# Rounding corners of table insert



## ranman (Oct 27, 2017)

I made my own aluminum mounting plate for my router which will end up in my future table top. 
I cut the plate with a table saw, then cleaned up the edges with my router. OK, ...so I now have a nice pretty and square plate.
I'm curious about a couple of things.
What's the "typical" radius of a store bought insert plate's corners? Mine it totally custom, so I suppose that's not really an issue.

I have a 1/2 inch bit with a top mount bearing. If I use that bit to round the aluminum plate's corners, will I also use a 1/2 inch bit to cut the corners into the table top?
I'll need to make patterns of course to round the plate and then to cut the hole in the table top.
A half inch bit will cut a 1/4" radius in the table top.
......... so when I round the corners *on the aluminum insert plate*,_* I assume*_ that I need to make the pattern with a 1/4 radius and that I can use the same 1/2" top mount bit to make the cut.

I'm just trying to wrap my head around making inside and outside corners that mate.


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## woodknots (Mar 7, 2012)

Randy - keep in mind that you are not routing a hole in the corners of the plate - you are rounding the corners. You will make a template that will allow you to (inside) round the hole in your table. Then you will round the corners of the plate to match that. What I'm trying to say is that you can round the corners of the plate with anything that you like because it's an outside corner.

When I recently installed a Kreg plate in a table, it called for a 3/4" radius for the inside corner of the hole I made in my table - I used a 1 1/2" forstner bit to give me that 3/4" radius.

Hope that all makes sense.


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## DesertRatTom (Jul 3, 2012)

The thing about a simple, shop made plate is that you will find it hard to use inserts, which can be changed to fit your different sized bits. Having the insert fit close to the bit size helps with above table dust collection. Suggestion on cutting the plate opening is good. As to cutting the opening for the bit, it needs to be a little bigger than the biggest bit you expect to use, which means for all smaller bits, you'll have way to large an opening. This is why most of us use commercial plates, some of which now have twist lock inserts instead of the 3-screw (_where'd that darn screw go?_) veriety of old. Kreg makes some nice aluminum plates for reasonable prices. And they have already rounded corners.


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## ranman (Oct 27, 2017)

Thanks, I know I'm rounding the corners of the plate. 
If I made a rectangular template to cut the hole in the table top, a 1/2 inch router bit would make an automatic 1/4" radius in the corners.

Now if I made a template with the same 1/4" radius, any diameter flush trim bit with a top bearing would follow and cut the correct radius. I happen to have a 1/2" bit. I'm just rounding the corners a little.

I suppose I could use a larger diameter Forstner bit to make the corners in the table top, and then make a pattern for the insert plate with the same radius for rounding the corners.


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## ranman (Oct 27, 2017)

DesertRatTom said:


> The thing about a simple, shop made plate is that you will find it hard to use inserts, which can be changed to fit your different sized bits. Having the insert fit close to the bit size helps with above table dust collection. Suggestion on cutting the plate opening is good. As to cutting the opening for the bit, it needs to be a little bigger than the biggest bit you expect to use, which means for all smaller bits, you'll have way to large an opening. This is why most of us use commercial plates, some of which now have twist lock inserts instead of the 3-screw (_where'd that darn screw go?_) veriety of old. Kreg makes some nice aluminum plates for reasonable prices. And they have already rounded corners.


Way too late. My plate is part of a lift I made......... it's just about done. I went a _*wee*_ bit off the deep end constructing it. One of these days I'll post some photos of it.


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## woodknots (Mar 7, 2012)

ranman said:


> Thanks, I know I'm rounding the corners of the plate.
> If I made a rectangular template to cut the hole in the table top, a 1/2 inch router bit would make an automatic 1/4" radius in the corners.
> 
> Now if I made a template with the same 1/4" radius, any diameter flush trim bit with a top bearing would follow and cut the correct radius. I happen to have a 1/2" bit. I'm just rounding the corners a little.
> ...


Correct - I think we were saying the same thing in two different ways. I only used the Kreg with a 3/4" radius as an example, but you could use what ever radius you want.
Be sure to post some pics when you're done - I'm interested in seeing the finished product - sounds good.


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## ranman (Oct 27, 2017)

I assumed that we were on the same page. 
I will post some photos, but not before I do a bit more wet sanding with the 1500 grit and hit it with the buffer and mag wheel polish. :grin:


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## Cherryville Chuck (Sep 28, 2010)

For simplicity use the same radius as the bit you will use to rout the recess. Or leave it square and then chisel the corners square. Either way works. Whichever you think is easiest for you. It's kind of like the same issue with mortises and tenons. Do you square the mortise or round the tenon? Whichever is easiest. Both work.


