Four stroke three cylinder radial of my own design
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cooksservices
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There are a couple of people that have offered to do plans for this and one of my other engines too. The trouble with this engine is that the main crank pin is large for the master rod size so that has compromised the size of the link rod bronze bearings. I think if I were to design that part again I would slim down the main crank pin to share a bit of room with some bigger link rod pins. This is something we will have to look at if we make some plans for the engine. Apart from that I am really happy with how everything has worked out. Especially as every part of this engine was made totally on the fly. I have fired up a drop box account and stuck around 300 photos of the build some good, some bad and some ugly but I haven’t hidden any part of this build. I have only had a mill for two months and a lathe for around two years so my set ups and operations may well not be the right way to do things but I know they worked for me. I hope that this will inspire other less experienced members here to just have a go. With a little imagination and some common sense it’s quite simple to design fixtures and set up parts for machining. If it doesn’t look like it will hold it probably won’t, if it looks like it’s going to dig in it probably will. I was quite surprised with the milling machine how much of the work is in the setting up. Generally it seems that actually taking the cut is the quick part.
I’m not sure what order the pictures are are going to come up so it might be worth clicking to sort the photos by the date they were modified, that way you should be able to scroll to the bottom then work through from the start of the build.
https://www.dropbox.com/sh/myi7t57zxx82hr7/AABtWzR52Rx9V6OHttBfN-hba?dl=0
I am more than happy to answer any questions on the set up and build.
Thank you again for all the great comments!
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cooksservices
Well-Known Member
Those are actually the exhausts, I designed them with two things in mind, one was that I wanted them to give a performance classic aero kind of look and also in the hope that they would echo slightly and amplify the exhaust note. They don’t really sound quite as sweet as it did with straight slash cut pipes but much louder and I absolutely love the way they look!
I made a solid steel former and beat some steel sheet around them from either side to make two halves then trimmed the two halves down and very gently mig welded the two halves together. Lots of filing and sanding later I had three nice looking exhausts. I then welded in some steel tube the make spigots to fit in the exhaust mounting flanges that were then welded on and drilled out again. There is some pictures in the drop box album that hopefully match up with this description.
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Thanks for sharing the pics and videos - really helpful to see how you’ve done things.
Congratulations on a beautiful running engine. That is very impressive.--Brian Rupnow
cooksservices
Well-Known Member
Thank you Brian, that means a lot coming from you.
Thanks for the pictures! If you get a chance, I'd love to know some of the basic measurements: bore, stroke, diameter of crankcase, that kind of thing.
cooksservices
Well-Known Member
Hi I’d happily tell you any dimensions that I can remember or that can be measured from the outside. There is a couple of people that would like some slightly more detailed measurements to draw up some plans, I’d be happy to note them down too if I ever strip the engine down. Thanks, Sam.
Here's what I am particularly interested in:
Measurement from the outside:
Cylinder diameter
Crankcase diameter (approximate)
If you remember or if/when you strip down the engine:
Bore
Stroke
Size of valves
diameter of crankshaft
diameter of camshafts
Measurement from the outside:
Cylinder diameter
Crankcase diameter (approximate)
If you remember or if/when you strip down the engine:
Bore
Stroke
Size of valves
diameter of crankshaft
diameter of camshafts
