RMweb Premium SR71 Posted March 8, 2020 RMweb Premium Share Posted March 8, 2020 I'm sure this has been answered before but Google wasn't my friend... How is the valve gear on an 8f attached to the crank pin, it looks soldered but some experiments this morning have been unsuccessful. Older solders seem to have a higher melting point but I don't want to persist and damage something! (3 rail btw) Link to post Share on other sites More sharing options...
Il Grifone Posted March 8, 2020 Share Posted March 8, 2020 It is soldered. Unless the crank pin is removed from the wheel (IIRC it is splined and force fitted) the chassis will act as a heat sink and require a fair bit of heat to melt the solder. (I assume you mean the return crank to the crank pin - the other end is riveted.) The 2 rail valve gear is the same as the 3 rail. The difference lies in one side of the 2 rail version being fitted into an insulating bushes in the wheels on one side. 1 Link to post Share on other sites More sharing options...
RMweb Premium SR71 Posted March 9, 2020 Author RMweb Premium Share Posted March 9, 2020 Thanks Il Grifone. I must be doing something wrong. Had 120w iron and a fairly chunky tip this evening but didn't touch it. Tried melting in fresh solder as that has worked for me in the past but while it went on fine the original solder won't budge. Link to post Share on other sites More sharing options...
Il Grifone Posted March 10, 2020 Share Posted March 10, 2020 Possibly it could be welded? I always thought it was soldered, but have never had to remove one - one did detach itself.... Unfortunately I am rather a long way from my 8F at the moment (and locked in by coronavirus) so unable to check. They could have used a high melting point solder, but I don't see the point. Careful work with a file should shift or are you trying to refit one? Link to post Share on other sites More sharing options...
Nimbus Posted March 10, 2020 Share Posted March 10, 2020 I would say the crank was staked on to the crank pin, which had a flatted section to prevent the crank turning on it. The Nim. 1 Link to post Share on other sites More sharing options...
RMweb Premium SR71 Posted March 10, 2020 Author RMweb Premium Share Posted March 10, 2020 I think a file is the answer. I've confirmed solder will adhere to the valve gear so it should (hopefully) be reversible. Once it's apart I'm sure the solution will be obvious as always... Thanks again, will update with results. Link to post Share on other sites More sharing options...
roythebus Posted March 11, 2020 Share Posted March 11, 2020 Try a small grinding disc to remove the errant solder in case it's weld! Link to post Share on other sites More sharing options...
RMweb Premium SR71 Posted March 11, 2020 Author RMweb Premium Share Posted March 11, 2020 Well I can say... don't file or solder it! It's riveted. This is the other side I popped out. The crank pin is machined with a top hat and then a rectangular section piece which the eccentric fits over and is then pressed down to retain it. Eccentric and crank pin on other side once I'd figured this out... too late. Thanks for the help all and hopefully this thread will now come up in Google if anyone else wants to know. Link to post Share on other sites More sharing options...
Il Grifone Posted March 12, 2020 Share Posted March 12, 2020 And there I was convinced they were soldered. I should have known better! I suppose a riveting operation is very easy in a factory. It's a wonder Tri-ang kept their tiny screws for so long! Link to post Share on other sites More sharing options...
Ruffnut Thorston Posted March 12, 2020 Share Posted March 12, 2020 Tiny screws make replacement easier? Link to post Share on other sites More sharing options...
sagaguy Posted March 12, 2020 Share Posted March 12, 2020 It`s called gagging or spinning,mushroom head spun over at high speed. Ray. 1 Link to post Share on other sites More sharing options...
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