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Aug 13, 2016, 09:22 PM
the kitty litter of rcgroups
rdwoebke's Avatar
Thread OP
Mini-HowTo

full break boom repair


A friend gave me this Neos fuselage at the Nats. I'm going to do a repair thread.

Ryan
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Aug 14, 2016, 04:49 PM
Registered User
Pappyjkns's Avatar
Ryan:
That looks nasteh! Hmmm.....I thought I was the only boom breaker! Looking forward to your repair posts.

Cheers!
Lyle
Aug 14, 2016, 05:58 PM
Registered User
First thing to do is build a jig to hold it in alignment. Far enough above the workbench to allow wrapping.
KFC aka Bill
Aug 15, 2016, 12:37 AM
Samuel

Stark Boom Repair


Since I do repairs as a job, I have a few simple and effective tricks to share.

First before joining the boom together with CA, buy some similar size heat shrink and have it put on the boom.

After correct alignment use CA to hold everything together. And use some ca to apply some spread tow if needed.

After wet sanding, use carbon tow and epoxy, dry the epoxy as much as possible and apply heat shrink.

wait 24hr and peal off heat shrink. Strong and reliable fix with only 1.5g added
Aug 15, 2016, 09:42 AM
Wayne Wimbish
wdwimbish's Avatar
Nice job Sam.

Now I want to see how Ryan does it...

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Aug 15, 2016, 09:51 AM
the kitty litter of rcgroups
rdwoebke's Avatar
Thread OP
Quote:
Originally Posted by wdwimbish
Now I want to see how Ryan does it...
I'm not super fast but will try to post at least something each week.

Quote:
Originally Posted by Pappyjkns
I thought I was the only boom breaker!

Given apparently Sam fixes booms for a living it seems there are many people who break them.

Ryan
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Aug 25, 2016, 08:02 PM
the kitty litter of rcgroups
rdwoebke's Avatar
Thread OP
I started by cutting a piece of 1/32 balsa into a rectangle. Then I slowly rolled it into a tube to slip into the boom. I then mixed up some epoxy and a lot of filler and epoxied it into one half of the fuselage. The idea behind this is to make a self aligning jig to get it back together for applying the real repair to the outside.


Ryan
Latest blog entry: Supergee wing mount pylons
Aug 26, 2016, 08:28 AM
Carboweave, Ask For It By Name
Chuchuf's Avatar
Ryan,
I would do exactly what you are doing nut instead of Balsa, I'd lay up some really light carbon into a tube that is slightly larger than the tube you are repairing. Then cut the tube (it will have some spring back) and insert it and CA or resin in place. Structurally much stronger and light.
If you can't make a tube, lay it up flat and it should roll when dry if it's really light carbon.
Of course I'd use Carboweave.

Very nice fix Sam.

Terry
Aug 26, 2016, 08:40 AM
the kitty litter of rcgroups
rdwoebke's Avatar
Thread OP
Yeah, that might be a way to go, that isn't a way I am going to go. I might mention this fuselage isn't round. The purpose of the balsa inner tube is just to get it aligned and strong enough so I can apply the real fix to the outside.

I also want to do a type of fix that is instructional. I figure anyone can get some scrap 1/32 balsa or buy a sheet.


Ryan
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Aug 26, 2016, 08:59 AM
Time for me to Fly...
Mr. Wiz's Avatar
I'm wondering why you used epoxy and filler for the tube instead of just wicking in some thin ca? Also, did you use a piece of "L" shaped metal to help with alignment?
Last edited by Mr. Wiz; Aug 26, 2016 at 09:06 AM.
Aug 26, 2016, 09:30 AM
the kitty litter of rcgroups
rdwoebke's Avatar
Thread OP
Quote:
Originally Posted by Mr. Wiz
I'm wondering why you used epoxy and filler for the tube instead of just wicking in some thin ca?
A few reasons:

1) I thought the extra time of the epoxy would be easier for positioning it.
2) CA likes to really wick its way into balsa and I was concerned that might not be quite enough of a bond given the stuff just wicks in like crazy but you are trying to bond it to the inside of a fuselage so that when I was handling the fuselage when putting carbon on the outside if it popped loose that would be a big bummer
3) the fuselage is oval and kind of pinched on the sides actually and I thought having super thickened epoxy would help to get a bit better bond to try to avoid the thing popping off when I am handling it.


Quote:
Also, did you use a piece of "L" shaped metal to help with alignment?
I haven't yet but I also haven't done the other side yet. I have done L shaped metal before trying to align a round boom repair and somehow that seems to actually mess the alignment up more for me sometimes. So I think I might just try to eyeball it as best as possible when I do the other side. Haven't decided for sure yet. Haven't decided for sure yet. This thing being oval in shape I think that complicates the idea of using a L shaped piece of metal.

Ryan
Latest blog entry: Supergee wing mount pylons
Aug 26, 2016, 09:50 AM
Aurora Builder
I think the best bet is CA and eyeball the joint. Gerald has a very excellent repair thread here on the groups as well.

Nice repair Sam, very very clean. Any recommendation on type of heat shrink?
Aug 26, 2016, 05:01 PM
Registered User
Really tough to do the eyeball and get it straight. Also agree with Ryan that the 90 degree "L" doesn't much help with with the oval booms, but it can work if you can use two "L", one on each side.

All bets are off when it breaks right behind the wing
Sep 07, 2016, 08:39 PM
Registered User
I'm doing a boom repair and of course I glued up the boom with CA before putting the heat shrink on. I dare not re-break the joint, because I won't be able to re-glue the old cured CA joint very well. So, does anyone have any other recommendations for a final wrap besides heat shrink tubing? I'm thinking of using a strip of thin silicone rubber sheet and just wrapping it over the top of the carbon/epoxy/polyethylene repair sandwich, but I'm just sure I can get it tight enough.
Sep 07, 2016, 08:58 PM
the kitty litter of rcgroups
rdwoebke's Avatar
Thread OP
I have in the past done a spiral wrap with electrical tape.


Ryan
Latest blog entry: Supergee wing mount pylons


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