Worm gears
Re: Worm gears
Art
Pinion I feel would be easy, it's a low helix gear with an additional z axis move in the centre.
I'll include this picture stolen without credits from Bob Whorefields site as he steals everything and credits no one ;D
It would be easier using a vee cutter and as most pinions / wheels are done in a soft material i single flute cutter similar to an engraving cutter could be used. After all the most common angles would be 20 and 29 degrees or 30 for the trapezoidal guys in EU land.
Worms them selves are just screws so using anything other than a lathe is just an exercise in getting a good spanking [ mind you that's not bad at the right hands :o ]
If you were serious though it's simple job to hand write a code and mill one with the exact same cutter, or Gearotic could even spit the code out given you fill a few boxes in.
This was just a test once to see how easy iy would be to do a square thread.
Pinion I feel would be easy, it's a low helix gear with an additional z axis move in the centre.
I'll include this picture stolen without credits from Bob Whorefields site as he steals everything and credits no one ;D
It would be easier using a vee cutter and as most pinions / wheels are done in a soft material i single flute cutter similar to an engraving cutter could be used. After all the most common angles would be 20 and 29 degrees or 30 for the trapezoidal guys in EU land.
Worms them selves are just screws so using anything other than a lathe is just an exercise in getting a good spanking [ mind you that's not bad at the right hands :o ]
If you were serious though it's simple job to hand write a code and mill one with the exact same cutter, or Gearotic could even spit the code out given you fill a few boxes in.
This was just a test once to see how easy iy would be to do a square thread.
John S.
Nottingham, England
Nottingham, England
Re: Worm gears
John:
I never knew there was any helix to the pinion, it is a function of the cross angle one wants? Like 90 degree would be standard, no helix?
Art
I never knew there was any helix to the pinion, it is a function of the cross angle one wants? Like 90 degree would be standard, no helix?
Art
Re: Worm gears
Yes the helix angle of the pinion, lets just call it a wheel, is equal to the helix angle of the worm.
If you get a worm, or piece of all thread and offer it up to a spur gear it will sit canted to one side because of the helix angle.
To sit at 90 degrees [ normal setup for worm and wheel l the wheel will have to carry the same angle.
I think this picture off Google images shows it well.
If you get a worm, or piece of all thread and offer it up to a spur gear it will sit canted to one side because of the helix angle.
To sit at 90 degrees [ normal setup for worm and wheel l the wheel will have to carry the same angle.
I think this picture off Google images shows it well.
John S.
Nottingham, England
Nottingham, England
Re: Worm gears
John:
Thank you, I handn't looked into them deep enough to realize all that,
the helix is obvious once you consider it , I guess I hadnt till now. :)
Art
Thank you, I handn't looked into them deep enough to realize all that,
the helix is obvious once you consider it , I guess I hadnt till now. :)
Art
Re: Worm gears
When I tried to generate worm gears for 3D printing, I found that the tooth form changed from the top to the bottom of the gear, though probably not enough to matter much with real world gears.
http://www.thingiverse.com/thing:270309/
I imagine nobody is silly enough to try to produce the pointy bits at the top and bottom on a working part.
http://www.thingiverse.com/thing:270309/
I imagine nobody is silly enough to try to produce the pointy bits at the top and bottom on a working part.
Re: Worm gears
Hi Nate:
Those look like the pressure angle is way too high, .. or is that on purpose I wonder?
Art
Those look like the pressure angle is way too high, .. or is that on purpose I wonder?
Art
Re: Worm gears
They're designed to mesh with acme screws, so the pressure angle is - nominally - 14.5 degrees. The thing is that the screw is really only a trapezoidal rack on the plane that contains its axis, and does more interesting things as you move away from that plane. I think I also profile shifted aggressively so that the gear could 'grab' more of the screw thread.ArtF wrote: Hi Nate:
Those look like the pressure angle is way too high, .. or is that on purpose I wonder?
Re: Worm gears
>>profile shifted aggressiv ely so that t
Ahh, that would explain it.. :)
Art
Ahh, that would explain it.. :)
Art
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Re: Worm gears
Oh well, accept my vote for worms also
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