tolex is not my friend

[FunkyE9th]

FYI...From the Dec/Jan 2007/08 issue of Wood magazine, they did a torture test on joints (drawer joints). Rankings from best to worst...

1) Box joint
2) Lock Miter
3) Lock Rabbet
4) Through-dovetail
5) Sliding dovetail
6) Rabbet with nails
7) Shouldered Dado
Half-blind dovetail

[Andy Le Blanc]

I remember a Taylor guitar video demo when they went with that ugly neck
joint...... 250lbs..... snap.......248.....snap..... 262....... snap
the right join in the right place........

[muchxs]

FYI...From the Dec/Jan 2007/08 issue of Wood magazine, they did a torture test on joints (drawer joints). Rankings from best to worst...

1) Box joint
2) Lock Miter
3) Lock Rabbet
4) Through-dovetail
5) Sliding dovetail
6) Rabbet with nails
7) Shouldered Dado
Half-blind dovetail

Yeah, great. I just love it when non-engineering types attempt science. I say this because the science needs to be qualified by identifying the variables and I question the validity of the entire study. It might be relevent to drawers but it doesn't relate to amp cabinets. I know from experience that a rabbet with nails and a shouldered dado are both weak joints and sure to fail eventually in a guitar amp application. The joints are as strong as the glue to begin with, when the glue fails... and it will... the joints fail as well.

The late '70s Fender cabinets use a rabbet with staples, that's rabbet with nails for all practical purposes and it's similar to to a shouldered dado. They all fail in Fender's heavier amps like the Super Reverb, the Twin Reverb or the Pro Reverb. Every so often you'll see a late '70s Deluxe or a Princeton with open joints. Look at any master volume SF Fender next time you're at your favorite vintage guitar shop, the tolex is almost always split near the top edges. That's because the joint has failed to one degree or another. In the worst case it's bad enough that the cabinet rattles.

A drawer endures a limited range of stress compared to an amp cabinet. An amp cabinet is stressed in planes that a drawer isn't.

I know what I see as far as vintage amp cabinets go, start the clock at 1955 or 1965 or so then bring the cabinet to me in pieces. For example '50s and '60s Fenders stayed together. I've restored any number of 150-200+ year old pieces of furniture with dovetailed drawers. A dovetail is a mechanical joint designed to work with archaic bonding technology. Hide glue is great when it's fresh but it's made from carrion, microbes like to eat carrion so over the years they'll happily feast on the hide glue. That leaves 200 year old dovetails with compromised glue, still they stay together.

The woodworking guys don't have to deal with a couple things we have to take into account, namely severe and constant vibration and our intangible... mechanical impact, that's when the cabinet gets banged around during transport. Some cabinets get beat, some of them don't. It depends on how much you gig, whether or not you have road cases and how careful your crew are. Some amps get handled more in a year than furniture gets handled in decades, sometimes centuries.

BTW my spouse teaches epidemiology and biostatistics... to doctors... at a very well known medical school. She's a PITA sometimes because she's like debating the debate coach, still, she can pick apart the flaws in a study in seconds flat. She has to, it's her job.

[ic-racer]

I know from experience that a rabbet with nails and a shouldered dado are both weak joints and sure to fail eventually in a guitar amp application.

Well, you brought this up, and I can assure you that your "experience" is not Science either.

The joints are as strong as the glue to begin with, when the glue fails... and it will... the joints fail as well.

Ok, references, statistics, sampling error, glue in question, mode of failure please...

The late '70s Fender cabinets use a rabbet with staples, that's rabbet with nails for all practical purposes and it's similar to to a shouldered dado. They all fail in Fender's heavier amps like the Super Reverb, the Twin Reverb or the Pro Reverb.

"They all fail..." surely you are not intending us to take you seriously.

A drawer endures a limited range of stress compared to an amp cabinet. An amp cabinet is stressed in planes that a drawer isn't.

Well, you are going to have to explain this one. Do you mean a limited number of different vectors, or smaller vectors. I'd like to see the data. Besides what if I store my amp in a drawer?

The woodworking guys don't have to deal with a couple things we have to take into account, namely severe and constant vibration and our intangible... mechanical impact, that's when the cabinet gets banged around during transport. Some cabinets get beat, some of them don't. It depends on how much you gig, whether or not you have road cases and how careful your crew are. Some amps get handled more in a year than furniture gets handled in decades, sometimes centuries.

Some pretty bold generalizations here. My amps stay in the studio, and my kids beat the furniture to heck...

she can pick apart the flaws in a study in seconds flat. She has to, it's her job.

Ask her what she thinks of your post.

[Andy Le Blanc]

whoa nelly.......just finished tolex on a head...... its a hot day and the cement
and tolex reacted very differently with the higher temps.... the shop feels like
80s ...... the last time it was in the 60s..... the tolex seemed to loosen
its got to be the evaporation rate of solvent...... it flashed off much quicker
a tailors tape made measurements around the cab and rounded edges a bit
tighter with less waste.....

one test a guitar cab should pass is the "wing-in it out the back of the truck"
test...... over kill is the best way to chose a good join......
a combo cab couples the speaker to the room and has to be stronger than
the idiots who toss them in and out the van

[muchxs]

I know from experience that a rabbet with nails and a shouldered dado are both weak joints and sure to fail eventually in a guitar amp application.

