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Two rotary tables, cutting a bevel gear -- octoidal tooth generation.
Posted: Mon Sep 17, 2018 7:11 am
by JustinO
This is a short video of a pair of rotary tables rolling a conical blank against a virtual crown gear with an embedded flycutter. If the tooth faces of the virtual crown gear are planer/great circles, the tooth faces of the generated gear will be octoidal.
https://youtu.be/RxRbuPIKu6I
--Justin
Re: Two rotary tables, cutting a bevel gear -- octoidal tooth generation.
Posted: Mon Sep 17, 2018 7:46 am
by ArtF
Well done! The Gcode must have been complex to imagine as it was written..
Art
Re: Two rotary tables, cutting a bevel gear -- octoidal tooth generation.
Posted: Mon Sep 17, 2018 9:40 am
by JustinO
Art,
The Gcode is shockingly simple once you've worked it out, but it feels impossible at first.
The hard part is setting up -- getting the rotary axes to intersect, and touching off at that virtual point of intersection.
Then there is the minor subject of having to build the machine!
This is a paying job. They're paying decent money, but it is more work than it is worth. It is a nice project, and a worthy cause.
Schanck Observatory Times
https://www.facebook.com/670361143169824/
I used your software to make wire frames, rotate them around, then photoshop them over the not so good photographs of the original gears. It helped to confirm the toothcount....
Someday, I'll be able to actually feed myself making gears!
--Justin
odhner.com
Re: Two rotary tables, cutting a bevel gear -- octoidal tooth generation.
Posted: Mon Sep 17, 2018 11:54 am
by ArtF
Justin:
You did well. I guess its like so many other operations
in more than 2 dimensions, the hardest part is the concept,
gets easier in implementation..
Art
Re: Two rotary tables, cutting a bevel gear -- octoidal tooth generation.
Posted: Wed Sep 19, 2018 8:21 am
by Mooselake
Impressive!
I looked up octoidal bevel gears, and while I still don't understand the description the
Wikipedia bevel gear page has a picture of a double bevel helical gear in case Art gets bored :)
How do you like that CNC Sherline? I'm thinking that the new southern shop needs a small CNC mill and have been looking at that, a Taig, or maybe a DIY SX2 conversion (the Delta metal shaper has preempted a new machine up north, it's making chips!). Like all Mooselab projects it'll take way longer than it should to actually do something
Kirk
Re: Two rotary tables, cutting a bevel gear -- octoidal tooth generation.
Posted: Fri Sep 21, 2018 4:51 am
by JustinO
Hi Kirk,
I think Sherlines are a great value. There is always a glut in the second hand market. Technical schools get grants and buy lots of them, then they are auctioned off when the next grant comes in ten years later. The huge supply, and the interchangeability is great. If you break something or wear it out (I never have), you can buy a replacement easily. The used Sherlines I have bought are worth as much as they were when I bought them. Except for my first machines, I always try to buy Sherline stuff used, and only buy new if the parts I need are unavailable or expensive on the used market. One thing about CNC is that I have been able to sell some of my accessories -- radius cutter, threading, and have hugely expanded what I can do:
https://youtu.be/AXiFeOCwV28
--Justin
odhner.com