Author Topic: Design and build side shaft hit and miss engine from bar stock  (Read 29383 times)

Offline Brian Rupnow

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Re: Design and build side shaft hit and miss engine from bar stock
« Reply #135 on: December 22, 2018, 04:11:01 PM »
In this shot we have the second step of machining the connecting rod. The first step was to machine a piece of 1/2" aluminum stock down from 1/2" to 7/16". The small end has the 3/16" hole drilled and reamed. All of the other holes are what form the radii between surfaces on the rod.

Offline Brian Rupnow

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Re: Design and build side shaft hit and miss engine from bar stock
« Reply #136 on: December 22, 2018, 09:23:26 PM »
So---Today was con-rod day. I can't believe it, but it has taken the entire day to make this little beastie. I wanted to post a pic of it installed on the engine, but it doesn't fit. How can that be? It fits perfectly on a piece of 1/2" cold rolled round stock. Out comes the micrometer, and guess what.--The center journal on my one piece crankshaft isn't 0.500". It is 0.520" diameter. POOP!!! I'm not even going to try to set that crankshaft up in the 4 jaw chuck again. I will now figure out how to set up the con-rod in my mill and open the big end up to 0.520".  Don't let all of those pill bottles in the background disturb you. I get a fresh supply of them full of pills every month, and the old bottles are perfect containers for teensy weensy little bolts and nuts.

Offline Brian Rupnow

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Re: Design and build side shaft hit and miss engine from bar stock
« Reply #137 on: December 23, 2018, 02:56:16 PM »
So here we are. Two things going on here. One shows the con-rod sandwiched between two scrap pieces of aluminum plate and set up in the vice to be bored out to 0.520" diameter to match the oversized crankshaft journal, and a second picture of the con-rod in place in the engine assembly. There is currently no piston in there---I'm waiting for some diamond lapping paste.


Offline Craig DeShong

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Re: Design and build side shaft hit and miss engine from bar stock
« Reply #138 on: December 23, 2018, 09:45:08 PM »
The center journal on my one piece crankshaft isn't 0.500". It is 0.520" diameter.

I used to go absolutely BALLISTIC when that happened in my work; but a good friend and a machinist I highly regard told me once that "The mark of a good machinist is someone who can cleverly get out of the situations they find themselves in".  I don't know if that's really true, but it makes me feel a lot better when crap like this happens in my shop and I figure a way out like you just did.
Craig

Offline Brian Rupnow

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Re: Design and build side shaft hit and miss engine from bar stock
« Reply #139 on: December 23, 2018, 11:45:04 PM »
Craig--A number of people have told me they admired my ability to find "work arounds" and ways to salvage machined parts and pieces when the "went south".   I've never really thought about it too much, I just thought that everybody done that. The crankshaft journal being oversize came as a big surprise. I'm sure I measured it when I was machining it, but that operation of machining with the crankshaft offset and the cutting tool stuck out half a mile is so nerve racking that perhaps as soon as I seen that it had cleaned up all right I just left it without a final measurement. Opening the hole in the con-rod to fit the journal was a bit of a brain twister. the con-rod doesn't have parallel sides. Fortunately the width of boss at both ends was the same, so sandwiching it between two plates was the answer to holding it. Thanks for stopping by and saying hi.---Brian

Offline Johnmcc69

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Re: Design and build side shaft hit and miss engine from bar stock
« Reply #140 on: December 24, 2018, 12:00:56 AM »
Better than a bent crankshaft.
 Nice work Brian.

 John

Offline crueby

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Re: Design and build side shaft hit and miss engine from bar stock
« Reply #141 on: December 24, 2018, 01:13:23 AM »
Nice recovery!

 :popcorn: :popcorn: :popcorn:

Offline Brian Rupnow

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Re: Design and build side shaft hit and miss engine from bar stock
« Reply #142 on: December 24, 2018, 01:45:22 AM »
I haven't given a lot of thought about carburation nor exhaust yet. The rocker arm for the exhaust valve sets at the bottom of the head, so consequently the carburetor and intake valve will get the port closest to the top of the engine. I think that for a carburetor I will use a variation of Malcolm Stride's Jaguar carb, with the throttle removed and a solid carb body. My fuel line from the built in gas tank is going to run out from that hole in the very bottom of the cooling reservoir block, so it may be interesting getting a fuel line from down there up to where the carburetor is.

Offline Roger B

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Re: Design and build side shaft hit and miss engine from bar stock
« Reply #143 on: December 24, 2018, 09:28:17 AM »
Coming along well  :praise2:  :praise2: We all have these 'small' measuring problems. One end of the of the crankshaft on my diesel is 11.5mm instead of 12mm which cost me an 11.5mm reamer  ::)

Are you going to put a non-return valve in the fuel line as the tank is somewhat below the carb?
Best regards

Roger

Offline gbritnell

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Re: Design and build side shaft hit and miss engine from bar stock
« Reply #144 on: December 24, 2018, 01:34:30 PM »
Brian,
On most of the hit and miss engines the valve set-up is horizontal whether pushrod operated or by shaft like yours. The exhaust is generally to the outside with different configurations for the intake. On Associated engines there is a tower over the intake on which the exhaust pivots while on others like the Domestic side shaft the valves are staggered so the exhaust rocker arm can pass by. Stacking them like you have will still allow for an operating engine but will just look very different from conventional hit and miss designs.
gbritnell
Talent unshared is talent wasted.

Offline Brian Rupnow

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Re: Design and build side shaft hit and miss engine from bar stock
« Reply #145 on: December 24, 2018, 01:49:44 PM »
Roger--I will have a one way check valve in the fuel line running up to the carburetor. George--I'm not worried about it looking a bit unconventional---Nobody around here has ever seen a hit and miss engine.---Brian

Offline Brian Rupnow

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Re: Design and build side shaft hit and miss engine from bar stock
« Reply #146 on: December 25, 2018, 03:31:36 PM »
My diamond lapping compound came in yesterday. This morning, bright and early before the Christmas crowd gets here I got up and diamond lapped the piston into the cylinder. I think it went quite successfully. the piston and the inside of the cylinder have taken on a dull grey finish, and the piston will not fall thru the cylinder, but will go with a slight push. If I hold my hand over one end of the cylinder and try to push the piston thru from the other end, it air-locks and won't go.

Offline Brian Rupnow

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Re: Design and build side shaft hit and miss engine from bar stock
« Reply #147 on: December 25, 2018, 10:03:59 PM »
The Christmas crowd has come and gone, and I have reassembled the engine.  Everything goes round and round, and has amazing compression when I seal the end of the cylinder with the palm of my hand. This is a good sign.

Offline crueby

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Re: Design and build side shaft hit and miss engine from bar stock
« Reply #148 on: December 25, 2018, 10:08:47 PM »
Excellent results!
What do you use to clean the diamond paste off the surfaces, dont want any particles staying behind and continuing to cut. I have used the paste in sharpening chisels/planes, but not in lapping much so far. Does it just wash off, or do you need a solvent of some sort?
 :popcorn: :popcorn: :popcorn:

Offline Brian Rupnow

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Re: Design and build side shaft hit and miss engine from bar stock
« Reply #149 on: December 26, 2018, 12:10:38 AM »
Wipe off with dry rag. Wipe off with rag soaked in laquer thinners. Hold under hot water tap and scrub with Dawn dish detergent and an old toothbrush.