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-   -   Widen hole? (http://www.diyaudio.com/forums/construction-tips/206010-widen-hole.html)

nonsuchpro 5th February 2012 05:16 AM

Widen hole?
 
Hey all ;)
I recently re-acquired an old 4x10 bass cabinet I used to own. The speakers were trashed so I bought a new set of 4. Unfortunately, they are a bit bigger than the originals so I need to widen the holes. Normally, I use a dremel with a sanding cylinder but it takes forever! What it the best way to make the holes a few cm wider?
Thanks in advance! :cheers:

JRKO 5th February 2012 03:15 PM

jigsaw - sloooooow and steady

nonsuchpro 6th February 2012 11:39 AM

Quote:

Originally Posted by JRKO (Post 2892966)
jigsaw - sloooooow and steady

Yeah tried that but the holes are recessed so I couldn't get the whole hole. I did it with a sanding drum for the drill, that worked.

Thanks!

amt 6th February 2012 06:09 PM

1 Attachment(s)
Sorry Im late to the game but an easy and accurate way is by using a router. Attach a scrap piece of plywood to the inside of the speaker baffle using the existing mounting holes. It needs to span the hole and be centered in it. Then you add a shim in the center of the ply that is flush with the front baffle. Then just use this as a center pivot point for your router/circle jig. The toughest part of the procedure is finding the exact center of the hole.

amt

Cal Weldon 6th February 2012 07:11 PM

Not hard if you draw lines between the speaker mounting holes. Can't miss.

My question is: it sounds like he has rebated holes and you have him fastening the board through holes that need to be cut (inner hole and rebate hole). I would suggest drawing lines (using the speaker mounting holes) further out and mounting and mounting the board there. Can you remove the baffle so you can get at thee back to mount the board?

You might also want to shim the board to keep it away from the back of the baffle for better clearance?

nonsuchpro 8th February 2012 12:39 AM

Thank you for the replies. It was just millimeters I needed to shave off so the sanding drum really did the trick and quickly.


http://i39.photobucket.com/albums/e1...o/FILE0075.jpg

Cal Weldon 8th February 2012 02:56 AM

Nice.

ODougbo 9th February 2012 09:40 AM

1 Attachment(s)
Good, never thought of that - some trades use hot glue for temporary jobs like this.

Here's a few couple of bits that I use (all very, very cheap). I swapped the bearing out on the middle one, the idea is that you make a
shallow pass and then come back with the flush bit (on left).

The taper bit works really nice, I bought that and didn't know what to do with it. Same idea, make a very shallow pass and then come back and clean it up.

Sometimes you can make a large hole in scrap wood - and then come back and use-the-outside-edge of the router. This is the slowest way, but works nice.

btw....this is the bit that any speaker builder will enjoy, about $40 but cuts wisper clean and has a bearing top and bottom.

Down Shear Trim Router Bits with Upper Ball Bearing by Amana Tool






Quote:

Originally Posted by amt (Post 2894522)
Sorry Im late to the game but an easy and accurate way is by using a router. Attach a scrap piece of plywood to the inside of the speaker baffle using the existing mounting holes. It needs to span the hole and be centered in it. Then you add a shim in the center of the ply that is flush with the front baffle. Then just use this as a center pivot point for your router/circle jig. The toughest part of the procedure is finding the exact center of the hole.

amt



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