Brian does Ridders flame eater

[Brian Rupnow]

Okay--The bearing stands are counterbored and the bearings (complete with seals and full of factory grease) , crankshaft, and flywheel are installed. Time for some comparative testing. This is hillbilly work at its finest. Using an online stop-watch, I gave the flywheel a spin and started then stopped the stopwatch. I repeated this  5 times. The average length of spin comes out to 7.18 seconds from when I flicked the flywheel into motion until all motion stopped. Next step will be to remove the seals, wash out any factory grease, then reassemble and check the "free-wheeling" time again.

[Brian Rupnow]

The results are in, and they are incredible. I disassembled everything, pulled the seals out of the bearings, then washed them in laquer thinners and blew them clean with compressed air, then reassembled everything exactly as it had been with the previous test. I did   five runs, using the same finger pressure to spin the flywheel (That is the hillbilly element) and the average length of free-wheeling was 2.51 minutes. That means that on average, the bearings without grease will spin 21 times longer than bearings with grease.

[Brian Rupnow]

As this assembly continues, I thought I might have an alignment issue with the centerline of the cylinder and the center of the very small ball bearing on the end of the crank throw. So--I made myself a special weapon, and installed it. I was right. The tip of that special weapon should fall directly on the center of the bearing.---It doesn't. Now I have to figure out what I'm going to do about it. I don't want an offset in my connecting rod!!!

[NickG]

I’m glad the spin test results went well, at 7 seconds I was about to reply it’s not free enough, who’d have thought the seals & grease would make that much difference! I think if your bore and crank pin are square offsetting your con rod may be safest option?


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[Brian Rupnow]

Hahh!!!--It was the old "slot the bolt holes and move the cylinder over a bit" trick that saved the day.-I have to declare now--This was not a fault with my drawings. It was more a testament to accumulated tolerances and my inability to position everything dead nuts accurately when machining. Anyway--We're good now. The point of the new weapon is on center of the small bearing.

[Brian Rupnow]

Here's a little trick your mother probably never told you about. When you locate a bearing into a prepared pocket that is "size on size", the bearings lose all ability to "self align" with each other. This can cause binding and make the shaft reluctant to spin freely. If you make the pocket about .001 to .002" oversize, then use a bit of Loctite on the outer race before assembling things, this lets the bearings align with the shaft and with each other. The trick though, is to not get any Loctite down into the balls of the bearing. So---as you see, I use masking tape and a scalpel to make a temporary "shield" on both sides of the bearing to keep Loctite out. Add my Loctite, reassemble everything quickly, tighten the bolts and let it set for 24 hours. The bearings will be perfectly aligned, and you can then safely disassemble things and remove the tape from the exposed side of the bearing. On the other side of the bearing that becomes inaccessible, just leave the tape there. It won't hurt anything.

[NickG]

Good point about the bearings Brian. Some people fall into the pit of thinking they should be a tight press fit only to find that crushes the outer race and causes a load of friction in the bearing. Your slots in the bottom might help things along too. Once assembled, you could turn over a few times with the cylinder pedestal bolts finger right which should allow it to find its own sweet spot before tightening. I had a look at the changes Jan has made, apart from the piston being graphite (I know you’re going for CI) I can’t see how it will be that much more reliable. I am not yet convinced that stainless steel will fix the ‘corrosion’ problem as I thought it was products of combustion sticking to the cylinder rather than rust. We’ll soon find out though. Jan has also increased the bore quite a bit, in theory that makes it more powerful, but it’s meant the port is even bigger and thus the chance of sucking in cold air. Think the flame will need to be on the large side to run this, it’s dimensions are quite beastly! Great to watch keep up the good work.


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[Brian Rupnow]

I'm down to the point now where I'm making pieces so small that it should be against the law!!!

[b.lindsey]

Ah, the really fun stuff   Looking good though Brian.

Bill

[bent]

Dunno if you looked at my build for the glass cylinder version, Brian.  But you'd maybe notice I left the crankshaft about 2x longer than the drawing - so that I could shove it around a bit and get everything to line up; I also spaced the flywheel supports a bit further away from the "line" of the piston, just to build in some adjustment slop.  I usually look for ways to do that when building prototypes in the shop, to the extent that it has become habit...though all that extra shaft hanging off the engine looks a bit dorky I guess.

I told the apprentice (young guy at work who's getting his engineering degree) that I did it to make room for the PTO pulley to drive a supercharger 

[NickG]

It’s good to leave a generous clearance with these so There is no excessive friction. Mine has about 20thou either side on the crank pin. Bearing inner is a slide fit on pin. It wouldn’t be great for high speed but this engine is relatively slow running, especially mine! <a href="https://www.youtube.com/watch?v=wkk4Bn6j-jM" target="_blank">http://www.youtube.com/watch?v=wkk4Bn6j-jM</a>



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[Brian Rupnow]

Today I managed a con rod. It wasn't easy and it isn't pretty. Actually this is the second attempt. The first attempt--I don't want to talk about it. The bearing was only available with shields, which made it 5 mm wide rather than the 3 mm that I expected. This lead me to making a con-rod .094" thick with a 5 mm wide (0.197") hub.  I am going to attach the bearing to the con-rod with a dab of Loctite. Right now it's a slid-in fit.

[Brian Rupnow]

Yesterday afternoon I decided to buy a 12" length of cast iron to make pistons from. I do have lots of short pieces in my stock drawer that would have each been good to make one piston, but this cylinder is kind of a special case, because the internal valve and the piston must both be lapped fits. Since both the internal valve and the piston would both have to be exactly the same diameter, I decided that this was the best way to do it. My cylinder is about 2" long. I turned a length of cast iron down for a length of 2 1/2" to a point where it would just start into the cylinder but not slide in. Then I coated the machined area with 600 grit carborundum paste and very carefully with the lathe running at its lowest speed, I manually worked the cylinder onto the rotating cast iron. This is very dangerous, and you want to be prepared to immediately let go of the cylinder if it "grabs" and starts to turn with the cast iron. By letting the 2" long cylinder move to the very limit of the turned cast iron and then sliding it back and forth, this  resulted in the full length of the bore being lapped to size, and guarantees that the parted off pistons from the cast iron will be lapped to the correct outer diameter.

[Brian Rupnow]

Mechanically, the engine is finished. I will endeavour to build the alcohol burner this coming week, and then see how much is involved with actually getting the engine to run.
<a href="https://www.youtube.com/watch?v=yJYLv-NUWR8" target="_blank">http://www.youtube.com/watch?v=yJYLv-NUWR8</a>

[NickG]

Looks good Brian and nicely made. Looking at how it’s turning over, I think There will be too much friction at present but that’s part of trouble shooting with these. Jan ridders has a video that gives a good idea of how loose it should be. Should spin over for several seconds with the valve out on a flick of the flywheel. Good luck.


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