Blockhead

[PaulR]

Made the end caps from brass hex - because I've got some in the right size that never seems to get used so why not - and Loctite'd in place. Also made the pistons and rods, next will be the crankshaft/valve.

[Sanjay F]

Looking good and the build is motoring along! 

[PaulR]

Filed the flats on the shaft using my cross-drilling widget so it could be flipped 180 in the vice. I thought about milling the flats but realised I don't have an end mill small enough to do the exhaust flat; doing it the manual way was probably quicker anyway. Just need to drill the longitudinal hole and that part is finished.

[PaulR]

Finished drilling the valve and made the crank disk only to find I don't have an Allen key for the 2.5mm grub screw  so will need to sort that. Next will be the crank pin which will have a little step to keep the yoke away from the disk.

[PaulR]

Chucked the grubscrew idea and turned down the head of a stock stainless screw to make a slotted one instead. Also made the crank pin, just the yoke and flywheel to go.

[PaulR]

Mostly finished the yoke but have to give the fingers a rest! Made some filing buttons to do the ends, took care to get the holes at the end of each slot in the right place then eyeballed some smaller ones in the middle (my eyeballs must be wonky  ) and did more filing. Still need to tart up the ends and do some fine adjustment to the slot but it's mostly done. Should really have made a cross hole for the piston rods to screw into before I started but should be ok to do at the end.

[Michael S.]

Hi Paul, that must have been a lot of hard work with the file. It looks great though! 👍

(My fingers always hurt a little after filing like that. Must be getting old.)

Michael

[PaulR]

Hi Paul, that must have been a lot of hard work with the file. It looks great though! 👍

Thanks Michael. I couldn't resist finishing it off this evening so the fingers are really hurting now!

[Sanjay F]

Nice finish though given your manual labour and shortened fingers - well worth it!

[PaulR]

Nice finish though given your manual labour and shortened fingers - well worth it!

Cheers 

Made a simple flywheel and put the bits together but it was impossible to turn over by hand because the hex section of the crank pin was pushing the yoke away from the frame - some slight miscalculation or error in my partial plan. I took it out and put in a 3mm screw and the engine then turned over nicely by hand so I connected up the air supply and it went pretty well, even self-started at one point, reading 0 to 5 psi. That's with one screw instead of four holding each cylinder on (so pretty leaky) and almost no lubrication 

I'll make a new pin but put the hex section on the outside and sort out some sort of supports for the whole thing. This and the previous engine seem pretty solid designs but I don't like the construction method for either so I'll maybe try a third variant and somehow drill longer passages in a thicker frame... thinking.


<a href="https://www.youtube.com/watch?v=bsSHpd7aLUs" target="_blank">http://www.youtube.com/watch?v=bsSHpd7aLUs</a>

[Sanjay F]

Another runner ....... a round applause for that man! 

Well done Paul

[Michael S.]

Congratulations, well done 👍

[Roger B]

A runner     

[PaulR]

Roughed out some supports and a little base to do some running in. Probably need to fit some rubber feet to stop it going walkies when running at speed 

<a href="https://www.youtube.com/watch?v=LmvbdSONjgs" target="_blank">http://www.youtube.com/watch?v=LmvbdSONjgs</a>

[vtsteam]

Runs great Paul!