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how do you cut circles in plastic sheets?

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  • Member since
    December 2002
  • From: Connecticut, USA
how do you cut circles in plastic sheets?
Posted by Aurora-7 on Thursday, December 19, 2002 9:09 AM
I want to simulate spinning props using clear plastic. I've read several ways of how to simulate the blur of the prop blades but it's how to cut a perfect circle that I'd like some advice on. What have some of you used to do this?

 

 

  • Member since
    November 2005
Posted by Anonymous on Friday, December 20, 2002 11:45 AM
I use a circle template and very carefully cut around it with an exacto knife. I have never done this for a prop on a plane kit but I have done it for the tire mud plugs on sprint car kits. I'm sure it would work the same.
Good luck,
Pat
  • Member since
    December 2002
  • From: Canada / Czech Republic
Posted by upnorth on Friday, December 20, 2002 5:11 PM
Some mathematical compasses can be fitted with specially made blades in place of the usual lead pieces.

I used to have a student grade Staedler drafting compass that I found blades for in a drafting supply shop. It worked very well for cutting circles out of sheet styrene that was up to .040" in thickness.

I know that Evergreen makes clear styrene sheets up to that thickness, so if you can find a drafting compass with blades available for it, I'd say very lightly score the outer diameter of your prop disk onto the plastic then gradually adjust your compass to smaller diameters and lightly score circles until you come to the centre of your disk. After that, set your compass back to the full diameter and cut the disk out of the sheet with a little extra pressure on the blade.

Once you have it cut out, indicate the positions and colors of the prop blades with a wash of their color and streak the paint in the direction the prop would turn.
  • Member since
    December 2002
  • From: Connecticut, USA
Posted by Aurora-7 on Sunday, December 22, 2002 7:40 AM
Thanks for the advice, guys.

 

 

  • Member since
    November 2005
Posted by Anonymous on Saturday, December 28, 2002 10:24 AM
Just want to let you know that the manufacturer Olfa of Japan makes a very nice
circle cutter.
HTH,

Mark
  • Member since
    November 2005
Posted by Anonymous on Sunday, December 29, 2002 11:17 PM
You might also try a craft store and check in the framing department for mat cutters. you can find some that cut circles and elipses.
  • Member since
    December 2002
  • From: Third rock from the sun.
Posted by Woody on Tuesday, April 15, 2003 7:49 PM
A drafting circle templet and a frisket knife. You can find the templets at drafting supply stores or Hobby Lobby. I bought my frisket knife at Walmart. The circle templet has marks that will let you mark dead center.

" I wish to have no connection with any ship that does not sail fast; for I intend to go in harm's way." --John Paul Jones
  • Member since
    February 2003
  • From: Grass Valley, CA
Posted by seaphoto on Wednesday, April 16, 2003 10:44 AM
To expand on the drafting compass recommendation, find a compass that uses leads that are about 1/16" or so; this is pretty common, I found mine at Staples. Typically, look for the professional looking compass as opposed to the type where you insert a whole pencil.

Then go to the hobby shop and find the replacement blades for the x-acto retractable knife. This is a small blade with a while plastic holder molded onto it, with two steps. Cut the larger of the two steps off, and you will find that the second smaller step will fit nicely into the drafting compass.

I use this not only to cut circles in plastic, but also in sheets of solid color decal film, to duplicate the thin warning circles found around modern naval weapons.

Hope this helps a bit

Kurt

Kurt Greiner

Interested in large scale, radio control warships? http://www.warshipmodelsunderway.com

  • Member since
    November 2005
Posted by Anonymous on Thursday, April 17, 2003 8:49 AM
Expanding on the circle template idea use it and scribe your circle on a piece of sheet metal & cut your hole out of that & make you up a series of patterns & that way you won't cut into the drafting template. You can drill a smaller hole in the sheet metal & file up to your required dia
  • Member since
    January 2003
  • From: NE Georgia
Posted by Keyworth on Thursday, April 17, 2003 9:58 PM
In another thread I mentioned using my Olfa circular cutting tool for jobs such as this. It will cut circles up to approx. 8 inches in diameter. Not bad. Comes with a spare blade as well. -Ed
"There's no problem that can't be solved with a suitable application of high explosives"
  • Member since
    November 2005
Posted by Anonymous on Tuesday, April 22, 2003 2:25 AM
Leather Craft stores and websites have huge assortments of "circle" punches in different sizes and shapes.

http://www.tandyleather.com/
http://www.leatherfactory.com/
  • Member since
    January 2003
  • From: Washington, DC
Posted by TomZ2 on Thursday, May 8, 2003 3:50 PM
QUOTE: Originally posted by Aurora-7

I want to simulate spinning props using clear plastic. I've read several ways of how to simulate the blur of the prop blades but it's how to cut a perfect circle that I'd like some advice on. What have some of you used to do this?


I've done exactly what you've trying to do. Two suggestions:
(A) If you're doing a multi-engine aircraft (e.g., a P-38 -- EVERYBODY does a P-38 sooner or later), use a circle cutter as described elsewhere in this topic, but cut the circles a little large and mount them NOT TOUCHING on a common axis. Now you can use a disk sander (I used my Shopsmith) to make them EXACTLY the same size. It also leaves a nice "blur" at the edge, which leads to ...
(2) [foolish consistancy being the hobgoblin of small minds!] If you take your prize(s), mask all but where you want the blurs to occur (nominally wedges in the same number and spacing as the prop blades that aren't going to be there) with Scotch Brand Magic Tape, spin them up (one at a time this time) on whatever you've got that passes for a lathe, and lightly touch with 0000 steel wool -- the result, after stripping the mask off, is a first rate prop blur.

Occasional factual, grammatical, or spelling variations are inherent to this thesis and should not be considered as defects, as they enhance the individuality and character of this document.

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