Stewart Hart | 20/02/2016 08:30:17 |
![]() 674 forum posts 357 photos | Ive been asked a ? by a reader about cutting a 45Deg helix on a myford lathe using the change gears, he is aware that the myford change gears won't cater for this but was wondering if it could be archived with a special gear ratio, I was unable to answer his ?. The only method I know for this type of job would be to mill it using a dividing head geared to the mills feed screw, I did discuss the possibility with him for fabricating the part. Its fore compressor vane on an experimental turbine he's working on. If any one could help I'll pass the information on to him. Cheers Stew
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John Haine | 20/02/2016 08:53:36 |
5563 forum posts 322 photos | A method was described in the book on the Quorn build. This uses a milling spindle mounted on the cross slide to cut the thread, with gearing down from the leadscrew to the spindle. Feed was by turning the leadscrew handwheel. In effect it's what you describe but using the lathe as a mill. |
Neil Wyatt | 20/02/2016 08:54:32 |
![]() 19226 forum posts 749 photos 86 articles | I think he may have to do it the hard way: Make an extended gear banjo so he can gear the leadscrew done sufficiently. The exact ratio to get 45 degrees will depend on the diameter. Mill the slot with a toolpost attachment rather than trying to cut it. Drive the lathe by hand from the leadscrew not the other way around. Neil |
Bazyle | 20/02/2016 09:19:25 |
![]() 6956 forum posts 229 photos | Depending on size it should be possible to rough it with a Dremel or battery drill for the powered spindle then clean up with very fine conventional tool cuts. |
Roderick Jenkins | 20/02/2016 10:58:33 |
![]() 2376 forum posts 800 photos | The longest lead I can get on my S7 is about 5 inches which equates to a diameter of 1.6" for a 45 degree helix. That's using a 6 gear train. If you can contrive an extra gear pair then that would help enormously. What we really need is a worm and wheel somewhere in the system - I don't know if anybody has ever done that, I guess you would need to put bevel gears or crossed helicals in their as well. Rod |
John P | 20/02/2016 11:14:41 |
451 forum posts 268 photos | Hi Stewart As some of the other contributors have said a useful starting reference In the second photo is the gear change quadrant for the Myford made to cut The third photo shows this 718 inconel turbine wheel milled from a The fourth photo shows a model compressor wheel made from HE 15 I find it easier to use this prototyping wax for test cuts it can be saved and Interested to see how this works out. John |
Muzzer | 20/02/2016 18:16:34 |
![]() 2904 forum posts 448 photos | Posted by John Pace on 20/02/2016 11:14:41:
...The fourth photo shows a model compressor wheel made from HE 15 aluminium milled on the Dore Westbury using 4 axis cnc... Sounds as if you have a CNC-controlled Dore Westbury with a 4th axis? That must be a unique machine! Certainly seems to have cut the mustard on the compressor and turbine wheels - incredible to manage this in the home workshop. Couldn't see any pictures in your albums - any chance of a photo or two? Murray |
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