The Craftmans Shop > Model Engineering

Side Valve i.c. engine from Bar stock

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Brian Rupnow:
So here we have it, gentlemen- The material (or at least most of it) for my new engine. The thick slab of bronze is destined to become a flywheel. The thin piece will become trim pieces such as the tappet guide. The steel flatbar in two different thicknesses will become crankshaft webs. the large aluminum block will become the crankcase, the two smaller blocks will become combustion chamber immediately below the cylinder head and the backplate. I have enough round steel stock on hand to make the crankshaft from. I have yet to purchase the cast iron for the cylinder and the piece of aluminum which will become the baseplate. My supplier with the giant size self feeding bandsaw charges me $10 per slice through the bronze, so I think the total price came to around $35.00 for material.

Brian Rupnow:
Mystery Solved----Kind of---I chucked up a piece of cold rolled round stock in my rotary table/3 jaw chuck, put the #4 gearcutter back in the mill, and took a full depth 0.090" cut. The gearcutter was shrieking at a "normal" speed for this kind of work, and I was again getting sparks off the cutter. ---And that was WITH cutting oil.  A close examination of the cut cold rolled shows material being "extruded" around the sides and end of the cutter path. I have concluded that the gear cutter was duller than a hoe!!! It probably wasn't the fault of the 1144 stress proof material after all. Some ham-handed bugger who uses my mill MAY have run the cutter up against a hardened jaw on the 3 jaw chuck the last time the cutter was used and put away. I don't recall doing it, but I am the only person who ever works in my little home machine shop. Anyways, a quick phone call to Travers in South Carolina, and I am $60 poorer and a new cutter is coming UPS.---Brian

Brian Rupnow:
One burning question remained--On the cast iron cylinder, due to very close clearances and constraints, I ended up with a #5-40 tapped hole 0.079" off the side of the cast iron part. I wasn't sure if I could do that or not without the thread breaking out thru the face. This set-up answers my question, and it's an answer I didn't want to hear. There is still enough thread in the cast iron to hold sufficiently, but it looks crappy. My next stunt will be to drill and tap the hole .188 back from the edge, and then machine material away until I have my .079" edge to center distance and see what that looks like.

Brian Rupnow:
And the short answer is---that doesn't work either!! The thread still breaks thru. This is going to call for a small design change on the affected drawings :doh: :doh:.--Brian

Brian Rupnow:
Okay!!! At 0.095" edge distance, we are golden!!! No break out of the threads thru the side at that edge distance. I will write that on my wall of "things to remember" and make the slight design change to my drawings.---Brian

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