Hi, Need a tip or two. Long story short: I am sick and tired of plastic wheels and would like to make a new cnc machine based on metal parts all the way. Another build gave me ideas for how to proceed: Textile machine bearing structures CNC engraving machine See the pictures on how the guy attached the rods to the v-slot extrusion. One thing that has me stumped is how to ensure I drill the holes through the metal rods correctly so that the holes on each end are perfectly parallell vertically. It taks zero effort to mess this up, something my lack of metal working skills most likely will ensure happens... One idea is grinding a flat spot on a rod, punch and then drill that on my ****** drill press. Then screw down the rod on a v-slot rail to secure it in place. Rinse and repeat on other end. Any ideas for another approach? Grinding down a flat spot with my meagre tools means filing and that SUCKS.. Any briliant insights would be much appreciated.
Put it in a v-shaped jig, use a drill press with a fence, find center, drill the center hole first, bolt/screw it to the jig so it won't roll, and then drill the rest. Or, do as others have and attach the rod to the v-slot with epoxy, but if I were doing it I would use a square rod/tubing and then steel v wheels.
It is a very good idea, and the durability must be great. I would worry a little about any slippage I might get with polished metal on polished metal. Your idea of making a flat spot is good, but I know I've seen videos on Youtube about how to drill rod like you need to. I can't remember the clever technique they used though. Treat yourself to a Grinder, they're really quite cheap nowadays.
It's a fairly simple with a proper jig... I would recommend using steel bar stock to prevent the bit from wandering.
By the miracle of trigonometry, technically you don't actually need perfectly square, centered and parallel holes. You just need the average force of the screws to be at a sufficiently shallow angle to the V of the V-Slot (which does include perfectly square, of course) that the larger effective force is directed down and into the center of the groove. Alternatively, by drilling oversized holes and counterboring with a 118 degree drill bit, you can allow the entire screw to float in the hole and only exert force with the head on the part where it's drawing the bar directly down into the V-Slot... Slot. You could then, theoretically, CNC a jig to re-drill perfect holes, should you be so inclined.
