CNC woodturning lathe project engraving on a sphere
Posted by
Keith Clark
on 2006-01-14 15:14:30 UTC
I hope you guys can give me some more help. I certainly appreciate
the help so far and feel I am gradually making progress. Does anyone
have any suggestions or comments on the following...
CONFIGURE THE LATHE AS MILL?
I imagine that the router mounted horizontally on the cross-slide
would be just like the spindle motor on a mill and might be called the
Z axis as one discussant suggested. Could I take some text, or a
digitized photograph for that matter, and lay it onto the surface of a
30 inch diameter sphere using a CAD/CAM software such as BobCad? Then
could I generate the G code to do the job as if it were a mill with a
4th axis being the spindle?
IS THERE A RESOLUTION PROBLEM?
I am also trying to figure the needed resolution for the construction
of this CNC woodturning lathe. The problem is that this thing has to
work on a 30 inch diameter piece of wood. Here is my logic.
SURFACE TRAVEL PER STEP? - .047"/step
A microstepping drive generates 2000 pulses per revolution so there
would be .18 degrees of rotation per pulse(360/2000) given that the
motor is coupled with a 1:1 gear ratio.
A 30 inch diameter log would have a circumference of 94.2 inches
(3.14xD). Surface travel on the outside of this log would be .047
inches/step (94.2/2000).
Surface travel on a 10 inch diameter log would be .0157"/step (31.4/2000).
GEAR REDUCTION? - 47 at 30" diam and 15.7 at 10" diam
If I wanted a resolution of .001"/step with a 30" diameter log, I
would need a gear reduction of 47 (.047/.001). For the same
resolution at 10 inch diameter the gear reduction would be 1/3 or 15.7
(.0157/.001).
There is quite a bit of disparity between the resolution at the
two example diameters. Does this matter? Do I have to change the gear
ratio as the diameter varies or do I just need to set up the minimum
required resolution for the maximum diameter to be turned and let the
software to the rest?
Thanks,
Keith
the help so far and feel I am gradually making progress. Does anyone
have any suggestions or comments on the following...
CONFIGURE THE LATHE AS MILL?
I imagine that the router mounted horizontally on the cross-slide
would be just like the spindle motor on a mill and might be called the
Z axis as one discussant suggested. Could I take some text, or a
digitized photograph for that matter, and lay it onto the surface of a
30 inch diameter sphere using a CAD/CAM software such as BobCad? Then
could I generate the G code to do the job as if it were a mill with a
4th axis being the spindle?
IS THERE A RESOLUTION PROBLEM?
I am also trying to figure the needed resolution for the construction
of this CNC woodturning lathe. The problem is that this thing has to
work on a 30 inch diameter piece of wood. Here is my logic.
SURFACE TRAVEL PER STEP? - .047"/step
A microstepping drive generates 2000 pulses per revolution so there
would be .18 degrees of rotation per pulse(360/2000) given that the
motor is coupled with a 1:1 gear ratio.
A 30 inch diameter log would have a circumference of 94.2 inches
(3.14xD). Surface travel on the outside of this log would be .047
inches/step (94.2/2000).
Surface travel on a 10 inch diameter log would be .0157"/step (31.4/2000).
GEAR REDUCTION? - 47 at 30" diam and 15.7 at 10" diam
If I wanted a resolution of .001"/step with a 30" diameter log, I
would need a gear reduction of 47 (.047/.001). For the same
resolution at 10 inch diameter the gear reduction would be 1/3 or 15.7
(.0157/.001).
There is quite a bit of disparity between the resolution at the
two example diameters. Does this matter? Do I have to change the gear
ratio as the diameter varies or do I just need to set up the minimum
required resolution for the maximum diameter to be turned and let the
software to the rest?
Thanks,
Keith