This post has been a long time in coming. I’ve been working on these two gears for the past 3 weeks and have finally finished them up to my satisfaction (i.e. they pass the Good Enough inspection departments rigorous testing process (borrowed from Stan)). It has been a harrowing journey though!
I didn’t have any stainless 3/8” rod to use for the worm, so I just used some 12L14. This seemed OK too. After I made my first skimming pass at 48DP, I (stupidly) released the half nut on the feed.
Oops… So I had to do it again. That’s why there’s a double track mark there:
To make sure I DIDN’T do that again, I used some mostly ineffective tape on the handle. It wouldn’t have kept me from moving the lever, but its purpose was to remind me NOT to! And it worked for that
Here’s the completed teeth. Looked pretty good to me – a little chatter there, but not bad.
Then I drilled & reamed the center hole at 3/32”, per plan.
And finally, drilled & tapped for a 2-56 set screw.
And I hold it up next to the gear, and find it doesn’t mesh as well as I think it ought to. I should have made the teeth (tooth?) on the worm a little deeper (its really just one tooth on a single start worm, right?)
So, I took this opportunity to order some stainless and went off and worked on the 20tooth spur gear. And last week my 303 came in. So, yesterday, I cut a new worm. I also widened the tip on the tooth form tool a little. And here’s the result of that attempt. I think it meshes much more fully than the other one did.
Ok, On to the 20 tooth spur gear. I had to make a new cutter for this gear. I don’t show any pictures here, but I went through the whole – button, heat treat, cutter, relief, heat treat process. And that took a full session there. Then I made this cool blank for the 20 tooth spur. I’m getting smarter too!
At some point, I realized that Rudy solders spacers or bushings onto each gear. But since I’m making my own, I can build them in myself. So that’s what I did here:
And here’s my 20 toot gear blank, all ready for cutting teeth.
For a mandrel, I used a 3/16” fine tooth bolt that I just happened to have in a bolt junk drawer. I thought this was brilliant. Here’s the completed gear.
Unfortunately, once I got the teeth cut, I noticed that something wasn’t looking right. I put it in the lathe to clean up the edges a bit and that gear wobbled around like nobody’s business! My 3/16” bolt wasn’t as straight as I thought it was! And it screwed up my gear something terrible.
So, I backed up (as I often do) and started over (as I often do). This time, I used a longer piece of brass and so I could clamp that in the collet for tooth cutting (no mandrel required). It cost a little more brass, but it worked MUCH better.
Here’s just after all the teeth have been cut.
Back to the lathe to cut off to length.
Here are my two attempts at that 20 tooth spur gear. The one on the left is the second attempt (the good one), and the one on the right is the first one (the one I’m calling bad – yes, that one did NOT make it through my QC department). You can see the teeth aren’t all the same length on the bad one.
And in this view (good on right, bad on left again) you can see the teeth aren’t even straight.
And here’s a shot of the good worm, and the good 20 tooth spur. I’m much more pleased with these than the first round!
That should complete all the gears for this project! I doubt you’ve been counting, but I have. And my last 12 build posts have been about nothing but gears, and this started in July! I’m much less scared of gears now than before, but it has been quite a journey for me. I may not be speedy, but I’ve learned a lot. And the gears on the NEXT project will be even better.
Thanks for following along,
Kim
Edit: Some setting got changed in Picasa and I was uploading huge images. Sorry about that, I've fixed it.
