Cutting small, perfect circles?

I need to cut four identical perfect circles that are slightly smaller than a dime. This is too big for a punch, and too small to use a
compass. The only templates I have for circles currently are plastic, and I doubt I could scribe one circle before trashing the template.
Any suggestions on how to cut a too big for punches, too smaller for a compass circle?
Thanks!
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Mark Wilson wrote:

The Olfa compass cutter goes down to 1cm diameter. But if it's too small for a compass cutter, you have to make a punch. Find some metal tube of the right diameter and sharpen one edge - voila, a punch!. If no tube is exactly right, get the nearest undersize and expand the end using a cone of some sort (not ice-cream, of course). What are you cutting - polystyrene, paper, or something tougher?
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Templates are for drawing not cutting. You could draw the circle on aluminum, etc. and then after you cut it you'd have a usable master. Or you could get the appropriate drill and make your hole in an appropriate metal. hth
The Keeper (of too much crap!)
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
That's not quite true. I use a template and a dentist's probe (the sharp needle-like one) for cutting small circles and it works pretty well.
The hard part is keeping it from moving while scribing the circle.
Cookie Sewell
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On one project I wanted some circular ribs out of thin plastic. I used scotch two faced tape to attach the plastic sheet to a piece of flat wood, and then cut the two diameter circles through the plastic slightly into the wood using my drill press and a variable size circle cutter. You can clamp the wood to the drill press plate or use a vise to hold the wood. I actually cut multipe pieces glued to the same board. Then carefully pealed the part off the wood and cleaned it. The tape was the Scotch stuff. Basically brown paper with adhesive attached. You press the adhesive side to the wood - peel off the paper and are left with an adhesive surface to attach the plastic. The tape is in a standard size roll so you have to lay strips next to each other. I believe they also make sheets of the stuff - but some of these products have become hard to find as glue up artwork has been replaced with computer graphics. I doubt the thicker stuff that has a backing with adhesives on both sides would work - bot a rigid enough mount. In this case I wanted it to look like aircraft structure - so i also drilled the lightening holes while still on the wood.
Val Kraut

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

one
working.
metal
Probably a lot safer to form and assemble the cylinder FIRST and sharpen the edge LAST with a grinding wheel. Always try to finish with the same number of fingers you started. No fewer and no more. ;-)
WmB
To reply, get the HECK out of there snipped-for-privacy@earthlink.net
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
wrote:

Thanks for the quick answers. I am cutting thin styrene. I'll take a look at the Olfa solution (since a Michael's is down the road), but then go pipe hunting.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
I solved my own problem. As I suspected, using a compass that is over 7 inches tall to scribe/cut out a perfect circle slightly large than 1/4" is tricky--it is way too easy with a 7 " lever arm to flip the compass or "walk" it across the styrene.
So, I stuck the needle point of the compass through the styrene, put the compass in a slight forward lean to more easily scribe, and rotated the styrene sheet UNDER the stationary compass. Depending on the angle you hold the compass at, you can make straight edged or slightly beveled disks. While the process is NOT 100% repeatable, I was able to make the 4 disks I needed in about 15 minutes and 6-8 tries. Like a scribing effort, light but consistent pressure is the key, as well as moving the styrene sheet quickly. If it spins quickly under the compass, there is less chance it will get an oddball hang up or dig too deep a gouge in any one spot.
On Wed, 15 Sep 2004 20:06:36 GMT, Mark Wilson

Mark Wilson
Change .org to .net to reply by e-mail
"If we lose the war in the air, we lose the war, and we lose it quickly." --Field Marshal Bernard Montgomery
http://home.earthlink.net/~mmwilson2 /
RAAM FAQ: http://home.earthlink.net/~mmwilson2/RAAMFAQ/index.html
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
If you're cutting plastic, try a circle template from an art store, Use a needle in a pin vice to gradually score a cut. This works but requires a little edge clean up after. For clean edges, try a lathe or possibly chucking a roughly shaped sheet in a minidrill and using a blade or pin as a cutter. Chek
--
Change' boos' to 'bos' in address to email directly
"Mark Wilson" < snipped-for-privacy@earthlink.net> wrote in message
  Click to see the full signature.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Mark Wilson wrote:

If the plastic is fairly thin, then I think a *quality* bow-compass should suffice. One with two points (a.k.a. "divider(s)"). For more control, hold the "divider" still, and at a slight angle, and rotate the *plastic* beneath the divider.
--

Greg Heilers
Registered Linux user #328317 - SlackWare 10.0
  Click to see the full signature.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
One source I would never had thought to look at was in a scrapbook store that carried all sorts of art supplies. There are a number of punches made for fancy paper work that can be used. I picked up three for about $2-3 each and now have punches that produce 1/2" and 3/4" inch circles as well as the cast 5-point "fat" star used on T-28s and T-35s.
Can't hurt to look!
Cookie Sewell
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On Wed, 15 Sep 2004 23:01:46 GMT, Greg Heilers

Thanks--that's what I ended up doing, and thinking I had discovered something new...;)
Mark Wilson
Change .org to .net to reply by e-mail
"If we lose the war in the air, we lose the war, and we lose it quickly." --Field Marshal Bernard Montgomery
http://home.earthlink.net/~mmwilson2 /
RAAM FAQ: http://home.earthlink.net/~mmwilson2/RAAMFAQ/index.html
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Hobbico makes the tool you need. It's a "Circle Cutter" p/n HCAR0230 $6.69 ea. Cuts paper, film, leather, vinyl, fabric, plastics, rubber, and more. Circles cut from 10mm-150mm (as in .39"-5.9"). Your dime is 17mm. The tool comes with spare blades but extra are $4 pkg. Mine came in my shop (for my R/C car repair shop) today and I'm using it to cut ventilation holes in nitro R/C bodies that are typically .03" thick lexan or polycarbonate plastics.
Dave
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
HobbyOasis wrote:

you can use spent brass. as in guns. if you have a friend that reloads, then ask for some of his. otherwise hit a local gun show. make sure the primer is spent first, for safety.put the plastic on a piece of pine, use a hammer to strike the circle. you can also sharpen the brass with xacto blade to make a finer cut.
jack
http://public.fotki.com/jackwendt /
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
HobbyOasis wrote:

My memory was jolted by your reply ,I remembered my compass cutter hiding at the back of the drawer in my hobby desk . Made by DAFA comes with spare baldes and leads for drawing as well as cutting . 10mm-150mm circles ,even has a little plastic centering thingy to put the centre pin in so you don't poke a hole thru the centre of the circle you cut out .
Thanks for the memory recall
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Mark Wilson wrote:

You can get a set of wad punches from an engineering supply shop ,they start at 3/16 " and usually go up to 5/8" or 3/4" , maybe you can buy them individually also they are generally used for cutting gaskets etc . I have a set of Blue Point wadd punches sold by Snap-On they come in a plastic case and the interchangeable cutting edges screw on to a mandrel ,it even has a spring loaded centre pin for locating the centre of the circle you want to cut out. Can't remember the cost but they will last a lifetime
Just need end grain hard wood or a block of lead to use as cutting surface .
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Any halfway-equipped chemical lab stockroom or supplier should have cork borers. These come in various sizes, usually nested as a set. For this kind of quantity, I'd just try to make friends with the local high school chemistry teacher or anyone you know who works in a lab and ask for a favor. -- C.R. Krieger (Been there; bored that)
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Polytechforum.com is a website by engineers for engineers. It is not affiliated with any of manufacturers or vendors discussed here. All logos and trade names are the property of their respective owners.