SFU1605 Ballscrew Standard vs Anti-backlash

[JamesOAB]

Thanks @Voicecoil and @JAZZCNC for both replying to me it very much appreciated

Good news about the standard ballscrew having low backlash

@JAZZCNC I see your point about the pitch of the 1605 will result in slower speeds, I guess i can live with this for a bit but upgrade the Y axis once everything else is up and working, For the two X axis at 1200mm do you think 1610 will be be ok for the this length or should i push for 2010 or 2510 ?

Sorry if this is silly question but If I use a larger pitch does this require more force out of the stepper motor and if so is there a resource that i can get this info from

Many Thanks

James

[JAZZCNC]

@JAZZCNC I see your point about the pitch of the 1605 will result in slower speeds, I guess i can live with this for a bit but upgrade the Y axis once everything else is up and working, For the two X axis at 1200mm do you think 1610 will be be ok for the this length or should i push for 2010 or 2510 ?

Sorry if this is silly question but If I use a larger pitch does this require more force out of the stepper motor and if so is there a resource that i can get this info from

Not a silly question at all, it's actually a good question because it shows you have either done a little research or have reasonable engineering knowledge.
Strictly speaking in theory, yes, because the torque will be lower, but in reality, going from 5 to 10mm won't make a jot of difference provided you have reasonable overhead in the size of your steppers because the difference isn't that great and you'll have more than enough torque with a 10mm pitch. In fact, It's a common mistake for new builders to underestimate the forces steppers connected to ball-screws provide. For instance, the Z-axis with just a 3nm motor will easily punch a nice clean hole thru 18mm MDF without the spindle turning so you can imagine what 2 x motors working together will do.

Regards the 1200mm screw then you'll just about get away with 1610 however I would advise you to have both ends machined to accept fixed BK bearings as it offers extra support which makes the difference.
You could go with 20mm to be sure but then you have to think about the extra inertia and the effect it has on the motors. If your motors are 4Nm or more then you won't have any troubles, even 3Nm will work but 4Nm gives you plenty of overhead.

If I was fitting 3Nm then I would buy 2020 screws and connect them to the screws with timing belts and use a 2:1 ratio, this will increase the torque and halfs the screw speed which lowers inertia and chances of whip.
To be honest, I would connect the motors to the screws anyway even with a 1:1 ratio because it lowers resonance which allows the drives to run the motors smoother and faster.