Routing the edge of a circle ?

[Rob Matarazzo]

I have a project in the works where I will need to make a groove around the edge of several circular-shaped pieces of wood. The circles are 14" in diameter and made out of 3/4" thick poplar. I plan on using a roundnose router bit (3/16" radius). The groove will be about as deep as the bit's radius and will go around the entire edge of the circular piece, centered between the two faces. I hope I'm explaining that well.

I've never made this kind of a cut before, so I'm looking for some advice. My initial thought is to rig up some type of temporary jig on my router table were I could mount the circular piece sort of like a ferris wheel and slowly spin it around as the bit cuts the groove.

[Jeff Duncan]

I've done rabbets in mdf freehand before to make inserts for my shaper. It worked fine as the mdf is pretty even in density and the bearing kept too much material from being removed. Not sure how well it would work in hardwood though, especially when you hit the end grain?

good luck,
JeffD

[glenn bradley]

Circle cutting jig. For $35 I would probably just buy this one (http://www.rockler.com/product.cfm?page=30473&filter=circle) on clearance. I made one for larger stuff. Works at the bandsaw and router table.

[Bill Huber]

I am still not sure how deep the groove will be but I would just use a slot cutter with a large bearing on the router table. Use a started pin and just turn the circle around, you can open the fence so the circle will just touch the bearing.

The slot cutter bit, there are many different companies that make them.
http://www.eagleamerica.com/product/v146-0130/ea_-_slot_cutters

Bearings for the slot cutter.
http://www.eagleamerica.com/product/196-0022/ea_-_slot_cutters

[Bill Huber]

Circle cutting jig. For $35 I would probably just buy this one (http://www.rockler.com/product.cfm?page=30473&filter=circle) on clearance. I made one for larger stuff. Works at the bandsaw and router table.

So how are you cutting the groove?

[Stephen Cherry]

I vote for Glenns bandsawing of a blank, with Bills bearing, but with this bit to get the radius:
http://www.carbideprocessors.com/radius-flute-cutter-3-16-radius-1-4-shank-whiteside-3182/

If you are making a bunch of these, you may want to make a good circular template to clean up the bandsaw marks

[Rob Matarazzo]

Just to clarify what I'm trying to do, this is a cross section of what the piece will look like:


224456

[Matt Day]

I agree with Stephen. The Ferris wheel idea might work somehow with some kind of jig, but it sounds like it could be unsafe and might turn into a spinning wheel of death! :)

[Bill Huber]

Just to clarify what I'm trying to do, this is a cross section of what the piece will look like:


224456

Ok, now I see what you are doing and I vote for that bit that Stephen put the link to, it looks just like what you need.

[Sam Murdoch]

Yes, I agree with using the bit that Stephen has linked to. That will allow you to work flat on the bench with a handheld router. Clamp your circles down and feed the bit completely under your control. Using a router table either for this operation or for the operation you originally suggested can lead to Matt Day's scenario of the "spinning wheel of death" :eek: . Really hard to control hand feeding a circle - they want to roll you know :).

[Stephen Cherry]

Really hard to control hand feeding a circle - they want to roll you know :).


Just had a flashback if trying to cut a small diameter branch on the bandsaw. It wanted to roll also, so it did.

[Bill Huber]

Yes, I agree with using the bit that Stephen has linked to. That will allow you to work flat on the bench with a handheld router. Clamp your circles down and feed the bit completely under your control. Using a router table either for this operation or for the operation you originally suggested can lead to Matt Day's scenario of the "spinning wheel of death" :eek: . Really hard to control hand feeding a circle - they want to roll you know :).

I don't know, I have done a lot of circles on the router table and never had a problem or it even feel like it wanted to take off and spin. I do not take a full depth cut, I do 2 or more passes but just have not had a problem. The closer the fences are to each other the less depth of the cut.

224474

[glenn bradley]

So how are you cutting the groove?

Doh! I must be off today. I thought I read that he wanted the groove halfway between center and the outer edge like a juice groove on a cutting board. Please disregard; I'll go back out to the shop where I only embarrass myself, in front of myself :rolleyes:

P.s. Like Bill, I feed into the bit and control the material and have no problem with curved pieces trying to get away.

[johnny means]

You want one of these.

http://www.amanatool.com/bits-fv/54300.html

[Keith Westfall]

Kind of the same as Bill using the fence, but you could make a "V" block (with an open end on the vee) to hold the circle as it is cut by the bit. Just position it on the table as required to get the depth of cut you want.

NOTE:! Haven't tried it - but seemed like a good idea....

[mreza Salav]

What Johnny said. No need for jig or anything, just do it on the router table.

[Prashun Patel]

I'd find it safer to use a plunge router on the blank, instead of doing it on the table.

