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HomeAircraftHelicopterMain Discussion › Please help with a muffler
10-11-2005 10:40 PM  12 years agoPost 1
sir777

rrApprentice

Moscow, Russia + Lloret de Mar (Girona), Spain

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Hi everybody! I need some help again. I have a funtech hn50 muffler. There two threaded holes in it- one for the pressure tap and another one just for screw (I think,it is for putting pressure tap on the on the bottom of the muffler). I completely (it seems to be my curse, I strip everything I can ) stripped the hole on the bottom, where I should put a screw to close it. I've also almost stripped the hole where the pressure tap is, but not completely and it holds somehow. What can you recommend me doing with it? I thought that maybe I can fill the bottom hole with some material, but really I don't have any idea. Please help.

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10-11-2005 10:41 PM  12 years agoPost 2
HERRORHH

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North Carolina

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Try using a bit of "J-B Weld" on the screw...

If you don't have time to do it right the first time...When will you have time to do it again?

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10-11-2005 10:42 PM  12 years agoPost 3
HERRORHH

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North Carolina

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And again on the pressure tap...

If you don't have time to do it right the first time...When will you have time to do it again?

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10-11-2005 10:50 PM  12 years agoPost 4
sir777

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Moscow, Russia + Lloret de Mar (Girona), Spain

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Thank you for quick answer. But I don't have that "J-B Weld" in my country, so can I use just some epoxy?

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10-11-2005 10:55 PM  12 years agoPost 5
HERRORHH

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North Carolina

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I have not used epoxy myself. I'm not sure that it will get a bite on the metal.

If you don't have time to do it right the first time...When will you have time to do it again?

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10-12-2005 09:29 AM  12 years agoPost 6
trvo

rrVeteran

Bognor Regis,UK, Aurorra Ltd

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You can use the longest drying epoxy on it with no problems, many times I have sealed my Muscle Pipe's with 24 hour epoxy with no problems when I had done them up too tight. Just make sure you slightly etch the surface with some sandpaper to make sure you get a seal.

Trev.

-----
Trex 600e
Trex 600n
Aurorra Ltd, Align UK, Align Factory, CSM, Quick UK, Heli-Lessons

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10-12-2005 05:47 PM  12 years agoPost 7
w.pasman

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Netherlands

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Let me guess, you did not degrease the screw or threads before tightening.

Every glue I know will melt at muffler temperature. Additionally this is a highly stressed area, even if epoxy would not melt it would not have the strength required.

My advice: get a new muffler and always degrease the threads before fastening.

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10-12-2005 07:44 PM  12 years agoPost 8
Leif

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USA

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Rather than replace the muffler, you could also re-tap the holes for a larger thread.

For the hole on the bottom of the muffler, simply find a stainless-steel screw with the next larger size (perhaps M4). Use an M4 tap to re-thread the hole and plug it with the M4 bolt.

You could try a similar approach with the pressure-tap nipple, but you'll need to get a new nipple with a larger thread. There are also kits on the market to fix problems like this. The approach is to drill and tap the stripped hole for a larger size thread, then fill it with an "insert" that has the larger size thread on the outside, and the original size threaded hole in the center.

Any decent machine shop would be able to help you in a jiffy.

In the future, seal the threads with a bit of high-temperature RTV (I use Ultra-Copper RTV) before you install them. This will prevent leaking and will keep the parts tightly threaded in place without the need to overtighten them.

Leif

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10-12-2005 08:49 PM  12 years agoPost 9
w.pasman

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Netherlands

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Rather than replace the muffler, you could also re-tap the holes for a larger thread.
Yes that might work. But most engineholes I saw so far won't fit larger bolts.

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10-12-2005 09:41 PM  12 years agoPost 10
Leif

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USA

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But most engineholes I saw so far won't fit larger bolts.
The question was about stripped holes for the pressure tap and the secondary tap location, not the engine to header mount.

Leif

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10-13-2005 09:59 AM  12 years agoPost 11
sir777

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Moscow, Russia + Lloret de Mar (Girona), Spain

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Nope, I did it, I even put some red loctite on the screw and on the tap. It is just my hands, which want to put too much strength. I've just put some POXIPOL on it, seems to hold very tight. It is somekind of cold epoxy.I am not sure, if it will hold temperature, but will see. If it fails, I will try to re-thread the hole to the larger size. I've read here on runryder about different types of threaded inserts and "helicoils", but don't have any idea where I can buy it here. Thank you for tips!

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10-13-2005 03:34 PM  12 years agoPost 12
Bato

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Monterrey, Mexico

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I'll suggest re-taping. Whenever I strip (not often but it has happen) I'll try to re-tap. You'll fly with more confidence knowing that everything is as it should be.

Also, you don’t have to be Hercules in this hobby. That's what lock tight is for. Believe me, I've learned that the hard way (stripped screws, etc.). Just tighten until the screw reaches the bottom and then add a slight (SLIGHT!!!!!!!) additional turn. Just to make sure its tight. The lock tight will do the rest.

Hope it helps.

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10-13-2005 06:15 PM  12 years agoPost 13
airdodger

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Johnston USA

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Whew, just use some screws to plug the holes you have and go drill and tap a new hole. I don't know what size your pressure tap is but they make different sizes also. Chris

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10-13-2005 07:32 PM  12 years agoPost 14
sir777

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Moscow, Russia + Lloret de Mar (Girona), Spain

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I got your idea, airdodger, but just one question: it doesn't matter where I will put a new tap?
If my current solution fails, I will try your tips.

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10-13-2005 09:36 PM  12 years agoPost 15
airdodger

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Johnston USA

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Just put it close to the other one. Chris

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