Aileron bellcrank - tips?

[samiam]

Have been mulling over the bellcrank plans for the past day or so and gathering all of my parts. Before drilling any metal, I was wondering if anyone had any tips on these important assemblies. A couple of thoughts:

-Are the holes okay to be enlarged with a regular 3/16" bit in a drill press, or will that lead to any bolt slop? Is a reamer necessary?
-Any tips on how to cut phenolic block? Just outline and band-saw away?

Any other tips would be appreciated.

[Rick524]

Its been a few years since I built my bellcranks, but I do remember drilling the final holes
with a metric bit. The size escapes me now but its an option if you are having trouble getting
the holes just right. The plans used to suggest using paper for shims. I used aluminum pie plate
to cut my shims from. Its about .005 thick and seems more durable than using paper. Aluminum
foil is another option. Just a couple of tips I used...good luck with your project!

Rick
Sonex 524

[samiam]

Thanks Rick - that was one of my questions as well - by paper shims, do they LITERALLY mean paper?

[kevinh]

I just used a bandsaw and it worked great (a little cleanup on a belt sander). I can't remember if I used a reamer or not - you can test on some scrap because there is plenty left over on that piece. I used paper for my shims and it worked fine, but aluminum foil does sound smart. I didn't need much - I think two sheets of office paper.

[Bryan Cotton]

Mike,
I think they meant paper. I can't remember if I needed shims or not, but mine were going to be made out of aluminum flashing style of paper. It is 0.010" thick.

For the pivot bolt, I used a 3/16" bit. Remember the bolt squeezes the bushings to the bellcrank and if you nicely line bore your bronze bushings that will be a low friction joint and the bolted connection won't spin. For the rod end bearings, again, you are clamping the ball to the horn. The eye of the rod end spins around the ball. You are not relying on the friction of the bolt to keep it from spinning, but the clampup. The holes should still be nice and snug to transfer the loads but you should not need a 1 ton press to get them in and out.

Also as Kevin says mark that phenolic and bandsaw away. I finished it up on the belt sander.

[Darick]

Mike,
We (at my former employer Garrod Hydraulics, Inc) used shim stock frequently. As I recall, the three most common materials were steel, plastic, and vegetable fiber which was just often referred to as paper. All types were available in thicknesses from .001 to .015".
McMaster Carr has a great online catalog with lots of general information included at the heading of many of their items. It's a great reference.

[samiam]

I'm back - more issues with making my bellcranks, hoping that someone can help out.

I have the angles, and have pressed the brass collar into the 7/16" hole. However, after pressing it into the hole, it no longer easily takes the steel bushing to allow it to freely rotate. I am sure pressing the piece in distorts the hole just enough to interfere. I'm just not sure what to do about it.

I went so far as to order new brass collars from ACS and just tried again, but still no luck. I even tried re-drilling the collar after pressing it to 5/16" for the steel bushing, but it still does not fit nicely.

Anyone?

[kevinh]

After pressing the collar in and making the full assembly I ran a reamer through so that the steel bushing can rotate without play. I actually had to run the bushing up an down the reamer a fair amount to remove enough material...

[kevinh]

btw - the bolt that is called out to join that bracket is too short (or you can go washerless) ;-). (This old pict reminded me)

[Bryan Cotton]

Excellent picture Kevin. Mike, it shows what I did not articulate well before- you need to line bore through both bushings so the holes line up. Reamers make nice round holes though I think I used a drill to do mine.