Well bugger, I busted a backplate.
07-19-2012, 05:17 PM
#1
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Well bugger, I busted a backplate.
It had to happen sooner or later I guess. I'd been flying my pee wee powered roaring 20 around having a grand old giggle when after fitting a new reed in it the engine would run for about 30 seconds and die. I got tired of that kind of malarkey and hung the plane up for a while.
I finally got around to looking at the engine, and sure enough, when I pressurised the tank, one of the bottom screw recesses was leaking. I opened it back up and the pot metal has split as the pot metal backplates are wont to do.
Is there any way to fix this? Cox international doesn't have any 020 backplates, so am I screwed?
I finally got around to looking at the engine, and sure enough, when I pressurised the tank, one of the bottom screw recesses was leaking. I opened it back up and the pot metal has split as the pot metal backplates are wont to do.
Is there any way to fix this? Cox international doesn't have any 020 backplates, so am I screwed?
07-19-2012, 06:19 PM
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RE: Well bugger, I busted a backplate.
Clean it very well and carefully.
All the oil needs to be removed.
Soap and water.
Maybe compressed air.
Make sure all is dry.
Mix the JB Weld.
Heat the backplate a tad with a heat gun / hair dryer.
Heat the JB a bit so it will flow into the crack.
Put it on the crack with a sharpened match stick.
If you have a loupe or magnifying glass, use it to see how you are doing.
If need be, use the heat again to flow the JB into the crack.
After the JB has cooled a tiny bit, build up a little fillet over the injury, if that is possible.
Put the wonderfully repaired piece aside in a warm, benign place and don't bother it for 12 hours.
All the oil needs to be removed.
Soap and water.
Maybe compressed air.
Make sure all is dry.
Mix the JB Weld.
Heat the backplate a tad with a heat gun / hair dryer.
Heat the JB a bit so it will flow into the crack.
Put it on the crack with a sharpened match stick.
If you have a loupe or magnifying glass, use it to see how you are doing.
If need be, use the heat again to flow the JB into the crack.
After the JB has cooled a tiny bit, build up a little fillet over the injury, if that is possible.
Put the wonderfully repaired piece aside in a warm, benign place and don't bother it for 12 hours.
07-20-2012, 10:43 PM
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RE: Well bugger, I busted a backplate.
Keep an eye on Ebay for the yellow nylon helicopter version backplate-sometimes they come with attached (very small!) clear plastic rectangular tank. This mount fits straight into the Pee wee crankcase and contains the reed housing, air intake and needle. The main thing is they can convert a broken Pee Wee back into a Pee Wee sized 'product' engine-requiring an external tank. The circular mounting flange can be trimmed back a bit for aero use and drilled to match the Pee Wee tank backplate spacing.
ChrisM
'ffkiwi'
ChrisM
'ffkiwi'
07-23-2012, 07:31 AM
#9
RE: Well bugger, I busted a backplate.
I would do the Ebay thing too. If you want to fix it, a countersink from the back side of the backplate, and then a matching boss that would come in from the back would work. It could be JB welded in. Of course you would need a lathe. A flush rivet kind of thing. As was mentioned before, a piece of tubing coming out of the (a) hole would work good too. Make sure to use a short screw on the inside of the tank to hold it on to the crankcase. A bigger tank is always useful. I know a guy ran a Babe(y) Bee with a huge tank like that to set an endurance record with a mouse racer kind of plane years ago. I had the same thing happen to my Baby Bee a long time ago. I don't think I said "Bugger" though.
07-23-2012, 07:55 AM
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RE: Well bugger, I busted a backplate.
I'm a fan of JBWeld also when "all else fails". Just depends on how pretty you want it. 
Good luck on it whatever you decide, it's a heartbreaker when something old breaks and you can't find parts. I've seen some .010's and .020's for sale here and on RCG lately, so that may be an option although possibly costly. There's also the blasphemous option of electrifying it and moving on to something else. [:'(] (fending off rocks, sticks and rotten vegetables from the gallery) LOL
Good luck on it whatever you decide, it's a heartbreaker when something old breaks and you can't find parts. I've seen some .010's and .020's for sale here and on RCG lately, so that may be an option although possibly costly. There's also the blasphemous option of electrifying it and moving on to something else. [:'(] (fending off rocks, sticks and rotten vegetables from the gallery) LOL
07-26-2012, 08:07 AM
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RE: Well bugger, I busted a backplate.
Those crappy Zinc lead(?) alloy backplates would often deform and even break under the screws.
Discovered as a Kid (with No spare $) that Solder stuck to the backplates as if they were of copper :-)
IMO JB weld is surprisingly lo grade epoxy... the power of advertising in action.
Discovered as a Kid (with No spare $) that Solder stuck to the backplates as if they were of copper :-)
IMO JB weld is surprisingly lo grade epoxy... the power of advertising in action.
