BobCad question ...

WilleeCue

WilleeCue

The Barefoot Cuemaker
Silver Member
I have an existing Bobcad drawing that I would like to cut into a cue forearm as a point. Since it is long I would like the depth to be equal over the entire length. How can I lower the Z axis on one end of the drawing so that the pocket depth will follow the taper of the forearm? I can change the view to "front" and it apears like a straight line down the X axis but I havent yet figured out how to grab one end and move it doen so that all the lines follow that slope. As you are propple aware the manual that comes with BobCad is sorely lacking on the "Basic" stuff. I know I could just lower the back end of the forearm but hey ... I have this nice computer program that is suposed to be able to do all that for me. Besides, I would like to learn more about it also.<grin>
 
I've never done inlaying execpt simple shapes on furniture, so take this for what its worth...

But I think there might be a potential problem if you use the apporach you described. Unless you tilt the head of your machine so that the cutter is perpendicualar to the bottom of the pocket (whcih would now NOT be parallel to the the table of your machine), you will end up with the walls of the pocket not being perpendicular to the bottom of the pocket. I think this problem would be most noticible on the front and end of the pocket, and hardlly noticible on the long sides of the pocket. This would probably cause problems fitting the inlays, but it might also be so slight of an angle that it wouldn't cause problems.

Also, you would not be milling the bottom of the inlay with the entire width of the endmill. Only the leading (or trailing) edge would be in contact becasue of the angle. You might have to use a ball mill becasue of this, and at the very least, the surface finish would not be as good as if you were cutting with the whole width of the endmill.

Nick
 
WilleeCue said:
I have an existing Bobcad drawing that I would like to cut into a cue forearm as a point. Since it is long I would like the depth to be equal over the entire length. How can I lower the Z axis on one end of the drawing so that the pocket depth will follow the taper of the forearm? I can change the view to "front" and it apears like a straight line down the X axis but I havent yet figured out how to grab one end and move it doen so that all the lines follow that slope.
Willee, I'm not a CNC user as yet but just going to reply to these out of my understanding.

From what I understand, what you want to do is have the walls of your cavity perpendicular to the center axis of the forearm yet wants the bottom of your cavity to be parrallel to the outside surface. This will make the joint end of your cavity have a wall to floor angle that's less than 90 degrees and the a-joint end to have a wall to floor angle that's more than 90 degrees. How do you plan to cut your inlay piece? Do you have a precision tilting table to hold your inlay material at an angle while being cut in your CNC?

It's just how I'm visualizing the situation. If I'm wrong then I apologize.

Edwin Reyes<-CNC illiterate

Edit:
I just thought of this solution after I pressed the submit button. I doubt though that the CNC in the pic that you posted has the capability. Tilt the head of your CNC at an angle perpendicular to your Z-axis slope, if you've found how to program in the slope. This will still allow you to cut your inlay material as you'd normally do, with perpendicular side to bottom angle.
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Last edited:
cueman said:
An easier fix would be to use a offset dead center on the tailstock end to raise the forearm up. That is what I use on my manual Cue Smith Inlay Machine. Doesn't raise it up totally level but gets it a lot closer.
Chris

You are right Chris, as lowering the tailstock center a bit untill the top of the cue is level would keep me within a few thousands down the lenght of the butt. I made an adapter to do just that and it works OK. I was puttering with BobCad and trying to get the Z axis to ramp keeping the depth constant to the top of the wood. The software and the CNC machine are both capable of doing this I just am not capable of figuring out how to tell it what I want it to do. <grin>

I have asked Unique Products about designing and making a tailstock for the Cuemonster that could be adjusted downward but they feel that this is not a very importaint issue or a needed feature. It becomes importaint if you are engraving a long design in the forearm and want to keep the depth set at .015". As the engraving bit (30 deg. point) goes deeper it cuts a wider line so it is importaint to keep a constant depth for the whole design.
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