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Holding screws in

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Tony j22/04/2019 07:59:55
53 forum posts
4 photos

Good morning All

I have a canopy that is located with two peg at the front and then two M3 screws screw into the sides . Now I was flying the other day and returned with one screw missing. So is there away that I can stop them from coming loose in flight. I thought about thread loc but thought this may not suit as they need to go in and out on a regular basis so any suggestions please .

Many thanks in advance.

Kind regards.

Tony J

Percy Verance22/04/2019 08:10:40
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7793 forum posts
150 photos

Hi Tony

I think you may need to find out why you lost the screw. Are both the prop and spinner balanced? Either can be a source of vibration.

Peter Miller22/04/2019 08:32:07
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9815 forum posts
1156 photos
10 articles

Use stiff nuts inside

Andrew Ray22/04/2019 08:47:23
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680 forum posts
19 photos

I have drilled out the hole in a canopy when I had the same problem, glued in some fuel tubing that was a snug fit on the screw. Worked a treat. The fuel tube also needs to be a snug fit in the hole you drilled.

Steve J22/04/2019 08:49:54
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1010 forum posts
37 photos

Assuming that you have steel machine screws into t-nuts, Loctite 248.

Steve

trebor22/04/2019 09:01:32
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1886 forum posts
212 photos

I gave up using locktite as even the kindest stuff used to strip fine Chinese threads made of China's best metal, instead I use Uho por which is very sticky and shake ressistant. Even the other half's old nail varnish comes in handy and it looks good too blush

Manish Chandrayan22/04/2019 09:24:04
553 forum posts
65 photos

I am assuming that canopy needs to be removed frequently, either to change the batteries or access equipment inside.

I am also assuming that the original screws that were on the model and one of which bailed out was metal M3.

This is a common occurrence and Locktite, nail varnish etc do not work in this situation. My way of avoiding the screws bailing out is to use nylon screws instead of the provided metal ones. Once snugged in they remain snug.

Other option is to remove the existing blind nut and epoxy a nyloc nut. This will allow you to use metal screws but the torque required to loosen or tighten the screw may dislodge the nyloc nut

kc22/04/2019 09:52:52
5839 forum posts
168 photos

Any sort of rubbery adhesive works well to lock screws. I used Evostik impact or Thixofix to hold silencer screws in - never came loose until needed to unscrew.

Of course shakeproof washers as found on lots of electrical items ( dozens in an old washing machine ) could be used in this instance if they are small enough sizes.

Ronaldo22/04/2019 10:01:46
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224 forum posts
17 photos

I solder steel nyloc nuts onto captive 'T' nuts. Sounds impossible I know, but it does work if you can set the soldering iron temperature just hot enough to melt the solder and not the nyloc insert.

I've used this method for all kind of fixings where vibration is an issue.

Doc Marten22/04/2019 10:04:38
172 forum posts
2 photos
Posted by Andrew Ray on 22/04/2019 08:47:23:

I have drilled out the hole in a canopy when I had the same problem, glued in some fuel tubing that was a snug fit on the screw. Worked a treat. The fuel tube also needs to be a snug fit in the hole you drilled.

This is a good option but I'd use PTFE or Nylon from a control snake to give you the same principle as a nyloc nut. Brass tube also works.

Nigel Dell22/04/2019 10:08:20
353 forum posts
24 photos

I found that just changing the metal bolts to nylon stopped this, if they are suitable for purpose that is, It was just to hold a canopy section access hatch on the fuz in my case, the Seagull models iSport has the exact same set up.

Capt Kremen22/04/2019 10:31:56
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260 forum posts
63 photos

Where the screw hole already exists and the screw is loose, take a small piece of 'soft wood' e.g. match stick. Break off enough to insert as filler in the hole, using a spot of glue to stop it coming out. Re-insert the screw. The screw will then cut a new tighter thread fit. (This is a common remedy for musical instrument loose screw strap buttons which are subject to constant wear and tear).

Bob Cotsford22/04/2019 13:32:27
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7759 forum posts
431 photos

I try to replace screw retention on hatches with a spring latch, either a single central latch or one each side mounted in the fuselage side mounted so that the sprung pin locates into a notch in the edge of the hatch tab. As I'm all electric now I want quick access to the battery so screwed on hatches are out.

Peter Jenkins23/04/2019 00:09:23
1187 forum posts
128 photos

I slip a bit of fuel tubing over the bolt but with a washer between the bolt head and fuel tubing. When tightened, the fuel tubing provides sufficient pressure to stop the bolt loosening and falling out. I've used this to retain the canopy on a Capiche 140 with what has to be the roughest 4 stroke 180 made - Saito! The bolts stayed tight all day. Cheap and very effective.

Tony j23/04/2019 01:31:39
53 forum posts
4 photos

Hi

Thank you all for your replies lots of interesting ways of dealing with the issue , its good to know that I am not alone with the problem.

Kind regards

Tony J

Jon Laughton23/04/2019 10:26:08
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1158 forum posts
102 photos

A small collar of silicone fuel tubing between the head of the M3 bolt and the fuselage side may do the trick - just tighten it up well before flying. Alternatively fir the both toa Seacraft cup washer and a spring washer for the same kind of effect

FlyinBrian24/04/2019 11:41:16
504 forum posts

Small "O" rings on the M3 bolts or as abve slivers of silicon fuel tube.

ken anderson.24/04/2019 12:54:06
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8367 forum posts
771 photos

try a rubber washer under the bolt head.....

ken anderson...ne...1...rubber washer dept.

Cuban824/04/2019 13:41:06
2402 forum posts
9 photos

A cut down servo grommet works well, the round type rather than rectangular Futaba ones. Full grommets hold cowls in place without losing screws as well.

Bruce Collinson24/04/2019 14:09:03
324 forum posts

Modelfixings sell small O-ring grommets, included in their socket-head servo screw packs (which I endorse unreservedly, five get used for every one that secures a servo) and are great for cowls and canopies upto say 10cc in old money. I'm sure they're sold seperately, although much better value in the assortment pack.

BTC

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