hi, i'm going to make cnc machine but don't know how to chose the correct leadscrew diameter ? does any one know how to teoritical calculation ?
It just depends on what you are doing. Length, diameter, pitch, load, mounting method, material type, and I'm sure there's more, all have a factor.
There is a calculation shown somewhere deep within the forum but I wasn't able to find it. There are plenty of resources online though. A few quick finds include: Lead Screws: Selection Process https://www.thomsonlinear.com/downloads/screws/Neff_LeadScrews_bruk.pdf Ball / Lead Screw Sizing Tool
I think this may be the one your looking for Rick. Its a great calculator that covers most machine styles belt or lead. Joseph Prusa's and Nathan Zadoks - RepRap Calculators Hope it helps