Lathe Carriage Lock

I haven’t done much with my lathe yet, since I’ve been busy with life and other projects (I finally finished the sprinkler system in my front yard – after 3 weekends of “it’s too hot to work outside”), but I have managed to find time to make a necessary improvement: a carriage lock.

The problem was that the manual gear-driven movement of the carriage when the auto-feed was not engaged was too free, so that when I cranked the cross-slide across the face of a workpiece, the carriage shifted left and right, making it difficult to create a perfectly flat surface.

I assumed I wasn’t the only person encountering this issue, and did a quick Google search to find out how others had addressed it.

Basically, the solution was to make a low-profile clamp that pulls the carriage down against the rails, much the same way the tailstock is held in place.

Since I was planning to copy the effect of the tailstock locking mechanism, I used the clamping piece from it as a template to create the parts.
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After milling out pieces for the top of the carriage and the bottom of the rails I drilled and tapped holes to allow a 5/16″ bolt to apply clamping pressure.
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I tested this out and found that it effectively locked the carriage, but it also tended to pivot too much underneath the rails and would jam up and prevent the carriage from moving even when the bolt was loosened.
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Luckily I had made the pieces out of thick enough metal to re-cut the bottom piece on the other side, this time with a much tighter fit between the rails so that it would have minimal ability to twist.
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This solved the problem. I can tighten down the bolt to lock the carriage and loosen the bolt while leaving the lock installed without worrying about the movement of the carriage being impacted.
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I may re-visit this design in the future, to see if there is a better way to design the clamp, but as it is I can fairly quickly lock and unlock the carriage using 1/2″ socket wrench.

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