[GreenKeys] gears

[W2HX]

Congrats! That is a great job. Also, there is a fellow who makes reproduction gear sets for an old HP 8640 signal generator that had (I think) nylon gears that become brittle over time and break. This guy makes them from brass which will outlive us all. 

Would you share the cad drawing?

73 Eugene W2HX
Subscribe to my Youtube Channel: https://www.youtube.com/@w2hx/videos
 

-----Original Message-----
From: greenkeys-bounces at mailman.qth.net <greenkeys-bounces at mailman.qth.net> On Behalf Of Stan Voynick
Sent: Saturday, January 21, 2023 5:41 PM
To: Greenkeys at mailman.qth.net
Subject: Re: [GreenKeys] gears

Larry,

  I don't think this is talking about me, although it sounds *so* familiar because I've doing something very similar for my Model 28 TD.  

  When I acquired it, it had 67 WPM gears, and I have not been successful at finding 60 WPM gears to install, so I designed a gearset in a CAD program, and had them 3D printed in "Nylon 12"  I just received the newly printed gears just this week, and did a first test run a couple nights ago.

  I've attached a photo of the original gears (67 WPM, ratio  11:49) next to my new 3D printed gears I just received a few days ago (60 WPM, ratio 18:88.)  I've got some other photos of them as I installed and tested them in my M28 TD; maybe I'll throw those up on a blog page or something if anyone's interested (I know Steve Campbell is!)

  Here's a link to video of a test run (1:45 long); there are some additional technical details in the video description if anyone's interested.

https://youtu.be/mo6j4bXJ5v4  

   The M28 TD is a good application for 3D printed gears, as (a) that's a fairly low-torque mechanism, (b) looking at that driven gear, for a given amount of torque required to drive its intermediate shaft, the driven gear has a relatively large radius (in the world of TTY machines) so this further reduces the circumferential tooth forces between the two gears, and (c) this gearset is a helical tooth design on parallel shafts, which is a fairly "easy" application, compared with a 90° drive application like the motor-to-mainshaft gearset on a M15, for example.  That's a higher-torque shaft, with a smaller-radius driven gear, and the gearset is essentially a worm-drive which acts with a lot of "slip" between the gear-tooth surfaces. (Probably why that gearset is a metal pinion against a fiber/composite driven gear.)  I don't know if I would try a nylon gearset in that location...

   This has been a fun experiment.  Will they last for years?  Months?  Weeks, even?  Who knows - but I can say with pride that they have served me me well for a number of MINUTES now, and they're still going strong! 

73,
- Stan
WB7RPG

> On 01/20/2023 4:26 PM PST Lawrence Godek <lawrenceg94 at gmail.com> wrote:
> 
>  
> I was listening to a fellow on 40M AM the other morning and he was 
> addressing some gears that his QSO partner was getting made. He uses a 
> 100W laser machine and does some excellent work.  I wonder if he could 
> cut some 60 wpm gear sets and would be glad to talk with him about it 
> the next time i hear him on the air.  What was the material that those 
> white gears were made from?  Some kind of plastic or fiber?  He 
> mentioned making gears from something similar.  apparently he is some 
> sort of Machinist and lives about 250 miles NW of me.  But would it be 
> worth the exercise to see if he could do it?  Make both the big and 
> small motor pinion as he was mentioning that the gear he was 
> fabricating had quite fine teeth on it.
> 
> I can't remember his call sign for some reason, maybe i'll hear him on 
> the air again as he had a booming signal into my QTH.
> 
> Larry W0OGH
> 
> 
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