Bell Crank Idea

[LushPyle]

New Bellcrank.pdf

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Here is a bell crank design I did that is obviously based on the Blanton design. I was trying to find a way to allow for crossing pull rods and still keep the adjust-ability. I found this to be a real challenge and I'm still not 100% convinced but I am reasonably happy with the design and I wanted to get some other takes on it. The captive threaded standoffs are based on one I found on the McMaster-Carr site.

[Bent]

LushPyle,
Aside from that one inherent problem, the Blanton style bell crank is top-notch. I talked with Jerry Blanton about those cranks and he said you will just have to do some rod-bending to make everything fit. That is just the nature of the beast I guess. Not a big deal. Other builders bend rods using "normal" bell cranks anyway.
Jerry says he not only tunes his pedals but also times them with this crank. Imagine the limitless adjustment possibilities we would have with having regular tuning at the end plate PLUS tuning/timing at the crank. If we want to apply those cranks to our ideas, maybe we should just put up with that one weakness and start bending rods!

[Bent]

LushPyle,Is the up and down adjustment accomplished with the standoff and screw?

[LushPyle]

Yes it is. The pull could located anywhere along the length of the slot. And you are right about bending the pull rods with the Blanton bell crank and of course he used them for tuning the pulls as well which is a concept I have never really warmed to although I am sure it works well enough. I was trying to come up with a design that would give the range of adjustment without having to bend rods.

[richard37066]

LushPyle -

Congrats! Seems like it would work just fine. If I had any criticism/suggestion at all it would be that you increase the diameter of the "threaded standoff". If I assume that the drawing is to scale, then there would be a tendency to try to pull the standoff through the slot (it's diameter appears to be only marginally greater than the width of the slot) thus spreading the width of the slot and tending to ruin the simplicity of adjustment. Attendant to that is the possibility of distorting the "collar" portion of the standoff. You've got plenty of wiggle room in the design of the standoff and the link to the rod. Having to increase the diameter of the hole in the link should still leave enough "meat" so as to not cause any concern regarding strength.

My interest in this is that I, too, am working on a version of the Blanton. I'm attempting to design something whose width is that of the spacing (width) of the changer fingers thus affording the opportunity to "stack" two bellcranks side-by-side for adjacent pulls - should that be desirable. It's a challenge. It is now in very good sketch form - and quite elegant. So elegant that someone like Bent would scream bloody murder at having to mill the constituent parts! There's gotta be a better way.

Back to the drawing board.

Richard

[Steel Freak]

Bent can you show us some Blanton bellcrank pictures please? I have never seen them up-close but heard a lot of good things about them. I am unsure about what type I will be using on my project and these might be an option.

Pat

[ljs]

I got this picture from the SGF a while back.

8764_blanton bell_crank1.jpg (6.08 KiB) Viewed 2243 times

LaVern

[Steel Freak]

Thank you so much Lavern and that must be the best looking bellcrank I have ever seen. I wish I had all the tools and the skills to produce something like that. It sure would look pretty nice under my to be steel.

Rhodes

[ljs]

Glad to help.
LaVern