Which Rod End Bearings

[RICK MARTIN]

Hey Guys,

I need a little help. My Bee was built with 1/4" x 28 femle threaded heim bearings which attach to 1/4" x 28 male threaded inserts in my chromoloy control tubes.

I'd like to make new rods and use the conventional system which uses a female insert and a male heim bearing. But the big issue is to go to the larger diameter threads. I'd like to go to at least 5/16" threads.

So I open the catalogs and there they are. but there are many different kinds made from many different alloys. And as you know they are quite expensive. I think it's safe to say that I will stay away from the "Aurora" bearings.

So which ones are the "Standard" type (strong enough without overkill) to use in a control rod application for our gyros? If you want to be really nice, you could even give me the part number for Spruce or Wickes.

Thanks,

[MikeBoyette]

Rick,
Give Dad a call I'm sure he has them in stock. You could use Dave as a delivery man.

[Ron Iaconis]

I have rod ends that are 5/16 threads and use a 1/4 bolt for the ball,,,,,,I see that Bensen called for 3/8 threads,,,,,,,can anyone tell me if I can trust my 5/16 threads ? I got them from Dillsburg , Penn AeroPlaneWorks

[Ron Iaconis]

Originally Posted by MikeBoyette

Rick,
Give Dad a call I'm sure he has them in stock. You could use Dave as a delivery man.

Mike....How can I reach Dick DeGraw?

[Rick Whittridge]

I use the 3/8 with 1/4 hole rod end . I have bought them thru Wicks. The ones you by at the bearing houses are not X-RAY`D . That`s the differance in the prices between the two.

[RICK MARTIN]

Same question as Ron "5/16 or 3/8?". Of course bigger is stronger. But in my light weight application where the 1/4" has been used on the prototype for 12 years without mishap, can I use the 5/16" safely? Yes I know this seems like a silly question.

I just want to know what the standard is for most single place gyros. It seems like it is 5/16".

And more importantly, of the "good" bearings, which type/metals are appropriate.

Mike, you present a good solution to my problem. But.......
The first person I called about this was your dad. In fact I was really busy at the time and I just asked him to build me a set of rods. But when he said he wanted $250.00 for a set, I freaked. And I didn't have the spare cash at the moment. I believe in supporting our builders, suppliers and manufacturers, but I just couldn't bite that bullet when I have a buddy with a machine shop (the inserts are not commercially available) and could get my own rod ends. After checking bearing prices, I'm not so shocked anymore (they have gone up incredibly since I bought my original ones several years ago). So Ernie probably thinks I'm a cheap SOB and I'd rather not bother him with this again.

And of course there is the fact that I do like doing things myself when I can.

[Ron Iaconis]

I have Bensen Plans from 1974,,,,and even updates from more recent years.
In the section for the rod ends, it shows rod ends being 3/8's threads and 1/4 in for the ball end holes. I know that Bensen recommends 3/8 for the threads,,,,But I instead used 5/16,,,,,Now I am having second thoughts and am looking for people that have used 5/16 and get some opinions/advise as to safety concerns. Also has anyone ordered from Dillsburg Aeroplane Works from Pennsylvania? I have and I ordered these rod ends from Dillsburg. Note ,,,,,that I had a ground loop and totaled my machine,,,,and the rod ends( the 5/16's ones) did not show any sign of damage,,,,NONE!!!!!! nor did my joy stick components/rotor parts/,.,,,no damage sustained to any control linkage. Only the rotor bearing developed roughness( which I am replacing) and the 3/16 steel washer under the rotor bearing bolt had " cupped" sllightly.

[RICK MARTIN]

Anyone else have info or an opinion?

[Ron Iaconis]

Rick,
I am just " biting the bullet" so to say and removing my rod end inserts and drilling them out and re-tapping them to 3/8/ X 24 threads to fit the larger rod ends. I will not feel comfortable untill I install the 3/8 shank rod ends, even though I saw that the 5/16 survived a flip over occurance. UpDate: I am re-thinking this whole thing and feeling that after all is said and done,,,I may stay with the 5/16 shaft male threaded rod ends......still will keep an opended thought process for a few more months.