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## hawkeye10 (Jul 28, 2015)

Cherryville Chuck said:


> For simplicity use the same radius as the bit you will use to rout the recess. Or leave it square and then chisel the corners square. Either way works. Whichever you think is easiest for you. It's kind of like the same issue with mortises and tenons. Do you square the mortise or round the tenon? Whichever is easiest. Both work.


I vote this to be the best answer but all answers are good. :wink:


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## JIMMIEM (Apr 4, 2010)

I had a somewhat similar situation. I need to make rounded corner applied edging for a table top. The table top needed its corners radiused and the applied edging needed its inside corners radiused to match the table top corner radius. Plus the applied edging needed its outside corner radiused too. I found an article on the net with instructions on how to make the templates....it involved several steps but the templates came out exact. In your situation I would do the table top radius first assuming you will use the forstner bit or some other available template. Then do the plate to match......a template for the plate is easily done on the router table.


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## JOAT (Apr 9, 2010)

DesertRatTom said:


> The thing about a simple, shop made plate is that you will find it hard to use inserts, which can be changed to fit your different sized bits. Having the insert fit close to the bit size helps with above table dust collection. Suggestion on cutting the plate opening is good. As to cutting the opening for the bit, it needs to be a little bigger than the biggest bit you expect to use, which means for all smaller bits, you'll have way to large an opening. This is why most of us use commercial plates, some of which now have twist lock inserts instead of the 3-screw (_where'd that darn screw go?_) veriety of old. Kreg makes some nice aluminum plates for reasonable prices. And they have already rounded corners.


Didn't know that when I made my router plates. All I use are 1/2" bits, and I think the hole in my plates are 1 1/2". Works fine for me. But it would actually be no biggie to make different size inserts if I ever decide to. I don't know if I would enlarge the hole or not, likely not, but would make inserts to fit the hole, with different size holes in them, and glue some support pieces on the bottom of the plate, to support the inserts. As my top is 1/2" plywood, inserts of 1/2" plywood should be able to go into place and be right on. Possibly use magnets to hold the inserts in place if need be. Any reason why that shouldn't work?


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## harrysin (Jan 15, 2007)

When making the jig for routing the hole, decide the diameter of the bit that you will use, also the outside diameter of your chosen template guide then use this simple formula: guide dia. - bit dia. + size of the finished hole. For example, a 1/2" bit and a 1.5" guide + 2 1/2" finished hole: 1.5 - 1/2" + 2.5 = 3.5".
The simple corner jig shown takes just minutes to make and you decide on the radius. I saw the corners off first. The shot was of a quick set-up for a member several years ago.
The pdf shows how to make a very simple circle routing jig.


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## ranman (Oct 27, 2017)

Thanks for the photos Harry. Do you coat the edges of the template? If so, what with?
By attaching a template to the under side of a work piece and using a bottom bearing bit....... is that so the template can be attached without damaging the top side (the good side) of the material you are working on?


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## harrysin (Jan 15, 2007)

ranman said:


> Thanks for the photos Harry. Do you coat the edges of the template? If so, what with?
> By attaching a template to the under side of a work piece and using a bottom bearing bit....... is that so the template can be attached without damaging the top side (the good side) of the material you are working on?


No, I've never found it necessary to coat the edges, just keep the router pressed firmly against the template. Regarding whether to have the template on the top or bottom is just a matter of choice, also on what bit you have, top or bottom bearing.
Whilst the photos show wood being routed, Aluminium routs quite easily, I find that slowing the router is the best, too fast and it tends to melt the Aluminium and bits stick to the cutting edge requiring repeated stops to remove.


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## ranman (Oct 27, 2017)

I can't slow my router electrically, so I used a 1/4 inch bit instead of a 1/2 inch bit and used wax on the bit and the aluminum and routed slowly. 
In rounding the corners, I can do 98% of the corner cut with a jigsaw and a final cut with the router


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## ranman (Oct 27, 2017)

I can't slow my router electrically, so I used a 1/4 inch bit instead of a 1/2 inch bit and used wax on the bit and the aluminum and routed slowly. 
In rounding the corners, I can do 98% of the corner cut with a jigsaw and a finish cut with the router. I still haven't decided on the radius. I don't think it's important. I just want to remove the sharp edge for a cleaner look.


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## Cherryville Chuck (Sep 28, 2010)

Randy if your router doesn't have speed control or soft start you can use an after market speed controller. I think Rockler has them.


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## ranman (Oct 27, 2017)

Not in the budget Chuck. Still gots to make me a table. I could probably just file the corners, but then they wouldn't match the finely machined finish of the rest of the plate. :dance3:
A speed control is a ways down the road.


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