Another Rupnow Air Hit n Miss Engine

[bmac2]

Though I’m tempted to build a Solar Wind Turbine Biomass Gasified Powered Brine Pump or whatever that stuff is on the homepage.
I feel like I’m the only one that hasn’t built Brian Rupnow's Hit n Miss Version of Chuck Fellows "Horizontal Single".
This will be engine No.6 for me so first let me impart upon you my vast knowledge of hit and miss engines . . .
I like them . . . . . and I think there cool. . . . . This could be a long build

 

[bmac2]

Looking over the plans and Brian’s excellent build log I should be able to pull it off. As usual “All good things start with a 4x6 Band saw”. To those of you who enjoy this hobby without one I salute you. Mine is a fourth hand dumpster dive I got for free and needed a lot of love and a little welding to get it to where it is today, cutting relatively straight and it hardly throwing the blade any more. But without it I’d be collecting stamps.

I don’t have any 1 1/4 stock so I’ll flip the page to Metal Butcher’s “Chuck’s single” and make the base, frame sides, and front from 1/4'' thick aluminum with 4-40 screws.

 

[bmac2]

The cylinder is 1 ¼ mystery metal. And I’m going to building up the flywheels.

 

[bmac2]

Cleaned up the two blanks for the sides and when Krazy glue them tougher before laying them out and milling them to the final dimensions.

 

[bmac2]

I decided to try doing the cylinder in the mill. Turned out to be a bad idea, the bore turned out fine but it took me over an hour to get it trued up in the lathe to cut the shoulder.

 

[Brian Rupnow]

Although I would like to take credit for that engine, I can not. It was designed by Chuck Fellows, and he is the true originator of this marvelous little engine. I wanted to build Chuck's engine, but had to draw it up in Solidworks and create drawings to work to. So--Thank me for all the pretty drawings, but please, give credit to Chuck Fellows. He is the true genius behind this engine.---Brian Rupnow

 

[bmac2]

Hi Brian
This is definitely Chuck’s engine. I think Chuck Fellows is the engine whisperer or something. I’m just going for the 2 stroke version chickening out on the gears, and want to give the hit and miss a try which I thought was your addition.
I hope I can do justice on both of your efforts

 

[bmac2]

Damn the weather is bad everywhere. At times like this I just close my eyes and say “at least I’m not in Winnipeg” (-50 yesterday with the wind chill)
On with the build. I decided to go with a built up the crank with Loctite and pins. Let it sit overnight and cleaned it up on the mill.

 

[bmac2]

I’m going to try Brian’s trick with the piston and start with a piece of 1 x 1 aluminum.

 

[bmac2]

Yep. That square end sure comes in handy once it’s moved to the mill.
Center it up and done. That is one fast setup.

 

[bmac2]

The bearing blocks are simply brass sized per the drawings, and I drilled them in place with witness marks on the inside. Once all the holes are tap and the blocks are bolted down I dialed it in on the lathe to drill/ream the holes. I picked up a couple of sets of feeler gauges from Busy Bee Tools a while back for a couple bucks each and use them as shims when I just have to have that extra little bit to get things on the center line in the lathe.

 

[bmac2]

Wanted to try for a classic I beam style for the con rod because this is the first engine I’ve built with a rod big enough it try it on.
After drilling the holes for the screws and adding witness marks I split the blank

 

[bmac2]

Once taped and screwed together started to rough out the shape

 

[bmac2]

With a piece of 1/8 in the small end and another in the ¼ hole in the big end to set the angle I milled it down to the final width.

 

[bmac2]

Now. To round off the small end I saw this method on http://www.modelenginenews.org/index.html (Making Conrods, Made Easy) and decided to give it a try

 

[bmac2]

Ok. Milling cutter intact, conrod intact, and no blood. I’ll call that a success.

 

[bmac2]

Oiled Up the bits so far and let them running In

 

[Swifty]

I'm following along Bob, just watch out for your fingers if you are rotating that rod by hand. Cutters are prone to grab and not very forgiving.

Paul.

 

[bmac2]

I hear ya Paul. If that rod had been less than 3” I never would have tried it. It would pull a bit on one side then push when cutting the other. Once centered it was pretty much neutral but no replacement for a part solidly bolted down to my rotary table.

 

[bmac2]

So it’s time to start the head . . . I cut out the blank and cleaned it up . . . But I’m not sure I like it. It just looks too big. When I was looking for another engine to build I snagged a bunch of pics of engine (I know. I leach) and remember seeing this. Tried to find it again but despite the search engines valiant efforts I gave up but I think once again it came from that deep mind of Mr. Fellows.