I know this subject has been covered a lot, but I am still really confused. I was hoping some of you elders could help me out.
I built a JRGO type machine and have been having a blast with it. But the X-axis (the long one) lead screw is whipping like crazy. I really notice this during rapids, but am pretty sure it influences my slower movements. I am using 3/8” 12 pitch ACME screw, 200 oz steppers, and LoveJoy couplers to go from 3/8 to the 1/4 motor shaft. The lead screw nut is a home made Delrin type. On the far end I am using a ball bearing with a nut on each side captured in two pieces of MDF.
I can think of at least four things wrong;
The lead screw is only supported at one end, causing the motor bearings to take a beating.
The lead screw is in compression, so any tendency to whip is encouraged.
The ball bearing is taking lateral thrust (which I don’t think it is built for).
The LoveJoy coupler allows the lead screw to “pull out” again encouraging whipping.
So if I want to fix this right, I am thinking about changing to a 1/2 inch screw to make it more ridged and mounting bearings on both ends.
Now the questions:
1) What is the maximum rpm for a particular lead screw? (I am doing 60 ipm rapids)
2) Is 60 ipm to fast for a MDF/gas pipe design or a 3/8 rod?
3) Are different kinds of ACME rod stiffer than others? (3/8 rod is MSC 01205897)
4) Can someone point me to mountable end bearing supports that would be more professional than my captured roller bearing? (Or even an end bearing support that requires some aluminum tooling on my part.)
5) How do these bearing supports work? Do they have a set screw or C-clip or require nuts?
6) Do I need to have the ends turned down and tapped? (I will if that is what I should do, but I’m not sure how to get it done right now.)
I have been studying the catalogs and can not seem to understand all the varieties. I don’t mind spending some money on the problem if it will yield something that I can transport to my next machine.
Thanks in advance,
Steve