Wanted. Seat sling brace - spider assembly

[Peter av8]

Seat sling brace - the tube and wire spider assembly thing wanted for BC12D. Complete or incomplete considered. Or accurate drawings?

Pete at [email protected]

[Hank Jarrett]

Re: Wanted. Seat sling brace - spider assembly

Pete,
I have a spider at home now and have checked the dimensions against my two others. It should be pretty simple to make and as for dimensions, well, they must have been to the nearest inch because they are all a little different. The parts are fairly simple and I think it should be pretty easy to build one, but complex as hell to put together! We will definitely need some step by step instructions and photos. Of course I would have had to take it all apart to ship one if I had an extra anyway so no additional labor there. At least we will have a documented process to assemble them on the group here and all the dimensions and materials if anyone needs one. I will post a parts list for materials soon.
One thing I am having a problem with is what the wires are made from. They are NOT high strength steel. Seems like maybe farm fence wire more than anything else. I have dimensions but the diameter isn't even consistent. It appears to be some pretty cheap soft steel wire of three different diameters.
Hank

[Hank Jarrett]

Re: Wanted. Seat sling brace - spider assembly

Got the preliminary sketch done and measurements of the parts. Try to post a materials list in the morning.

Hank

[Hank Jarrett]

Re: Wanted. Seat sling brace - spider assembly

The spider consists of a ½" dia tube, 35" long that is the core of the spider. It sits span wise just below the seat sling between the vertical and horizontal parts of the seat. The front V is .131" dia wire and is ~48" long if straightened. The aft "Vï" is ~.131" dia and about the same length. The end rectangle wires are ~.125" dia and are about 3.75" long. The center rectangle is.125" dia and about 4" long. The end wires are .125ï" dia and about 37" long. The triangles are from .125" wire and are about 10" each for all 4. They have a piece of 3/8" .065 wall tube over them 2.25" long (DON'T FORGET TO PUT THE TUBE ON BEFORE YOU BEND THEM AND BRAZE THE WIRE and put them on the tube before the rectangular wire goes on!)
The aft wire "V" and a forward wire "V" interlock at the center of the tube and are held by the wire box loop that also holds the seat belt triangles (the larger wire goes AFT). The ends of the two"Vs" go outboard to the tabs on the longerons where they are attached with the shackles along with the side wires.
The side wires connect to one front and one rear "V" end with the shackles and wrap around the tube in the center going through the tube end wire box loops that hold the outboard belt triangles. I may need to do a video of how all these pieces knit together!
The side wires and the rear V measures .192" dia and the front measures .131". The rectangular retainers are .125" wire. All of the wires are a fairly low strength steel, almost like welding rod or "farm wire". Easy to bend by hand except in the end loops of the wires. Even the loop in the middle of the end wires can be hand bent around a dowel. The loops appear to be wrapped with fine wire and soldered or are brazed. It does NOT look like weld. The tube has six 1/8" holes drilled in it for the rectangular wire retainers and the wire retainer actually feels like heavy coat hanger wire.
The tube with the triangles and belt rollers go together first with the "coat hanger" wire rectangles. All the rest of the wires can be added after it is all painted. Still messing with the "drawing" (I hesitate to call it a drawing since it is more of a sketch/tracing, but it is good to make one. I will do a GOOD drawing for the archives. I am sure there will be a ton of questions but this will give anyone who wants to make one a place to start and the materials needed. The wire has me stumped. Not sure what it is, but seems very much like old farm fence wire, defiantly NOT something like 4130 steel rod or music wire. When you bend it it feels like welding rod and the diameters are NOT consistent. In fact NONE of the measurements are consistent from one spider to the next. Everything seems to be plus or minus over 1/4".

[senior]

Re: Wanted. Seat sling brace - spider assembly

Interesting, I have a complete unit I did not use in my plane.
I thought it was mismatched as some of the individual piece lengths & thicknesses were different.

[Hank Jarrett]

Re: Wanted. Seat sling brace - spider assembly

The big "V" wire goes in back since it gets the tension load in an "arrival". The wires that go forward are to keep the cross tube located with the side wires. All four transfer the seat belt loads into the lower longerons.
If I was building one from scratch I think I would probably go with the closest size wire I could find since it looks to me like the welds or braze on the loops are the weak point. The rear "V" is just pushed a little through the center rectangle but the front wire has to be pinched together and slid through loop ends first so it needs to be bent for assembly. I don't think the big rear wire will bend enough to go with all larger wire.
I looked at several spiders and all of them are a little different with different lengths of wire and non-symmetric pieces. It is NOT a precision part!

Hank

[Hank Jarrett]

Re: Wanted. Seat sling brace - spider assembly

If anyone is trying to make one I still have the one I was sketching on the dining room table. I will be taking it back to the airport for storage soon, so if you need any more dimensions, let me know. I "think" one could be built from the sketch, but I haven't tried it.

Hank

[Ragwing nut]

Re: Wanted. Seat sling brace - spider assembly

I have a couple available if anyone still needs one.

[Peter av8]

Re: Wanted. Seat sling brace - spider assembly

Thank you Hank. Your time and effort - and the info is very much apprecoated. All the best, Pete

[Peter av8]

Re: Wanted. Seat sling brace - spider assembly

Are you able to send one to the UK? Obviously all pre-paid from this end. Cheers, Pete

[Hank Jarrett]

Re: Wanted. Seat sling brace - spider assembly

I think the cost to ship one (even a fairly short distance) would be ridiculous. It weighs next to nothing, but assembled it would take a really big box and even taken apart it isn't small and is a BEAR to put together if you don't have an example available.
If you make the parts you can be talked through the assembly with some photos. The parts are not complicated. The assembly just is. The wires lace through each other and are easy to get wrong.
Did anyone ever figure out what the wires are made from? CERTAINLY not a 4000 series steel or music wire. When you bend it, it feels like fairly soft farm fence wire. The tube is 4130 and the loops are almost like coat hangar wire and I suspect they are just welding rod.

Hank

[Ragwing nut]

Re: Wanted. Seat sling brace - spider assembly

I could send one to the UK, but shipping would be more than the cost of the part.

[Peter av8]

Re: Wanted. Seat sling brace - spider assembly

Thanks Hank - food for thought for sure. Cheers, Pete

[Peter av8]

Re: Wanted. Seat sling brace - spider assembly

Many thanks, and I guess you're right. I'll have to give it a lot of thought. Pete

[Hank Jarrett]

Re: Wanted. Seat sling brace - spider assembly

Honest guys, this thing would NOT be hard to make, just complex to assemble right. I am sure I could put together a series of photos to show the right sequence.

Hank