I have a chance of getting a 12" cube of elm from a barn beam. I was thinking of mounting an old console FR driver to make a funky tabletop speaker for a mono setup. I don't have any power woodworking tools, but my brother-in-law has a router and a Porter Cable circular saw. Anyone have any ideas on how to bore a 7" hole in a 12" deep block of wood?
I would rout to flush fit the speaker and then remove the center un-routed material with in this case a sawzall.
A hammer and wood chisel would work for hollowing out the interior, if you don't mind being old-fashioned and have some time on your hands. Multiple passes with a drill and Forstner bit would also be an option for roughing out the interior, followed by finish work with the chisel...
With due respect, it will be a lot of work, for a very poor cabinet (to put it mildly).
It will be as bad as using a 12" long piece of 7" diameter sewer pipe.
Not better than my very first DIY cabinet: a 4" speaker glued to the end of a 12" long cardboard tube.
It will be as bad as using a 12" long piece of 7" diameter sewer pipe.
Not better than my very first DIY cabinet: a 4" speaker glued to the end of a 12" long cardboard tube.
Thank you for your concern. The plan is actually to cut a large wedge off the back of the block with the circular saw once the hole is bored, in effect making it a small monolithic footed open baffle. I have a small amount of room on a TV console for placing the speaker to get it off the ground, there is no floor space available for a speaker stand or large board open baffle. I felt it would be much easier to bore the hole in the cube before trying to cut the wedge off, but if you have a method of boring a large hole perpendicular to a face of a triangle, I would love to hear it. Now you could certainly argue the merits of a 12" baffle for 7" driver, but it most certainly will not mimic your first DIY efforts........
I didn't know what a fly cutter was, so I did a quick Google. The internet tells me it is a bit used to machine metal, is that correct? And I didn't see one for sale that had the required diameter of 7", so it appears I would also have to purchase a tool blank to clamp it to and and machine it to the appropriate diameter. If I was going that route, I would probably be better off buying a simple 7" hole cutter designed for wood for the drill press, would I not?
With the hole cutter, you would still need a chisel to open out the hole, as the hole cutter would only do the periphery of the hole. The forstner bit approach seems to be the least onerous method for hogging out a large volume of material, as long as you have a sturdy drill press. The fly cutter will also only handle the periphery of the hole.
First perhaps using a 1/4” bit route a circle 5 1/2” in diameter about 1/2” deep. Then drill a series of holes using a drill bit of up to 2” diameter to the depth you require with the groove as a centering guide. Follow that with a route of 4 1/4” diameter and similar drilling. The last drilling route would be 3” in diameter followed by a series of holes. Finally just drill out the center.
With the router, you can cut a final circle of the right 7” outside diameter perhaps 3/4” deep using a 1/2” diameter bit. Best done with a template you can make with the router and a scrap of wood.
You can use a chisel to do a bit of cleanup on the inner mess but as all you are looking for is volume, the inside doesn’t need to be completely hollow.
With the router, you can cut a final circle of the right 7” outside diameter perhaps 3/4” deep using a 1/2” diameter bit. Best done with a template you can make with the router and a scrap of wood.
You can use a chisel to do a bit of cleanup on the inner mess but as all you are looking for is volume, the inside doesn’t need to be completely hollow.
The fly cutter I have has a drill bit (1/4 inch) that sets the center hole, and an arm perpendicular to that bit has an adjustable slider that holds a cutter bit that resembles something you might see on a lathe. You set the hole diameter with that. This goes into a drill press, and you clamp the work piece down and slowly lower the drill press's spindle to cut out the hole. It cuts a very clean, smooth hole in wood.
Well yeah, that sounds like your average fly cutter, but it still will only do the outside periphery of a hole. I suppose you could start with a small hole diameter and adjust for a little larger each time, but that sounds kinda tedious...
Think again.
A 12" open pipe is still a 12" open pipe.
Speaker backwave will find no difference between cardboard walls or solid wood, as long as diameter and length match.
This Lady is doing better than you and me, since she chose a longer tube 🙂
Nothing personal, it´s just that I think it it IS quite small for an open baffle.
And quite resonant to boot, while a flat 24" by 24" piece of plywood with a speaker in the center, its rough acoustical equivalent, will minimize that.
But there won't be a pipe. You do understand I am going to take a wedge off the top back of the block so the driver will be exposed from the top? From the side it will look somewhat like a triangle. So what is your calculation for a half pipe? I know there won't be any bass, but I'm ok with that. And given that wood density charts show that a 12" cube of elm will weigh around 30 - 35 lbs, I doubt it will be terribly resonant, but I guess we will find out....if I can figure out a way to bore it first before I cut off the wedge
You are most definitely correct afa about the safety part!! I have almost zero experience in woodworking. My brother-in-law said I should find somebody with a lathe and hollow it out like a bowl, but I doubt there are too many wood lathes in my small town that can safely mount and spin a 12" 35 pound block of wood. And of course the added time and expense would really kind of defeat the purpose of a quick simple project.
You also need to consider the chances of your piece cracking once machined.
Elm may not be so forgiving. I would be more inclined to cut the block onto thick slabs instead and make some sort of enclosure.
Elm can be nice and you may look into ways to exploit the non-straight wood grain.
Elm may not be so forgiving. I would be more inclined to cut the block onto thick slabs instead and make some sort of enclosure.
Elm can be nice and you may look into ways to exploit the non-straight wood grain.
Your description is not clear, ´please post a drawing.
A cell phone picture of a hand sketch is perfectly fine.
I am not worried about wall vibration, but about air vibration in a pipe.
But I´ll wait for your drawing, if possible showing some dimensions.
Boring a large hole has come up for me in my latest projects, which use aluminium for the cabinets and/or faceplates. Faced with a 121mm hole to bore for the mid-bass I started with a hole saw. That failed in my 550W Bosch hand drill - too much friction despite lube. Haven't tried it in my 220W drill press yet. Tried the hole saw in my hand brace, but no better. I have a tank cutter coming - that's a kind of fly cutter. Maybe that will work. Last resort would be drilling multiple holes round the circumference.
All advice welcome!!!
All advice welcome!!!