Author Topic: Metal Bellcrank (Read 4649 times)

Motorman · « **on:** February 16, 2015, 01:37:01 PM »

How do you attach flexible lead out cable to an aluminum bellcrank (Fox 3") so it's dependable for years to come?

Thanks,
MM

FLOYD CARTER · « **Reply #1 on:** February 16, 2015, 01:49:07 PM »

Treat the metal bellcrank just the same as a plastic one. Use small diameter alum. or brass tubing bent into a "U", and this goes over the cable at the bellcrank. You have to drill out the bellcrank a bit for the extra diameter of the tubing.

Floyd

bill bischoff · « **Reply #2 on:** February 16, 2015, 04:18:45 PM »

What's the application? If you want super bulletproof, stack two bellcranks, bolt a ball link in between for the pushrod, build the leadouts with eyelets, and capture them on posts between the bellcranks. You'll also need a spacer between the two bellcrank bushings. If you make your own eyelets and posts, you can make the diameter plenty big for increased bearing area. If you really love overkill, put everything on ball bearings!

Robert Zambelli · « **Reply #3 on:** February 16, 2015, 07:12:50 PM »

This is what I use - simple and efficient.

Bob Z.

Bill Little · « **Reply #4 on:** February 16, 2015, 07:17:14 PM »

We used to bush the holes with brass tubing. Peen over the ends of the tubing. Then I learned about the "u" shaped tubing around the wire. I have done both sometimes!

If I decide to use some metal BCs I will do the "double" system.

BIG Bear
RNMM/AMM

Avaiojet · « **Reply #5 on:** February 17, 2015, 05:34:08 AM »

Laminated Bellcranks since 1962! Talked about it and Posted photos many times in my builds. Glad it's catching on.

I'm still using this setup on ALL my current models. SS bolts as end posts for eyelets. I place the ball link on top.

Same setup in my full blown stunt ship almost ready for paint.

Motorman · « **Reply #6 on:** February 17, 2015, 11:44:39 AM »

Didn't want to go double but kinda worried about metal to metal with the brass tubing system. With 2 bellcranks how do you tighten the bolts, is there a spacer inside the eyelet?

john e. holliday · « **Reply #7 on:** February 17, 2015, 11:50:13 AM »

So far I have not wore out a metal bell crank like the Fox ones using brass tubing that has been run through a torch to anneal it. At one time I could get little eye lets to bush the bell cranks with. Can't find them any more so that is why I use tubing. It also holds the cable so it can be wrapped or swagged.

Bill Little · « **Reply #8 on:** February 17, 2015, 02:23:45 PM »

A lot of the early Brodak kits had metal BCs. I let my son build a Fancy Pants by the plans for a product review in Stunt News. He flew the heck out of that plane for a couple years when the lead out finally broke. Inside loops until it finally hit on the LG. Tore out one gear and was a pretty easy fix. Brodak going with nylon BCs later was a major upgrade if building by the plans. A newbie might not know to bush the BC or lead outs.

BIG Bear
RNMM/AMM

Motorman · « **Reply #9 on:** February 20, 2015, 09:37:43 PM »

Was the Brodak bellcrank bushed with tubing or cable wrapped right on the bellcrank?

MM

Bill Little · « **Reply #10 on:** February 20, 2015, 10:22:01 PM »

Quote from: Motorman on February 20, 2015, 09:37:43 PM

Was the Brodak bellcrank bushed with tubing or cable wrapped right on the bellcrank?

MM

Hi Walt,

No bushing anywhere. Bare cable on bare metal. Lasted about 1 1/2 years and the cable broke at the BC. The purpose was to build the model directly by the plans as a "newbie" would. So we did.

BIG Bear
RNMM/AMM

Brett Buck · « **Reply #11 on:** February 21, 2015, 01:06:33 AM »

Quote from: Bill Little on February 20, 2015, 10:22:01 PM

Hi Walt,

No bushing anywhere. Bare cable on bare metal. Lasted about 1 1/2 years and the cable broke at the BC. The purpose was to build the model directly by the plans as a "newbie" would. So we did.

  Thats way better than the ARF Noblers managed.

   I have seen many failures of the "cable through tube" system, too, unfortunately. That's why I came up with the trick bellcrank - not to save weight, not to be stiffer, but to keep the cable alive longer.

   Brett

Dick Pacini · « **Reply #12 on:** February 21, 2015, 08:31:03 AM »

Quote from: Brett Buck on February 21, 2015, 01:06:33 AM

Thats way better than the ARF Noblers did managed.

I have seen many failures of the "cable through tube" system, too, unfortunately. That's why I came up with the trick bellcrank - not to save weight, not to be stiffer, but to keep the cable alive longer.

Brett

Pix?

DanielGelinas · « **Reply #13 on:** February 21, 2015, 08:47:13 AM »

Guys,
Forty years ago nylon bellcranks were already known as a superior replacement for the old metal bellcranks. Today we have even better bellcrank setups.
Could someone let me know why bother using a metal one today?
I'm surely missing something here

-Dan

goozgog · « **Reply #14 on:** February 21, 2015, 10:20:22 AM »

Funny thing you should mention it.
The pictures show what I was working on
today down in the Saturday morning Fun Pit.

