Author Topic: Mystery engine  (Read 3636 times)

Online RayW

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Re: Mystery engine
« Reply #30 on: February 05, 2021, 03:51:31 PM »
I think you're right Graham. A completely new crank seems the way to go. I know what you mean about the odd dimensions. I've done the same myself. Ordered a new pair of gears today so will be able to modify them as necessary to fit the new crank. Will just need to bore out the main and big end bearings then to fit.

Ray

Online RayW

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Re: Mystery engine
« Reply #31 on: March 01, 2021, 05:20:55 PM »
The new crankshaft is now finished. I have made the new one a bit more robust than the old one with slightly larger diameter shafts and journal. The webs are identical in profile and dimensions to the old ones, with just the thickness being increased slightly to 1/4". I have added 1/8" keyways as the flywheels were only held onto the old crank by a single locking screw each and had quite a noticeable wobble. Hopefully, boring them out for the larger shafts and adding a keyway will result in a more secure attachment with truer running.
The only other change I made was to adjust the length of the shafts either side of the webs as the old crank was very short one side and unnecessarily long the other, and the short side would not have left much room for a key.

Ray

Online RayW

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Re: Mystery engine
« Reply #32 on: Today at 05:46:50 PM »
Made good progress over the last few days. New gears machined to size and fitted, with the roller for operating the exhaust valve pushrod on the back of the large gear.
Flywheels bored out to fit new crankshaft and keyways cut.
Ray