GearHeads Corner
April 16, 2021, 12:48:50 PM *
Welcome, Guest. Please login or register.

Login with username, password and session length
 
   Home   Help Search Login Register  
Pages: [1]
  Print  
Author Topic: "Helical lever"  (Read 188 times)
0 Members and 1 Guest are viewing this topic.
JohnHaine
Newbie
*
Posts: 10


View Profile
« on: March 24, 2021, 04:43:25 AM »

I have just been reading in a horologic al publicati on about the use of this configura tion in a series of 19th century clocks.  Essential ly it describes a wheel / pinion configura tion using helical teeth, where the pinion had a veryu low tooth count, usually 1!  The advantage claimed is that you can make a pair of gears with a large reduction in one step, with low, essential ly rolling friction.  The pinion looks like a corkscrew and the wheel thickness must be at least the pitch of the helix.  Helix angle was usually 45 degrees.

I had a quick try at designing a pair of gears like this in Gearotic but it didn't let me set the pinion tooth number lower than 4 - is this a programme d limit or can it be made smaller please?

Such gears would be nice because often in a clock you want a 60:1 ratio which is difficult in a single step because lowest practical pinion count of 6 or 8 so the wheel gets rather large, so usually a 2-step reduction is needed.  Also, helical gears should contact only at the mutual pitch points, so might use straight flanks at an appropria te angle so be easy to make.
Logged
ArtF
Administrator
Hero Member
*****
Posts: 5740



View Profile
« Reply #1 on: March 24, 2021, 05:40:51 AM »

Hi John:

     Your stopped by the program at 4 teeth because at that point the formulas used turn into
singulari ties. I can picture your gear, it does sound very much like a worm gear rotated
90 degrees to be inline with its pinion.
    I cant help as of yet, but worm gears and cams are on my immediate future list. I never
offered them before as Gearotic was written back in the day before 3d printers were very
popular. Now, with Ticker, I've started the framework for a program to create 3d models
with no concern for how to make them as its output is only triangula ted models. This makes
things much easier. I hope to see worm-gears this year as a module, but I cant as yet give
you a timeline.
    Your is an interesti ng point though and I appreciat e your bringing it up, I hadn't really
thought of how one could rotate the action of a worm gear, in your case by 90 degrees.

  Ill keep this in mind for this years developme nts as well as things such as the sinusoida l
herringbo nes I saw posted earlier this week.

Art

 

 
Logged
JohnHaine
Newbie
*
Posts: 10


View Profile
« Reply #2 on: March 24, 2021, 05:52:05 PM »

Thanks Art, that's useful to know - and hopeful!  I can sort of picture how a pinion could be cut, using a 4th axis and a small endmill to gash then shave the teeth.  The article described experimen tal gears where the pinion was planed on a lathe driven through the leadscrew but the tooth form was highly non-optimal.
Logged
ArtF
Administrator
Hero Member
*****
Posts: 5740



View Profile
« Reply #3 on: April 01, 2021, 08:33:51 PM »

John:

   Yes, the toothform places quite a restricti on generally .
Im playing with better ways. (Heres a recent test of a worm
configura tion..)


Art

* Worm-Gear.mp4 (4540.23 KB - downloaded 16 times.)
Logged
Mooselake
Hero Member
*****
Posts: 650



View Profile
« Reply #4 on: April 02, 2021, 11:13:11 AM »

What does the flurry of sawdust at the end mean?  A bad parameter destroyin g the gears?
Logged
ArtF
Administrator
Hero Member
*****
Posts: 5740



View Profile
« Reply #5 on: April 02, 2021, 11:39:19 AM »

lol.. its actually a burst of fireworks as a particle test set to go off on a timer.. I was debugging it. Smiley

Art
Logged
Pages: [1]
  Print  
 
Jump to:  

Powered by MySQL Powered by PHP Powered by SMF 1.1.11 | SMF © 2006-2009, Simple Machines LLC Valid XHTML 1.0! Valid CSS!