[Alan Coats]

Originally Posted by RICK MARTIN

Hey Guys,

I need a little help. My Bee was built with 1/4" x 28 femle threaded heim bearings which attach to 1/4" x 28 male threaded inserts in my chromoloy control tubes.

I'd like to make new rods and use the conventional system which uses a female insert and a male heim bearing. But the big issue is to go to the larger diameter threads. I'd like to go to at least 5/16" threads.

Thanks,

Rick,

Is there any special reason for the larger size, or are you just being extra careful after the recent incident?

Do you know of any problems people have had with the stock 'Bee arrangement?

Thanks,
Alan

[Ron Iaconis]

OK,,,,I just pulled out my Ralph Taggart Book that he made available to all wanting to download the building instructions for the Gyro Bee. In his drawings I see that he uses 1/4 inch threaded ( female) shaft for the rod ends. In my humble opinion I would think that that is a little under sized for my comfort zone. But I suppose that it's acceptable for a light weight machine. In the past on my Bensen Gyros I have had a 3/8 shaft and sometimes the ball hole was 3/16 and sometimes it was 1/4 and even 5/16 in . So,,,I am sticking my neck out and saying that 5/16 shaft( threaded end) and the 1/4 inch ball end hole should be acceptable. And yes, I believe that we are all zeroing in on the latest accident in Florida.

[Doug Riley]

3/8" shank has been the standard since I started in gyros some 36 years ago. I would be wary of going smaller IF you use an aluminum female insert. I would not use 5/16" to thread into aluminum.

Ernie's pushrod setup is excellent -- not only does he use 1" tubes instead of 3/4" or 7/8", but his inserts have a shoulder that resists loads in the "push" direction without involving the cross-bolt.

Aircraft style rod ends are a superior product compared to the commercial ones and are priced accordingly. The aircraft units are made in three pieces -- the center ball, a bronze insert in which the ball turns, and the outer shank-ring housing. Commercial ones are two-piece: the ball turns directly inside the steel ring.

The aircraft units are rated significantly stronger, although the decent commercial ones are plenty strong as well. There's the remote possibility of a bad weld in the commercial units -- if using them, you might have them magnafluxed first. We used to get this done on Heim brand commercial rod ends for $1.00 each -- none ever failed the test.

A nice side benefit of the aircraft units is that they can be supplied with a hole in the ball of a different diameter than the shank (e.g. 1/4" hole with 3/8" shank), while commercial units normally have the hole the same diameter as the shank. You can bush down a commercial unit with a simple Oilite insert, however.

Even 1/4" rod ends are far, far stronger than the push tubes. I worry more about the ease with which the shanks can be bent. They're trash once that happens. With either size, avoid bumping or yanking on the pushrods sideways, and inspect before each flight to make sure the housing isn't binding on the surrounding arm at any point in its travel. If it does, it'll put a bending load on the shank, which is a bad thing.

[Ron Iaconis]

Doug,
Has the Gyro Bee changed from the 1/4 shank? And what or why do you not recommend that the 5/16 X24 thread " Not " be screwed into an aluminum insert? Is it OK in your opinion to thread a 3/8 shank into an aluminum insert?

[Doug Riley]

Ron, I'm not involved with the Gyrobee anymore, and I never WAS involved in the design part of it. As you may be aware, the 'Bee plans called (perhaps still do call) for FEMALE 1/4" rod ends, screwed onto AN male inserts. The male inserts are made to the usual specs for AN bolts -- 125,000 PSI. These AN inserts secured inside 9/16 x .065 4130 pushrods with AN3 cross bolts. I know of no problems with these. I worry more about their vulnerability to abuse than their strength in normal use.

If you're screwing male rod end shanks into aluminum, that's a different story. 6061-T6 is about a third as strong as AN hardware steel. The worry there would be that the female threads in the aluminum insert would strip out. It would be nice to test them to see what load it would take to strip them out.

[Ron Iaconis]

Well,
I see your point regarding the rod ends( Female) made from AN material and screwein into another AN stud. Yes the rod end( male) made from steel ( not sure of type steel) screwing into aluminum is a different matter. I will have to think this over,,,and then decide if to go to 3/8's from my now 5/16ths rod.
For me it will involve drilling out the 5/16 hole and rethread it to 3/8. We will see.