Jig for Cutting a Perfect Circle?

[Becky]

I am trying to figure out if there is some jig or set up to facilitate cutting a perfect circle on the scroll saw.  I've seen videos about how to do it on a band saw but as best as I can tell, that method would have the wood hanging over the table instead of lying flat on it.  Plus there is the question of being able to secure the jig solidly to the table so it doesn't move.

I've been pondering this for a while and finally just decided to ask and see if anyone else has figured it out.  Pictures or diagrams would be very helpful.

I am looking for circles maybe 10 inches or so in diameter at the moment though I guess a good jig concept would work for any diameter that could fit a saw's throat depth.  I would plan to cut these from 1/4" BB plywood but again, that ought to be changable (in a perfect world, lol).

Any ideas for doing this?  Thanks for your help.

[daneklund]

I would create a 1/4" wood base plate that is stuck to the table surface with double stick tape.  Then, using a small center pin hole thru the piece you are cutting and into the base plate.  This would work for circles of 5" radius or so.  Sort of limited by the size of the base plate you make.  My approach - I am sure there are some better ideas out there.  Looking forward to seeing them.  Good question.

[chips]

 Hmmmm.... Interesting idea Becky.

  Just off the top of my head I would think you could do as Eclipse mentions only make the 1/4" board long enuf and wide enuf to support the piece you want to cut. double-side tape it to your table. Put a hole in the board for the blade. set the rest up like you would for a bandsaw. The nice part is that you can put a hole in your project wherever you want to start..... not like a bandsaw where you have to start on a board edge.

  The downside might be that scroll saw blades tend to want to wander off to the right unless you compensate for it. But might be an interesting experiment to try.

[dunk]

If you have a dedicated sander cut out your circle and then use the jig on your sander.

[dgman]

Becky, As Dunk suggested I would make a jig for a disk sander. I just cant see doing this on a scroll saw.

[BilltheDiver]

If you don't have access to a bandsaw, how about a router table.  Circle cutting jigs for router tables work well and are easy to come by.

[Becky]

I don't have a band saw or a router.  I do have a small disk sander on the side of my cheap-o belt sander.  I've never even used it.

I'm not going to be able to do anything this week probably so maybe someone with a magic bullet will come along yet.   

[cloetpatrick]

  Il est facile de fabriquer un semblant de tour ? bois avec une simple foreuse dans le cas o? vous n'en auriez pas. 
Voir ici;

http://stevedgood.com/community/index.php?topic=1158.msg8841#msg8841

[jimbo]

Easy on a lathe, does it have to be perfectly round? or just round , if so mark and cut your circle on the scroll or band saw preferably just out side the mark and then sand it round on a disc sander, if that is not good enough ther is plenty of sights on how to make a jig, but they do not always cut true
Jimbo

[Becky]

No, it doesn't have to be perfectly round.  Just "eyeball" round.

What I am wanting to do is make some of those Pennsylvania Dutch hex signs using segmentation.  To do that I'd need to start with a circle of wood because they are all round.  So it doesn't have to be perfect like for a clock gear but it needs to be not noticably unround.

It's sounding like the sanding approach is going to be my best bet.

Thanks for all your suggestions and help.

[sgood]

Becky, the sanding jig is by far the best approach with the tools you have on hand. Also don't rule out that you can cut a very accurate circle with the scroll saw free hand. With a bit of practice you can keep a tolerance of +/- the width of the pattern line. From a few feet away it will look round. Give it a try you might surprise yourself.

[cloetpatrick]

  Yes, it's true Steve, I think I need a perfectly round circle with a central axis perfectly centered. I'm having a lot of experience in the field, but as for the gears of a clock, which must be accurate to 99.9%, I've never been as accurate as a lathe. .. Now, if only to make "right round" without it being too precise, it is true that a simple template is fine. We were not on the same wavelength ... Moreover, here, should not a central axis that is seen to make a cut in! ... 

[jimbo]

You can make it perfectly round on a lathe, but after it is cut the wood may move, unless it is ply and glued on the cross, wood moves after is cut on the long grain not so much on the end grain, make sence?
Jimbo

[dunk]

What is a

Pennsylvania Dutch hex signs

??

[jowshu98]

Mike,

Having grown up in PA these are everywhere there. They are a very beautiful form of art, tradition and history. Here is an article I found that explains them. http://www.padutch.com/hexsigns.shtml. I thought of making one for my house a while back and completely forgot about it with everything else going on; I think I might just give it a shot when things slow down a little.

Don