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This is my first build of one of Bill's cab's. I am building a T39. It is being made with 27" wide panels. I hope I didn't make too bad of a mistake, When I assembled panels 3 and 4 they are out about a 1/4" at the peak but are ok at the other end. I installed the chamber reducers and let the PL cure some before fitting panel 3, that's when I noticed it was out. Is this a bad mistake or will I be fine?

daveode wrote:Is this a bad mistake or will I be fine?

Something's not cutting square. I'd figure out where the discrepancy came from before proceeding further.

Pain in the butt enough as it's shown, there's the potential to get down right ugly to work around this twist (literally) as the build progresses.

You are using a framing square , right?

Yes sir! a square all the way! The whole cab is nice and square, The chamber reducers are not tho.... the way they are cut there is no square side on them. I matched them up to the drawling on the cab before installing them too? I have no idea how it became a 1/4" out?

So this is a problem that should be ripped out? The whole cab is square, just at that peak it is out. It's not twisted.

That exact same thing happened to me on my first one. Culprit, the assembly table not level it had a twist on the surface, so when the corners where the side and top meet were square the opposite side of the top was being pushed up and caused the misalignment. I figured no biggie Ill correct as I go along and because I had not figured out what was causing the problem the rest were not square. Managed to save the built with a de-wringing jig. Second cab was built on a framed out 3/4" sheet of ply as my work table, not a misalignment in sight.

Hope this may help you find the root cause of the problem.

pumpsfast wrote:Managed to save the built with a de-wringing jig.

Bingo. If the cab isn't twisted now, it sure will be soon enough, come time to put the panels and bracing on that wrap around it.

You can certainly press forward with a misaligned joint like that, but it's not going to be fun IME.

Oh! is that what you mean? Lol! Yup, I was going to adjust the braces to keep panels 5 and 6 in line. I'm using 1/4" braces dadoed 1/8" on each panel to make it fit. of course I will dry fit the panels with the braces first before I glue and screw!

But I do want to know if the 1/4" out at the peak will affect the horn in a negative way so bad that I should rip it out? or if it will not matter much?

daveode wrote:But I do want to know if the 1/4" out at the peak will affect the horn in a negative way so bad that I should rip it out? or if it will not matter much?

Sound-wise, it'll be just fine.

Worst case is mostly cosmetic where the misalignment translates to the outer-most panels, and you end up with a warped cab that won't sit exactly flat.

Just be mindful of where that panel is situated when it comes time to fasten down the final side. You want to make doubly sure your nails or screws hit their intended target along that edge.

Looks pretty good, but what kind of plywood are you using?

From the pictures it looks like 3-ply with thin veneer. Not the best material for solid cabs as it warps easily, and the thin veneer breaks away from the core much more easily than "real" plywood with even ply thickness.

Rune Bivrin wrote:Looks pretty good, but what kind of plywood are you using?

From the pictures it looks like 3-ply with thin veneer. Not the best material for solid cabs as it warps easily, and the thin veneer breaks away from the core much more easily than "real" plywood with even ply thickness.

+1

I can see 5 plies in there.....

Rune Bivrin wrote:Looks pretty good, but what kind of plywood are you using?

From the pictures it looks like 3-ply with thin veneer. Not the best material for solid cabs as it warps easily, and the thin veneer breaks away from the core much more easily than "real" plywood with even ply thickness.

Yeah, I know it's not the best choice but It was really hard for me to find anything anywhere! If they had good plywood in stock, it was 3/4", and if it was out of stock, I had to order like a pallet!! I thought 1/2" plywood was easy and common, I guess not. I even went to cabinet making shops and no luck. Even the stuff at Lowe's that Bill approved, all the Lowe's wouldn't stock it....anywhere at any store?! and same thing, I had to order a 1/2 a tractor trailer worth??!!

I've been able to get SPF (spruce/pine/fir) plywood at the local Home Depot in 4x8 sheets....and reasonably void-free.....and 5-ply. I'm pretty sure that it is available where you are.

daveode wrote: I even went to cabinet making shops and no luck.

Did you inquire where the cabinet shop buys their material? I can't believe it's that hard to find some good 1/2" plywood.

I meant cabinet making shop, There was only one that I knew of. No I didn't ask! but they made mostly cherry cabinets I'm such an ass! I should of asked! I'm also new to this area and I really was asking around. Everyone was like Nope, I have no clue?! It made no sense to me, so I said the same thing " I can't believe it's that hard to find some good 1/2" plywood" One reply was, No one buys that expensive stuff, so we don't stock it.

There is a Diamond M Lumber a few towns over (like 30-35miles), Before I build the Otop 12's, I will see if they have anything. I do plan on building a lot more cabs(T39 OT12's) so I'm hoping that by the next one I find something somewhere soon!

daveode wrote:I meant cabinet making shop, There was only one that I knew of. No I didn't ask! but they made mostly cherry cabinets I'm such an ass! I should of asked! I'm also new to this area and I really was asking around. Everyone was like Nope, I have no clue?! It made no sense to me, so I said the same thing " I can't believe it's that hard to find some good 1/2" plywood" One reply was, No one buys that expensive stuff, so we don't stock it.

There is a Diamond M Lumber a few towns over (like 30-35miles), Before I build the Otop 12's, I will see if they have anything. I do plan on building a lot more cabs(T39 OT12's) so I'm hoping that by the next one I find something somewhere soon!

It can't be too hard to find in a giant metro area like where you are. I'm in the middle of Texas and I drive 30 minutes to pick it up for $25 a sheet 5x5.