john stones 1 - Moderator Posted February 19, 2017 Share Posted February 19, 2017 You're a very thorough n meticulous man Gary me i would have laid some more glass cloth where my cut outs were gonna be. John Quote Link to comment Share on other sites More sharing options...
Gary Manuel Posted February 19, 2017 Author Share Posted February 19, 2017 Haven't ordered any Silicone trim yet. It's just a thought at the moment. All I've done so far is rule out the PVC grommets. What I'm concerned about is that the silencers are only held onto the headers via the PTFE tubes and spring clamps. I think they might start to move around when the engine vibration starts. I don't want the vibrating silencers to come into direct contact with the cowl - even if it's reinforced at the point of contact. I'm still thinking of a solution but I have one or two ideas. Suggestions welcome. Quote Link to comment Share on other sites More sharing options...
john stones 1 - Moderator Posted February 19, 2017 Share Posted February 19, 2017 Rich ? used some heat proof silicone on the joint i think. Quote Link to comment Share on other sites More sharing options...
Gary Manuel Posted February 19, 2017 Author Share Posted February 19, 2017 Posted by john stones 1 on 19/02/2017 21:44:23: Rich ? used some heat proof silicone on the joint i think. Silicone won't stop it moving it's too soft. I think you might be thinking about the gap he filled between the fuselage mounted clamp and the silencer - because the fit was too loose. Quote Link to comment Share on other sites More sharing options...
Rich too Posted February 20, 2017 Share Posted February 20, 2017 that's correct, the clamp was slightly loose so I used the silicon to fill the gap. are you trying to prevent the muffler and exhaust outlet from turning in the header? a small screw through the header/muffler joint? Edited By Rich2 on 20/02/2017 06:52:29 Quote Link to comment Share on other sites More sharing options...
Gary Manuel Posted February 20, 2017 Author Share Posted February 20, 2017 That's a good idea Rich. Quote Link to comment Share on other sites More sharing options...
john stones 1 - Moderator Posted February 20, 2017 Share Posted February 20, 2017 I would look through the Loctite range of product myself, if you remember the demo we had there's a vast range of stuff. John Quote Link to comment Share on other sites More sharing options...
Rich too Posted February 20, 2017 Share Posted February 20, 2017 i would try a small hole, thread it to M3, put a small M3 screw in there with some Loctite on the threads. Quote Link to comment Share on other sites More sharing options...
Gary Manuel Posted February 20, 2017 Author Share Posted February 20, 2017 The problem with a screw is that it needs something to tighten up against, to prevent it coming loose. The PTFE is probably too soft to do this - especially when it gets hot. What I'm thinking at the moment is to drill a pilot hole through the PTFE tube and into the stainless steel silencer or header pipe below. Then drill the PTFE hole a bit larger and push a servo mount spacer into the PTFE tube. Then screw a self tapping screw coated in strong threadlock into the stainless steel, till it tightens against the servo mount spacer. This should then be nice and solid to hold the screw in place, if all goes well. The servo mount spacer should also spread the load of the vibrations a bit to help prevent the PTFE tube from rubbing against the screw and tearing. The final step would be a turn or two of silicone self fusing tape around the PTFE tube / screws to hold the screws in place in case it does try to vibrate loose. I don't need to decide just yet as I will start the engine with the cowl off initially, to see whether I think it needs anything doing or whether I'm concerned over nothing. Waiting for tail wheel / prop order from ProBuild before I finish, then wait for field to dry out a bit before flying. Quote Link to comment Share on other sites More sharing options...
Rich too Posted February 20, 2017 Share Posted February 20, 2017 I see, sorry I misunderstood and thought it was for metal to metal contact. I don't think you will have a problem, I haven't done anything on my Yak. Your holes might be a bit small though, see what happens when you fire it up..... Quote Link to comment Share on other sites More sharing options...
Gary Manuel Posted March 4, 2017 Author Share Posted March 4, 2017 I got a bit more done today. One thing I have a habit of doing at the field is either dropping or misplacing small screws. The worst culprits are the ones that attach the canopy to the fuselage. I recently bought a second- hand model that had a nice tool-free method of fastening the canopy, so I've stolen the idea. Here's how I've done it. This is the standard arrangement. 4 bolts / washers are used to screw into these captive nuts. First job is to epoxy a length of snake outer between the captive nuts on each side. A length of "well vaselined" metal pushrod pushed through to hold everything in alignment. Short length of snake outer also epoxied into the fuselage holes. End of the pushrods bent at 90 degrees and short lengths of snake inner pushed onto them. These are fairly standard stick on cable tidies. Cable tidies stuck onto the side of the fuselage ...... .... which nicely grip the metal rods. The other end of the rods push through the snake outer and out of the other side. They are marked ...... ..... and cut to length. The end is tapered a bit to help it slide in. I'll tidy it up a bit later. Quote Link to comment Share on other sites More sharing options...
