7x16 Mini Lathe [page 12]

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Sunday, Jun 25 2017

Saddle adjustments

The mini-lathe saddle has two adjusting plates, the documentation calls them “press boards”, to control the drag and ridgidity of the carriage as it traverses the ways. The plates are used in place of a solid frame with an adjustable gib. No doubt the plate method of adjusting the saddle is cheaper. The issue is that adjustments don’t hold and the lathe has to be partially disassembled to get at the adjusting hardware.

Three cap screws are used to hold each plates against the bottom of the ways. Tighten the screws too much and the carriage wont move. Too loose and the carriage rocks and/or twists. There are two more adjusting screws that push the plates away from the ways. In theory enough tension can be obtained to keep the cap screws from loosening due to vibration while applying just enough pressure for proper drag and stability. In theory. In practice the cap screws soon loosen and all carriage stability is lost.

Saddle bottom with studs

Saddle bottom with studs

Saddle bottom with studs
Need nylock nuts

Need nylock nuts

Need nylock nuts

Instead of using cap screws I installed 6 30 mm studs cut from m6 x 1.0 all thread. The studs stick up about 15 mm. I planned on using nylock nuts to hold the adjusting plates on the studs but didn’t have any on hand. Until I order some I’m using regular 6 mm nuts with spring washers.

I was able to adjust the carriage so there was no rocking or twisting play although there is more drag than I’d prefer. I think I’ll be able to get it adjusted as I desire once I get the needed nylock nuts. If that doesn’t give me the desired feel I’ll look at shimming the adjusting plate instead of using the two adjusting screws. That may be a more stable way to set the required distance to get the desired feel.

 

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