"Peanut Butter & Jelly" Swapable Firewalls

by Fly'n-V | December 27, 2013 | (13) Posted in Tips

Has this happened to you?

Gust of wind...or maybe just "plane" bad luck...

Heaven forbid it wasn't the old flying skills just aren't perfected yet, like my case.  LOL!

I used to cut and drill my own firewalls for the swappables but I love the FT design and you really can't beat the price (IMHO) for time saved when building.   The only issue I've had with laser cut firewalls is that they tend to snap off at the top on those less than perfect landings or dirt naps.  Also, they are a bit thin for those "beefier" motors...

I decided to try laminating two of the prefab firewalls with some CA and I have to say...It works great!

(BTW: I don't work for or get a kickback from FT if they sell twice as many prefab firewalls...LOL)  Although, i would like to see them sold in an even number pack (4 or 6) for this purpose.    Back to the tip....

I lay two firewalls out like sandwich bread...mirrored.

Then add the CA around the perimeter and center like this...

Then fold over the "bread" and clamp...

I love these little Quick Grip clamps...Nope, I dont work for Irwin either...

After clamping, I put a thin bead of CA around the edges like this...

Let the CA cure for a few minutes..per the manufacturer's specs and then remove clamps.  I usually let them cure at least an hour after removing clamps.

The PB&J firewall is pretty tough (haven't broken one yet) and gives a bit more wood for the screws to bite into for those "beefier" motors.

 Half inch screws get all the way through and protrude a bit but I just give them a blob of hot glue on the sharp ends.

 

Hopefully this helps someone....and as always, Thanks to the FliteTest crew for all you do to make this hobby a fun and affordable experience!   Sr12

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COMMENTS

solarflash on January 9, 2014
I've done pretty much the same thing using 5 minute epoxy. The only other step I take is putting small dents into the plywood with a small nail or punch to give the ply some tooth for the epoxy to set into. I use this method when putting a plywood doubler on the sides of a balsa profile fuse.Never had a doubler come unglued.
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mark d on January 7, 2014
Hey they have a new deal for an even number of firewalls... 10 for $10 :P
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tophe75 on January 7, 2014
If you (like me) own a 3D printer there is a lot of FT parts on thingivers, I have made a collection: http://www.thingiverse.com/tophe75/collections/ft-parts

Enjoy.
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sailorJohn on January 10, 2014
Don't have a 3d printer I cut them out with a jig or hacksaw then drill the round holes with a forstner drill bit for clean half inch holes ( I have a small drill press).
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Fly'n-V on January 11, 2014
What kind of materials are you using? I've used various thickness light ply and use to cut my own off of the FT template, in fact I added the pass through hole for motor wires before their "new" firewall came out...lol. I just started ordering and doubling theirs since time was a factor for me.
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alibopo on January 7, 2014
This is a good solution for a thinner ply firewall. I use 6mm (1/4 in.) MDF - medium density fibreboard - for my swappable pod firewalls. (It's made from reconstituted wood - a bit like chipboard, but much, much finer structure.) MDF is softer than ply but has no grain, so no linear weakness. It cuts and sands fairly easily but can be a bit vulnerable to damp. A coat of CA or varnish along the edges works wonders, strengthening and waterproofing. I find Ply a nuisance to cut and drill due to splintering (I can be a bit of a bodger at times), but MDF is easy to work, 'strong enough' and hasn't let me down yet.
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Fly'n-V on January 10, 2014
Great point on turning the firewall 90 degrees....I've ordered two separate packs of just firewalls at different times and some of the swappable kits with firewall included...they are all cut in the same bias of the ply. For you guys with 3D printers...I'd love to try a couple of them...let me know if there's a way to trade or purchase. (Firewall that is...not ready for 3D printer investment...LOL)
Thanks all for some good points made and info exchange! Sr12
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pintokitkat on January 7, 2014
I tended to break the skewers and not the firewall, but then I print my own firewalls and use carbon fibre rods to replace the skewers. I have put the .stl file for the firewall on Thingiverse - http://www.thingiverse.com/thing:221202
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wolfpackt99 on January 7, 2014
*wants 3d printer*. What printer do you have?
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thejosh108 on January 8, 2014
I have done the same thing only with hot glue, but don't be afraid to cut and drill your own, you can use 1/8" or 1/4" hobby ply for the same effect.
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sailorJohn on January 9, 2014
Just was out in the freezing garage drilling new firewalls and I noticed that 3 ply plywood is stronger in one direction because the outer plys.
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sailorJohn on January 9, 2014
From the picture it appears that it would be stronger to turn the ply 90 degrees.
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alibopo on January 10, 2014
VERY good point - well observed. Someone should get a quick word to Josh to get them to cut future FT firewalls with two vertical ply layers and the single horizontal layer - instead of the other way round, which is clearly more vulnerable. Maybe it's a random thing, or are they all cut this way? I've always made my own so I don't know...
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"Peanut Butter & Jelly" Swapable Firewalls