Rich too Posted March 5, 2017 Share Posted March 5, 2017 Great idea I will look for some alternative materials to make it less obtrusive. Quote Link to comment Share on other sites More sharing options...
john stones 1 - Moderator Posted March 5, 2017 Share Posted March 5, 2017 Not taken with that Gary, poor by your standards, wants something to cover the holes up for a start, maybe something like those DIY screw head fittings and the yellow inner on the wire wants something to replace it, maybe some brass tube...no chance of winter build trophy with that John Quote Link to comment Share on other sites More sharing options...
Gary Manuel Posted March 5, 2017 Author Share Posted March 5, 2017 Yes, I said I would tidy it up later. The holes on the right hand side can be covered completely as the rod does not need to poke all the way through. Quote Link to comment Share on other sites More sharing options...
Gary Manuel Posted March 5, 2017 Author Share Posted March 5, 2017 Tidied up a bit. Rods now pass through the clip and cover the hole underneath. Right hand side holes covered up. Quote Link to comment Share on other sites More sharing options...
Rich too Posted March 5, 2017 Share Posted March 5, 2017 Posted by john stones 1 on 05/03/2017 08:34:30: Not taken with that Gary, poor by your standards, wants something to cover the holes up for a start, maybe something like those DIY screw head fittings and the yellow inner on the wire wants something to replace it, maybe some brass tube...no chance of winter build trophy with that John I was trying to be more subtle John! Quote Link to comment Share on other sites More sharing options...
Rich too Posted March 5, 2017 Share Posted March 5, 2017 Posted by Gary Manuel on 05/03/2017 13:17:50: Tidied up a bit. Rods now pass through the clip and cover the hole underneath. Right hand side holes covered up. That's much better Gary, perhaps change the tube for black stuff? Quote Link to comment Share on other sites More sharing options...
Gary Manuel Posted March 5, 2017 Author Share Posted March 5, 2017 Posted by Rich2 on 05/03/2017 13:32:39: That's much better Gary, perhaps change the tube for black stuff? Yes I agree. I don't have anything black that is thick enough at the mo, but I'm on the look-out for something. I might put a bit of black heat shrink tube over the top of the yellow if nothing else turns up. Edit - The other thing I have in mind is to paint the rod a bright colour so I can see them when I put them on the ground. I spent ten minutes looking for one of them earlier. It was right in front of me Edited By Gary Manuel on 05/03/2017 14:13:58 Quote Link to comment Share on other sites More sharing options...
Gary Manuel Posted March 7, 2017 Author Share Posted March 7, 2017 I've got the 3mm screws, rubber washers and captive nuts to fit the cowl, so here goes... Position of the holes marked at 1 and a half inch spacing. Pilot holes drilled. Holes ground out to match the 3mm thread size. The holes on the bottom half were then ground out to match the EXTERNAL diameter of the captive nuts (no photo of that bit). Captive nuts epoxied to rectangular pieces of lite ply ...... ........ slightly thinner than the captive nut barrel, so that a bit of the barrel protrudes. Captive nut / ply assemblies epoxied in place, with the captive nut protruding into the cowl surface to ensure proper alignment. The front 2 and rear 1 on each side are not straight forward and will require a bit more preparation once the (24 hour) epoxy has set. Close up from inside. Edited By Gary Manuel on 07/03/2017 16:57:54 Quote Link to comment Share on other sites More sharing options...
john stones 1 - Moderator Posted March 7, 2017 Share Posted March 7, 2017 Yes that's much better, good thinking moving the catch Quote Link to comment Share on other sites More sharing options...
Gary Manuel Posted March 7, 2017 Author Share Posted March 7, 2017 I have also sprayed the canopy securing rods and applied black heat shrink over the top of the yellow snake inner. Looks much better now, and is actually a slightly better fit in the clip. Quote Link to comment Share on other sites More sharing options...
Gary Manuel Posted March 9, 2017 Author Share Posted March 9, 2017 Cowl fixings finished. Rubber washer still to fit between the screw and the cowl. I'll put them on when cowl goes back on after the engine has been run. While I was looking at the cowl, I removed the rubber grommets from around the exhaust pipes, ground a couple of mm of material off all round and replaced with heat proof silicone strip. Plenty of clearance now. Quote Link to comment Share on other sites More sharing options...
john stones 1 - Moderator Posted March 9, 2017 Share Posted March 9, 2017 Very tidy Gary Weather's picking up as well for you John Quote Link to comment Share on other sites More sharing options...
Gary Manuel Posted March 9, 2017 Author Share Posted March 9, 2017 Posted by john stones 1 on 09/03/2017 16:14:41: Very tidy Gary Weather's picking up as well for you John Thanks John, The front 2 and rear 1 on the other side aren't aligned quite as well Can't do much more till my tail wheel arrives as positioning of everything else is CoG dependant. Tail wheel has been on order since Christmas. Arrived in UK on Monday and will be posted by Pro-build UK to me today hopefully. Quote Link to comment Share on other sites More sharing options...
Rich too Posted March 10, 2017 Share Posted March 10, 2017 very nice and good luck doesn't look as though i'll get my maiden in before end of April Quote Link to comment Share on other sites More sharing options...
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