at a resale shop that cleans out houses and estates. There were several items missing that I needed to purchase to get it back to operating condition. That done, I used it to make some t-nuts for the table as a small "get familiar with the machine" project. I noticed that the Z-axis has a lot of backlash due to the rack and pinion set up and fine adjustment arrangement, and that if you are not careful the spindle assembly could have an unwanted drop. This could gouge and possibly ruin a part being machined. I did some research on the problem and found several very helpful tips to help eliminate excessive backlash which I am currently incorporating (shimming the rack, remaking the handle key, etc). While I was working on these items I had a thought that part of the problem was that the spindle head wasn't completely counter-balanced by the torsion spring/arm arrangement, and that a little more spring tension might keep the head in place even when the lock is released. I disassembled the counterbalance spring assembly to see if there were any kind of adjustments similar to a drill press. There was no easy adjustment possible. The fixed end of the spring fits into a hole through the assembly into the main column. There was enough room to drill a new hole about 45 deg. counter clockwise from the original that would provide a little more wind up. So I moved the fixed end of the spring into the new position and reassembled everything. It takes a little more effort to move the spindle assembly down in fine adjustment and drill press mode, but when I set a head position and release the lock, the head stays put. I just thought I would pass this along since I didn't see it in the research I didn't know if anyone had tried this approach. Hopefully it might help someone out. Thanks.