Help On How To Set Up And Make This Item.

Wreck™Wreck said:
You can't turn this part between centers as they are not on center as there is 4º included between the features being turned as far as I can tell from the limited part description. The turning is easy, the work holding is difficult.
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Where's the problem ? So far as I know offsetting the tailstock to produce work like this is as old as the invention of the metal-cutting/screw-cutting lathe -

This sketch is highly exaggerated dimensionally but I think that the concept is easily perceived.

offset_zpsv5qmj7rc.jpg
 
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kd4gij said:
Short of a highend cnc. It will eather be made in 3 pieces and welder by a certified welder or Machined streight and bent to the 2 deg.
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None of the above :), the first of these were made in the late 60's, no High end CNC then, one piece, no welding and bending is out.
It's not a matter of if but how on a lathe, that has been my question, am trying to come up with a fixture, there is a way just have to find it.

Ken
 
Why couldn't you use Jim's idea of offsetting the centres, but rather than offsetting them on the part move the headstock centre the required distance. This could be as simple as a centre in a four jaw or a jig made on the mill. With a jig the connection of the lathe dog could be aligned co-planer with the centre of rotation and the turning centre.
If the equivalent of the lathe dog was positioned on the flat section with a pin that can be attached or extended on either side to mate to the drive, indexing of the two angles should be no problem.

Greg
 
f350ca said:
Why couldn't you use Jim's idea of offsetting the centres, but rather than offsetting them on the part move the headstock centre the required distance. This could be as simple as a centre in a four jaw or a jig made on the mill. With a jig the connection of the lathe dog could be aligned co-planer with the centre of rotation and the turning centre.
If the equivalent of the lathe dog was positioned on the flat section with a pin that can be attached or extended on either side to mate to the drive, indexing of the two angles should be no problem.

Greg
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Thanks Greg,
My mind is short circuiting for the night, I'll re-read that again tomorrow, maybe it will click for me then.

Ken
 
f350ca said:
Why couldn't you use Jim's idea of offsetting the centres, but rather than offsetting them on the part move the headstock centre the required distance. This could be as simple as a centre in a four jaw....
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Actually that was my suggestion, LOL, but your idea would work just fine. Whatever is easiest so that one of the centers is offset to produce the two degree angle :)
 
Ken_Shea said:
Randy,
The headstock center and the stub center drill alignment(at the head) looks like it could be a problem yes/no?.


Ken
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Ken, if you are referring to the fact that the center is sort of "crooked" with respect to the axis of the center drilled hole and does not fully engage the center-drilled hole, remember that the sketch is highly exaggerated and that the actual angle is only four degrees. It really shouldn't be a problem, in my opinion, but as I said, just try it with a piece of hardwood, for example.

If one is worried about the center "wallowing out" the center drilled hole, I posted an alternative method for turning with the tailstock offset from the headstock axis here:

http://www.hobby-machinist.com/threads/lathe-tailstock-tooling.32941/#post-278066
 
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How about you make it all straight then bend it in a press? Do you need corners that are congruent to the angles? Then leave a little material and then after bending do a final machining…Good Luck, Dave.
 
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