1" Bore x 1" Stroke Vertical i.c. Engine

[Sparky_NY]

Dwell angle doe not have to be huge. All it takes is to get the needed current flowing in the coil, storing the spark energy. Longer than that is just a waste, overheating the coil.

With electronic ignition, even that is not needed. Just the signal to trip the SCR and blast the coil with a pulse.

Understood, was just wondering why the unusual cam profile compared to what is normally seen.

[brian Rupnow]

Sparky--I really don't know. When I started building model engines 12 or 13 years ago, I copied someone else's cam and it worked fine, so I've never seen reason to change it.---Brian

[Sparky_NY]

Sparky--I really don't know. When I started building model engines 12 or 13 years ago, I copied someone else's cam and it worked fine, so I've never seen reason to change it.---Brian

Ah yes, the old "if it ain't broke, don't fix it" theory. Nothing wrong with that, I practice it often.

[brian Rupnow]

If my time was worth anything, this might be the most expensive cooling fan in the world. It is fully fabricated and uses 3mm sealed ball bearings on the fan shaft. I fabricated the 1" pulley as well. if I had known how well this was going to turn out, I would have bought a new piece of 1/16" steel plate to make the fan from. All I had on hand was a rather pitted and horrible piece of 0.050" thick metal that started life as an inspection hatch on an electrical box. I have a little cosmetic work to do on the fan yet, but now that I have the experience of making a fan, I may just buy a piece of metal and build another fan. I was going to put a groove for the drive belt into the flywheel, but it seems to track just fine as it is, and I hate to cut on the flywheel.
https://www.youtube.com/watch?v=nzoX08Kq-40

[Sparky_NY]

Wow, with the effective ratio between those two pulleys and considering a reasonable RPM for the motor, that little fan is REALLY going to spin super fast ! Watch the fingers for sure !

If the metal pits bother you, you could always take a bit of epoxy and a toothpick and fill them in and sand smooth. Auto spot putty would also work nice if you had some around.

[brian Rupnow]

Someone asked the other day what the oil level in the crankcase would be. The oil level is determined by a removeable plug in the side of the crank case. This picture shows the oil level.

[brian Rupnow]

In the time honored offered tradition of "Making it up as I go along", today I have a con rod up on the lathe. The overall shape of the con rod, the bolt on cap, and the bores in both ends are finished in previous steps. Here I have made up a simple fixture to which I can attach the con rod in order to turn meat away from both sides, so I end up with a raised "boss" at the big ends. What is shown is the first step, machining the side material away to expose the first big end boss. Now I will flip the part over in the fixture and do the other side "big end boss". I will probably finish up the other ends with my rotary table and milling machine.

[brian Rupnow]

Todays fun limit has been reached. We have a finished connecting rod. Sometimes I wish I had a media blaster to even out the finish on things I machine so they would show up better on camera. ah well, nobodies going to see it once it's installed in the engine. It is aluminum 6061 t6 material. I don't generally put bronze bushing shells in these con rods, as they never see heavy lugging loads and aren't run often enough to make a difference.
.

[sid pileski]

Is it camera angle, or is the split of the rod cap off center??
How’s that going to install on the crank?

Hmmmmm....

[brian Rupnow]

Must be the camera Sid. What's happening with your clock?

[sid pileski]

Clock is getting the finishing work now.
took some time to get the stepper motor running right between the help of a member here and a fellow at work.
I’m not going to do high polish on the parts of this one. I found a coating specifically for copper and brass jewelry. Hopefully it will keep the tarnish at bay.

[brian Rupnow]

Here's a picture of a half grown piston. It will reach adulthood tomorrow. Why is the skirt so thick?---I really don't know. That's made from an old piston drawing that I brought forward and used on this engine. I think I'll thin that skirt down tomorrow when I have it up on the rotary table.

[brian Rupnow]

This morning I lapped the cylinder with a 1" expanding lap using 400 grit lapping paste (you can just see a corner of it in the foreground.) until it was about 1.002 finished diameter. I had turned the piston to 1.003" diameter yesterday, An expanding lap will always leave a small "bell mouth" at the end of the cylinder, and it can work to your advantage. Once the piston would just start to go into the cylinder end, I mounted the cylinder in my 3 jaw chuck on the lathe, and using a handle I had made up to hold the inside of the piston, coated the piston liberally with 600 grit compound and slowly worked it into the cylinder with the lathe running at about 50 rpm. Once it would pass completely thru the cylinder I stopped and cleaned everything up with laquer thinners. The piston to cylinder fit is perfect.

[nickel-city-fab]

Brian -- I'm curious about the lap -- is it a shop-made item or could you share plans for it? Why do expanding laps cause bellmouthing? I could see using them in the future, so trying to learn. I haven't done much "real" lapping, just a lot of sand-papering. Thanks.

[brian Rupnow]

Nickel--Do a Google search for Acro Laps. They are a brass barrel with longitudinal slots that don't carry thru to the ends. This brass barrel rides on a steel shaft that is plain on one end and has a threaded shank on the other end. As you tighten the threaded shank, it squeezes the brass barrel and makes it expand.--think of a snake that has swallowed a frog. Trouble is, it doesn't expand evenly over it's full length. You coat the lap with lapping paste and I lock the plain end of the steel shaft in the three jaw lathe chuck. Slide the cylinder over the lap, and adjust the threaded end until you feel some drag on the inside of the cylinder. Turn the lathe on low rpm and work the cylinder back and forth over the lap until the lapping paste has worn away some of the cylinder---you can definitely feel this with your hand holding the cylinder to keep it from rotating. This leaves a beautiful finish on the inside of the cylinder. The problem with bell-mouthing the cylinder occurs when you don't hold the cylinder perfectly in line with the rotating axis of the lathe. This does require a bit of practice. eventually The laps wear out, because some of the lap is worn away each time you use it.