Routing circles on the table can be tricky because you have to rotate the piece as you push it into the bit. The bearing helps, but I just find it tricky. Also, if (like me) you don't have a thin router base, sometimes slotting type cuts are too high above the table to allow the bit to be fully seated in the collet without an extension.

Doing the cut with a handheld will eliminate those 2 probs.

For future reference, if you can't find a bit that allows you to a slotting type cut, I'd find it safer making a jig to hold the router horizontally - rather than make a ferris wheel jig for the piece.

[Sam Murdoch]

Her I go again with my 2¢ :D. I have routed profiles on 3" and 4" and bigger circles with hand held routers with bearing bits by just setting them on those "carpet" pad friction pads and had no issues with control (though the 3" diameters were a little scary until I had done a few). I would NOT EVEN THINK ABOUT trying to feed a circle into a router bit on a router table set up. Those of you above who are saying that this is a safe procedure - have you done it? I'm not saying that it can't be done. I am here to learn. I understand that in this case the depth of the intended cut is pretty minimal. Is that the main criteria? I'd be happy to know that this is a safe technique and would likely do it myself in the future. Thanks for indulging my (and Prashun's) skepticism.

[joe milana]

I say we have Tom Hintz try it and post a video.......JUST KIDDING!!!!!!!!!!

[Lee Schierer]

Because you plan on using poplar, be aware that on each segment your grain at the edge of the cut is going to look like ////////-----\\\\\\\\\ At some point where the grain reverses you are likely to get a lot of tear out unless you can set you jig to make light cuts. Use a circle gutting jig like you would use for making circles with a band saw so you can creep in on the edge cuts.

[mreza Salav]

Her I go again with my 2¢ :D. I have routed profiles on 3" and 4" and bigger circles with hand held routers with bearing bits by just setting them on those "carpet" pad friction pads and had no issues with control (though the 3" diameters were a little scary until I had done a few). I would NOT EVEN THINK ABOUT trying to feed a circle into a router bit on a router table set up. Those of you above who are saying that this is a safe procedure - have you done it? I'm not saying that it can't be done. I am here to learn. I understand that in this case the depth of the intended cut is pretty minimal. Is that the main criteria? I'd be happy to know that this is a safe technique and would likely do it myself in the future. Thanks for indulging my (and Prashun's) skepticism.

And exactly what is wrong with doing it on the router table with a bearing bit? I've done round over bits over circles and curved pieces numerous times on the router table.
BTW, how exactly would do an arched raised panel? don't you do it on the router table?

[Matt Day]

I don't know, I have done a lot of circles on the router table and never had a problem or it even feel like it wanted to take off and spin. I do not take a full depth cut, I do 2 or more passes but just have not had a problem. The closer the fences are to each other the less depth of the cut.

224474

What I was refering to with my spinning wheel of death scenario, would be if you flipped the circle you have in your picture 90* like a ferris wheel as the OP described and used a core box bit or as the OP calls it a roundnose router bit.

I'd be fine with doing it as you have shown Bill.

[Sam Murdoch]

And exactly what is wrong with doing it on the router table with a bearing bit? I've done round over bits over circles and curved pieces numerous times on the router table.
BTW, how exactly would do an arched raised panel? don't you do it on the router table?


I'm not saying anything is wrong just suggesting that that is a risky procedure. There is a huge difference between running a complete 14" diameter circle that if it starts to spin you've nothing to control the spin, in contrast to running the top of a panel to which you have 2 long straight sides to hold on to. I am asking if anyone has truly done this or is just speculating. You are saying that you have. Good info, and I accept that this is safer than I would believe. Not trying to challenge anyone or get your ire up. My question is a word of caution to less experienced folks who might go into this without considering the potential risks.

[mreza Salav]

I'm not saying anything is wrong just suggesting that that is a risky procedure. There is a huge difference between running a complete 14" diameter circle that if it starts to spin you've nothing to control the spin, in contrast to running the top of a panel to which you have 2 long straight sides to hold on to. I am asking if anyone has truly done this or is just speculating. You are saying that you have. Good info, and I accept that this is safer than I would believe. Not trying to challenge anyone or get your ire up. My question is a word of caution to less experienced folks who might go into this without considering the potential risks.

I apologize if my tone sounded harsh (there was no such intent), I was really trying to figure out if I am missing something.
As I said I've done this a number of times, one was doing round over on the top and chamfer on the bottom of this round table:

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You'd typically have a starting pin and rotate the circle against the pin and the bearing of the router bit.
I don't find it more difficult to control than routing a straight line.

I should add that I've used this method and it works for *me*. I don't want to be suggesting something to somebody who might not feel comfortable doing.