Lead Screws For CNC Routers

Depends if you want recirculating ball lead screws or not! I've heard people have had success using stud rod (if it's a smallish machine) It comes in various sizes and as it's normally roll formed it tends to be pretty uniform! What sort of dimensions are you looking at?

42'' and 22'' I have found a great way of forming the lead nuts out of nylon plastic how much backlash would I expect to have with stud rod and what would be the pitch. The nylon nuts should follow the thread quite tightly I am quite thrilled with their design and elasticity. Also what do you think of belt drive and has anyone a drawing of a belt drive train I have not seen any details of their setup.

The pitch! Well that totally depends on the stud rod you use! As for the backlash, you can eliminate most of that using two nuts! All depends on how well the machine is made! Be careful of the nylon, If you are zipping back and forth, it may just melt!

Hi

Nylon is a bearing material and is also used for gear wheels i have also seen it used as a bushing material. The beauty of the thing is that exact thread pattern can be cast into the nylon with a little heat without having to find a die to match the stud it's not my idea but a suggestion posted on the internet

Agreed, nylon is a bearing material but it is not a high load bearing material! If you intend to take heavy cuts, you will put a load on the nut which (depending on the size of load of course) will generate heat, and if that load is high enough, it will melt the nylon! It all depends what you intend to use the machine for! If its for routing wood with no great load on the drive nut then I guess nylon would be ok but if it's a bit more grunty, I'd go for a phosphor bronze nut!

Is this all designed? by the time there is a bearing each end and housing, and an axis, you need to take around a foot off the length for the working area.

Belt drives, -my own setup is stepper in the middle, belt going off each side to drive the y axis. with a little foresight, the stepper could have gone underneath the bed, making the machine a pass through, and easily able to handle work larger than the bed. Toothed belt of course.

There are some good fora: cnczone.com, and machsupport.com, the latter with good information about calibrating your machine, ie working out steps per inch depending on your thread pitch etc.

Making an antibacklash nut is probably the easiest part of the project, and you may find some info regarding the use of nylon. I did read somewhere of slicing a brass nut at 90 to the thread, and tapping a small grubscrew into one half to push against the other, thus spreading the threads slightly, and taking out any slack. It's at the cost of friction though.

jim

I'd check Instructables for cnc stuff, it's a pretty cool site. Here