| Gallery, Projects and General > Project Logs |
| New Project Started! |
| << < (24/28) > >> |
| jim:
thats a work of art! are you going to try an ally piston? |
| NickG:
Jim, I think I might try one as it looks like the shop where I was going to get my cast iron is having a xmas break! The ally seems ok for the valve, but that's without any heat and there aren't any sideways forces on the valve. So I fear the combination of the differential expansion and a bit of sideways force on the piston may cause binding with the ally. For what it takes, I think I'll turn one up from ally, even if it doesn't run I'll be able to tell you if the friction dramatically increased etc. I could end up making 3 sets of piston and valve at this rate and I have already made 2 or 3 before hand! Nick |
| NickG:
Hi all, Got more done in workshop last night - got the valve finished and the piston made, both from aluminium this time. All was going very well until I used my new tail stock die holder to thread the bit that goes inside the piston for the wrist / gudgeon pin and it snapped! I think I’d done the undercut too deep, so I did it again without an undercut! Luckily it didn’t take long the 2nd time as everything was set up. It took me ages to get the vice clocked back square on the milling machine etc. The piston is pretty much to Jan’s original design now, just the wrong material! Anyway, the piston and valve both had a very nice fit. Excellent seal whilst hardly any friction. It was 00:50 hrs by the time I finished that so I thought I’d leave test run for today. Just tried it and there was good and bad news! Here is the good news: This is actually quite a bit more free running than before and with a better fit, that can only be a good thing. However, when I pre warmed the cylinder to get rid of any condensate first, my worst fears came into being! I half expected this to happen! The engine had seized completely due to the aluminium expanding faster than the cast iron! :doh: So at least this exercise tells us something we thought anyway - it’s not easy to use aluminium pistons with cast iron where heat is involved! It may be possible with the correct clearances though – not sure how to calculate this and have no desire to. :smart: I’ll have to wait for some cast iron now. Promising though, If I can achieve the same fit with the cast iron there SHOULD be nothing stopping it from running! Here is a pile of scrap – there were a couple of other components that got shot straight in the bin in anger – at least the experimental flywheel can be saved for future projects! Nick |
| jim:
i'm gutted! :doh: i really thought it'd run! like you said to me before about using the "correct" material! looking forward to the cast iron piston being made :thumbup: |
| Stilldrillin:
--- Quote from: jim on December 31, 2009, 03:47:27 PM ---i'm gutted! :doh: i really thought it'd run! like you said to me before about using the "correct" material! looking forward to the cast iron piston being made :thumbup: --- End quote --- Me too! I really thought you had sorted it this time Nick. Onwards an upwards........ :thumbup: David D |
| Navigation |
| Message Index |
| Next page |
| Previous page |