T48 Build Thread

[miked]

Hi Tom: Those are interesting measurements...I don't have the Nov11 plans...I guess there was an incremental update of some kind? And at this time of the evening I'm not going out to the sauna...garage to measure. Heheheh. Having only 1/2" b/t the front edge of the bottom and the top edge of the handhold would worry me. These cabs are light (AFA subs go) but not THAT light so you could lift them with only a half inch of wood holding the cab up.

This is one of those "After I built this cab, I realized that..." (insert epiphany here) moments. Ugh. I hate those! These cabs aren't an erector set where if you put the wrong length piece in there, you just unbolt 32 different pieces and bolt in the correct piece and go from there. I've learned a hard lesson; PL IS PERMANENT. LOL!

I'm hoping that a rested brain and a fresh set of eyes will set me on the right path in the AM. Thanks.

[Tom Smit]

You can put a piece of 1/2" half-round at the front lip for extra strength and a more comfortable handle (similar to the quarter-round idea).

[miked]

I'm no scientist of any kind, but my experience building cabs says "wouldn't that "bump" interfere with the sound being projected out of the horn?" it's a "blockage" right at the end of the horn path. I'm just spouting stuff off the top of my head...but rarely, the stupid question might be valid...

[Tom Smit]

Nope. The object is too small for those large sound waves.

[miked]

Like I said: "Rarely..." Thanks, Tom. I guess it really doesn't matter how far into the mouth the 6/10 braces are. You can't mechicanally fasten the angled end anyway. And that's another thing that has me concerned. (Per the plans) If both sides are on before I attach the 6/10 braces and their horizontal brace: How am I supposed to get PL on the ends of a 23" wide piece when the space it fits in is 23" wide?

[sine143]

Slather it up lol. then clean up the mess

[Bruce Weldy]

Slather it up lol. then clean up the mess

Exactly.

[Ryan A]

Or, slather it on, make a mess, let it dry (if u have the time), then clean (chisel) it up

[Radian]

Just a quick note about PL squeeze-out & cracking.

It's nothing to get upset over or worry about. Upon fastening two pieces together, the stuff that oozes out of joint does nothing for the strength of the joint.

The excess adhesive cracks because the outter most surface is curing (skinning) while the inner (uncured portion) is still expanding. In the case of PL Premium, it expands quite a bit.

The more that squeezes out, the more abundant the cracking will occur.

It bears no indication of what's actually taking place along the joint interface.

You can try and smooth the squeeze out with a finger, but that usually leaves a hideous, bubbly mess.

It's not caulk, so if cosmetics are a concern, just leave it cure then come back with a chisel and slice it off. Once the PL is removed and if you still desire a fillet, lay down a bead of Bondo and smooth that out instead. It might sound like a lot of fuss, but it's actually easier working with filler than trying to sculpt PL.

[miked]

Thanks for that explanation, Radian. That makes sense. I do plan on lightly misting the joints before I PL; even at daybreak, my garage it 88F this time of year and gets up to 100 on a sunny day. I'm about to post a midday update. We're getting there.

[miked]

I took a break to grab some lunch. Here's what I've done so far today:

Finished cutting all handholds and jackplate holes.
Cut one new back and one new bottom b/c apparently sometimes I can't read a ruler. Thankfully I had leftover pieces big enough.
Rounded over all handholds.

Have I mentioned I love routing templates? This one was easy to make since the cutout was rectangular. Just used the rising cut method on the TS. (Thanks, Bruce).

Template for jack plate.


Lovely cutout.




Handhold in top rounded over (1/4" roundover, BTW). Just on the top edge as the bottom edge of the hole will butt up against the quarter round. Pic shows rounded over vs. non-rounded over hole.


Stack of bottom panels, handholds rounded over on both sides. The center line of the holes are 2" from the edge...I went with that. Hope it works out.


Stack of tops.


Stack of backs. Even on the backs of the holes, which don't get rounded over, I broke all edges with 220-grit sandpaper. The jackplates may look a little high up, but I put them there by choice. I wanted as short an internal run of wire as possible. Less to tack down, less to vibrate too.


6/10 horizontal braces, handle hole and rounded over.


I realize that I have not cut holes for the casters yet. Bruce advised me to wait until at least the back is on so I will be better able to visualize how the backing plates for the casters will sit, how far to make the cut, etc. It's an easy cut with the circ saw, anyway. Check Bruce's "Old style T39 thread" at the bottom of the first page of "Build Threads" to see his caster backing blocks. I plan on doing something similar if not ripping him off outright. Again.

So, aside from putting the angles on the internal panels, all cutting is done. This afternoon's task: Mounting the drivers to the baffles to ensure the bolts line up with the tnuts, and checking for cone slap, which I really doubt I'll have, but better to check now than be able to do almost nothing about it later. Devil's In The Details, right? I know I have two or three holes on the driver side that don't line up well with the t-nut, so I'll have a bit of drilling to do, but no biggie, really.

Aside from actually assembling the cab, the only major things left to do for Prep Work are:
Mount drivers to baffles to check for proper bolt fit and cone slap.
Figure out the size of my access panel and one piece flange and get those glued up.

Thanks for looking.

[miked]

I really hate t-nuts. You drill things as carefully as possible, etc and they never line up. Threading the bolts in without the driver in place, they are fiddly, but they go it. With the driver there, I can't get half of them to thread and I don't want to push too hard b/c then they will strip. I am concerned. Sheesh, all that wasted time!

I am considering just going with Kreg screws and avoiding all the mis-threaded, stripped out drama completely. I could fill the t-nut holes in the baffles with PL easy enough.

Would these be long enough? I can't remember if I used lockwashers or not when I used these screws on my OTops. Should I use a 2" screw instead? I don't know if they sell 2" Kreg screws? (My local Lowes apparently DOES have 2" Kreg screws...)



Thoughts? Man, am I pissed the heck off right now.

[Michael Murphy]

Do you think opening up the driver Holes by à mm or so will give you some wiggle room? Or perhaps loosely install the bolts that are able to catch and then run the no. 1. tap to line up the driver hole. Its what i envision id have to do.

[miked]

OK, crisis averted, I think. After widening a couple of the holes and running the bolts thru the nuts numerous times, I got one driver bolted down. Ran 21v @ 30Hz through it and no slap at all. One baffle down, three more to go. Have I mentioned that I HATE T-NUTS?

Now I just have to hope that I didn't strip anything put them in there, or else I'll be "Kregging It" anyway.

These are going to be a royal PITA to actually get bolted in the cab, but nothing clamps down a driver like t-nuts.

[miked]

I can update quickly b/c I have an old laptop in the garage.

This is just stupid. First baffle took me hours to get all 8 bolts in. The second? About a minute. At least things are looking up!!!!