Holes in cab bracing

[Ben Esparza]

I've seen a few pics of Tuba builds and noticed a lot of them have various sized holes cut into the interior and bottom braces like the pic below. I just bought the Tuba 30 plans and see no reference as to cutting holes in the braces. Being a newbie, I'm sure the subject has been covered before. However, I was wondering if those holes have any effect on the sound or are they there just to cut down on the overall weight of the cabinet?

[Chris_Allen]

The holes are to increase the free flow movement of air and to save a little weight. You can probably save up to 70% the weight of the panel.

Chris.

[Tim A]

The only holes that count for air flow are in the first panel. After that it's weight savings. Not a big deal if you're using 1/4" bracing, but it can make a difference with 1/2". The holes in the visible braces also look cool......

[Chris_Allen]

I thought they all counted for free air flow but the first ones were the only that were necessary.

[SoundInMotionDJ]

The plans clearly state that the first set of braces need the holes, and the rest are for weight/aesthetics. In larger cabs, holes in the mouth braces can also be hand holds for moving the cabinet....plan accordingly when attaching those braces.

--Stan Graves

[bgavin]

plan accordingly when attaching those braces.

Yes indeed. Those holes are the very first thing somebody is going to grab when muscling that box around. Do not make them so thin they will break when Popeye grabs hold.

If you have not yet cut holes in braces, you are in for a pain in the ass. I use Forstner bits in a drill press, two braces clamped together, and it still takes forever.

[Scott Brochu]

I use Forstner bits in a drill press, two braces clamped together, and it still takes forever.

I would say that they are dull than.

[Tim A]

I use Forstner bits in a drill press, two braces clamped together, and it still takes forever.

Forstner bits are made to cut clean holes with clean bottoms, but they're not known for speed. Get some hole saws. If you're doing mostly small holes (7/8"-2-1/8") one of those little Skil Dial-A-Saws will work very well, they don't overheat and cut quickly.

[gdougherty]

I traced out angular bracing on the large back bracing pieces in my T48's and cut them with a jig saw. Left about 1.5" strips on the edges and a W shapped set of cross braces from front to back in the middle.


Biggest pain with the forstners was drilling through 3 sets of braces and the occasional pieces getting stuck and spinning as you broke through a piece or layer of plywood. Going slower helped but took longer as well.

[Sydney]

On my T24: Cut holes on unseen braces - Switched to truss style webbing on the rest.
Rounded edges and coated w Duratex for contrast.
Sorta visible in this pic

[bgavin]

Forstner bits are made to cut clean holes with clean bottoms, but they're not known for speed. Get some hole saws. If you're doing mostly small holes (7/8"-2-1/8") one of those little Skil Dial-A-Saws will work very well, they don't overheat and cut quickly.

Thanks for the tip. I do get very clean holes, but it is time consuming. Drill a pilot, then cut with Forstner half-way on each side. The bits are new, and not dull.

[gdougherty]

Forstner bits are made to cut clean holes with clean bottoms, but they're not known for speed. Get some hole saws. If you're doing mostly small holes (7/8"-2-1/8") one of those little Skil Dial-A-Saws will work very well, they don't overheat and cut quickly.

Thanks for the tip. I do get very clean holes, but it is time consuming. Drill a pilot, then cut with Forstner half-way on each side. The bits are new, and not dull.

The other thing you can do is drill down from one side without the pilot with the brace resting/clamped on a scrap block. The scrap block will help keep the other side clean as well.

[AntonZ]

Get some hole saws. If you're doing mostly small holes (7/8"-2-1/8") one of those little Skil Dial-A-Saws will work very well, they don't overheat and cut quickly.

When using a hole saw, drill a few smaller holes (regular wood drill) on the cirkel. It allows the saw dust to drop down and away from the saw. It is not the sawing itself but rather the accumulating sawdust that causes the typical overheating of hole saws. Much longer saw life, speeds up the process immensly, also.