Cheers Dave/Graham
Well, I've bin quietly making progress not as fast as I would like but progress nevertheless.
Next part the crank but before I can assemble the crank I need a couple of other parts first:- the eccentric sheaves and the bearings.
I had a bit of a false start with the sheaves it was my intension to have them as plain disc the straps being kept in place by adjoining bits but after I made them I realized there would be too much space between the parts and some of the part wouldn't have a smooth face so they would catch, so decided to make the sheaves edged so that the straps would be retained. I also went about making them a different way to the method I've used in the past I've got more confident with the mill so decided to use the mill to drill the off set hole.
First turn a chunk of bar up to the required diameter and put a small centre drill in it.
Potty Over Crank Wall EngineThe retaining the bar in the chuck transfer it over to the mill centre it under the quill.
Potty Over Crank Wall EngineZero the dials and off set the table and drill the hole right through the bar, I drilled it letter U to allow a final clean up with a 3/8" hand reamer.
Potty Over Crank Wall EngineThen back to the lathe and machine the groove for the straps using a parting tool, then part off to length.
Potty Over Crank Wall EngineFace to length using the back stop in the chuck.
Potty Over Crank Wall EngineThen drill and tap M2 one thing a learnt from the first attempt was that the taps are to short to get through the thicker section of the sheaf as drawn, (broke a tap) so for these I tapped through the thinner section.
Next bit the bearing no pic of this as they are simple enough.
The crank shaft is fabricated
So to make the crank shaft webs.
Again I changes my method to take advantage of the accuracy of my mill.
Cut a chunk of plate and milled it to size enough to make all four webs.
Than onto the mill drill four evenly spaced holes down one side again letter U move the table over to give the correct throw and drill down the other side
Potty Over Crank Wall EngineBring to size with hand reamer.
Potty Over Crank Wall EngineCut off with a slitting saw
Potty Over Crank Wall EngineThen with a couple of same size bars in the holes, mill thickness to size.
Potty Over Crank Wall EngineTurn up a 3/8" mandrel with a M8 nut and in the lathe radius the ends.
Potty Over Crank Wall EngineThats them done.
Potty Over Crank Wall EngineNow for the crank shaft journals:- first with the bits roughly assembled check the main journal length cut it off the bar then in the lathe face of centre, and turn and thread both ends.
Potty Over Crank Wall EngineCut off and face the crank journals to size.
Now to stick the crank shaft together with high strength loctite, its important not to rush this and to do it in stages letting the loctite cure between stages.
Stage one glue the crank journals to the webs using spacers, the main shaft is there just to keep everything lined up.
Potty Over Crank Wall EngineStage two glue one of the crank journals to the main shaft the correct distance from the end. (no Pic)
Stage Three glue the remaining crank journal to the main shaft 90 deg to the first at the correct distance. Using 1*2*3 block:-not forgetting to assemble the sheaves and the bearings in-between first.
Potty Over Crank Wall EngineNext as I keep my trousers up with a belt and brasses, pin the cranks in place, I just put the pins 1/2 way through that will be enough to stop things slipping, but as an insurance against having to break the crank down to change something one of the pins a drilled all the way through so that I can nock the pin out and take the crank apart to get at the sheaves and bearing.
Potty Over Crank Wall Engine
Potty Over Crank Wall EngineCut the bit out of the middle you don't want
And her we have it finished in the housings its turns over nice and free
Potty Over Crank Wall EngineStew
