A different opposed piston engine---

[Brian Rupnow]

This is what $50 buys this morning!! A piece of 5/8" aluminum 5" x 5/8" x 16", a piece of cast iron 4" diameter x 1 3/8" long, and a piece of 1/2" square cold rolled x 19" long. The plate will give enough material to build the complete plate frame (I will have to mill part of it down to 1/2" thick for the front bearing support plate.)--Also, the cast iron will build my flywheel. The plate was $30 The cast iron was $20 (would have been $15 if I had chosen hotrolled 4" dia. steel instead.) The 1/2" square cold rolled was thrown in as a free-bee. I got it because, if that welded crankshaft I made is hinky, I will make up a second one with 1/2" square webs instead of 3/16" thick, and Loctite/dowel it together instead of welding it.

 

[johnmcc69]

Nice start! Why didn't you choose the cheaper hot rolled?

John

 

[Brian Rupnow]

John--I don't have a good answer for that. I asked for a price on hotrolled steel, stress-proof steel, and cast iron. They didn't have any stress proof, (which I've been wanting to try, because everyone says it machines so nicely.) I picked the cast iron, and I don't have a good reason why!!!---Brian

 

[Brian Rupnow]

Well---It's a start. It seems like I spend a lot of time getting parts READY to start machining them!!!

 

[jwcnc1911]

Brian, had a little time to look at the solid tonight. Generated toolpaths and designed a fixture for the flipside.

Hopefully I can get out in the shop soon.

Another great design, and most of all, thanks for sharing with the community! I look forward to seeing it run.

 

[Brian Rupnow]

Well JW, you and I were working together today---just a thousand miles apart!!! I finished the flywheel today and 95% of the frame plates, but had to stop about 4:00 because my legs were killing me from standing at the machines all day. Damn, I hate getting old. Tomorrow I will assemble all of my finished parts and post a picture.---Brian

 

[Philjoe5]

This what I love about bar stock engines. It all starts when you go to the metal store, buy a few chunks of metal. Then the story unfolds or unravels as the case may be.

Good luck on this one Brian

Cheers,
Phil

 

[Brian Rupnow]

Its early in the morning here, and my good wife is still sleeping, so its time to spend some quiet time on the computer. I can use this time to catch up on a whole bunch of detailing. I will post these now so you can see the direction I am moving in, but don't bother to copy them, as I will post an updated download file to all of the drawings at the end of this job. Many of these drawings undergo minor revisions when I actually come to build the part, for one reason or another. I will correct any drawing that changes, so that the final download file will have all corrected drawings in it.

 

[Brian Rupnow]

And a few more details--

 

[Brian Rupnow]

As promised yesterday, here is the first assembly, consisting of the crankshaft, flywheel, and all but one of the frame components (the plate the cylinders attach to). I set my glasses in the foreground to give a sense of scale on this engine. Its not very big!!! So far, so good. The parts all fit together. (I don't have the crankshaft bushings in place because I haven't made them yet!!!)-----Brian

 

[Brian Rupnow]

Okay jwcnc--I have a place to mount the two bits you are making for me!!! I haven't put the snap ring grooves in yet.---Its safer to wait and get everything mounted BEFORE cutting the snap ring grooves. I have also mounted the camshaft. That's enough for me for today.---Brian

 

[Brian Rupnow]

There will definitely be some head scratching involved with making this part!!!

 

[gus]

Well JW, you and I were working together today---just a thousand miles apart!!! I finished the flywheel today and 95% of the frame plates, but had to stop about 4:00 because my legs were killing me from standing at the machines all day. Damn, I hate getting old. Tomorrow I will assemble all of my finished parts and post a picture.---Brian

Getting old is a part of life ,we cannot avoid. After two engines,Gus was burnt-out after building the Webster and the Rupnow Engines.This explains for "The do nothing for last four weeks".

Spring cleaning in ten mins from now and back to "work" on the second. New Year Day tomorrow will be hooking up the big slimy fish with friends.

Happy New Year.

 

[Brian Rupnow]

Today I had to go down to my "nut and bolt" store to pick up the 3/8" socket head capscrews that hold the cantilevered pivot shafts and camshaft into the main vertical support plate. While I was there I asked the sales guy if they carried any of the "low head" style of capscrews. He did, and the head on them is roughly 0.180" shorter than the head height on a standard 3/8" shcs. He didn't have any 5/16" shcs in that style, but he did have some 5/16" flat head capscrews. So---I bought them and installed them this afternoon. This allows me to move the flywheel in 0.185" closer to the main support plate. I will have to cut that much off the long hub on the flywheel, but that will still leave me room for a couple of set screws. I like this much better, allowing me to keep the flywheel tucked in tighter to the main vertical support plate.

 

[Swifty]

I'm enjoying following this latest build, will be very interesting to see it working.

Paul.

 

[Brian Rupnow]

Swifty--I'm venturing where "Angels fear to tread" here. I will be pretty excited if/when it runs.--Brian

 

[Philjoe5]

Brian,
This engine design is really neat. I have been studying the part you're going to have CNC'd trying to figure out how I'd make it on manual machines.

I'm enjoying this thread also

Cheers,
Phil

 

[dave-in-england]

Brian,

Why don't you use Stainless Steel Countersunk set-screws ?

No need to mess about setting up tooling for making the counter-bores for the cap-heads,

when a countersunk tool will do, and the screw heads will fit perfectly flush with the alloy plate.

 

[Brian Rupnow]

Dave--I don't understand your post. Flathead capscrews (which you are calling countersunk cap screws) are available in in plain steel, and the tooling for them is readily available. Why would I want to use stainless steel? I did use that style of flathead capscrew on the center hole where my camshaft sets, but used the lo-head capscrews on the larger 3/8" bolts which hold my pivot shafts. I had to maintain SOME space between the back of the flywheel and the vertical main body plate so I would have room for a hub and set screws on it.

 

[dave-in-england]

Sorry about the confusion Brian,
You mentioned the need for more space behind the flywheel, where the cap heads are sticking out.

These countersunk screws would fit right flat with the body.

I prefer the bright and shiny stainless screws, they don't cost much more than the dull steel variety. ;D