Quick router question re widening a woofer flange cutout.

[JRS]

Hi guys. Been absent a while but now in my hour of need (finally in a position to build my 3-ways I have been thinking about for way too long), have a quick question.

I'm looking to get a pair of the Denovo flat packs ( 2 cu ft) to use for bass cabinets--the only issue is that the cutout for the flange is roughly 1/8 smaller than I need; basically looks like I need to widen the existing flange cut from 0.56" to 0.64" or so. I have a decent router but have never used a trim bit with a bearing and could use a hand selecting the right bit for a one time job. The cut out is the right size so don't need to mess with that--simply widen the recess.

Any advice greatly appreciated.

[mattsk8]

Re: Quick router question re widening a woofer flange cutout.

You really have 3 options...

1. Arduously use a Dremel type tool to try to grind the hole out bigger. That said, every time I tried that it was never a perfect circle, and making the hole 1/8" bigger this way might be impossible to do with good results.

2. Depending on the size you need, get a rabbeting bit that would make the hole exactly what you want. But you'll be limited to what's available and may not find one that'll work. http://m.woodcraft.com/search2/searc...ing+router+bit

3. Glue a piece of wood to the back side of the cutout you have now, then glue another to that piece that sits inside the cutout you currently have. Now you can use a Jasper Jig (assuming you have one?) to cut your recess the size you need it to be.

Option 3 will yield the best results, but this is assuming you have a Jasper circle cutting jig.

[ngjockey]

Re: Quick router question re widening a woofer flange cutout.

What i did recently is router out a disc the same size as the inside hole and another bigger but enough to fit the router bit between the the area you need to cut. Glue the two together with a drill bit aligning the centre holes. In my case, I used 1/8 hardboard, matching the recess depth. Be careful to keep any force on the router going toward the centre if it does slip. Probably want to tape any finished surface.

[jonpike]

Re: Quick router question re widening a woofer flange cutout.

You really have 3 options...

3. Glue a piece of wood to the back side of the cutout you have now, then glue another to that piece that sits inside the cutout you currently have. Now you can use a Jasper Jig (assuming you have one?) to cut your recess the size you need it to be.

Option 3 will yield the best results, but this is assuming you have a Jasper circle cutting jig.

I did #3 for a sub box that was about 1/8" too small for an RSS315. Made a crossbar that screwed onto the ft baffle from the back, with a stack up of wood to be level w the front of the baffle in the center, for the router and Jig pin. The key thing, is to determine the center of that circle with a pretty high accuracy. Otherwise, your widened hole will be not centered. You can imagine what happens if you end up with too much of that.

I found this to be surprisingly challenging, maybe because I had to keep it centered in that 1/8" tolerance for a 12" hole. Many cross measurements were done and came out a bit off. Finally thought I had it, and it was still a bit off when cut. Luckily, inside the margin of error. Smaller should be easier, but this is one to measure many times, then cut...

[JRS]

Re: Quick router question re widening a woofer flange cutout.

ngjockey,

I think you lost me: I stack circles filling the cut out and the bigger of the two is close enough to the recess edge that I can use a rabbit? Likely obvious which bit and how to most people, but would it be any easier than providing a temp center like Matt talks about and using a spiral bit with a jig just as if one was starting from scratch?
Thanks--I always appreciate hearing different approaches as my inexperience keeps me from seeing the simple solutions to minor issues like this.

[JRS]

Re: Quick router question re widening a woofer flange cutout.

Matt,
Thanks, I have been there done that with option a--i just get ever widening and wobbly spirals that I might be able to sell as Native American art. Dremels are good for many things but not this I suspect. Option 2 is proving elusive as the biggest rabbit I can find has a 1/2 inch reach--about an eighth short. Option 3 its likely gonna be.
Thanks,
John

[JRS]

Re: Quick router question re widening a woofer flange cutout.

I have visualized this and worried about exactly what you describe. That may be the advantage of trying to cut a dummy disc exactly the size of the cutout as that will be certainly centered.

[ngjockey]

Re: Quick router question re widening a woofer flange cutout.

ngjockey,

I think you lost me: I stack circles filling the cut out and the bigger of the two is close enough to the recess edge that I can use a rabbit? Likely obvious which bit and how to most people, but would it be any easier than providing a temp center like Matt talks about and using a spiral bit with a jig just as if one was starting from scratch?
Thanks--I always appreciate hearing different approaches as my inexperience keeps me from seeing the simple solutions to minor issues like this.

One disc sits inside the cutout to keep things straight. Another bigger disc in the recess area.

[trevordj]

Re: Quick router question re widening a woofer flange cutout.

I think it would be easier to simply cut the proper sized hole out of a scrap piece of wood, secure it so your baffle (it should be pretty easy to center), and then use a flush cutting bit to cut the new hole diameter. The way above would also work but seems more complicated.

[jhollander]

Re: Quick router question re widening a woofer flange cutout.

+1 option 3.

[bret191]

Re: Quick router question re widening a woofer flange cutout.

I have run in to the same problem too.
My solution is a very straight forward easy solution.
Using a piece of wood a bigger than the hole needing the trim I tack it to the back side (using screws) of the piece needing the trim then I cut a hole just a little smaller diameter in a scrap piece of wood the same thickness as the hole needing the trim tack it to the fish plate you just screwed to your work piece measure and drill a new pilot hole for the routers jig pin and then install router and adjust the bit to the size needed to cut the new recess, I start small and work my way up.
You will get a perfectly round hole every time and only takes a few minutes, and will work on holes that are off to one side or holes that are too small too.

GOOD Luck!

[JRS]

Re: Quick router question re widening a woofer flange cutout.

Thanks guys for all the thoughts and wishes--approach c (with or without wood plug to ensure centering or a new center) looks doable even for a novice like myself. And truly I have like an 1/8" play (actually half that) with the cutout, so even if I am a bit off center with my pilot hole, no ever one will ever know but yours truly.

Thanks again, happy holidays to all. I'll post again when I get it done (or need advice after making a wreck of things!:o)

[billfitzmaurice]

Re: Quick router question re widening a woofer flange cutout.

Glue a piece of wood to the back side of the cutout you have now, then glue another to that piece that sits inside the cutout you currently have. Now you can use a Jasper Jig (assuming you have one?) to cut your recess the size you need it to be.

Screw, not glue, as these will be temporary. OP, what you're doing is to in effect return the baffle to an 'uncut' state so that you can use a Jasper to re-cut the recess.

That may be the advantage of trying to cut a dummy disc exactly the size of the cutout as that will be certainly centered.

It's not worth the effort. You just have to make sure that the jig pin placement hole is centered in the driver cutout.

[philthien]

Re: Quick router question re widening a woofer flange cutout.

One more option...

Create a template by cutting a hole equal to the size of the O.D. of the driver, in a piece of 1/4" scrap plywood or hardboard.

Now align (center) the template over the existing baffle hole, and secure with double-sided carpet table.

Finally, use a pattern bit with top-mounted bearing in your router to trim the existing rebate to the template.

[mattsk8]

Re: Quick router question re widening a woofer flange cutout.

Screw, not glue, as these will be temporary. OP, what you're doing is to in effect return the baffle to an 'uncut' state so that you can use a Jasper to re-cut the recess.

No, glue not screw... just don't get carried away with the glue. Once I'm done I take a wood chisel and knock the temporary piece out. I'm not a fan of using screws (especially in the tweeter area because it's already small) because you're making another hole that doesn't need to be there, plus it's not as stable as it would be with just glue. This was one I did where I swapped the original tweeter with one that was quite a bit bigger diameter. The red rectangle would be the board I glued to the backside.