# Circle cutter



## bigone5500 (Feb 9, 2014)

I have had an idea to make a cutter jig for my router from some 1/2" polycarbonate. Is this material ok to use for a circle cutter jig? Is 1/2" too thick. I have access to some 1/4" too. The jig I have in mind will be to cut circles no larger than 4' diameter.


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## RogerInColorado (Jan 16, 2013)

I presume you are talking about a circle cutting jig for a band saw. I would make such a jig from plywood or even MDF and save the polycarbonate for applications where you can take advantages of it's properties. Plywood is very adequate for a circle jig and I can't right now conceive of any advantages polycarbonate would offer over plywood. It work well as the adjustable slider for setting the circle diameter.


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## mobilepaul (Nov 8, 2012)

bigone5500 said:


> I have had an idea to make a cutter jig from some 1/2" polycarbonate. Is this material ok to use for a circle cutter jig? Is 1/2" too thick. I have access to some 1/4" too. The jig I have in mind will be to cut circles no larger than 4' diameter.


polycarbonate is really expensive...

you did not say what the jig is for: bandsaw, router, etc.

here are 2 that will cut up to 52" with a router for less than a sheet of polycarbonate

http://www.rockler.com/rockler-circ..._campaign=PL&gclid=CLqJzd-Kl70CFcURMwodemMALA

Jasper 300J Model 300 Router Circle Cutting Jig - Amazon.com

here's one for bandsaw, still cheaper than polycarbonate sheet and are all ready to run

http://www.woodcraft.com/Product/20...g&matchtype=&gclid=CPnCyNOLl70CFY0-MgodPzMAug

here's a review of the accuright http://www.newwoodworker.com/reviews/crtrcircljigrvu.html

here's a video of the one above






here's a bunch of jigs, see what others are using

https://www.google.com/search?q=circle+cutting+jig&biw=1440&bih=681&tbm=isch&imgil=UNv8WZfBvd2HnM%253A%253Bhttps%253A%252F%252Fencrypted-tbn0.gstatic.com%252Fimages%253Fq%253Dtbn%253AANd9GcS3MOC6KNXfTOQmkiHYk6TZksZ5JH2gq3ynOrMy78uS6ZxC1540%253B448%253B336%253BtrgUqssdBG1sYM%253Bhttp%25253A%25252F%25252Fwww.instructables.com%25252Fid%25252FHow-to-Make-a-Router-Circle-Cutting-Jig%25252F&source=iu&usg=__l0TqnciooM0u_2kBoVnbfgDdK2w%3D&sa=X&ei=YZwlU-S8MOmQyAHJ6IHIBg&ved=0CD0Q9QEwAA#facrc=_&imgdii=_&imgrc=UNv8WZfBvd2HnM%253A%3BtrgUqssdBG1sYM%3Bhttp%253A%252F%252Fcdn.instructables.com%252FFOG%252FXUYI%252FG0ZWKJP4%252FFOGXUYIG0ZWKJP4.MEDIUM.jpg%3Bhttp%253A%252F%252Fwww.instructables.com%252Fid%252FHow-to-Make-a-Router-Circle-Cutting-Jig%252F%3B448%3B336


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## Fred Hargis (Apr 28, 2012)

Could it be you mean a router circle cutting jig (trammel)? If yes, it would do fine for that. But like the others, I'm puzzled over the exact question.....


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## builder64 (Jan 1, 2014)

Something like this? 1/4" is fine, but 1/2" won't hurt either.


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## bigone5500 (Feb 9, 2014)

My apologies...

I failed to say that this is for a router. It will go on the Skil model 1830. The last post has just what I am talking about.

I have updated the original post.


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## bladeburner (Jun 8, 2013)

1/4" will be fine. I hold workshops on this jig. I can be used as a circle cutter or ellipse jig. Note that the router is not screwed to the jig, but it held attached with a 1" guide bushing. Therefore, any router will fit, the cord and vac hose don't twist or tangle and with the router always facing you you never have to take your hands off of the handles. 

Drill the the hole for the guide bushing with a forstner bit and cut the slot with a 3/8 straight router bit. Using a shop made platen makes slot cutting safe and simple. When using the jig as an ellipse jig, you'll need support blocks under the router end to keep the jig level with the ellipse engine, but not necessary as a circle jig. Actually, on mine I leave the supports in place and simply flip the jig over since I placed the supports where they don't interfere with the router.

Here's some pics:

Ellipse configuration.










Wrenn router dock.










Platen (made from found lumber).










Ready to attach to platen


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## Jory (Feb 19, 2012)

*Circle cutting jig for routers*

1/4" is fine. But that depends on what you are doing with it. I use 1/4" for cutting recesses in white oak and then clearing part of the center for carvings. With multiple passes I have cut to a depth of 3/4" in oak. As well as using it for inlay work. One additional recommendation is that if you want the circle to have no hole in the center as I do. You can use another piece of the material with a 1/8" hole drilled in the center and by applying double back tape to it, it can be the pivot point for the router. Obviously you also drill a hole in the polycarbonate attached to the router at the appropriate distance from the bit. You will also use some pieces of the material with the double back tape to lift the router end of your "compass" to match the height of the material that is stuck to the work piece. While I use some 1/8" rod from Enco you can just use the drill bit as the pivot.
This system works wonderfully just don't try to cut too deep on a single pass and go slowly.


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## bigone5500 (Feb 9, 2014)

Thanks!


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## Al B Thayer (Dec 10, 2011)

bigone5500 said:


> I have had an idea to make a cutter jig for my router from some 1/2" polycarbonate. Is this material ok to use for a circle cutter jig? Is 1/2" too thick. I have access to some 1/4" too. The jig I have in mind will be to cut circles no larger than 4' diameter.


Great idea. I made one in the same fashion. The poly became the base. I think 1/4" would be the best thickness for a large one.

Al

Nails only hold themselves.


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## Al B Thayer (Dec 10, 2011)

bigone5500 said:


> My apologies...
> 
> I failed to say that this is for a router. It will go on the Skil model 1830. The last post has just what I am talking about.
> 
> I have updated the original post.


There all made that way. If you incorporate a way to micro adjust it. You will like it much more. That's the tough part about using one.

Al

Nails only hold themselves.


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## bigone5500 (Feb 9, 2014)

I was thinking of attaching it to the work piece via a small wood block with glue then when I am done knock it off then sand away the glue. That way I don't have to worry about nail holes. The block needs to be large enough I think to be able to hold the fixture and withstand the forces of the router pulling on the wood. 

I have a habit of overbuilding things once in a while. Simplicity must be bliss...

*edit* If I try to knock off the wood block, it may break some of the work piece out...bad idea...

If I take a carriage bolt and turn it down on a lathe making it have a piercing point, I can use that over and over. I will however have to fill in the indention that it leaves.


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## bladeburner (Jun 8, 2013)

I use dbl-sided tape to secure the pivot block.


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## Al B Thayer (Dec 10, 2011)

You can use hot melt glue. The force on the router is not very much. If it is your doing something wrong. The dbl side tape is a good idea too. The box stores sell an super version.

Al

Nails only hold themselves.


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## Boxedin (Apr 8, 2014)

3/8" acrylic is what I use, mostly because that seems to be readily available to me. It's fairly inexpensive if you go to your local plastics supplier and go through their cut-offs rack, if they have one...


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