Gallery, Projects and General > Project Logs
Wrestling with Robbo........
Stilldrillin:
Well..... I've done all I can to improve the existing parts.
It is so close to running! And very much improved, over the lifeless lump I first tried.
I've had a good think, and a measure round........
I read, somewhere, the displacer volume needs to be around 1.6 times, (or more), the power piston volume.
The displacer measures 1.32" dia x .45" stroke. The power piston measures 1.018" dia x .73" stroke. Giving a ratio of only 1.037.... Hmmm....
If I reduce the power piston dia. to .8"...... This will give a ratio of 1.68....... If my sums are correct.
Anyone got a comment? Or two pennorth?
David D
sbwhart:
Just checked the calc through using my long winded way and I get .796 so .8 is the man to go.
:D :D
Stew
OldMetaller:
Nice work David! I could see some Old Machinist's tricks being wheeled out there! I especially like the Delrin dodge!
Regards,
John.
Stilldrillin:
Thanks for your comments Chaps!
I found the advised ratio is 1.5....... So, I made the steel cylinder with a bore, around .843".
Stuck it into the original cylinder, using high temp slide lock. Then honed it, using a piece of delrin, and fine grinding paste........
All done.......
Turned the piston to +10 thou' , and parted off.......
Screwed onto an M5 threaded mandrel, and finish turned.
Removing the last thou' or so with fine emery, backed by a 6" rule, a la Cedge.........
Looks ok, I think.........
Lit the burner......
So sorry for the amateur dramatics! But....... You know how it is..........
It's been a good day! :D :) :D :)
David D
Rob.Wilson:
:clap: :clap: :clap: :clap: :clap: She goes like the clappers David :clap: :clap: :clap: :clap:
I always fined your "bring em back to life" threads a great read ,,,,,,,,,,, well done :thumbup:
Rob
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