09-17-2014, 06:36 PM
Interesting...
Pix, I can see that working, you'd need decent rollers though as the helically slotted tube would have to be fairly thick, and the interrupted bend (?) might tend to open the slot out - at least I can picture that happening! Have you thought about using a timing belt and pulleys on your mill's X-axis screw/handle to provide a drive to a rotary table / dividing head? an added shaft on the DH worm with a pillow block at the far end might be all you'd need to get drive to it for spiral milling, if you could gear down enough?
That helix and slot arrangement could work, but I don't have a Proper Milling Machine nor a hefty sheet roller, and I'd have to translate it so the outer sleeve moved back and forth with rotation of the inner - I suspect I'd want to make the helix angle around 45 degrees to make it "bidirectional" so the linear movement of the sleeve could rotate the angular movement of the shaft as well as vice versa...
It may be simpler for me to try the ballscrew idea, rather than have to make up the roller-bearing carriers though, at least with the equipment I have available at home (I'm sure the CNC kit at work would be capable of machining the lot, but that would mean producing a CAM file AND persuading the workshop manager that someone should run the job at lunchtime - last home job I had done cost a box of Krispy Kremes!).
This may be something I'll try once my house move is done and I've set up the tools in a bigger space, assuming the bikes don't fill the bigger garage completely!
SO... back on track, anyone see any problems with the ballscrew, at least in theory?
Pix, I can see that working, you'd need decent rollers though as the helically slotted tube would have to be fairly thick, and the interrupted bend (?) might tend to open the slot out - at least I can picture that happening! Have you thought about using a timing belt and pulleys on your mill's X-axis screw/handle to provide a drive to a rotary table / dividing head? an added shaft on the DH worm with a pillow block at the far end might be all you'd need to get drive to it for spiral milling, if you could gear down enough?
That helix and slot arrangement could work, but I don't have a Proper Milling Machine nor a hefty sheet roller, and I'd have to translate it so the outer sleeve moved back and forth with rotation of the inner - I suspect I'd want to make the helix angle around 45 degrees to make it "bidirectional" so the linear movement of the sleeve could rotate the angular movement of the shaft as well as vice versa...
It may be simpler for me to try the ballscrew idea, rather than have to make up the roller-bearing carriers though, at least with the equipment I have available at home (I'm sure the CNC kit at work would be capable of machining the lot, but that would mean producing a CAM file AND persuading the workshop manager that someone should run the job at lunchtime - last home job I had done cost a box of Krispy Kremes!).
This may be something I'll try once my house move is done and I've set up the tools in a bigger space, assuming the bikes don't fill the bigger garage completely!
SO... back on track, anyone see any problems with the ballscrew, at least in theory?
Rules are for the obedience of fools, and the guidance of wise men...
(Douglas Bader)
(Douglas Bader)