# circles and rounderd corners



## smorgan.mus (Dec 15, 2011)

Fairly new to world of router tables; trying to make coasters and need advice on technique for making perfect hole-less circles and squares with rounded-off corners.


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## bobj3 (Jan 17, 2006)

The key is templates like below you can find them for corners also.

Circle/Grommet Templates - Rockler Woodworking Tools

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smorgan.mus said:


> Fairly new to world of router tables; trying to make coasters and need advice on technique for making perfect hole-less circles and squares with rounded-off corners.


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## harrysin (Jan 15, 2007)

smorgan.mus said:


> Fairly new to world of router tables; trying to make coasters and need advice on technique for making perfect hole-less circles and squares with rounded-off corners.


As Bj has mentioned, templates are the way to go, but I would suggest that you make your own which will result in coasters the EXACT size that you want, plus of course the cost is far lower and to top it off, you have the satisfaction of having done it yourself and learned quite a lot about routing.
The first shot shows the template being made with a circle routing jig which can be made as simple as shown in the second shot or more advanced as in the third shot. The next shot shows a template guide fitted to the bottom of the router and it is held hard against the edge of the template as you rout in a clockwise direction. The final shot shows an easy way to make an accurate template for straight sided projects, be these square, rectangular triangular etc.

Calculating the size of opening is straight forward, choose a template guide and bit, then it's guide diameter minus bit diameter plus the size of the finished item.
For instance, you want a 3 3/4" coaster and want to use a 1" guide with a 1/4" bit, then, 1" - 1/4" + 3 3/4" = 4 1/2" which is the size of hole in the template, it's as easy as that. Having said that, if you need further help, don't hesitate to ask and if you wish, let us know what size template guides and straight bits you have, and the size of the coasters in order to receive more specific advice.


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## bobj3 (Jan 17, 2006)

Hi

Or you can get a pattern router bit and no need to do all the math, just drop it in the template and cut out the coaster you want to use..no need to make it a hard job.

They make pattern bits in many profiles., here's just some of them.
http://www.grizzly.com/search/search.aspx?q=pattern bits&cachebuster=5863976104945269
Here's a neat one that will do all the work for you in one pass of the bit.
http://www.grizzly.com/products/Classical-Plunge-Pattern-Bit-1-4-Shank/C1680

http://www.grizzly.com/products/Deluxe-Pattern-Bit-5-pc-Set/H5540

Plus the easy way to make your own templates.
http://www.harborfreight.com/18-piece-carbon-steel-hole-saw-set-68115.html
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## harrysin (Jan 15, 2007)

Are you just testing that I'm fully awake Bob, as I see it, a coaster normally has square sides which suggests a straight bit would be used. Now, if we used, as you suggest, a straight bit with a top bearing, won't the bit start cutting before the bearing touches the template? Or am I missing something, in which case a little demo. would help me.


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## bobj3 (Jan 17, 2006)

Hi Harry

That's when the 3/4" thick(or thicker) template comes into play, all template are not 1/4" or 3/8 thick Harry 

" coaster normally has square sides " say what, that's like saying most cups/glasses are sq. 

Pattern bits are so much better than using the guide way..
What you see is what you get. 


http://www.ebay.com/itm/1-pc-1-2-SH...642436878?pt=Routers_Bits&hash=item20bef1470e
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harrysin said:


> Are you just testing that I'm fully awake Bob, as I see it, a coaster normally has square sides which suggests a straight bit would be used. Now, if we used, as you suggest, a straight bit with a top bearing, won't the bit start cutting before the bearing touches the template? Or am I missing something, in which case a little demo. would help me.


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## harrysin (Jan 15, 2007)

Perhaps I should have said "all the coasters that I have here at my home and all the coasters that I've ever seen have square sides"

Am I wrong Bob or is it you who regularly advocates 1/4" material for templates?

The bit on that link has a cutting length of almost 2 1/2", so, when the bit touches the material, the bearing is still miles away from the template. I know it's late at night here Bob and that I'm probably missing something obvious so PLEASE show me how it works.


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## bobj3 (Jan 17, 2006)

Hi Harry

Yes I like the 1/4" thick templates but it's not the only way as you know

Most of the coasters I have look like hockey pucks.

Pie is sq. buy not all coasters ..go to just any bar and you will get a round one I'm sure.

I got the tip from the CMT templates,all are 3/4" thick MDF stock.

CMT 3D Router Carver System - Woodcraft.com
Buy CMT 3D Router Carver Classical Cabinet Door Template Model RCS-302 at Woodcraft

CMT 3D Router Carver System Presented by Woodcraft - YouTube
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harrysin said:


> Perhaps I should have said "all the coasters that I have here at my home and all the coasters that I've ever seen have square sides"
> 
> Am I wrong Bob or is it you who regularly advocates 1/4" material for templates?
> 
> The bit on that link has a cutting length of almost 2 1/2", so, when the bit touches the material, the bearing is still miles away from the template. I know it's late at night here Bob and that I'm probably missing something obvious so PLEASE show me how it works.


