Author Topic: Brunner air compressor now Wrights Shop engine  (Read 3668 times)

Offline Myrickman

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Brunner air compressor now Wrights Shop engine
« on: February 26, 2017, 09:40:01 PM »
Since I made the inverted air compressor into a demo for the flip flop cam, I got to thinking about a smaller version. I have a Brunner air compressor I picked up years ago and got to looking at it...it looks like it could be turned into an engine resembling the one in the Wrights shop now at the Henry Ford museum. So I'm winging this one from bits I have around, yet want to make something easy to fabricate if others like how it turns out. The stroke of the Brunner is 2-1/4" so a 3/4" tall head makes it a 3:1 CR. Bore is 1-13/16" The Wright's engine has a long projection sticking out of the head which I believe to be a front cross head for the piston....what do you folks think? The conversion will have same said projection, but it will me merely cosmetic. The valve chests are made from cast iron rod which will be silver soldered to the head ring. I milled two round grooves on opposite sides of the head ring for the valve chests. Did a bit of head scratching to get the passages for the valves to not hit the head thru holes. Crank will have to me remade as the compressor has one side cut off flush with the outboard bearing. The crank bearings are 15/16...these will get babbitted to 5/8" as will the lower con rod end. Have a nice flywheel to get cast as a pair which should lift well.  :stir:

Offline Myrickman

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Re: Brunner air compressor now Wrights Shop engine
« Reply #1 on: March 26, 2017, 09:21:25 PM »
Got all the head work done except for silver soldering it together. This one will be hot tube ignition with the hot tube going on the intake chest. Valves are also done...1/8 stems with 7/16 heads. In the background are the pieces for the crank. I opted for a 9/16 crank diameter as I have most of the Babbitt fixtures from the Swan build. The fixture in the second photo shows how I align the bearings with the bore. Shims are installed on the left side and both sides of the left bearing are poured at once. Then the bushing is removed on the right side and it is poured. Not showing are the washers on the inner bearing died to keep the Babbitt from running out. Still debating if I will I make a working front cross head on the top side of the piston or make the projection cosmetic. Also dropped off the 7" flywheel pattern at the foundry...should be close to the line drawing in the first post.

Offline yogi

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Re: Brunner air compressor now Wrights Shop engine
« Reply #2 on: March 26, 2017, 11:17:46 PM »
That's a cool project Paul!  :ThumbsUp: :ThumbsUp: :ThumbsUp:
I have an old compressor that would be a candidate for a conversation...
I'm looking forward to see more...

Offline Myrickman

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Re: Brunner air compressor now Wrights Shop engine
« Reply #3 on: April 06, 2017, 10:10:19 PM »
I found this image courtesy of the Henry Ford digital archives showing the engine internals. Pretty neat setup with the cross head assembly coming out of the piston crown, eh? Does not explain the governer, but gets me closer....

Offline Myrickman

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Re: Brunner air compressor now Wrights Shop engine
« Reply #4 on: May 06, 2017, 11:28:37 PM »
More shop time this weekend on the Wright model. Made the cross head piston for the top of the larger piston.  It is 3/4" diameter. Had to cut ring grooves in the end for sealing. I have some 0.05" mini parting tools to make the ring grooves but needed a proper holder so that was fabbed from a piece of 1/2" square stock. The ribbed guide for the smaller cross head piston was silver soldered to the head plate as were the valve bodies to the combustion chamber. I inserted a piece of graphite rod to keep the valve chest holes lined up with the holes to the cylinder in the combustion chamber during soldering. I've had good luck silver soldering using a weed burning torch on a BBQ propane tank. I get the part red hot then wipe the solder along the joint. I'm using Safetysilv 55. The mains were babbitted and trimmed to fit the crank. Con rod was babbitted but not bored. Still have to weld the crank up but so far, everything fits up. The piston slides ok in the two bores given the head bolts are not adjusted to get the axis of the cross head concentric with the larger piston..

Offline Myrickman

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Re: Brunner air compressor now Wrights Shop engine
« Reply #5 on: May 21, 2017, 10:10:07 PM »
Spent a little time this weekend making most of the flip flop crescent mechanism. Figured out that by making a 1.5" square of 1/4" flat stock and mounting it on the four-jaw rotary table with one edge across the Chuck center line, it was easy to make the inner surface of the crescent. First a 1/4" end mill makes 90 degrees of the inner crescent surface. Then the rotary table is offset 1/4" towards one of the crescent legs and the piece is moved 1/4" in the chuck towards the top of the cam. The end mill is inserted where the first cut left off and the rest of the crescent inner surface cut. The outer surface defining the cam profile  is simply rough sawn away and finished on the belt sander. Still have some outer sanding work to do to make the sharp ends, but with the 1/4" follower pin in place, you get the idea. The crescent pivots about a 1/8" pin which goes through the holder and has a retainer spring to provide some friction to keep it in either of the two positions. In operation, the rocker arm pivots about 2/3 the way from the crank to the exhaust valve to reduce the lift at the valve chest.

