New, heavier spindle...a problem?

[bridgecity]

Please forgive a double post, I just noticed this forum and it seemed more applicable than the one I posted in previously.

I have a small (20" X 14") CNC Crafter router. It is very well built running 4 to 1 ball screws with delrin (?) nuts with 300oz/in steppers. Up until now I have had a Porter Cable 690 router as a spindle, and I have seen this CNC machine with Porter Cable 7518 3.25hp routers (12 pounds in weight) mounted on them successfully. I just bought a real 1.3hp spindle to put on it (not a router) and it weighs an unexpected 16 pounds. I have a concern about the weight on the Z stepper and whether the X and Y steppers will be able to deal with the extra weight. I don't think the mounting or the bearings will have any problem.

Any input will be appreciated.

Donn

[bridgecity]

Not even a wild*** guess?

Donn

[svenakela]

I don't think it's a problem. The problem would be rigidity when you start to push it, but that will be noticeable.

[bridgecity]

Well, thanks for the input.

To update, I've mounted the spindle and fortunately my small cnc is very rigid so there is no problem in that regard. I ran a test file and it seemed to move just fine, though the Z seemed to make working noises a little different than usual. I eased the ramping on all axis a little out of precaution.

My main concern at this point is the delrin nut on the z wearing out faster and whether I should mount a spring counterbalance on the z assembly to ease the pressure on the nut and Z stepper.

Anyway, thanks again!

Donn

[ironDigit]

a counterbalance would be quite logical if you think the weight is to much for the Z.

i'ld advise a gasspring instead of hanging a big block of weight on the back for inertia reasons/issues.if for example your Z-assembly weighs 20pounds install a 10pound gasspring but never a 20pound gasspring.

hmmm...Delr9n nuts on a ballscrew ? probably you got a trapezium leadscrew with delrinnuts or just steel nuts on a steel ballscrew.If its the steel ones you shouldn't worry too much as long as you keep it properly lubricated.if delrin i can imagine the nut wearing "faster"but i have no experience with delrin at all.

take alook at the benchtop mills cause these seem to use the counterweight most of all and there should be lots o info tehre if this didnt answer your question.