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## Phil P (Jul 25, 2010)

Of course there's always this type of bit for those who are undecided

Regards

Phil


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## harrysin (Jan 15, 2007)

It still doesn't make sense to me Phil., don't forget that these coasters, both round and square are being routed in one hit, in other words by plunging the router into the material, hence my use of template guides. Tomorrow I'll see if I can get into the shed and rout a round one and a square one using existing templates so the dimentions might be a little odd for coasters.


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## Jack Wilson (Mar 14, 2010)

DING, DING, DING, There's the bell, gentleman back to your corners for a 1 minute break between rounds!:lol:


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## bobj3 (Jan 17, 2006)

Hi

No need for a bell for me, I'm done with this one, no way to win, it's like a game of tic-tac-toe, no winners 

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Jack Wilson said:


> DING, DING, DING, There's the bell, gentleman back to your corners for a 1 minute break between rounds!:lol:


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## Phil P (Jul 25, 2010)

harrysin said:


> It still doesn't make sense to me Phil., don't forget that these coasters, both round and square are being routed in one hit, in other words by plunging the router into the material, hence my use of template guides. Tomorrow I'll see if I can get into the shed and rout a round one and a square one using existing templates so the dimentions might be a little odd for coasters.


Hi Harry

I don't see why it's necessary to plunge at all. If a series of templates are tacked onto the top of a sheet of material with, say, double sided tape the the cut cuold be started from the edge of the material. Obviously the initial templates would have goude holes in them from the trammel point, but that doesn't matter, does it?

Regards

Phil


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## harrysin (Jan 15, 2007)

Please see my today's thread "how to use template guides" which should clear up why bearing bits for coasters puzzle me.


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## harrysin (Jan 15, 2007)

Jack Wilson said:


> DING, DING, DING, There's the bell, gentleman back to your corners for a 1 minute break between rounds!:lol:


I appreciate your concern Jack but there was no agro involved on either side. I simply couldn't, and still cant get my head around Bj and Phil's idea of using bearing bits for the particular project. Perhaps after looking at my post showing what I had in mind, these two gentlemen will be in a better position to explain their method.


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## studtech (Sep 28, 2010)

I have made hundreds of coasters using double sided tape to hold down a square workpiece to a turntable jig on the band saw. Remove edge marks with the same jig on a benchtop disk sander. Seemed way faster and easier than any router jig I could think of. I add a reveal to the edge of the coaster using the router table.


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## JOAT (Apr 9, 2010)

And I do it different. I start with a piece of 1/2" plywood, and make a perfect copy of whatever I want to duplicate. Then glue that to another piece of plywood, and when the glue is dry, rout around it, using the top piece as a guide, and thus creating a 1" thick master. I don't like double-stick tape, so drill pilot holes for thin 1 1/4" long nails. I drill in a decorative pattern, even if the holes will later be concealed, just because I like to.
Then nail the master down to the wood you want to rout. You don't need to pound the nails all the way, but in that case I like extra nail holes for more holding power. Then rout. The 1" gives a nice grip and keeps your fingers just that much further away from the whirley parts.
If I can't pry the master off, because the nails were driven in too far, I just use a small flat 6" nail puller to pry them apart just a bit, then I can just pull it off. The nail puller is about 6" long, and cost me about $1 at the local hardware. Anything else is too large and/or too awkward for this.
Then you repeat as needed.


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## Ed Fleming (Aug 29, 2008)

Harry & Phil, do you guys get into these discussions often? Sounds like my wife & I at dinner!


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## harrysin (Jan 15, 2007)

Of course we do Ed., it keeps the forum interesting and encourages members to show how THEY make the project under discussion. Bj, Phil and myself have lots of respect for each other, there is no animosity involved.
Over time I've received lots of PM's and emails telling me how the member looks forward to logging on each day to see what Bj and I are up to.


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## Phil P (Jul 25, 2010)

harrysin said:


> Over time I've received lots of PM's and emails telling me how the member looks forward to logging on each day to see what Bj and I are up to.


And I'm one of them, Harry :yes4:

Seasons greetings

Phil


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## harrysin (Jan 15, 2007)

Thank you Phil., I do hope that you had a most enjoyable Christmas and that 2012 will be very kind to you.


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## Drew Eckhardt (Aug 2, 2008)

Phil P said:


> Of course there's always this type of bit for those who are undecided
> 
> Regards
> 
> Phil


Routing into grain like this 

bit
v
O 
\\\\\\\ 
work grain
<- movement

not this 

bit
v
//////
work grain
<- movement

can lead to broken lumber (think of the grain like a feather board or anti-kickback pawls - moving work or board so that the pointy bits are pushed down is easy but the opposite direction is hard).

The solution to cutting arcs that transition from one grain direction to the other is to flip the work over. Where you have symmetric pieces they can be flipped with respect to the pattern. That's easy with toggle clamps on the pattern, and less easy with nails/screws/tape. You could use a pattern on both sides of the work although any tipping will damage one of the patterns, that can involve a lot of material, and you might lack the bit length. You can use a top bearing bit and a bottom bearing bit either changing routers (takes more shop space and money) or bits (takes more time). Using a double bearing bit and just raising or lowering as required is often easiest.

Just like the link says 



> The two bearing design allows the cutter to be used with the template mounted on either side of the work and, consequently, it is possible to cut from either direction using only one template and without moving the template to the other side of the workpiece. This is especially useful when cutting curves which run both with and against the grain.


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