Sonotube Sub "endcaps"

[eRiCdWoNg]

How do you all make the endcaps? They are there for decoration and to hide the ends of the cloth. I plan to make them out of oak, and stain them to match the trim on my Magnepan speakers. I'm thinking almost of sending them to a professional wood shop to get the cut, cause I have nothing that can remotely make a perfect circular cut that will be 13" or so.

[kevyjo]

Well, if you have some time on youre hands, I have a way to make perfect circles without fancy tools. I made the endcaps triple layer (mdf in my case), two layers smaller fitting inside the tube, and one outside, but gluing them all together so they formed simple plugs. As far as the perfect circles go, this is time consuming, but works:
Draw slightly oversized circles for both interior and exterior parts of the endcap, and cut them with a jigsaw, trying to get as close as possible, but making sure that the cuts are always larger than the circle needs to be. if you are using two layers inside the tube, match the two smaller pairs of circles as close as possible and glue them together, making two double layer circles. THEN, stack the smaller and larger circles into two piles. take one of the piles, and try to center them on top of each other as much as possible, but MISMATCH the flaws in the cuts. Then sand them smooth using an orbital sander. keeping them centered again, rotate them until they are mismatched again (about 1/3 rotation), and sand them smooth again. repeat this process several times until no matter how you turn them, the edges no longer mismatch, and PRESTO, you have two perfect circles ( i know, im insane for doing it this way, but its the only way i could think of getting flawless circles using only a hand sander and a jigsaw)

[ultrachrome]

I picked up a plunge router from home depot for a $100 and use the jasper circle jig from parts express. It's almost $200 for router, jig, and cutting bit but you can't cut a better circle.

I've seen people use zip saws to cut decent circles in mdf but it proably won't do a good job on oak.

[kevyjo]

you might also look into renting a router from home depot. As far as cutting oak, i think the method I described above would still give you perfect circles in the end, but it is a pain in the rear, it just depends on what time/money ratio you want to settle on

[eRiCdWoNg]

PICS????

[amt]

The proper way is as ultrachome has done but over the years I have cut circles various lowtech ways. Start out with a ruff circle by cutting with a jig saw or coping saw. Next, find the center of the circle and either drill a hole though or partially if you what one side is to be unholely. Drill the same bit into a scrape piece of ply which is bigger that the circle and use as the the center pin. Now you can spin the circle CAREFULLY around the jig on a tablesaw(this works well but is quite scarey), against a drum sanding attachement on a drill press or even a sabre saw thats been mounted to the jig from underneath with screws.

These are crude methods but work well if you take your time to ensure that everything is properly clamped and secured to eliminate slop and go SLOW.

I cut all my circles/holes with a non-plunge router mounted on a piece of .25" aluminum plate. I create a new pivot point on the drill press each time I need a new diameter and make it with an engraver. The plate has a handle mounted on it for super stability.

amt

[ronc]

Ultrachrome is right. The larger jasper jig goes up to 18.5" i believe (aint gonna haul it out to look).
I tried jig saws and was never successful.
ron

[eRiCdWoNg]

Hmmm... well right now I am redoing a 5 year old sonotube setup I had slapped together when I was in high school using a Cerwin Vega car sub. I calculated the response and ports with a program on a laptop computer in the parking lot when I was buying the woofer a long time ago. Its home depot sonotube, thats taped together with particle board as the ends. Its also spray painted. However, it surprisingly sounded very good and blended so well with the main speakers that I never changed it.

I have some spare time now and I bought this much higher quality sonotube from a local concrete supply distributor and its much thicker and 1 continuous piece. Its also already 6 feet so now more cutting is required. This time I'm going to use MDF instead of the particle board and am going to do a good job making it look pretty. I have an extra grille cloth for my Magnepan speakers and I will use it to wrap the tube. I'll have to get it hemmed down at a taylor but that shouldnt be a big deal. Cant wait to hear how it sounds.

I'd really like to get the jig and router.... now that I think about it I have cut alot of circles with jigsaws before, never worked that well.

[BobEllis]

I made my own circle jig from an 8: x 18" piece of 1/4 plywood bolted to the base of my router. Like the jasper jig, I drive a nail through the ply to serve as a center point. Sometimes takes a few tries to get the diameter correct, so test on scrap before your good stuff.

With a 1/4" straight bit I wouldn't try to cut more than 1/8" per pass in oak, you'll bog down the router and risk scorching the wood.

Route a groove 1/16" or so larger in diameter than your tube on the bottom of the cap, wide enough to fit the tube into to cover the ends of the fabric.

[kevyjo]

Hey, you can always leave it about 6' long, the extra enclosure will sure get you deeper bass!