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Making simple nearly perfect discs

Post your favorite modeling 'tips' and 'tricks'

Postby elec_tech » Sat Apr 01, 2006 2:10 am

Well here I needed to make circles for my new build and I needed a way to make pretty decent circles with only my hand tools and my dremel. In most cases this would be cause for disaster in my "shop" but I found something very useful hidden in my Dremel tool kit.

What I am using in this demonstration is 3mm PVC foamboard known as Sintra. Great stuff it is, it's much stiffer than balsa and CAs extremely strong, especially when aided with a little baking soda. So here's the story behind my discovery, One evening this past week I was cleaning up my shop and was putting away the Dremel when I came across the Dremel circle cutter. Knowing I was needing to cut circles I thought I would give it a try, see how it worked and how I could put it to use. Turns out it was fairly simple and I came up with a quick technique as to how I could get all of my circles cut perfectly in a matter of minutes. The set of pictures describes the process accuratly enough, within 15-20 min I had all the circles I needed cut and ready for glueing. I am more impressed with the end result.

So here is where I drew on the circle diameter and center lines required for my build.

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The Dremel circle cutter tool setup
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I drilled a hole OUTSIDE the diameter I wanted to cut so that I could align the blade. This was important as I wanted the blade edge to trace the outside of the compass line, not the center of the blade. I also predrilled a hole in the center so the disc could spin and be cut.
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Notice how it's cutting cleanly as I described above.
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Finished discs ready for the next step.
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So, nice clean circles ready for any use, without a lathe or anything else, just a Dremel which I have been told is the ultimate modelers tool. Just figured I'd share my experience with it.

Dan
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Postby elec_tech » Sat Apr 01, 2006 2:00 pm

Ron (Raalst) asked me what blade I used, I guess I should elaborate here as well.

this is the blade that I used, It's a dremel all purpose cutting blade.... here in an exerpt from their website on it.

561 MultiPurpose Cutting Bit
A high-speed cutter with a 1/8" steel shank ideal for cutting wood, plastic, fiberglass, drywall, laminate, aluminum and vinyl siding.

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Dan
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Postby Bigdave » Tue Apr 04, 2006 8:44 am

Very cool tool! Thanks Dan! :cool: I will have to check my Dremel catalog. You are right about the Sintra, it is great stuff to work with. I was given some by our Fearless Leader (Mr Smalley) to try. Thanks again Tim! :D BD.
David Welch
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Postby elec_tech » Tue Apr 04, 2006 10:53 am

No problem Dave. If you ever need more of the stuff, visit you're local sign making outfit and see if they have any offcuts. It comes in varying thicknesses and colors.

As Sintra is only one brand name, PVC foamboard is also known as Celtec and a few others.

I've also found a link to a page that some guy put together describing Sintra and it's various properties and uses.

http://www.solarbotics.net/starting/200207_sintra/200207_sintra.html

Dan
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Postby FX Models » Tue Apr 04, 2006 4:16 pm

Hi Dan...

Notes on Sintra... I have been using it for about 2 years and I can tell you some things about it that you dont know perhaps. This will be illuminating to others as well. Sintra's chemical makeup is such that if you sand it or burn it, [ie heat it up] it will give off an acid. This acid is not an immediate searing acid but what it does is to linger in the air, and proceed to attack ALL steel items in your workshop. In our case, we worked with Sintra in 1mm, 2mm and 3mm thicknesses and within two weeks EVERY piece of steel in the shop rusted, from steel Allen head screws, to the floor mount post on one of the drill presses. Even steel rulers were not exempt so I suggest that you work carefully with Sintra. The recovery and replacement of items was very costly so just a word of warning...

I now hate Sintra and its now shop policy to refuse any job that brings it as a requirement...

-Marc
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Postby elec_tech » Tue Apr 04, 2006 4:39 pm

Intersting notes Marc, I will surely watch for any ill effects of it within my little work area.

Thanks...

Dan
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