# How to cut a clean 10" hole in 3/4" plywood?



## b2rtch (Jan 20, 2010)

I have to make 48×14"x14"x 3/4" plates out of plywood and to cut a 10' hole in the center to install speakers.
What it the best way to cut clean holes in the center?
Thank you for your help.
Bert


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## alba (Jul 31, 2010)

Bert I use the router.


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## b2rtch (Jan 20, 2010)

Ok and router and what? 
A downward spiral cut bit and what do I use to keep the radius,? A home made jig?
Can I do that on my router table?


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## crashn (Aug 26, 2011)

router with trammel. easiest way to explain is pictures. here is a link to the thien baffle page, where a person goes through building the thien separator. http://www.cgallery.com/smf/index.php?topic=429.0 in that page, he shows a trammel.


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## Alexandre (May 26, 2012)

LOL, this is hard to believe, but there is a 10" hole saw I have.
You want a 10 Foot hole?


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## b2rtch (Jan 20, 2010)

no, I do not want a 10 foot hole, sorry for the typo.
I figured it out this morning. 
I made a jig already, thank you all.


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## Alexandre (May 26, 2012)

LOL 
Imagine a 10 foot hole
LOL


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## b2rtch (Jan 20, 2010)

especially in a 14"x14" plate!


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## Bluepine38 (Dec 14, 2009)

And I was just going to say that a circle cutting jig on a big bandsaw would work, I missed the typo, and then
I realized that it would have to be a scroll saw cut. Time for another cup of tea.


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## PurpLev (May 30, 2008)

I cut some really clean circles (external and hole) here:
http://lumberjocks.com/PurpLev/blog/7085


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## b2rtch (Jan 20, 2010)

Thank you Sharon, I have a similar guide for my Bosh router but is it mounted in my router table. I want to try to use my rigid trim router (not plunge) as it is easier to handle.
I have a pretty good idea how to make a jig, my concern is that the Rigid router it not plunge, I do not know how this is going to work.


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## BinghamtonEd (Nov 30, 2011)

If you need to work around the plunge issue, You could drill a pilot hole larger than your router bit that just touches your circle's radius. Mount your circle jig such that the router bit starts in that hole. You can make multiple passes from this pilot hole by adjusting your bit depth. Put your piece on a sacrificial board, clamp it down, and make sure your circle jig is fastened through the workpiece into the sacrificial piece. This will help prevent tearout underneath and make sure your jig stays put on that last pass when the circle becomes separated.


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## b2rtch (Jan 20, 2010)

BinghamtonEd, good idea , thanks


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## woodworm (Jul 27, 2008)

Watch the vid presented by MLCS, you will have the idea to make your own Circle jig on Router Table. I made one for cutting full and part of the circle using the same jig. Good luck. 
http://www.mlcswoodworking.com/shopsite_sc/store/html/smarthtml/graphics4/router_circle_jig104.jpg


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## b2rtch (Jan 20, 2010)

woodworm, I really like the video, it gives me all kind of ideas. 
Thank you very much.


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## BinghamtonEd (Nov 30, 2011)

Do you have another piece with a similar 10" hole? If so, you could just use a pattern bit to duplicate the hole. Back in my college days I used to build subwoofer boxes for cars and had several patterns for 8, 10, 12, and 15 inch speakers. Sold them for beer money


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## b2rtch (Jan 20, 2010)

BinghamtonEd, good idea but I think that I am going to cut them on my router table.
For added safety I am going to buy a foot switch at HF tonight to control the router.


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## Alexandre (May 26, 2012)

I got my 10" hole saw from here http://www.customholesaw.com/index.php?main_page=page&id=3&chapter=1
Although, I think a router would be better and smoother.


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## b2rtch (Jan 20, 2010)

$254.90, pretty expensive


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## DS (Oct 10, 2011)

If I had to make a lot of these holes, I would take my time and make a template out of either 1/4" MDF or 1/4 Plexiglass. Then use a pattern routing bit and a pilot hole to route these on your router table.

Take your time on the template and the rest is easy peasy.


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## DrDirt (Feb 26, 2008)

Couple ways (many I'm sure) but two ways to cut this with a router

I just thought also a disk - undersized - which would place the hole dimension at 10 inches with the router bit could be made out of MDF and then just double stick tape it to the 14X14 squares, and route away. Still a lot of strain on the router.

Once you made the first one though you have a pattern.
Then you can cut quickly to rough size, the hole, with a jigsaw, then use your pattern to flush trim the other 47 pieces to make the holes all smooth and purdy


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## b2rtch (Jan 20, 2010)

Thank you guys, I am going to cut them on my router table.
What I am not sure yet is the bit I should use: a straight bit or spiral bit?
Up or down spiral?
What do think?


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## BertFlores58 (May 26, 2010)

Hi Bert (my namesake),
The way I do cut a hole for the speaker is to use a portable router that has a cicle attachement (or you can make one). Here is the link:

I normally use spiral bit. But others will do also. Hope this will help you out.


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## b2rtch (Jan 20, 2010)

Interesting idea, thank you Bert.


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