I'm building a new CNC machine.
It is a fixed Gantry. the moving table X is around 50 pnds.
the Z axis assembly also weighs about 50 pnds. Which rides on the Y axis
They are riding on HIWIN rails. with blocks EGR20CA. the rail is about 20mm or .78 inches wide
I have 690oz Clearpath Servo motors with 200oz continuous torque. They can turn at 1748 rpm
The only thing left to do is buy the proper leadscrew and gearing. It will be belt driven.
Im thinking of keeping a 1:1 ratio with the gearing. so ill basically just be transferring the motion with the gears
so far this is what im calculating and want to know if im doing something wrong.
I could get a leadscrew, 1 start 0.2 inch lead, 5 TPI.
0.75 Inch in diameter 0.563 minor diameter. (length of leadscrew is around 42 inches)
its critical rotation speed is around 1500rpm (thats with 2 ends supported simple. with one bearing on each side.)
is it ok to machine my ends to .5 inches so they fit my pulley clamp bushings?
Which would theoretically give me if I understand it correctly:
right around 300 inches per minute @ 1500 rpm. Or 240 inches per minute @ 1200 rpm.
1500/5 turns per inch = 300 or 1200/5 turns per inch = 240
Im thinking of getting 2 pulleys the same size overall diameter of 2.39 inches one on the motor and one on the leadscrew. link here : McMaster-Carr
To simply transfer the motion to the leadscrew.
Is that size diameter for the pulley good? i cant find any smaller ones that have a clamping Hub. will my motor be able to turn the pulley successfully?
if i understand it correctly smaller gears are better?? what about slippage if i go small on both of the gears?
Im thinking my servos would be able to turn them since my leadscrew would have 1 start at 5 TPI. i would have a bit of mechanical advantage. wouldnt I?
One thing I don't understand as well is how much force is required to move each axis. if the table weighs 50 pnds but its mounted on the rails does this make it lighter?
Probably not right? since i still have to push it around sideways along the rail? I would like to know how much force is required to move each axis.
Ive include some pictures of my machine build so far as well as an image showing motor specs.
thank you so much!