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25 Aug 2022 09:15 - 25 Aug 2022 09:16 #26132 by Phillip Ford
Replied by Phillip Ford on topic Back to Basics
If only you had asked. You could have popped over and had a rumage in the cupboard. I have loads of mufflers for two/four strokes that may have fitted. Well, at least you had something to do to keep idle hands occupied. :)
Last edit: 25 Aug 2022 09:16 by Phillip Ford.

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25 Aug 2022 18:20 #26134 by Brian Jackson
Replied by Brian Jackson on topic Back to Basics
Thanks for the offer of a "rummage in the cupboard" Phil, perhaps next time. Its a bit odd that I have a silencer with no matching engine, every engine I've sold over the past years has had a silencer with it. This one reminds me of the type that was supplied with the Irvine 53. Whatever its origin, its doing the biz now.

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12 Sep 2022 16:41 #26183 by Brian Jackson
Replied by Brian Jackson on topic Back to Basics
Its been a while since I've been able to get back to the building board, however, my thrift and diligence have been rewarded, and with the accrued cash I invested in some balsa block and thick sheet.
Now I can get on with the satisfying business of hiding the Merco behind a wall of balsa, then carving away until the engine sees daylight again. Its quite rewarding to do, especially when standing ankle deep in balsa shavings at the end of the job.
I have yet to do a bit of work on the exhaust/muffler joint. The exhaust stub on the engine is a bit of a challenge, I think it'll work out alright using a small toolmaker's clamp with two strips of brass held by double sided tape, one strip on the upper face of each clamp jaw. Lightly clamping this little lot to the exhaust stub and with a bit of nudging, it should be possible to dress the face of the stub using the brass strip as guides for the file. I did consider using a gasket, but these are fragile and tend to "blow" if the mating faces aren't completely flat. It'll be a case of gently inviting the slightly uneven surface back to straight and true, doing the same on the muffler stub and re-assembly with a thin film of Loctite. Sounds complicated, but isn't really. Pictures later from the bench
Meanwhile, balsa blocks beckon, I'm off to fill the gaping hole at the front of the fuselage.
I should mention that the Merco has all its ports suitably sealed with kitchen paper held in with BluTack, and there's a toothpick in the needle valve hole. All to be left in place until after the exhaust stub's done and the engine given a bit of a tidy-up with Fairy Power Spray. No, they don't sponsor me, but its the best stuff for removing baked on gunge that I've ever used.
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17 Sep 2022 17:22 #26195 by Brian Jackson
Replied by Brian Jackson on topic Back to Basics
The exhaust stub on the Merco is as flat as I can get it, there's a small "ding" that I'm going to leave, not worth doing a lot of filing just to remove a mark that's only about 1/32" wide.
!/2" sheet was cut and fitted to the front of the fuselage. The rear of the fuselage is being filled out with wide 1/8" thick strips. No point in gluing on a piece of 1/2" sheet when most of it will be carved away. This saves using expensive sheet as well as keeping the build of the rear fuselage quite light but stiff. The front pieces are only tack glued as they'll have to come off to allow the steerable nose leg to be fitted. Before re-assembling the pieces, I need to cut an access hatch to enable the nose wheel steering arm to be adjusted. I'll use hatch catches even though they aren't specified in the original design. I'm not a fan of bicycle spoke retainers.
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21 Sep 2022 16:47 #26202 by Brian Jackson
Replied by Brian Jackson on topic Back to Basics
I used an old spinner backplate to help line up the cut marks for the front of the fuselage, that was a few days ago. This afternoon I trimmed up the laser cut bits for the front of the fuselage, and glued them together. Did a second check on the marked out lines, removed the engine, and boldly cut off the front of the fuselage. Should have remembered the old saying "measure twice...cut once". For some reason I'd marked the cut lines from the wrong side of the spinner backplate. The cut is about 1/8" too far back, overall I don't think it'll matter, and I could add another liteply ring to the front of the existing one if the gap is too obvious. The next job will be to ease the engine out and fit some balsa infill. I'm looking forward to the final carving, very therapeutic.
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