This is a 4" unit with a ball bearing center
and brass sleeved lead out terminals.
Without the wires and push rod ball joint,
it weighs 1.0 oz/30 gms.

This is the third one I've made like this
and they pull test to 100 pounds,. No problem.
Previously I made three ball bearing units
but the ones on the lead outs were unnecessary.

I'm reluctant to use a plastic bell crank in a
modern plane. They were OK back when we were
flying Fox .35's and a big engine was a .46.
This unit is going in a plane powered by a
piped Ro-Jett .65.
Flying a plane that big in strong winds really
gets me thinking about the strength of my system!

Cheers!

Brett Buck · « **Reply #15 on:** February 21, 2015, 11:12:20 AM »

Quote from: Dick Pacini on February 21, 2015, 08:31:03 AM

Pix?

http://stunthanger.com/smf/index.php/topic,35062.msg356531.html#msg356531

Brett

peabody · « **Reply #16 on:** February 21, 2015, 11:49:40 AM »

Windy's "Tradition" had over 3000 flights on it.....the 4" Delrin bellcrank with 1/16" solid steel lead outs did not fail.
He rebushed the flap horn once and the elevator twice.
"Plastics, Mrs. Robinson"

Clint Ormosen · « **Reply #17 on:** February 21, 2015, 01:13:26 PM »

Quote from: DanielGelinas on February 21, 2015, 08:47:13 AM

Guys,
Forty years ago nylon bellcranks were already known as a superior replacement for the old metal bellcranks. Today we have even better bellcrank setups.
Could someone let me know why bother using a metal one today?
I'm surely missing something here

-Dan

Dan, I always wonder the same thing. I guess some people are just set in their ways. Makes no sense to me. You take the time to build a nice model and then tempt fate by putting in an inferior bellcrank? Whatever.

Motorman · « **Reply #18 on:** February 21, 2015, 03:55:58 PM »

Quote from: DanielGelinas on February 21, 2015, 08:47:13 AM

Guys,
Forty years ago nylon bellcranks were already known as a superior replacement for the old metal bellcranks. Today we have even better bellcrank setups.
Could someone let me know why bother using a metal one today?
I'm surely missing something here

It's for rat race, plastic parts will melt down to nothingness.

MM

DanielGelinas · « **Reply #19 on:** February 23, 2015, 01:48:54 PM »

Thanks for educating me.
I know nothing about rat racing😳😳
Regards
Dan

Andrew Hathaway · « **Reply #20 on:** February 23, 2015, 03:45:03 PM »

It can be difficult to fit a nylon bellcrank in a wing built for a aluminum bellcrank, because the nylon parts are thicker. Usually if things are tight, the bellcrank support needs to be dropped down in the wing. When working on a plane that someone else built 30 years ago, that means lots of cutting and replacing the bellcrank mount. Most of the time that's what I do in those cases, but I've got one or two recent planes that ended up with a Fox or Veco crank because it was the only thing that would fit without destroying the model. But these are also sport planes with 35s that aren't going to be flown thousands of flights.

Ara Dedekian · « **Reply #21 on:** February 24, 2015, 07:50:30 AM »

Quote from: Brett Buck on February 21, 2015, 01:06:33 AM

Thats way better than the ARF Noblers did managed.

I have seen many failures of the "cable through tube" system, too, unfortunately. That's why I came up with the trick bellcrank - not to save weight, not to be stiffer, but to keep the cable alive longer.

Brett

I'm stuck in the build of a Twister wing. Installation of the control system is next and all the choices available have me agonizing over which system to use. The temptation to use all the great info on this forum and go for a cutting edge, state of the art system is tough to resist, but I'm essentially a Bi-Slob/Ringmaster-sport/stunt flyer.

A laminated crank makes the most sense, but that means I have to fabricate it out in the garage which is running about 8 degrees F. these days. I'll use the plastic(?) Sig bellcrank so the U shaped tubes seem unnecessary. Metal cable through radiused plastic(?) holes, packed with grease, seems to me to accomplish what we're after, the reduction of friction and wear.

So Brett's observation of cable through tube failures is really welcome news. I'll just slap the Sig 'crank in place, wrap the cables onto it and get on with it!

Ara

This is my first jig built wing. Should have paid attention to the technigue a lot sooner. My wife allowing me use her countertop made it work!

Ara Dedekian · « **Reply #22 on:** February 24, 2015, 07:58:50 AM »

Correct Photo

Ara

Andrew Hathaway · « **Reply #23 on:** February 24, 2015, 01:26:20 PM »

The Sig bellcrank is fine, and the bare leadouts through the bellcrank will probably last a long time. But why not run a piece of brass tubing over the leadout through the bellcrank? It costs virtually nothing and is a worthwhile upgrade. Besides, after bending the tubing into a teardrop shape, it holds the leadouts in position while you wrap them, and gives you something to hold onto while wrapping the copper wire.