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Building Tips and technical articles. => Building techniques => Topic started by: Avaiojet on November 30, 2016, 08:09:14 AM

Title: Engine exhaust footprint made easy!
Post by: Avaiojet on November 30, 2016, 08:09:14 AM
I'm not sure if this is the right place to Post this tip?

I have this R/C Rossi I'm using for my Gee Bee R-3. The Build is at my "Sandbox." Anyone wanna play, c'mon over.

Anyway, I need a custom made tongue muffler for the engine. With that said I have to supply my muffler guy with the template, and I want to be exact.

Sooooooo, I did the sticky vinyl thing and trimmed the area with a #11 blade. A few times actually but I wasn't satisfied with any of the results.

I gave the task a bit of thought.

Clay would work for the imprint but I have no clay.

I decided to use my Stabilo and mark the edge of the exhaust flange. I used blue.

I then made a "stamp" with balsa which I pressed against the exhaust flange.

It didn't work.

Soooooooo, I then dampened the balsa with a bit of water and gave it a wipe with a rag to remove the excess water.

I again pressed the stamp against the exhaust flange and Presto Remco! it worked perfectly.

Here's the results.

Now I gotta get it in the mail.

Be interesting to see how others get this accomplished on engines muffler makers have no template for?

Charles
Title: Re: Engine exhaust footprint made easy!
Post by: FLOYD CARTER on November 30, 2016, 01:08:24 PM
I have transfered parts to paper by "rubbing" with a soft pencil.  The same way people transfer Egyptian hieroglyphics from stone to paper.
Title: Re: Engine exhaust footprint made easy!
Post by: Mark Scarborough on November 30, 2016, 01:18:45 PM
Another option is to put a piece of parchment paper over the exhaust, and lightly rap on it with a plastic or soft hammer( a brass hammer would work too) This will cut the paper where the edges and holes are leaving you with a perfect template,,

Mechanics have used this method for decades to create gaskets,,
Title: Re: Engine exhaust footprint made easy!
Post by: Lauri Malila on November 30, 2016, 02:33:47 PM
That's a rather simple symmetrical shape with a couple of squares and 2 holes. What's wrong with taking the main measurements with a vernier and then drawing a simple technical drawing with desired dimensions?
Machinists do normally nothing with a small 1:1 picture. Anyway, to operate a milling machine it's good to know the actual dimensions.. L
Title: Re: Engine exhaust footprint made easy!
Post by: Avaiojet on November 30, 2016, 04:35:56 PM
That's a rather simple symmetrical shape with a couple of squares and 2 holes. What's wrong with taking the main measurements with a vernier and then drawing a simple technical drawing with desired dimensions?
Machinists do normally nothing with a small 1:1 picture. Anyway, to operate a milling machine it's good to know the actual dimensions.. L

Lauri,

The dimensions are on a piece of paper taking the trip with the balsa rubbing.

He will have both, just to be sure.

Mark,

I know about that taping but I don't have a brass hammer.



Title: Re: Engine exhaust footprint made easy!
Post by: Dan McEntee on November 30, 2016, 04:52:29 PM
        All you need is a ruler and the ability to read it. Everything is symmetrical and can be laid out from a center datum line. You just need accurate dimensions for the holes centers and the opening size. Sometimes you make things more difficult trying to make them more simple.
     Type at you later,
    Dan McEntee 
Title: Re: Engine exhaust footprint made easy!
Post by: Avaiojet on November 30, 2016, 06:02:59 PM
       All you need is a ruler and the ability to read it. Everything is symmetrical and can be laid out from a center datum line. You just need accurate dimensions for the holes centers and the opening size. Sometimes you make things more difficult trying to make them more simple.
     Type at you later,
    Dan McEntee  

My muffler guy asked for a template, which was the reason for my tracing.

I could have easily drawn it in CAD.

I mentioned he's getting measurements also.