How do you cut those holes?

[ciscokid]

It's me again. Cisco. A while back I sparked much discussion regarding the use of hardwood for speaker enclosures. I have read all three pages of those posts with interest. After three readings, I understand almost half of it. Apparently I have much to learn. I have my speaker kit in hand and I am ready to start. I bought the Seas 'Thor' kit from a Canadian company called Solen. You all have convinced me that 3/4" MDF is the way to go. I may choose to cover the MDF with hardwood panels after construction being very careful to not create any voids that may cause vibration, but that is a long way off.

My question - I have been reading many posts on here and looking at some of your fine work. I am impressed with the precision circles and counterbores I am seeing. You must be using routers but what what jig are you using for this? Once I know the secret to these precision cutouts, nothing will stand in my way of embarking on this mission. Thank you all for your time and trouble.

[greenie512]

Cisco Kid – yep you definitely need some form of jig or trammel. I’m a convert of the Jasper Jig – check out

AU - SoundLabs - http://www.soundlabsgroup.com.au/c/Jasper/Jasper+Circle+Jigs.html

USA- Parts Express - http://www.parts-express.com/webpage.cfm?&WebPage_ID=3&manufacturer=89&filter=+circle+jig&raid=1&rak=jasper+circle+jig

Now you’ve just dropped lucky, I’m just started the rebuild of my Thors into their new “Small” Thor guess and so have a pair of veneered cabinets to the original design but built out of 25 mm thick MDF. If you are interested in them? PM me. However I’m in Brisbane, QLD so freight might be a bugger as these things are VERY heavy.

My old Thors …http://www.greenie512.net/greenie512/html/thor_tls.html

You've bought a great kit - you'll love em.

Cheers - Phil

PS - whats the rest of your gear - CD/amp.

[soundman]

For cutting all sorts of nice holes a router is your friend.
If you are doing a good number a template is the go.
for short run 1sies and 2sies the stock circle guide is prety good for larger holes and a simple sub base with drilled centres is just fine for small ones.

the trick with the recesses is to cut the recess first then the thru hole.

that way you keep your centre till.

cheers

[kiwigeo]

Heres what I use to cut rosette channels and the soundhole on my guitars. The jig rotates around a pin that sits in a 3/16" hole drilled in the wood being worked on.

[ciscokid]

I checked out the Jasper jig, Greenie. It is much like what I expected. Now for a dumb question. You've drilled the 3/16" hole in your circle center and you plunge the router and start routing. Everything goes great until you complete your circle. Now you have nothing left to support the center disk and, I would think, very little control over your router at this point. What am I missing? The picture shows the guy with a perfect circle in the middle. What's supporting it? I can certainly see why you would want to do any counterbores first!

There must be an easier way!

Oh, and the rest of my gear would hardly interest you guys. Just an old Onkyo surround sound receiver and a five disk Sony CD changer. Nothing fancy here. No Carver Silver Sevens or anything like that. :B

[Cliff Rogers]

....You've drilled the 3/16" hole in your circle center and you plunge the router and start routing. Everything goes great until you complete your circle. Now you have nothing left to support the center disk and, I would think, very little control over your router at this point. What am I missing? The picture shows the guy with a perfect circle in the middle. What's supporting it? I can certainly see why you would want to do any counterbores first!...
This sounds like a good subject for a 'How To' video.

[soundman]

AHH

either you whack some brads thru both the kept and the waste pieces holding then to a back board
or
you rout amost all the way thru then cut away the last bits leaving a couple of sections that can be finished of with a small saw or knife
or
you take your chances

In a speaker box it isn't such a bad problem a little knick or bump wont be seen.
I rout speaker holes on a vacume box.... after the last bit cuts thru the I plunge up and the waste remains spinning by the screw hanging from the guide:D
If I used a nail the waste would just drop away.
once the bit isnt cutting any more the machine is easier to handle....BUT...the break thru point can be a danger point.

over 10" I tend to leave a couple of webs to cut thru with a small hand saw

Bear in mind also with my vacume rig I want to rout all the way thru so the dust extraction works......
for most people only doing 1 or 2 nailing the job down to a back board is the easiest and safest.

cheers

[greenie512]

S/K – the Jasper Jig is designed to use a ¼” router bit, so it’s prudent to cut 18 mm MDF board in say 3 passes approx 6 mm deep. However, for the final depth setting I fold a thin bit of paper into 3 thicknesses put two bits of scrap 18 mm MDF almost together with this folded paper between them. I pace the router on top and plunge onto the paper, set and lock the depth.

Place the router back on the work piece and cut final pass, this leaves a paper thin skin at the bottom. If you get the depth correct, light passes through the skin – so cut a small section and check – adjust as necessary. This surprisingly holders the router (as long as you are not completely Kack handed).

Turn the piece around knock out the centre waste – vola – sand odd bits of “skin” off – perfect circular opening.

[ciscokid]

Thank you. That was very understandable. When I made that black walnut V-front guitar amp back in December, I had trouble cutting round holes for the 12" cones. I was using a Roto-Zip (think oversized Dremmel tool) and the flimsy compass attachment that came with it. Of course, after speaker installation nobody can see the ragged holes, but I want these Thors to be better than that. I already have a Porter Cable 690 and I see that the Jasper jig will work with it.

Thanks again for the help! :D