Following on from this thread:
https://www.modelenginemaker.com/index.php/topic,12765.0.htmlI've spent the last couple of days making this little abomination, which is a small 'wobbler' with two ports in the cylinder rather than the usual one. Not worthy of a 'build log' so here it is in a single post. The engine has a few other oddities:
- The cylinder is mostly round in plan view. I don't know why, I just thought it would make a change!
- It has a combined piston/rod
- There's currently no bearing on the crankshaft, it's steel on steel
I made a little brass thrust washer but left it out for now to ensure a decent gap betwixt crank disc and piston. I'll put it back in now I know it works. - There's a gap in the bore towards the far end (!!!) - it wasn't until I made the bore that I found the the sticky-out bit at the far end hadn't quite reached the bottom of hole before I soft soldered it in place. As the piston and rod are combined there's no chance of the piston going beyond the gap so I figured it wouldn't make any difference - it's like a negative piston ring
I needed about 25 PSI to get it started, at one point the crank pin came unscrewed and the piston became a bullet
After a bit more tweaking it runs now on next to nothing (zero on the compressor's gauge).
I need to shorten the crank pin a fraction
and make some sort of stand for it so I don't suffer vibration white finger.
About to make the bore:
After making the bore, the holes for the cylinder ports and the threaded hole for the pivot:
After sawing off and facing the end of the cylinder, making the piston and the port block - the freaky bit where the ports are wider than the two ports on the cylinder (TM Patent Applied For
)
After making the crank disk/shaft:
After making the flywheel, an unfeasibly large crank pin and one of the three 0.75mm thick washers (two for the pivot pin one for under the crank disk):
After fitting a spring (which is completely the wrong diameter but all I could find):
Running on a few PSI:
