Help : Best way to flush mount speaker drivers and other router tips wanted??

[Cacophonix]

Hi,

I am in the process of building my first DIY project - proac 2.5 clones. I have zero experience in woodworking . I already have the drivers from audiocomponents.nl and the XO is on the way from madisound. Now I'm having some issues in the cabinet construction.

I have a dewalt dw 621 router and the jasper circle jig. But how to flush mount the speakers?? Do I first cut the hole and then use the router to go round and rabbet? Or should I first cut a circle with depth = thickness of the flange and then cutout the driver hole? I want to get this done without having to buy too many router bits. I would also like to have curved sides. So are there any tips on how to do this? I know I need a router bit for that, but my concern is how do i make sure that I go straight while using the router?

Can any of the speaker builders share their experience in this area? I see many pages devoted to the construction of proac 2.5 but none of them shed any light on the flush mounting part.

Thanks a million,

Cacophonix

 

[pinkmouse]

Hi Cacaphonix

You need to cut the rebate first using the circle jig, then the opening. It is easier to do this before the box is built, when you can work on the flat!

To round over the corners of the box, you need a bearing guided roundover bit. This is self guiding, and will follow the shape of the box. These are very common, and availabe in a range of sizes, just look in your local toolshop.

Hope it all goes well

 

[Peter Daniel]

It depends on driver's flange, but sometimes it's convenient to mount the driver in a regular way and then use another piece with a thickness equal the thickness of a flange with a cut out hole and glue it to the original baffle. If it's 1/2" or more, I use another piece of MDF and if it's 1/4 or less, veneered plywood or cork or foam works well.

 

[DrewP]

What i did was to nail a brad into the exact centre of where I wanted the driver to be.

I built a perspex base screwed to the underside of my router with a circular cutout to give clearance for the blade and two holes drilled on the underside that fitted the size of the brad.

One hole was positioned so that from the centre of the hole to the outer edge of the router blade was the radius of the rebate, the other was to the radius of the driver cutout.

I dropped the router onto the hole for the rebate and cut that first (about 5mm for my fostex driver) then I moved to the smaller hole and taking shallow cuts did the hole gradually till I was within 1mm or so of the back of the panel of mdf.

The last mm I cut with a knife.

The holes came out perfectly round, and it was pretty hassle free and easy to reproduce precisely later on if i make more.

Of course now I've changed routers I"ll need to build a new template but it's not too hard.

Drew

 

[Cacophonix]

Thanks a bunch Guys! That pretty much what I was looking for regarding the rabbeting process

Now, If I may, onto some other basic questions I have
- Whats the best way to brace the cabinet? Make 1/4" grooves and fit the brace or just glue the brace?

- And my next question is about veneering. I have read this cool veneer tutorial that everyone seems to be referring to. But it assumes that we have enough veneer to cut a single piece and wrap it around the speakers. But with the proac being 40"H x 10"D x 9" W, I would need a minimum of 40"W x 38"L veneer. And given that on online auctions, I can find only smaller pieces, is there a good way to apply such pieces of veneer? I am assuming that one should not bend the veneer around corners against the grain pattern. I plan on using hi-gloss tung oil to finish the veneers. So should I stay away from any particular type of veneers?

Thanks a million again,
Rajiv

 

[Kanga]

Hi Rajiv

There should be no need to recess the braces. Provided that they are properly glued to each side, then they should work fine. You may want to read about my experiences with bracing. See post "cross brace not working".

With veneering, you should be able to find plain veneer in sheets 1200mm x 2400mm (47" x 95") or similar. What kind of veneer are you planning to use? Sounds like you are going the contact cement way, which I haven't done, but the recommendations there are to use NBL veneer. I'm not sure what sheet sizes they are available in. Have a look at some veneer suppliers on the net.


Mick

 

[jbandpc]

You need to cut the rebate first using the circle jig, then the opening.

This is what I did... but... When I dropped the driver in, the radius of the rabbet was ever-so-slightly too small. Any suggestions on enlarging the radius of the rabbeted part when the center of the hole is gone?

 

[x. onasis]

jbandpc-

I've got a couple suggestions for you.

1. If the driver cutout is smooth and parallel to the rabbet shoulder, you might be able to use a slot cutting bit with the size bearing that will give you the right outer diameter.

2. You could place a block in the cutout with a new pilot hole. This could be any piece of wood that will fit inside the cutout with a backer board large enough to secure it from the backside with some screws. Find the center with a small triangular scrap rotated inside the circle and marked on one edge each move.

3. Cut another board with the proper size cutout, and use it as a template in combination with a pattern makers' bit. These are like flush trimming bits, except the bearing is on top of the cutter.

I would go with #3, as you would then be able to cut the veneer with the same jig. It might not be a bad idea to make this jig large enough to index it. (with pencil marks or wooden stops) Then, when you have to center it again after veneering, it's all done.