How to join 2 cylinders at 90 degrees

[edholly]

I would like to join a cylinder at 90 degree to another to form a crankcase. Am struggling with how this might be achieved without welding. Have made a mock-up but still can't see a way without resorting to something like loctite.

Is there a loctite product that might do the work ?

It is a tall order, as the crankcase is destined for a model diesel engine around 2.5cc. Obviously the things that will be trying to undo it are the enormous forces involved with 10,000 plus pulses per minute, the compression and burning of the fuel making untold forces pushing the components apart, a risk of a compression lock on starting, and then there is heat that will most likely weaken any "gluing process".

Can't get it wrong as if it did come apart, then the top of the engine could possibly eject with the speed approaching a missile and injuring someone.

I've thought of using pins but the material has to be fairly thin and with a screw thread making it even thinner effectively so I don't think that is a solution.

Any ideas out there as to any way of bonding the two together ?

Have posted some photos of the problem, along with being privileged to watch a Falcon looking for a meal just in front of me for maybe a couple of minutes at Cronulla NSW recently. Really remarkable.

 

[ninefinger]

Why does the crankcase need to be round? Is it aesthetics or are you trying to be as light as possible? Either way, without casting it as one piece it will be difficult. how about this? Turn the cylinder for the piston down from a larger diameter and cut a saddle in it?

Mike

 

[Longboy]

Take a look see over at the hardware store for one of these. It would be in the cylinder/ crankcase bin next to plumbing fixtures.

 

[Jasonb]

Start with a square block for the crankcase and put your cylinders on two sides, can either have a bolting flange on the cylinder or cut a fine thread on it with matching threads in the crtancase.

You could leave it as that or shape the rest of the square do that it is round, maybe leave a couple of mounting lugs either side.

 

[tornitore45]

Material thickness can be changed locally. The cylinder can have a step/shoulder like suggested above and the crankcase can be bored off center to achieve lightness and strength where needed. Then a force fit thread machined.

 

[kwoodhands]

I would like to join a cylinder at 90 degree to another to form a crankcase. Am struggling with how this might be achieved without welding. Have made a mock-up but still can't see a way without resorting to something like loctite.

Is there a loctite product that might do the work ?

It is a tall order, as the crankcase is destined for a model diesel engine around 2.5cc. Obviously the things that will be trying to undo it are the enormous forces involved with 10,000 plus pulses per minute, the compression and burning of the fuel making untold forces pushing the components apart, a risk of a compression lock on starting, and then there is heat that will most likely weaken any "gluing process".

Can't get it wrong as if it did come apart, then the top of the engine could possibly eject with the speed approaching a missile and injuring someone.

I've thought of using pins but the material has to be fairly thin and with a screw thread making it even thinner effectively so I don't think that is a solution.

Any ideas out there as to any way of bonding the two together ?

Have posted some photos of the problem, along with being privileged to watch a Falcon looking for a meal just in front of me for maybe a couple of minutes at Cronulla NSW recently. Really remarkable.

Hard solder, sometimes referred to as silver solder. Takes heat well and if done well won't come apart. I like the idea of making the cylinder out of the solid even more than hard solder.
mike

 

[Brian Rupnow]

Ed--Mill it from solid.---Brian

 

[edholly]

Brian, I can't give up that easily !

Any consensus on whether this would be a safe option ....

Using 4 pins each 0.75mm thick pushed into 4 drilled holes as per photo. The 4 holes are equal spaced front and back to evenly take up the upward loads mentioned above. And there is about 1mm meat around them in the horizontal barrel and the same blow the bottom lip of the vertical barrel. They will be in shear so their strength I think should be adequate to support the Loctite retaining compound, which is a terrific product in its own right.

The meat around the horizontal barrel will be just enough to allow a fine thread to be put there.

 

[Brian Rupnow]

Well Ed, then try it and see---and good luck!!

 

[vederstein]

This may not be the look you're going for, but a completely different approach would be to use tie rods to hold the whole thing together.

This is how I constructed my rotary air engine.