Quote Originally Posted by Tenson View Post
Can you guys see my post? I was obviously posting okay but then it said I need my post approved by a mod?

Hmm seems okay again :)

So I'll probably put the lathe idea to the side for now, but it does seem like attaching a more meaty motor and chuck to the spindle bracket and then having a fixed tool clamped to the table will work best.


Now, the weakest part of this CNC machine seems to be the plastic (I don't know what it's called?) that links the trapezoidal rod to the moving arm/spindle. Everything in this machine is nice strong metal except this nylon part.

Is it worth changing them for metal ones or does it need to be nylon for low friction on the rod?

Alternatively I've seen ball-screw rods and ball-nuts for sale and I consider upgrading with these. What makes ball-screw better than the more normal screw thread I already have?

You can see the plastic bit in my picture here.
If you remove the screws and slide out the plastic nut does it have a long shaft cut into 3 separate pieces with a spring mounted over them? This is designed to push radially down onto the screw with slight force to keep the threads engaged and reduce the amount of backlash. If it has then it is an anti-backlash nut and is perfectly ok to use for a wood router. The plastic is self lubricating and has very good wearing properties. This nut looks to be Delrin. Correct me if I am wrong.
If it is just a standard nut with a thread then you will have backlash on the screw and your positional accuracy will be thrown out.
These type of screws are very good with all the dust and fibres thrown around when cutting wood and are self cleaning to a certain degree. It pays to keep them clean as wear and tear will occur if material is left to build up on them. A few drops of oil occasionally will help keep them smooth but will also attract dust. Some people just keep them dry. After all, they are self lubricating :-)
Ball screws are also very good but keeping the crap out of them is another story due to the small tolerances involved. Some manufacturers of high end machines blow compressed air through them with a small amount of lubricating oil to keep out the crud and other more simple set-up's have fibre washers or felt washers at either end to seal them from debris. There are some good spring steel covers on the market now that cover both sides of the screws and keep out nearly all of the dust etc but they are very expensive. They are like the spring inside a tape measure but much wider and pull out from the centre.
It's your choice and other people here will let you know how they fare with their set up's being good or bad.
Here is a bit of info on some types of plastics you may come across in your travels. Just a bit more ammo to chew on.
http://www.mcmaster.com/#plastics/=gix8tt

I hope all this helps you somewhat.
Rich.