filling extrusions was re:defiance vmc
Posted by
ballendo@y...
on 2000-11-30 19:34:44 UTC
Bill,
In my experience, Damping is more important in these machines than
rigidity. Ok, maybe not more important.
If you want more rigidity, increase the size of your extrusions. Also
re-think the structure and see if there are any "connections"(where
two or more pieces meet) that are not as good as they could be...
(more surface to surface contact, more fasteners, less cantilever,
etc.) Maybe a place where the extrusion was easier (you didn't have
CNC then, prob'ly) , but alum. plate (since you DO have CNC now!)
will make a better part...
For damping, plain sand (just slightly damp helps) works REALLY well,
and it is reversible (for moving/ modifications to the machine,
etc.). Pack it as you go! The increased mass will often allow the
router to perform MUCH better. At any rate, I'd try the sand alone
first, then see if you want to "mess" with it. :-)
Hope this helps.
Ballendo
P.S. not sure what you're gaining with the pea gravel. Less cement?
And given the choice of portland cement (in an enclosed vibration
laden environment) or Epoxy as the binder, I'd choose the epoxy for
it's "compliance" factor. (it bends without breaking)
In my experience, Damping is more important in these machines than
rigidity. Ok, maybe not more important.
If you want more rigidity, increase the size of your extrusions. Also
re-think the structure and see if there are any "connections"(where
two or more pieces meet) that are not as good as they could be...
(more surface to surface contact, more fasteners, less cantilever,
etc.) Maybe a place where the extrusion was easier (you didn't have
CNC then, prob'ly) , but alum. plate (since you DO have CNC now!)
will make a better part...
For damping, plain sand (just slightly damp helps) works REALLY well,
and it is reversible (for moving/ modifications to the machine,
etc.). Pack it as you go! The increased mass will often allow the
router to perform MUCH better. At any rate, I'd try the sand alone
first, then see if you want to "mess" with it. :-)
Hope this helps.
Ballendo
P.S. not sure what you're gaining with the pea gravel. Less cement?
And given the choice of portland cement (in an enclosed vibration
laden environment) or Epoxy as the binder, I'd choose the epoxy for
it's "compliance" factor. (it bends without breaking)
>I built a CNC router out of 80/20 Aluminum extrusion and
>while it works great, I was planning to fill the extrusions with
>a morter mix consisting of portland cement, sand, and some pea
>sized gravel to add some more rigidity. Anyone ever done this?
>Would the sand/epoxy mix be a better choice?
>Bill