Offline Myrickman

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Re: Brunner air compressor now Wrights Shop engine
« Reply #6 on: May 28, 2017, 11:14:25 PM »
Picked up my flywheels Friday and machined them sans keyways. Also finished the crankshaft with a bit of welding. Finally got to test fit everything for some family shots. Had to file a bit off the center of the rod where it was rubbing the top of the bore and do some other minor work to get everything to move freely. With the head on and the front piston guide attached she's got a bit of drag but nothing major. The crescent mechanism turned out well and with the spring, should flip flop with the follower. This one will be hot tube ignition. I've had good luck using 1/4" stainless steel tubing for the tube. It has poor conductivity and heats quickly with munimal heat. Once the keys are installed, I can work on the rocker arm for the exhaust valve.

Offline Admiral_dk

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Re: Brunner air compressor now Wrights Shop engine
« Reply #7 on: May 29, 2017, 11:07:04 AM »
Nice project - looking forward to see a video of it running.

Offline Dave Otto

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Re: Brunner air compressor now Wrights Shop engine
« Reply #8 on: May 29, 2017, 07:02:32 PM »
Everything is looking great Paul!

I had to go back read from the beginning to see about the appendage sticking out of the head.
Did you make patterns for the flywheels or were they available form one of the model suppliers?


Dave

Offline Myrickman

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Re: Brunner air compressor now Wrights Shop engine
« Reply #9 on: May 30, 2017, 10:06:41 PM »
Dave, the flywheels are patterned off another old steam engine I have. It was just the right size when you scale from the drawing; the spokes are a bit on the  heavy side but only I will probably notice that. Cattail did the castings from the original part. Paul

Offline Myrickman

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Re: Brunner air compressor now Wrights Shop engine
« Reply #10 on: June 11, 2017, 09:40:25 PM »
Getting close now... Got the fuel mixer made to run on propane. The valves still need to be seated in and I must source a copper o-ring to seal the head to the cylinder. Surprisingly everything turns freely and with a bit of running it in with a drill motor, she should be able to run under her own power. I was skeptical the extra snout and cross head would bind due to alignment, but not so.

Offline Ye-Ole Steam Dude

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Re: Brunner air compressor now Wrights Shop engine
« Reply #11 on: June 12, 2017, 11:18:32 AM »

The completed engine looks really good, job well done.

Offline Roger B

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Re: Brunner air compressor now Wrights Shop engine
« Reply #12 on: June 12, 2017, 11:45:12 AM »
Looking good  :praise2:  :praise2: Is that the hot tube above the mixer/inlet valve?
Best regards

Roger

Offline Myrickman

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Re: Brunner air compressor now Wrights Shop engine
« Reply #13 on: June 12, 2017, 12:05:03 PM »
Roger, it is indeed a hot tube. I've had good luck making them out of 1/4" stainless steel tubing. Trick is in the burner and getting it to heat the tube to red. Paul

Offline Myrickman

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Re: Brunner air compressor now Wrights Shop engine
« Reply #14 on: September 09, 2018, 09:13:57 PM »
Well this one sat on the back burner for over a year....it refused to run. So over the last few weeks, I fiddled with it on weekends...and fiddled....and fiddled. Try as I might, I could not get it to run on the hot tube. So I made a gasoline mixer and put a timer on the flywheel to sort things out. I had to modify a 10 mm spark plug to fit a 1/8 npt hole where the hot tube went. Turns out the intake valve was not seating well enough to prevent an erratic mixture. Before I realized this, it seemed to be getting decent compression...apparently not good enough. So I lapped in both valve seats several times and got them seating really nicely. A spring tension adjustment on the intake also helped. With this accomplished, it started easily and had a way more positive exhaust bark. I let it run on gasoline for 10-15 mins to seat in the rings....also helped the compression further. I replaced the spark plug and carburetor with the hot tube and propane mixer and it finally started on propane. I need to make a base for it out of wood to complete things. Ive been most of the last year working on the Myrick model posted elsewhere and kind of silent on this forum but hope to get back into the foray as fall approaches.