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Marty d's CH-701 build log


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The Sav cabin frame ends are open to the air. Dannys cabin frame is bent because his aircraft was picked up by a willy willy and dumped upside down..mine sat outside for a while after it had been crashed. It also had a life up in Blackwater for 160 hrs when it was built then down in Tottenham for another 180 hrs then it was crashed and sat outside for about 8 months. I noticed the rust inside when I pulled the cabin frame off to rebuild the centre section. When I pulled out the alu top tubes there was lots of rust on them and they were a bit corroded together. On my cabin frame when I built the girlfriend I put rustlac inside the tubes to stop it as I new it was a issue from others I had spoken to. So we are both going to make new cabin frames using my good one as a jig. This is how Danny found that the U tags are stainless steel on the Savs...I checked mine in the girlfriend and it is the same as both frames from the broken ones we have here.

 

 

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It worked!!!!!   I just popped the lower cowl out of the mould.  It came straight out, no sticking, no lumps and bumps and divots.  (Well maybe a couple of minor divots!)   Decided

Quick update - I finished trimming the lower cowl today (apart from where the exhaust will exit), located it properly and did a 1/8" hole on each side so I could cleco it.     Unfortunately

Step one is to cut your mat to fit the inside of the mould - lay the pieces out so you know whit bits fit which curves. Don't try to do the whole cowl with one big piece of mat. After applying ha

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How do you get a lot of rust internally in your frame?

Have a look at photo #3 in the set above. That is the end of the main cross tube with the tabs on the ends holding the mainspar of the wings. Although the tab will be welded in, the end of the tube remains open.I'm going to tip some etch primer in and slosh it around until the inside is coated - anyone got any other advice to stop internal rusting?

 

 

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Marty, you may or may not know how to truncate the tube ends where they meet another tube in SU?

 

It's also the same way the you bore a hole through any shape.

 

Draw your tube up to or through the other tube or shape otherwise

 

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Highlight all interconnecting parts.

 

The 'Edit' dropdown - select 'Intersect faces' - 'With selection'

 

Note if your parts are already grouped this will take a while to complete.

 

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Select parts individually and group the part before it can be removed from the other part.

 

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Remove part. Notice fishmouth. The hole can be made in the other tube by highlighting it and delete, or delete the black intersection lines. Sometimes can right sweep and select the lot, sometimes I have to delete the segments one at a time (PIA).

 

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Marty - We've got a local rust-preventative paint product called Metalfix (and MetalFix1000) which is not only safe, because it's water based - but you can paint over rust with it, and it converts the rust to a metal phosphate, and it will never lift.

 

It is expensive, though, something like $70-80 a litre from memory. I got lucky and picked up about 30 x 1 litre containers of MetalFix at an auction a few years ago, for $30 for the lot!

 

The iron tannate rust-prevention solutions such as Fertan and Exit-Rust are good stuff if you have some rusty areas that need treatment and protection. These are based on the non-toxic tannins from poplar bark, and other tree barks.

 

 

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And here's a hole. Draw a circle on a part, extrude through, highlight as required, Intersect faces and delete what you don't want.

 

744510772_t5.jpg.a58351f4e4003bea6e76672b97e9a13e.jpg

 

You can also extrude a tube isolated from the other parts, 'Group' it, then position it where ever you want that hole, then 'Explode' it (Edit - Face - Explode), Intersect faces etc...

 

 

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I don't really have a problem intersecting pipes on SketchUp - but printing the actual pattern to wrap around the pipe was a bit beyond it, as far as I could tell. Anyway, found another solution here - Tube Joint Pattern Generator - does the lot. I printed their solutions for each joint, taped it around the pipe and cut with a Dremel, and they fitted like a dream.

 

 

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  • 5 weeks later...
Your doing a beautiful job marty...I gather you have a good folder and guillo at home

Not at all Mark. I have a cheap little 750mm bending brake but for all the longer stuff I visit a sheetmetal worker about 10 minutes away. He's also doing my welding - or will, as soon as I can source some ER70S-2 rods for him to use.For the thicker parts (0.063" and over) I've learned that woodworking tools do equally well on aluminium. The old drop saw has proved very handy!

 

 

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. The old drop saw has proved very handy!

Just make sure to often clean the aluminium out that gathers between the teeth, it can lead to chunks of the blade coming off otherwise.

 

 

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I sourced some nylon today (HDPE actually) for use as fairleads, bearings on the nose leg and the little thingy that holds the two rudder pedal assemblies together. Cost me the grand total of $22 for enough to have plenty of stuff-ups!

 

 

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  • 3 months later...

Fuselage is together! (clecoed).

 

My local metalworker came through with the welded cabin frame and noseleg. Due to a lot of renovations, then school holidays, today was the first time I got down to the shed for a decent session.

 

It all seems to fit together pretty well so I'm chuffed!

 

1432752801_Fuselagetogether.jpg.050e3b4fe85afdce501726f3a7f835a1.jpg

 

 

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Fuselage is together! (clecoed).My local metalworker came through with the welded cabin frame and noseleg. Due to a lot of renovations, then school holidays, today was the first time I got down to the shed for a decent session.

 

It all seems to fit together pretty well so I'm chuffed!

 

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Go! Marty. 003_cheezy_grin.gif.c5a94fc2937f61b556d8146a1bc97ef8.gif

 

 

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