Cab building advice

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fiat_cc
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Cab building advice

Post by fiat_cc »

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Hi all.
I'm nearly finished an 18 watt variation. It's a single channel version using the tremolo channel as its basis, with a PPIMV and spring reverb.
I'm pretty comfortable with the electronics side. Still learning a lot, but I can read a schematic and layout, solder well and I have a decent understanding of lead dress. What I'm less comfirtable with is wood working. I've gotten myself a table saw, plunge router and a cheap little router table, drill press, jig saw etc, and I want to build an 18 watt combo cabinet using the Modulus plans.
I'll have lots of questions I'm sure, but to start...
How do I rout the cooling vent slot? How do I rout the round over for the cooling vent slot and control cutout?
I have a circle jig for speaker hole cutout, so the should be ok.
My biggest fear is going the tolex. I'm actually building two amps. One for me and one for my dad, so I want the tolex to look pro. Especially on my dads cab. I'm using Wine Buggy Taurus to cover these. I've watched a few tutorials, and will no doubt watch more, but none have shown how to do the cooling vent slot, or control cutout.
I will do piping around the grill cloth and valance, but not in the slots top and bottom as on the originals. I worry about cutting a 3mm slot into wood that's already only 12mm thick, and it adds complexity I don't need to deal with at this stage.

Really, any helpful pointers for a noob wood worker. I can measure, and have some limited metal work and machining experience, but really, I'm kinda petrified! I like to challenge myself, but this puts me way out of my comfort zone!!!

Cheers,
Reuben
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JMPGuitars
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Re: Cab building advice

Post by JMPGuitars »

The best piece of advice anybody can give you is to practice on scrap first...and make sure you have plenty of extra tolex to CYA.

Cutting out the vent hole can be done a number of different ways, it depends on what you have available. You could drill out the corners with a drill press, and then use a saw or router to cut out the straight lines. Then file/scrape/sand until it's actually straight and smooth. Use a 3/8" (give or take 1/8" depending on taste) round-over bit with your router.

You've seen videos for tolex; watch more, and view step-by-step tutorials too. Tolex is the hardest/messiest part until you've practiced a little. Figuring out the angles on the corner cuts isn't too bad, just remember that you will need to stretch the tolex the right way to get the smooth seams, so don't cut it shorter than you have to until it's glued and stapled.

Good luck with that. ;)

Which reverb circuit to you go with?

Thanks,
Josh
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Re: Cab building advice

Post by CurtissRobin »

There's an old saying, "Measure twice, cut once." It's not a platitude because you set your destiny by what you do first. So if you measure and mark, then measure again before you cut or glue, your odds of catching an error improve markedly. I've occasionally taken a measurement in the opposite direction, i.e. turn the ruler or tape measure end-for-end to be sure I'm not misleading myself. After you have mating parts cut, dry fit them; just hold them in position to see if any further attention will be needed before permanent assembly. My Daddy and younger brother were both carpenters and this was a lesson learned young.

TAKE YOUR TIME!! Slow-and-right is a much faster and less costly way to work than fast-and-repeat. Your concern about preventing problems tells me that you'll do fine.
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Re: Cab building advice

Post by fiat_cc »

Thanks for the responses.

I used this reverb circuit. http://el34world.com/Forum/index.php?topic=7957.0

I also have a more detailed build thread here. http://www.tdpri.com/threads/18-watt-variation.723856/

Yes, I'll be going slow. Thinking of building an extension cab first, to get the basic box building and tolex covering down, then do an amp cab with the extra routing and added tolex complication.
I've got a finger joint jig, table saw, router and table, so I'm hoping I don't screw up too badly.
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Re: Cab building advice

Post by JMPGuitars »

I use a variation of the same reverb circuit, it works great with these amps.

Practice everything on cheap pine first. Get some level of comfort running through the process before you use nicer woods..
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fiat_cc
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Re: Cab building advice

Post by fiat_cc »

Glad to know the reverb circuit will work. I did a bit of research, but I was still taking a punt without actually hearing it.

I've got a few sheets of nice birch ply, but yeah. I should probably buy a sheet or two of cheap 12mm ply for practice first...
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Re: Cab building advice

Post by kanj »

fiat_cc,

You mention you have some metal working experience - so besides the adage of "measure twice and cut once", use a sharp blade and mark all your cut lines as you would with metal by scribing your layout lines into the wood (measure twice and cut once is especially important here since it's no fun trying to sand out a misplaced scribe line... unless it will get covered with tolex). A scribed line is much more accurate, and easier to work to than a pencil line. I would use a utility knife rather than, say, an exacto knife blade, because the exacto blade will be thin enough to follow grain lines even in softer woods like pine. Working to a pencil line - depending on how sharp your or fat your lead is - will introduce small variances that will show up when you go to glue the cab up either as gaps, too tight a fit, and throws things out of 'square'. It's very easy to see a blade cutting along a scribe line vs. a pencil line.

For example, not having the boards that make the top and bottom, and the two sides the exact length to each other will make it impossible to have 90 degree corners on your cab... so when you go to cut out your baffle board for the speakers and fit it to the opening, you will end up tight or with gaps that require you to custom fit the baffle or even re-cut the whole thing over again. I would add a square to your tools, and perhaps something better than a plastic roofers square that they sell at Home Depot or Loew's. I use a machinist's square. If nothing else, a square is pretty handy when you have glue in all the finger joints and are clamping the cab up to dry.... it's pretty frustrating to find out that the corners are slightly out of square once the glue is dried.

Also, in reference to table saws, and specifically their fences.... unless you have a BIESEMEYER Fence or some other aftermarket fence (that has been properly set up), it is best to use a square or metal tape measure to set your fence. Check the distance at the front of the blade to the fence, and then at the rear of the blade to the fence to make sure they are the same distance (make sure you go off the same tooth on the blade by rotating the blade from front to back). Many of the current production 'home owner' quality saw's fences are pretty acceptable but it is worth checking to see if it is repeatably accurate. I have a great old 1960's Delta Rockwell cast iron saw that cuts beautifully, but I do the above measure on the blade to the fence each time I make a cut and tweek the fence accordingly so the blade is perfectly parallel to the fence.... otherwise you end up with a very slight taper....

This all probably sounds pretty "OCD" but anything you can do to improve the accuracy of your components doesn't get multiplied as you try and put them together.

And don't let all this make you nervous... you'll do fine! It's all a learning process anyways! Go for it! The best woodworkers I know still screw thing up and make mistakes here and there... but they also learned how to fix them along the way, too. It is a nice feeling when your first finger jointed cabinet goes together... let alone when it's all done! Good luck... you'll do fine!!
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Re: Cab building advice

Post by fiat_cc »

Thanks Kanj.

That's all solid advice. OCD is good for getting things right, so appreciate it in this instance!
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