View Full Version : cutting circles
01-06-2006, 12:45 PM
I am building one of the DeltaII rockets offered by Phillip Landesburg(sp) and am having a heck of a time cutting out circles for formers inside the body tube. I found some paper tubes to use as forms for the SRB (tampon applicators) that were just the right size, but didn't have anything handy for the body. I find that even with a circle cutter, my circles are varying significantly in diameter. I don't think the adjustment is slipping. Any ideas?
01-06-2006, 02:07 PM
How big are you needing.
I found a plastic circle template at the craft store, I draw the circle I need and use my x-acto knife to cut to the line. If you take your time you can achieve pretty good results. It's not fast, but it is successful.
If you over-size them and stack cut-outs together on a mandrill you can use sand paper to to tweak them to exactly the diameter you need.
I have also found a mandrill used to true wheels for Boy Scout Derby cars that allows quite a few pieces to be stacked and sanded at the same time. I use it to make wheels for planes, all the way up to 1/33 size.
01-06-2006, 02:56 PM
You need a good old fashion circle cutter from Fiscars. Google Search should help find your tool. For those realy small circles use a hole punch and them for the really small holes use a multi hole leather punch or a small punch set. Works great. But don't use it on your cutting board. Get a harder surface. Unless you like holes in you rcutting board. -- Don't Say a Word John -- :)
01-06-2006, 08:18 PM
Thanks for all of the responses. I have an Olfa circle cutter and did a search on this forum to find some good ideas I'll try tonight. I guess the only real problem is my lack of skill.
01-06-2006, 09:56 PM
Been there done that - for me it was a case of GFS (gorilla fingers syndrome).
The trick with Olfa (and other) circle cutters is to develop a light touch and
don't try to cut the circle out in a couple of passes - make lots of light passes and all will be well. The circle cutters are usually only plastic and can't handle much force without bending and going out of adjustment.
Try using a card shim under the adjustable slide. It helps in setting and in keeping that setting. Another useful technique is to find a pair of pliers that have serrations that match the knurled adjusting knob. This allows the knob to be securely tightened. When setting up the cutter make sure to only hold the black center turning knob while tightening with the serrated pliers. When cutting thick materials it is advantageous to drill a small diameter hole in the center for the center pin. The drill diameter should be about half the major diameter of the center pin. I've used the Olfa circle cutter on MDF with great success and accuracy using these techniques.
Also practice makes perfect...,
01-06-2006, 10:38 PM
I hope your search dug up this thread
01-07-2006, 12:33 PM
Yes, indeed, I found that thread. I think my problem lies in developing the light touch. I've been spinning the cutter as hard as I could between my fingers, to the point of developing blisters on my index finger. That should have been my first clue that I was doing it wrong! Now if I could master the whole "making everything fit seamlessly" like Swinger et al, I'd be set!
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