Involute gear clock

I still haven't cut a gear yet, but I'm getting closer. I'm just making a random 18-tooth DP16 gear that isn't meant for anything. You have to start somewhere, right? It is my earnest intent to do it right the first time. I went with the 18-tooth so I could use the front plate on the dividing head the first time out. The blank should be 1.250" and I turned it to 1.248", which should surely be close enough for my purposes.

2.jpg

I don't have or want to buy an arbor press, so I thought I'd try this setup and see how it works. I made a split arbor out of 1/2" drill rod, sized to reach across my mill vise. It's threaded 1/4"-20, and the bit without threads is dead on 0.250", verified by three different mics. I was proud of that! I dialed it in the last hair with a file. The mating side is reamed to provide enough clearance to screw the rod entirely together, and it fits almost flush. I didn't measure the error. I can barely feel it with my thumbnail. I don't have any short #7 or C drill bits, and these long jobber length bits really wanted to wander; even with a good center drill start. I mean it is what it is. It may not be that good in the scheme of things, but it's some of my very best work.

1.jpg

So anyway, the way this setup is supposed to work, the blanks are drilled C and then reamed 1/4". The blank won't fit on the arbor using hand pressure alone, so a few gentle taps. Screw the mating end on, and use the hexes to snug it all down tight. I haven't gotten so far as to fire up the gear cutter yet, but I'm hoping my setup will have enough grip to keep the blank secure.

I just barely have enough room to work around the vise, and this setup isn't going to allow me to cut gears over about 60 teeth, due to Y-axis limitations. It may not work well with all that stick out. It may be a dumb idea. Who knows. It was a fun few days making the split arbor, and setting all this up.

3.jpg

Tomorrow, I set about the painstaking process of dialing in my setup, and I'm going to have to use the dials, as I don't have DRO yet. Once I have a viable gear, I'll make another one a different size.

That pretty much concludes my involute gear clock build, sorry to say. One thing I've figured out from getting my hands on this is that I'm not going to have enough room to cut the higher tooth count gears. The point of using involute gears was both to see if I could do it and to use commercial cutters, but cheap Chinese cutters only come in a handful of sizes. If I'm going to pay $900 for a set of cutters, well, yeah, okay, I guess I will go with centuries of horological tradition after all, and just make fly cutters using plans from a book.

That is, in fact, what I'm planning. Building a clock from a blank sheet was just more of a thing than I could manage, so book to the rescue. I think I can build the clock in the book. It's a lot less complicated than the one Clickspring built. I mean, I didn't really want to spend three years hand filing and polishing metal anyway, to be honest. I just want a clock. That's why I'm spending $500 in tooling and probably another $300 in materials to build a clock similar to the one Hermle sells running for only $124. Machinist math!
 
Any progress on this project? I've been thinking of building a clock using involute gears. I've read the same thing about involute gears for clocks have no disadvantage over cycloidal.

I'm thinking of cheating and not use an escapement mechanism, but using a synchronous motor to power it.
 
Any progress on this project? I've been thinking of building a clock using involute gears. I've read the same thing about involute gears for clocks have no disadvantage over cycloidal.

I'm thinking of cheating and not use an escapement mechanism, but using a synchronous motor to power it.
I never did go any farther with the idea. I caved, and started building a clock using traditional cycloidal gearing, cut with fly cutters and all that jazz. The project stalled when I had a horrible angle grinder accident that sent me to the ER. It was bizarre going to the ER for myself. I went as a cheerleader and hand holder for my ex wife and kids countless times, but by some miracle, and probably due in some measure to actually paying attention to safety, this was my first time. I lost my emergency room virginity last month, and it was expensive and painful.

Anyway, I still love the idea. It occurs to me now that an escape wheel is its own weird little thing anyway, and whether you used one or went forward with your plan to cheat, the clock gearing would all end up the same either way. I'd be stoked if you built such a thing, and beat me to the finish line.

So far, I have only made one viable clock part, and now I have had to close my shop for the winter. I would love to have an acceptable means of heating my shop without generating water vapor inside the shop, but I have no such means, and can conceive of no viable implementation. My machine shop, sadly, is just a crappy Harbor Freight tent garage with a Race Deck floor. I wish I had $50,000 to build a real shop, but I don't.
 
So sorry to hear about your angle grinder accident. Hopefully, you fully recovered.

I've been researching the use of involute gears for clocks and found this thesis. It explains the advantages of using involute gears in clocks. The main dr
aw back I'm finding is that the pinions with cycloidal gears can have much fewer teeth. Typically, they can have 6, 7, 8 teeth compared to a involute gear having a minimum of 12 teeth. Even 12 teeth on an involute means the tooth is undercut.

But, the drivetrain would be quite different with the higher tooth counts.

For an cycloidal 8 tooth pinion:
Great wheel Center wheel 3rd wheel
96T 64T 60T


For an involute 12 tooth pinion:
Great wheel Center wheel 3rd wheel
96T 96T 90T
 
Back
Top