Well, you brought this up, and I can assure you that your "experience" is not Science either.

The joints are as strong as the glue to begin with, when the glue fails... and it will... the joints fail as well.

Ok, references, statistics, sampling error, glue in question, mode of failure please...

The late '70s Fender cabinets use a rabbet with staples, that's rabbet with nails for all practical purposes and it's similar to to a shouldered dado. They all fail in Fender's heavier amps like the Super Reverb, the Twin Reverb or the Pro Reverb.

"They all fail..." surely you are not intending us to take you seriously.

A drawer endures a limited range of stress compared to an amp cabinet. An amp cabinet is stressed in planes that a drawer isn't.

Well, you are going to have to explain this one. Do you mean a limited number of different vectors, or smaller vectors. I'd like to see the data. Besides what if I store my amp in a drawer?

The woodworking guys don't have to deal with a couple things we have to take into account, namely severe and constant vibration and our intangible... mechanical impact, that's when the cabinet gets banged around during transport. Some cabinets get beat, some of them don't. It depends on how much you gig, whether or not you have road cases and how careful your crew are. Some amps get handled more in a year than furniture gets handled in decades, sometimes centuries.

Some pretty bold generalizations here. My amps stay in the studio, and my kids beat the furniture to heck...

Talk to me again after you build a couple hundred amp cabinets, that's where I stopped counting. How many have I done by now? I have no idea. A lot. I don't need some experiment to tell me what works. That's the difference between a machine and a craftsman. I know what works and I know what holds up because I've done it, done it and done it some more. I know what breaks because I've repaired it, repaired it and repaired it again. Experience is access to a personal database, it's a freewheeling ongoing experiment. Controlled experimentation and accumulation of data may be useful to convince skeptics, IMHO that's a waste of my time. Read a book about it, do it yourself, get back to me when your cabinet comes apart.

I have no use for would-be engineers who think the math tells the whole story especially where craftsmanship is involved. I've dealt with countless process engineers who think that they can engineer the human element out of a process. The human element is craftsmanship and yes, you may not know that because craftsmanship is almost extinct. Craftsmanship takes up where science leaves off and you probably can't measure that. Craftsmanship is the instinctive assimilation of science, physics in particular. The visible result is that a craftsman can achieve a higher level of quality (than a less skilled worker) within many processes, that's an intangible that confounds process engineers.

A hack will embrace an expedient process and then fabricate justification why that process is superior. Frequently the only justification necessary is that it's quicker and/or it cuts cost, quality be damned!

I'm serious, go down to your local vintage guitar shop and look at late '70s SF master volume Fenders. There will be a visible split in the tolex in the vast majority of them where the joints have failed. Take a look then argue if you must. If the amp looks pristine you're either looking at a closet queen, that would be an amp that hasn't gone anywhere and hasn't been played much or it's been recovered. If it's been recovered without attention to structural issues there's a chance the covering will split again. How many have I seen? Hundreds. Enough to know the joints are inferior. It's really simple, I see late '70s Fenders with open joints. '50s and '60s Fenders use a different joint and they're at least ten years older. Older Fender cabinets fail if they're subjected to massive impact or if they've been wet, they don't bust open during normal use. (The exception would be BF chipboard baffles. The late SF fixed baffle solved that problem and created another set of problems in its place.) What do I need to do, a controlled experiment to prove my "hypothesis"? Figure out exactly why the late '70s joints fail? All I need to know is that joint is inferior in that application, period, end of story.

What do you want, a 100% failure rate to prove a process is inferior? Perhaps a 100% failure rate plus a thick white paper exploring the inferior material and the dynamics of the inferior process. If you get paid to sit in a cubicle and generate data on why things don't work I suggest that you take a day off, go sit in the park and invent something that does work.

One of our millwrights had to use a torch to remove a bolt from a machine frame. He then used an impact wrench to remove the bolt, the socket dropped off the impact wrench and on to the floor. After a minute or two he absentmindedly picked up the (still very hot) socket and bolt, he immediatley dropped it. He said, "Don't take me long to look at a bolt!" The moral of the story? It doesn't take me long to figure out what doesn't work well.

Contradict myself? That's my privilege.

[candh]

Per the "black" staples;
Believe it or nay, the indelible ink in a Sharpie, black of course, does a great job on the staples under minimal scrutiny. A single coat kinda turns black/grey not black. But it's a perfect shade for black Tolex's in most positions as it doesn't let the staple reflect light. Which is the #1 tell as the magicians say.


candH, Chris
I'd like to learn more of your technique. I need to learn to "round" those aforementioned channels. I decimated my vinyl 'cause those inner angles were way too sharp.

Noel,

Haven't checked in here for a few days.

Yes, vinyl requires a little TLC to not damage it. The most important thing is to smooth out the inner edge of the channels especially on the corners...as you've found out...lol. Use a flat file and then some 100 grit paper.
The vinyl has be hot...not warm...hot. So, lay your glue in the channel and on the vinyl..heat it up with a heat gun just to the point before it starts to melt and deform. Use your piping to "pull" the vinyl into the channel and hold it there while the vinyl cools and the glue sets. Wait a few minutes, trim the excess vinyl and repeat with the overlapping flap.

Cheers,

Chris

PS Noel, PM me if you want to talk more. I'd like to see some pics of your work so far.