ownthesky2010
Active Member
- Joined
- Aug 22, 2014
- Messages
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Hi All
I have another engineering dilemma to solve.
I started with the conrods for the flat twin version of my sidevalve .
Its basically a twin version of this one http://www.homemodelenginemachinist.com/showthread.php?t=23909
My original plan was to use simple fork and blade conrods with 2 ball bearings in each.
That would make a total thickness of 10mm vs the single with its one roller at 8mm.
This is no problem on the crankshaft side as I can just make the web 1mm thinner but it gets complicated fitting everything in on the timing side.
Im also a little concerned that the bearings wont take the load as they only have 10 balls (10 x 6 x 2.5 bearings)
After a bit more research today I have come up with an alternative method using a 10 x 8 x 6 roller , same as the single, with a light press fit in the fork rod and have the blade run directly on the outside of the roller casing (with a bronze insert).
My reasoning is that the fork rod then needs to handle more load as its directly connected to the crank and rotating 360 degree but the blade is only rotating a little and carries much less load.
I'm also assuming that the outside of the roller bearing would make a good bearing surface and the large diameter would give a large enough load spread to make up for the narrowness of the blade rod.
I figured that this would give me a better bottom end at the same width as the single and make the design a whole lot easier.
Am I barking up the wrong horse with this.
Should I stick with the original idea.
I will attach a pic of both options and the rod I have machined last night that I will probably just scrap now.
Sorry about the long winded explanation.
I have another engineering dilemma to solve.
I started with the conrods for the flat twin version of my sidevalve .
Its basically a twin version of this one http://www.homemodelenginemachinist.com/showthread.php?t=23909
My original plan was to use simple fork and blade conrods with 2 ball bearings in each.
That would make a total thickness of 10mm vs the single with its one roller at 8mm.
This is no problem on the crankshaft side as I can just make the web 1mm thinner but it gets complicated fitting everything in on the timing side.
Im also a little concerned that the bearings wont take the load as they only have 10 balls (10 x 6 x 2.5 bearings)
After a bit more research today I have come up with an alternative method using a 10 x 8 x 6 roller , same as the single, with a light press fit in the fork rod and have the blade run directly on the outside of the roller casing (with a bronze insert).
My reasoning is that the fork rod then needs to handle more load as its directly connected to the crank and rotating 360 degree but the blade is only rotating a little and carries much less load.
I'm also assuming that the outside of the roller bearing would make a good bearing surface and the large diameter would give a large enough load spread to make up for the narrowness of the blade rod.
I figured that this would give me a better bottom end at the same width as the single and make the design a whole lot easier.
Am I barking up the wrong horse with this.
Should I stick with the original idea.
I will attach a pic of both options and the rod I have machined last night that I will probably just scrap now.
Sorry about the long winded explanation.
