I'll throw out some things here;
I think it depends on your cnc software about mixing and matching. I use MACH2 and have mixed different pitch leadscrews, and now ballscrews on X and Y, stock rack and pinion on Z. Today my task is to put the ballscrew on Z. In MACH2 it's all about how many steps to go one inch. Was pretty simple for me.
If I had to do it all over again, I would have ripped my mini-mill apart as soon as I decided to CNC it, and put in ballscrews. Then again all the wasted parts when a leadscrew missed a step, got some money at the recycler. Once you hold a ballscrew in your hand, you will never want to use a leadscrew. Now you don't say what kind of machine your are looking at, and my friends Bridgeport clone has very nice leadscrews, but it's still a lot of turns per inch. I gained TONS of torque with ballscrews by being able to turn my steppers slower to go the same distance, ie 20 tpi leadscrews and 5 tpi ballscrews.
If your not a machinist, which I am definetly not, I would have someone turn the ends of the ballscrews for you if possible. I got my X and Y from homeshopcnc.com and he delivered them with the ends turned very nicely. I bought my Z without machining, and I know now why it costs so my to turn them. I had to made a collar to get it centered in a 4 jaw axis, then take small cuts to get throught the hardened threads. It was a learning experience, ya that's what is was....
One the 2 screws per axis, I have never done that, but MACH2 supports slaving steppers together for exactly that design. You must be building a gantry router to want that.
BTW you've found the best place to ask questions, and you probably can get more pointed answers in specific forums, i.e mini-mill, router, etc. There are some very knowledgable people here.
Good Luck!
Rod  |