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Hi,

I need advice on the two types and also what screw diameter I should use for a strong enough torque to mill copper. I was thinking a diameter of 20mm for x and y axis and a 16mm for the z axis? also correlating to that, what size should i machine the feeding bit on the screw for what size of coupler? is there a relation to the diameters chosen of the screws or does it solely depend on the ID of the hole of the coupler? any help would be highly appreciated!

philipp

TRAPESIODAL SCREW IS SELF LOCKING, THEREFORE HOLDING TORQUE IS NOT BE VERY HIGH , BUT THERE IS A PROBLEM WITH BACKLASH , IT IS A LITTLE BIT DIFICCULT TO ACHIEVED A SATISFIED AND LONG LASTING (WITHOUT ADJUSTMENS) CONSTANT ZERO BACKLASH . ON THE OTHER WAY THE BALL SCREWS IS NOT SELF LOCKING , THEREFORE SERVO OR STEP MOTOR NEED A BIGGER HOLDING TORQUE , BUT BALL SCREW NUT - ROD IST ALWAYS WITH ZERO BACKLASH (TEORETICLY BACLLASH IS 0,0) AND THEY NOT NEED ADJUSTMENS . , BUT THE PRICE FOR BALL SCREWS IS ALCO HIGHER THEH TRAPEZIODAL . DIAMETER FOR YOUR NEEDS I CAN NOT RECOMENDED BECAUSE I DO NOT NOW HOW BIG MASCHINE WOUD YOU MAKE AND HOW BIR MOTORS DO YOU HAVE . BUT , I BUILD A CNC ROUTER WITH 1,0 M X 1,0 M AND I USE BALL SCREWS L -1100 MM WITH DIAMETER 16 X 5 AND WORKS VERY WELL .

sweet! thanks a lot for your reply. that really helped a lot. I was going to build a ­frame­ that is 840x840 with aluminium extrusion in the size of 45mmx90mm (L or S, I don't know yet). So, do you think 16mm ball screw will do, or is 20mm better to be on the safe side when milling soft ­meta­ls? motors, I was thinking about a dual motor set up (left and right side of the ­base­ ­frame­ for the x axis, maybe 200-300ozin each? an a 400ozin motor for y? do you think those are good choices? not sure what motor I am going to use for the z axis yet. Cheers!

FOR YOUR CNC ROUTER IS VERY GOOD CHOISE BALL NUT AND ROD WITH DIAMETER 16 MM AND 5 MM STEP . MY MOTO IS "THE BIG IS NEVER TOO BIG BUT SMALL IS EVER TO SMALL" , THEREFORE MY SUGESTTUION IS TO TAKE A 400 OZIN (2,5 NM) MOTORS AND IF YOU HAVE POSSIBILITY BY ALL 4 MOTORS THE SOME TORGUE / MODDEL . THEN YOU AVOID PROBLEMS WITH MOTOR DRIVERS CONFIGURATIONS . SIMPLY , ALL DRIVER HAVE SAME CONFIGURATION .

Yeah true, I was thinking of buying the same motors, but then I thought in terms of dual motor set-up on the ­base­ that if i put 2x400ozin on x and 400ozin on y then I have a lot more torque on x but less on y, so y becomes the limiting factor. if i use 2x400ozin on x do they not add up in power? so doesn't it become 800ozin? thats why i thought 2x200ozin on x each side for good and stable movement and 1x400ozin on y. not sure I thought energies, just like volts add up? cheers!