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-   -   Firewall pass-thru (http://www.vansairforce.com/community/showthread.php?t=179490)

Mich48041 02-13-2020 08:40 AM

How about using a "conduit bushed nipple" available at hardware stores.
A google search will show pictures.

Brdog42 02-13-2020 09:16 AM

Quote:

Originally Posted by Mich48041 (Post 1407603)
How about using a "conduit bushed nipple" available at hardware stores.
A google search will show pictures.

Joe,
I was just looking at those yesterday. I don’t know what I don’t know, yes? I couldn’t find any made of steele. Either by description or magnet. I know my magnet works as now my ATM card doesn’t. Most of the items were listed either as zinc or galvanized. Is it solid zinc, or coated in zinc. Zinc melts around 790’F. So, if solid zinc, it’s not durable enough. Then the galvanized stuff can gas off nasty stuff. So why not avoid that entirely? The zinc part was only $.99, so I may pick one up today and put it through my friends torch to see what happens.

BTW, my Cessna 150 was built with a galvanized firewall and had a sound blanket on the back side/interior of the firewall. Plastic coated with what looked like fiberglass sandwiched between the plastic. Replacement firewalls are stainless steel. But how many 150s have an engine fire? Although, I think I was close. When I added a JPI fuel flow meter... I found the great looking fire sleeved fuel hose was extremely brittle. With very little handling, it leaked 100LL all over. Glad I added a ff transducer, new fuel line and avoided a time bomb.

Edit: stupid me. If it is solid zinc or coated, it doesn’t matter. It’s the zinc which gasses off on galvanized steel which is nasty. So, I’ll avoid either. YMMV. Tim

Brdog42 02-13-2020 09:29 AM

Thanks
 
Dan, thanks for answering my question. Thanks to all for posting experiences.

I’m rebuilding an -6A. A solid build but no Bronze Lindy. Flown, but sat in a back corner of a hangar for 15 years. I ran into the “Layers of an onion” thing. “While the wings are off and the tail is off and the engine is off, etc. I might as well get that fixed/changed/uncomplicated...”

The de-construction stopped in December. The new Vans -A engine mount and nose gear are on. I have a slick firewall. So this is a timely thread. Going the fiberfrax / SS foil route, as well.

Again,a big thanks to all those who’ve tested & shared knowledge on firewall forward.

Ron RV8 02-13-2020 10:07 AM

I used a couple of these I had without the set-screw... I reversed the nut and added fire-sleeve. Used for wiring and engine controls.

https://encrypted-tbn0.gstatic.com/i...2n9DFwl6xFCM8m

For bowden cable I drilled a couple of 3/8" hardware store bolts...

~600+ hrs... so far so good...

WingsOnWheels 02-13-2020 11:33 AM

Many of the home-depot conduit parts are zinc, so no good at all for this application. If you find them in steel, they should work well enough.

I made my own, 4130 tube welded to a base plate. The wires are wrapped with firesleeve tight enough that it is a job to get the sleeve inside the conduit. Then another firesleeve is on the outside of the conduit. a hose clamp holds it on the conduit and a stainless band clamp to the bundle.


jrs14855 02-13-2020 07:22 PM

Conduit
 
Non RV. I made my own same as Colin P but all stainless. Stainless machine screws and stainless all metal nuts to attach to firewall. In my opinion the long portion should be forward of the firewall and at least 1" long.
Several years ago these were available from the same source as the all stainless cabin heat boxes but I haven't seen them for a long time.

Sam_B 02-14-2020 05:44 AM

Thanks
 
Thanks everyone for their input, I appreciate it. I’ll get to work on fabricating something this weekend

PhatRV 02-14-2020 07:12 AM



I found this on McMaster. This version is all steel and not the galvanized stuff.

Sam_B 05-16-2020 08:32 AM

Another quick question
 
Perhaps this is evidence as to how slow I work, but I originally asked the question about 3 months ago and am finally getting to this. Now that I have a better idea where the wires, cables, and hoses will go, do I need to put firesleeve inside the pass through to protect the wires from the stainless pass throughs, or will the fire barrier seal adequately protect the tefzel insulation from the stainless on the ID of the pass through and limit wire to pass thru relative movement (and thus, abrasion of the insulation). Just wondering how big to bore the inside diameter, assuming smallest hole to accommodate the hardware going through it is best.

Comments from the brain trust?

Thanks


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