I'm hoping to make incremental positioning stop blocks as part of a table saw cross cut sled using a short section of threaded rod meshed into a longer piece of threaded rod, and was surprised to discover that the samples of 6-32 and M6 stainless steel threaded rods I got from from Mcmaster have thread counts that add up to enough error that such a scheme doesn't work for accurate positioning beyond a few inches. I see that there are different class fit to the threads on some more expensive variants, but the stainless metric piece was class 6g, and still not 25.4 threads per inch over a long span (as best as I could measure).
There was a higher end (for woodworking) cross-cut sled that used this scheme a few years back that touted a "precision lead screw" for this, but it couldn't have cost them more than a few dollars each given the price and quality of the whole tool. There are plastic racks sold by Incra, used in their stuff, but they occupy more space than I have available in my design. What would it take to produce (or find?) 6-32 and M6 rod (1 pitch ) in say, 24" lengths, that would be within about .005" of even spacing for that length?
There was a higher end (for woodworking) cross-cut sled that used this scheme a few years back that touted a "precision lead screw" for this, but it couldn't have cost them more than a few dollars each given the price and quality of the whole tool. There are plastic racks sold by Incra, used in their stuff, but they occupy more space than I have available in my design. What would it take to produce (or find?) 6-32 and M6 rod (1 pitch ) in say, 24" lengths, that would be within about .005" of even spacing for that length?