Thorp Air Command - T18.net

Has anyone made their own 9/16" pins per the drawing 231 ?
What procedure did you use to harden the pins?
Did you Cad plate?
I thought I saw a Quick pins number listed somewhere.

I have some Avibank 17984-916 pins and AN9 bolts that I test fitted to my reamer with good results. (Reamed a test block)

Any feedback is appreciated.

Thanks,
Bob MO

Years ago while building my S-18, I had a machime shop make some out of titanium, don't know what happened to them. I bought from Phil Tucker a set of his pins that were cad plated. Since I've only folded my wing twice in 17 years I have installed AN9 bolts. It takes 10 minutes to take the wings off for transport.

*** admin posted for William Williams ***

_________________
Forum Administrator

Bob,
I started out making the folding wings, then reverted back to the originals, after building spars, fittings, etc. I did make my own pins, 30+ years ago. I was corresponding with Lu Sunderland quite a bit at that time, & I got the wild (stupid?) idea to make mine out of stainless steel. I made them out of 431 stainless, had them heat treated to 195,000 psi, and then ground to dimension. I figured I'd lightly lube them, and no plating necessary. Lu thought they were just fine. A lot of screwing around for some simple pins, when I'd probably have ended up just bolting everything together like a lot of the guys do. If you make them out of 4130 chrome-moly, you heat treat to 150,000 psi, and cad plate.

John Evens N71JE
Arvada, CO

_________________
John Evens
Arvada, Colorado
T-18 N71JE (sold)
Kitfox 7 SS N27JE

Bob: There is a number listed for the rear spar "Quick Release" pins on a drawing, I'll look for the drawing # in the AM. Good luck finding "that" pin. I've spent many hours researching the plans called for pin and could not find it. There are outfits that can "Special Order" the pin, but I imagine the cost would be "Special Order" also. I found some double acting pins (surplus and I think I got the last 4) that are slightly longer than the plans pins and so far they are working just fine. Let me get the number off them.

RB

Thanks for the positive response's. I spent 2hours searching for the avdell or avibank or avi??? Numbers. Rich, your probably right. They were probably for the rear spar.
The pins are made from 4340 and I want to play with my new lathe, if I can get the specs for the tailspring. I think they are made from the same. ACSpruce has the 150,000 temp listed, but I was hoping for:
Heat cherry red and quench, heat to 325degrees and bake for 3 hours or something along that process.
I will probably make several pins and have them plated.
I did not know what was being used and thought I would ask.
I do have some extra 5/16, 3/8 & 9/16 Avibank Ball-lock pins if anyone is interested.
Thanks,
BobMO

Bob: Drawing #102R MS 17999C404. I spent weeks looking for them and finally came to the conclusion they were "surplus" and available at the time. Even sent a copy of the drawing to B & B Surplus (think it is B & B) in Kansas and he didn't have them. The A/C is at the airport and I keep the spare rear pins with the A/C, including spare mains pins. I'll get the number for the rear pins I used tom. AM. They are slightly longer and I believe they are "off the shelf" available. I also devised a way to easily insert and remove them. I'll take a pic of my Inserto tool (patent pending).

RB

Bob,
I assumed you were talking about the main pins (9/16"), & that appears to be the case. I don't know how the other pins came up. If you machine your own out of 4130, I would highly recommend having them heat treated by someone who does precision/mil-spec heat treating. This isn't something that you want to do yourself, unless you have a very accurate oven, possibly with inert gas atmosphere, etc. Also, when they are plated, make sure the shop knows how to properly bake them for hydrogen embrittlement, and does it within the accepted time period after plating - again, a shop that does aircraft-spec stuff. Are you sure you don't just want to buy a set from Mike Archer (if available)?... the voice of experience. Some may disagree.

John Evens N71JE
Arvada, CO

_________________
John Evens
Arvada, Colorado
T-18 N71JE (sold)
Kitfox 7 SS N27JE

John & Rich,

You are both correct. I was just wanting to see what others have done. I

Thanks

Bob: Here be the number for the pins I use on the rear spar.

Avdel NAS 1354DS7S05 Push/Pull BLS4R05D. Pretty sure I copied the numbers right ? You might be able to get them off E-Bay ? Although some knuckleheads charge WAY too much for even one ! Try that place in Kansas...B & B Surplus ?

Got another 2.0 today on NX115RX. Re-rigged one aileron, big difference. Shortened the links on the servo tabs...big difference. Not so HEAVY on the controls ! [;)] If I didn't have the "eyeball vents" in the dash, it would have been brutal. 90 + here the last 2 days. [}:)] 15.0 hours to date and other than the rig problems, no problems. Using almost no oil at this point...a good thing. [:D]

Faster and Farther

RB
NX115RX

Hey guys,

Seems it's been a while since pins for folding wings has been a subject. I checked with Mike Archer just a week or so ago and he's out. Thought I'd ask first if anyone has a set (#231) to sell before I go to make my own. And here's a curious thing: I can't figure out what the narrow finger is for on the lock that holds it in place (same drawing). Really thought I'd be flying in by now to some of the events this summer, but work gets in the way. Anyway, it won't be long!

Thanks, Les Krumel,
Albuquerque

Hi Les, I must have got the last set he had. After they arrived I checked the holes - yup bolt size. I kept them instead of sending them back.

Get with me and I'll get them coming your way.

Terry
850-974-5608 cell

Les,
If you note the side view of the 231L-1 lock, there is a small bend at the end of the narrow finger. Also note drawing 230L shows the -1 lock installed with mating #12 holes in the 215 fitting that match the end of the narrow finger. I would say that it is a "locking" method to keep the -1 lock in place. That said, my aircraft does not have the narrow finger on the -1 lock or the #12 holes in the 215 fitting and this wing was installed on the aircraft in 1978.

_________________
Bruce Finney
N18JF T-18C #262
Yelm, WA USA

Guys,

How about using hardened and nitrided "ejector pins"? They are common in the injection molding industry and come in 1/64" diameter increments and start ar 6" in length.

Jim Mantyla

I got all my folding wing parts from CSA . My -1 lock does not have the "little finger ? " I am saving my "Big Finger" for future political events ! The -1 lock is held in place by the gap cover .

RB

Bob - Just throwing this idea out there: If it's not too late, consider AN386 tapered pins, or a custom version if necessary. http://www.aircraftspruce.com/catalog/h ... perpin.php

The main feature of this type of pin is the threaded portion at the small end. The advantage is that you can draw the pin snug into the tapered hole... thus always eliminating play. The pin is retained by the nut. Note that there are special washers for AN386 pins.)

This method has been used on many types of glider wings with great reliability. Gliders are typically assembled and dissassembled every flying day, and wear is simply not a problem.

Of course, do the reasearch to make sure the AN pins are equivelent in shear strength.

D