Engines > From Plans

EPO - A Super-Simple Oscillator

(1/5) > >>

PaulR:
While still trying to work things out for my next project, being tired of looking at CAD and not having had any time in the workshop for a few days, I decided to make a really simple wobbler from a plan found online. I've built a few similar engines in the past but never with a pivot at one end rather than in the middle of the cylinder, so for completeness, here goes EPO, the End Pivot Oscillator.

I turned the 0.5" square cylinder and port blocks to size and marked up for the various holes and the recess around the crankshaft that needs to be milled or filed away. Unless I'm really losing the plot, I think I spotted what would be a terminal mistake in the drawings straight away: the port in the cylinder is shown as passing straight through, meaning air would come in and go straight out without having any effect. Anyway, I drilled and reamed the bore, the hole for the 4mm pivot and the 5mm crankshaft (might stick a ball race in there, need to look at diameters of what I've got). I drilled a 6mm hole at the end of the cylinder where the arched slot will go and will probably saw/file the rest out. Also drilled that 2mm hole in the cylinder...but not all the way through!  :Lol:

The plan calls for 1mm radius bevels on all edges which I probably won't do because 1) I'm not sure I like it and 2) doing it accurately and uniformly on all edges would be tedious :Lol: I think I'll need to adapt the inlet connection a little bit as well to make it more airtight and suit the air line I have.

Sanjay F:
and we're off and running again .......... didn't take long! Will be following  :popcorn: :ThumbsUp:

crueby:
Don't think I've ever seen one set up as an end pivot, should do interesting things to the motion.   :popcorn:

Jasonb:
I suppose you could think of an end pivot as the crank side of a double acting wobbler with the top half of the cylinder cut off. In which case the position of ports is similar and motion the same, only difference is this has the inlet above the piston as per a single acting.

PaulR:

--- Quote from: Jasonb on February 12, 2026, 06:53:55 AM ---I suppose you could think of an end pivot as the crank side of a double acting wobbler with the top half of the cylinder cut off. In which case the position of ports is similar and motion the same, only difference is this has the inlet above the piston as per a single acting.

--- End quote ---
Yes, it's just half a wobbler with the crank flipped over to the other side I suppose. At this scale the arc of the cylinder port can also be considered a straight line which makes things even simpler.

Thinking about trying to mill the aperture that the crank pin moves in using the vertical slide. The curved top is 6mm (as per the hole I've already put in) but I don't have a 6mm slot drill. Is a 6mm end mill likely to bind if the part is is fed across the bed then slowly advanced towards the headstock for each cut (I usually take no more than 0.005" at a time anyway)?

Navigation

[0] Message Index

[#] Next page