This particular cabinet pictured in an earlier post looks like it has lots of room for the router.
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Enlarging Speaker Hole
- Thread starter gregmari
- Start date
- Feb 12, 2006
- 61,011
- 5
- 220,859
- Disclosures
- Development Engineer-Mesa Boogie, Development Engineer-Genzler (pedals), Product Support-Genz Benz
Indeed, the pictures did not show up when I looked at the original thread. In THIS case, a small router and a round-over or chamfer bit might work fine.
I was talking about cabinets in general, most do not have so much space (certainly none of mine come even close).
Local car audio shop will have speaker rings to let things fit with out major modifications in case you ever want to use original drivers again. If the drivers works out, the ring can be used as a template for the final hole.
Not too many people can draw a round circle let alone sand one. One of the EV's already has a suspicious gasket already.
The first post in this thread has a photo...
The shortest distance from the edge of the hole to the lip is bigger than half diameter of many small and mid-sized routers. You only need approximately half the space, because the bit is in the center of the baseplate.Using a chamfer or roundover bit may work, but it may also leave a very thin plywood, or in this case OSB, edge on the inside. This may cause plies to separate which may buzz later on, which is why I suggested a rabbet converted to a flush cut. Doing it in two steps preserves the original shape and eliminates the need for any sort of template. The existing hole IS the template, you're just enlarging it by 1/16" (half of 1/8" - 13-3/4" to 13-7/8"). To increase a diameter, you remove half the needed increase all the way 'round.
The MDF standoff plates were suggested for larger routers or other situations where there isn't clearance for the router base. It essentially creates a smaller base for the tool to ride, allowing the rest of the base to overhang the lip in areas where it would have interfered. You'd simply extend the bit more to reach past the spacer. The same solution is effected if MDF strips are carpet taped around the hole or to the router base.
I'm a formally trained woodworker who has modified (customized?
) many assembled, installed, and finished cabinets, furniture items, road cases, and speaker cabinets since the 80's. This is a freshman level five minute job. If the OP were closer, I'd offer to do it for free while he waits. He could leave his car running. 
Hope my explanation helps!
- Feb 12, 2006
- 61,011
- 5
- 220,859
- Disclosures
- Development Engineer-Mesa Boogie, Development Engineer-Genzler (pedals), Product Support-Genz Benz
The picture in the original post was not visible when I posted my information, hence the general nature of my comments.
The roundover or chamfer amount is very small, I have done this procedure many times (on cabinets with much less clearance than his).
The roundover or chamfer amount is very small, I have done this procedure many times (on cabinets with much less clearance than his).
And if he doesn't get carried away, there's no reason the original driver or a new, different one can't be put back in there. It's not an irreversible mod.
At first I thought Plain Old Barry was mistaken, but when I took another look at the pic, I see he's right...the back of the box certainly does appear to be OSB. My hat's off to Hartke for using such premium materials.
Kinda looks like the baffle board is MDF, which would indeed make the OP's job a piece of cake, even with nothing more than rasp, or yes, even just sandpaper and a healthy helping of elbow-grease.Meanwhile, thanks Plain Old Barry for taking the trouble to show us the router bit technique. Many years ago, when I was attempting to resolve this admittedly minor problem, I didn't know about router bits with the pilot bearing on top. In fact, I tried to visualize how I'd kludge together something that did exactly that. (this was in the pre-Internet days) I've haven't had occasion to contemplate how to resolve the issue since, but I see how this technique could be useful. Happily, I rarely have occasion to do mods to old speaker cabs these days. My history with doing anything more drastic than this sort of minor modification to an old cab is that, at some point in the process, I end up saying to myself, "I could have just built a whole new cabinet for the amount of effort this is taking."
Gregmari asked the board for the time and we told him how to build a watch, but I think the actual answer surfaced a time or two. Good luck with it...that driver in that box should rock pretty good.
Nowadays, you can have bearings on both ends, so you can choose which side is guiding, as well as bits with dual shear angles. The second bit shears down both faces at the same time, ejecting the waste in the center, leaving perfect faces on both sides. Not necessary here, but very handy if both sides will be semi-visible and you don't want it to look like a beaver did it.
You can have this done with a rounded rasp file quicker than it takes to set up a router, and with much less dust. And the file will cost less than a cheap router bit, let alone a router.
You could have done it quicker than the time it took to read the dang thread. LOL
