m16 studding work instead of ballscrews ?

[HankMcSpank]

I've just gone through this very procedure .....I have 200 step steppers but send 'em 8 pulses per step. With M8 rod (1.25mm pitch), I worked out that it should take 1280 pulses to move the axis 1mm - I then compared this to real world situation using Mach's funky little 'calibrate axis' utility on the setup page ...it transpires my steppers need 1286 pulses to move the axis 1mm. (not that I think I'd have noticed!)


Edit:-

[edit2] I don't see the point of using M10x1.5 over M8x1.25 - it'll have larger drag (because of radius & circumference) than M8 for little gain in pitch. Irving's suggestion of 12mm x 3 acme/trapezoidal from Marchant dice sounds a better option.

All valid points & I must admit I am wavering a little (esp since you guys know what you're on about & I remain firmly in the 'haven't got a clue' camp!)

However, the other problem I have is that M8 rods are a Gnat's reproductive organ smaller in diameter than the skate bearings they are held in place on my machine - this means a bit of rod wobble (particularly noticeable at higher speeds) - at least going M10, I get a bit more erhm 'straightness', a bit more pitch (ok, miniscule but it all helps!) & can turn the M10 end down to mate with the bearing exactly so there's no slop. And more of an irritation than anything (ie if I was to stay with M8), I bought some oldham couplers with an 8mm bore - it's not ideal to have M8 threaded rod feed into those bores. (if I stay with m8, I'd have to buy some other Oldham couplers...they aint particularly cheap, & this is just a hobby and my 'discarded bits & bobs box' is starting to get full as I've made so many mistakes & bad purchases!) ...far better to turn M10 down to mate with these Oldham couplers with a smooth shaft.

I could stay with the M8 if someone can come up with a cunning way to remove this slop where the M8 rod feeds through the skate bearings (we're probably talking 0.4mm or so in total - but nevertheless that potentially 0.8mm discrepancy between each end which in the CNC world is a monster amount!)

Also...those TR12 with the 3mm pitch - bet you can't roll your own nuts with them that easily ...which starts making them less attractive to someone like me (who's CNC kit budget is miniscule!)

[irving2008]

Also...those TR12 with the 3mm pitch - bet you can't roll your own nuts with them that easily ...which starts making them less attractive to someone like me (who's CNC kit budget is miniscule!)

Assuming you're using Delrin nuts, you make sure you have a 100mm more than you need, chuck it in the lathe (or a drill chuck), spin it up and file a taper on it for the last 20mm, then at the other end file some flats to hold it in a tap wrench. It'll work fine as a tap for delrin with a bit of lube and some muscle....

Or find someone who has the relevant tap and borrow it...