cut & rejoin gear in half

[MachineTom]

As seen in the Patent work the gears are solid and screwed to the crankshaft. Since the counterweights are bolt ons, the gears were tricked over the throws and journals, two from one end, one from the other end, similar to small twin engines or air compressors made today. There is no way to machine those in place, no room for a slotter, shaper or mill.

 

[Rayanth]

Tom,

Not to try and start an argument, but I have it on reasonable authority that the three center gears were indeed split and rejoined over the crankshaft, not slid in over the ends as you suggest. I suppose I could redesign the crankshaft to try and accommodate them sliding over, however the side view doesn't show a few key areas that would certainly be in the way of doing so, even with the counterweights removed.

I suppose this will boil down to an issue of crankshaft redesign one way or the other. I will have to counterweight it, and thus will need to figure out how to calculate the counterweight amount...and if I can resize certain spots to allow gears to slip on that will be easier as well.

 

[steamer]

It would appear that the gears were registered and transmitted torque through the mounting splines.

The screws just hold the two halfs on center, but don't drive the gears, so the load on the screws is very small.

I would wonder if you couldn't "model" that as a machined square journal, which will transmit quite a bit of torque without a lot of radial force. A hex would load up the screws badly in the radial direction.

Modified form spline teeth made with a small ball nose end mill would work, and not raise such a stress riser as a square corner, or square bottom splines.

So, a modified spline could be made on the shaft. Now what to do with the gear?

Well, you could split it, re attach, bore and turn the OD. Locate in an indexing attachment and cut internal splines with an endmill to match the external splines in the shaft

See crap o cad sketch

I don't mind saying that I would NOT look forward to making it..... :

Dave

 

[Rayanth]

Well, I knew it would be a tough project from the get-go, but one thing that sets me apart from a lot of my peers is that if I don't have something 'impossible' to strive for, I can't ever prove them possible. I love a challenge and usually build my skills best while trying to meet those challenges.

I mean, shoot, i'm designing a 28 cylinder radial model engine when only one other exists that I know of =) AND I haven't done any machining in a little over a decade...

Ah well, that's what support groups are for =)

I do appreciate everyone's input so far, it has given me a great deal to consider. If only the museum I volunteer at would let me tear apart the spare 4360 we have gathering dust and rust...

Would it be a bad thing if I started a Work In Progress thread for just the CAD portion of this project?

 

[steamer]

Raynath,

I was a long time museum voluteer also. What museum do you voluteer at ?

I volunteered at Mystic Seaport.

Dave

 

[steamer]

Would it be a bad thing if I started a Work In Progress thread for just the CAD portion of this project?



Not at all, by all means! We'll be watching though ;D

Dave

 

[Rayanth]

Raynath,

I was a long time museum voluteer also. What museum do you voluteer at ?

I volunteered at Mystic Seaport.

Dave

I volunteer at the Seattle Museum of Flight's restoration center. My current project is a very rare Lockheed YO-3A, arguably the first 'stealth' airplane- prop driven, they could fly it 150 feet over the enemy's (Vietnam) head, and they wouldn't even hear it. Recon only, never armed. 11 were built, 4 crashed. It's a really fun project, when i'm not tied up at my day job (Boeing, 767 assembly mechanic)

- Ryan

 

[Rayanth]

I will look at starting a WIP thread this weekend, right now I just have some basic (and wrong) mockups of the crankcase with dummy cylinders :

I figure such a thread will let me ask questions with better references and input as things develop, rather than using up my Questions quota on this board =)

- Ryan

 

[Jasonb]

Take a look over on Smokstak, someone has just posted pictures of an 18cyl radial which looks to have a two part crank and similar gear arrangements.

Jason

 

[Rayanth]

Jason, thanks for the heads up, I took a look.

That engine is from plans written by Lee Hodgon's late father, and now sold by Lee Hodgson, at http://agelessengines.com

I had the opportunity of visiting Lee in Cincinnati when I was driving through this summer. Unfortunately his twin rows only use one front and one rear cam, thus there is no need to split gears to get in between cylinders (this is visible in the images in the post you refer to - you can see the holes for the pushrods on the forward end of the forward cylinders, and aft end of aft cylinders, nothing in between them)

Ryan

 

[Lakc]

There is a pic of an R4360 model's internals here:
http://www.enginehistory.org/model_engines.shtml
Looks like one piece gears and multi piece crankshaft, but really hard to tell.