I’ve recently bought a second hand Tormach 8L lathe from a private seller in my area and noticed that the Z-axis gibs were maladjusted as it was leaving a wavy finish on my parts that you could both see and feel. As soon as I noticed the finish I backed the gibs off to prevent undue wear, and have since readjusted the gibs.
Question is though; why is there is no information in the manual? After I finished adjusting my machine I did some research to find how others perform adjustments and found a video by NYCCNC where he adjusts the gibs on his Tormach PCNC 1100 CNC Mill and he referenced the manual from his machine there. Luckily I had already adjusted my machine in the correct way but having those instructions in the manual would have saved me so much time and effort from figuring out the correct method myself and having to research methodology after. A simple quick overview on gib adjustment could be given in the yearly maintenance section covering the basic functions.
If anyone is interested in the method used:
- Remove both gibs and ensure there are no burrs/nicks. This shouldn’t be necessary unless the machine is heavily worn. For reference my machine is from 09/2023 and I could still see all the scraping marks on the gib with only one or two small wear patches. The side with the notch for the retaining screw is the large side of the gib so it will slides out from that side. Clean as best you can and set aside.
- Set up a dial indicator on the bed ways to check backlash in the movement of the machine with no gib influence. I used a 0.0001” finger dial for the increased sensitivity, and used the machine in the lowest step movement possible as well. Record the backlash number on a scrap to reference later.
- Before installing the gibs ensure you oil all bearing surfaces generously with way lube.
- With the indicator in place install the gibs and check the backlash as you tighten the gib. As soon as the backlash increases you know the gib is too tight and needs to be backed off. Back it off in small increments until the backlash just goes back to the previous recorded number.
- Double check that both retaining screws for each gib are tight as they will allow the gib to move if loose and you’re done
Pictures of gib locations and which end is large/small, and showing the finger dial on the carriage to record backlash numbers
