This is a back post of thread I made about a year ago on my first engine build: David Goodfellows – Brassy Babe:
I did quite a bit of research and it was a resounding answer that a wobbler is a nice first timer. There were quite a few free plans online, I found Dave Goodfellows – Brassy Babe a nice looking engine but with the main thing being that he also has quite a significant write up with comments to help the build.
I have been working on it since Sunday evening and I was pleased that I could join a few bits together this evening and get some motion. It seems to turn OK. Obviously I presume it is a whole different ball game getting it to run under pressure but I`m pleased that I have got something that moves!! I`m also getting more confident with the mill which I haven`t really used all that much.
I made it all from scraps that I have been accumulating over time, the majority is made from brass or ally. I picked these plans due to the explanation but closer inspection would actually reveal that he is often lacking in dimensions! That was an issue, but it has also made me think about it and add to the challenge. I suppose I`m getting carried away, it isn`t really running yet, I was just thrilled to get it fastened together and it sync up and move!
Next step is to counter sink the screw hole and find a suitable spring to apply the pressure on the cylinder. I will then finish the frame and locate the remaining holes. Then I need to lap all surfaces as, especially the front running surface – I may even try and mill it. Then finally onto the flywheel.
You`ll be pleased to hear it is working!!!
Although many issues that have been mentioned are problems related to my engine, I have worked on two things that eventually got it going.
As davesWimshurst mentioned in the last post, the flywheel is too large and when upright is bearing down too much weight on the crank shaft which has too much “give” in the frame hole, causing it to bend down. This little engine is very forgiving and later I will rebuild the flywheel but for now I just spun the flywheel on the crank shaft and tightened it up with the grub screw on the other side. This shifted the weight for the better and now the fact that the cam action of the off-centre flywheel is actually acting to pull the piston back down through the none powered phase of the cycle. This made my engine work.
Second thing I did was to put a bit of grease on the piston, reducing the air escaping from my tapered piston at the top of the cycle. Clearly this was causing a loss in power as this really improved the performance of the engine.
So lots of errors and of course all down to my poor machining – BUT it is running and I certainly have more confidence and can learn from my mistakes for the next one. I am going to spend a little longer on this one – I`ll polish it all up, make a new piston and also turn down the flywheel on a mandrel so that it is true to the centre drilled hole. Certainly very proud of my first runner!