Router pattern jig for 3 inch circle


miranthis
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I need to make a shallow 3 inch round hole in a board and I thought about using a router with a pattern bit.  But, how do I make the perfect circle pattern?  I can make square and rectangular patterns all day, but I need the circle to be perfect.  most of the web examples show a jig for cutting larger circles, say 6 inch or larger.  TIA,

 

Jeff-in-KC

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4 minutes ago, miranthis said:

I need to make a shallow 3 inch round hole in a board and I thought about using a router with a pattern bit.  But, how do I make the perfect circle pattern?  I can make square and rectangular patterns all day, but I need the circle to be perfect.  most of the web examples show a jig for cutting larger circles, say 6 inch or larger.  TIA,

 

Jeff-in-KC

Forstner bit or hole saw.

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Just need to make a recess for a scout patch in a plaque, probably 1/8 inch into the board.  I've done this with Forstner bits for challenge coins, but this is substantially larger for a round position patch and also a larger troop neckerchief patch.  Also, I'd like to learn the trick to making the pattern out of MDF so I can also to ovals, pie slice shapes etc.  and not just buy multiple $30+  bits I may only use once.

 

Thanks though.

 

Jeff-in-kc

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This is very close to a recent thread but, I couldn't dig it up.  The jasper jigs are certainly versatile if you will be doing a lot of different sizes often enough to warrant storing it.  For a one-off I would cut a hole in some 1/2" ply with a circle cutter (yes, you have to store that too :D) and use a bearing guided bit or a template guide.

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Yeah I'd use a circle cutter too.  Unless you have a hole-saw that size.  There is no "one-size fits all" type of technique to making templates...you have to have a starting point for every shape out there.

The reason you only see 6" and larger hole templates being made with a router is because you can't make them any smaller due to the size of the router base.  Maybe with a trim router you could manage a tiny bit smaller.  Otherwise buy one of these...

http://www.leevalley.com/US/wood/page.aspx?p=32275&cat=1,180,42316

 

99K0901S1.jpg

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Just now, Immortan D said:

Nah you don't need one. Neither do I, with all those forstner bits we have lying around.

Right.  And that's the same reason that the circle cutter is a more versatile addition to a bit collection...if I need a circle that's 2-5/64"....I can make one.

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I will be using a trim router and I have done irregular shapes freehand, but thought a pattern bit would work better for a regular shape.  I have made mortise templates, just not something round.  Whatever solution I come up with will need to be non-maring so probably a clamp on deal.  Measured the larger of the two patches I need to recess for and it is 3 & 7/8 inch across.  Appreciate the input.

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Everything Vinny said! I had a fly cutter I was going to use to cut my sound hole on a guitar I built. Fly cutters are both dangerous and scary. They all have that "Made in China for mass export" feel to them. I personally would go with something like this for ease of use and the ability to do multiple sizes using a guide bushing and a 1/2" spiral bit

https://www.amazon.com/Router-Circle-Template-Peachtree-Woodworking/dp/B003UO676O 

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+1 on the scary fly cutter ! Practice and using MDF for your template is quite helpful. Rub some glue into the edge of the MDF to harden it & reduce wear from bearings. Never try one of these unless you are using a drill press.

Clamped down workpieces, slow feed rate and a tightly puckered backside are prerequisites !

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On 9/28/2016 at 11:33 AM, woodbutcher74 said:

Try drilling a hole with a forstner bit. Then use a rabbeting bit to enlarge the hole part way through. Switch to a patterning bit to bring the rest of the depth to the same diameter. Repeat as necessary to get you hole to the right size. Perfect hole every time.

Skip to 17mins.

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