Brian Rupnow's Double Horizontal Engine

[toolznthings]

Hi All,

Going to try and resurrect a build I did just over a year ago on Brian Rupnow's double horizontal with some changes. As memory serves me I'll get started.   

I did the cylinder block first from mild steel and there will be a picture of it later since I started taking pictures after it was complete.

The base plate was next and I made it a little larger than the plans. Rough sawed from aluminum plate with stock left for milling. Holes for the bearing towers were done first with dowel pin holes at the manual mill.. Holes were added to fixture for milling where they will be hidden on final assembly.
Made a couple of roughing passes and one finish pass on the cnc mill.

The finished base removed from the setup plate. The single large mounting hole was my part zero location.

Next on the build was the crank shaft assembly. I went to a 5/16" size shaft and turned the ends to be silver soldered to .250", with the correct distance between shoulders to establish the crank throw assembly spacing. The cranks throws were milled on a fixture using shoulder screws for location. The holes were spaced and drilled and reamed .250" on the manual mill leaving mill stock.( No picture of the milling. )

This is the simple soldering fixture for the throws, maintains width / parallel. 

Next step was a larger fixture to align the throws to the remaining shafts doing one side at a time and positioning a stop block to get the 90 degree throw.

Another view and pictures of the finished crank.

[yogi]

Another great build you are sharing Brian! I'll be enjoying this.
That crankshaft turned out fantastic. Thanks for showing your techniques. 

[zeeprogrammer]

What yogi said. Very nice crankshaft!

[Brian Rupnow]

Toolznthings--I am always happy to see someone build from plans I have posted. Good luck, I will be following along.---Brian Rupnow

[Dave Otto]

Nice work Brian, I will be following along and interested to see your setups and parts machining.

Dave

[Brian Rupnow]

Unless Toolznthings first name is also Brian, there is some confusion going on about who started this thread!!----Brian Rupnow

[Dave Otto]

Yes, Toolznthings first name is Brian; met him at NAMES this year, seems like a nice guy!

[toolznthings]

Thanks , Dave !
 
Yep ! I'm the other Brian. Sounds like we have an echo going on here.   

[toolznthings]

The bearing stands are the next parts to be done. The two outboard supports will be made from aluminum and will use a miniature ball bearing. ( McMaster # 57155K325 ) The center support will be brass with a removable bearing cap and bored to fit the center throw of the crank shaft.
I machined the thickness of all the blanks to .375 and stood them vertical in the mill vise and face milled the bottoms square to the sides. The outside aluminum stands were bored for the bearings. The center stand was bored with the bearing cap in place. Rough drilling here to get ready for boring.

The blanks are now ready to have the outside contour done on the CNC mill.
Part zero was the bearing bores and the finished bottoms were indicated in parallel to the x-axis using a piece of aluminum for a fixture. I keep several plates for doing this kind of fixture and add holes as needed. Re-face until they can't be used any longer.

After all stands were milled I added the tapped holes and dowel pin holes to the bottoms of all three stands working from the finished bores.

A trial assembly with the crank shaft. The small ball bearings are visible in the picture. I choose the bearings one with the outer flange.

[toolznthings]

Machining the connecting rods .....

The connecting rods will be made from 6061-T6 aluminum bar stock. The wrist pin hole will be bushed with 660 bronze bushings and the crank end will have 660 bronze split bushings. I started with wider stock in the mill vise and CNC milled the .900 width about 1 " deep.

A fixture was made to support the first milled profile with a pocket to align the .900 width and the next contour was milled.

[toolznthings]

Connecting rods .....

[toolznthings]

Connecting rods, still .....

The next step was to START ALL OVER ! I realized later that evening that the hole for the socket head screw holding the part on the fixture was in the wrong place in the rod. Obvious as seen laying on the print. Practice makes perfect .   

The fixture with the correct hole position.

Finishing the rod thickness at the manual mill.

On to the manual mill to finish the rod end caps and and bores for the bearings. You can't see the parallel under the rod in this operation.

The finished rods with a trial assembly on the crank. The bronze bearings in the rods are split with each half a tight fit in the rod and rod cap.

( I may not have noted in my previous post that the crank shaft diameters were increased to 5/16" in diameter. )

[toolznthings]

More machining ....

The piston assembly is next on the build. The piston head will be 660 bronze with a minimal bore fitting o-ring and the rod end will be cross drilled for a 1/16"
dowel pin.
Started by single point threading the piston end of the rod.

I made the piston next and left stock on the o.d. and length and used thread locker and assembled to the piston rod.
Back to the lathe to turn the final diameter concentric to the piston rod and finish face the length. Not pictured in this view I cut the o-ring groove to get a very light fit in the cylinder block.

To insure the correct overall piston length and a set up to drill the cross hole in the piston rod end I made a simple fixture.

The installed o-ring is in this picture. Not shown is the 1/16 cross drill and reamed hole. ( visible in future pictures. ) The purpose of this pinning is to be able to disassemble the the piston rod with out removing the piston itself and losing concentricity.

[gbritnell]

Nice work on the crank Brian, and the other parts as well. This is a little different build for you. What type of fit did you try for on the O ring?
gbritnell

[toolznthings]

Hi George,

Well I wish I could say it was calculated, but I did a trial and error fit until I felt that the drag was not going to produce to much friction in the bore.
I've done it on several engines and the ring seems to seal well under the conditions these little engines run.

Brian