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The failed attempt thread!
- Thread starter Armourer
- Start date
- Joined
- Feb 28, 2019
- Messages
- 530
A gear dish, or maybe a dish gear. This one amuses me.
So I made this 3" gear out of 1/6 brass and had a hard time getting it mounted square on a small pinion shaft. I figured that if I made it thicker - give it a bit of a hub, it would be easier to mount and then true it up. I decided to silver solder a second piece to the center. Then back on the lathe to turn the hub and true the faces.
Weird thing happened - every time I took a light cut it would cut near the center but not all the way out. I kept at it until I finally realized what was going on.
So, duh! It was dishing every time I removed material in the center. When I soldered the hub on, the big gear was cooler on the outside and as both cooled down I built a bunch of stress in. I did try to relax it after the screw-up by putting it in a heat treat oven but it stayed dished.
If I try something like this again, I'll use the oven to get it up to solder temp with both pieces at an even and consistent temperature.
So I made this 3" gear out of 1/6 brass and had a hard time getting it mounted square on a small pinion shaft. I figured that if I made it thicker - give it a bit of a hub, it would be easier to mount and then true it up. I decided to silver solder a second piece to the center. Then back on the lathe to turn the hub and true the faces.
Weird thing happened - every time I took a light cut it would cut near the center but not all the way out. I kept at it until I finally realized what was going on.
So, duh! It was dishing every time I removed material in the center. When I soldered the hub on, the big gear was cooler on the outside and as both cooled down I built a bunch of stress in. I did try to relax it after the screw-up by putting it in a heat treat oven but it stayed dished.
If I try something like this again, I'll use the oven to get it up to solder temp with both pieces at an even and consistent temperature.
Last edited:
- Joined
- Feb 27, 2014
- Messages
- 2,275
Something I saw on Clickspring Youtube channel would be to glue the gear to a solid backing plate with superglue. Make your cuts and then heat to release the glue. Chris uses this technique often.
- Joined
- Feb 28, 2019
- Messages
- 530
Yeah, that's how I turn the gear blanks and cut the teeth. In this case I really needed a hub for the gear and though I could solder one on - not so much! I ended up turning a hub into a thicker blank. Next time I'd do a two piece thing and use green Loctite (essentially gluing it together).
Clickspring has a wealth of info and is a great to watch.
- Joined
- Apr 8, 2013
- Messages
- 2,021
Why is it that I keep using all these time savers that DON'T save time. If I need to put the vice on my mill for a non critical part I save time by just using a square instead of indicating it in. Today I was making a small square for those times when my machinist squares just won't fit. After cutting all sides twice and freaking out over a sliver of light peaking thru one corner I remembered my "time saver".