I have a basic machine going, along the lines of a joescnc made mostly of 8020 extrusions and angle iron.
It won't be long before I need to select a lead screw for a CNC router used mostly for wood and plastics of a slightly larger scale, mine is 6X6 foot in size, with a workable size of at least 5x5' in size.
I have read the FAQ and took note of mention of whip in the thread when traveling at higher speeds, so I would like the highest resolution possible but would like to avoid sagging and whip over 6 feet of acme threaded rod. I was shooting for a 10 tpi with a double screw, meaning at 200 steps per rotation .001 of resolution. If I calculated that correctly, that should be more than high enough "resolution" for me for lack of the proper term.
I was thinking that 1/2 acme thread might sag under its own weight so much so that it will cause havoc, and was curious if anyone who has built a similar machine had any advice on how thick a screw would be sufficient to span that distance, I do plan to pen up the one end in two pillow blocks, and the other one, possibly two if I go the belt drive route. I would make the gear captive between two pillow blocks, or mounted bearings.
Thanks, I would certainly provide more information if needed. All I am really shooting for is a basic machine that get me up and rolling at this scale.
Thanks for you help,