Things I've learned building a J12L

Helpful hints on how to build 'em, and where to get the stuff you need.
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lowbob
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Joined: Fri Aug 15, 2014 10:21 pm
Location: North of Bob's Country Bunker

Things I've learned building a J12L

#1 Post by lowbob »

Just some random things I learned building a few speakers including a J12L:

- The closer to perfectly square your parts start off, the easier to build and the straighter the final box will be.

- When doing the linear cuts on the Jack Lite horn braces, put tape lines at the linear dimensions on a framers square. That way all you have to do is match the tape with the circular edge, draw your lines using the square and your right angle is there.

- Uncured PL can be removed with 91% isopropyl alcohol.

- A Jasper router jig can be roughly copied with a piece of 1/4" plywood.

- A little wax on the circular saw cutting jig where the saw sole plate rides, will make the saw easier to push, but will collect sawdust.

- When making the woofer spacer, it might be worth laminating the two pieces before cutting. That way the edges are cut at the same time and match.

- When routing circles, screw the bottom of the part you are routing to a 1X2, that way you can clamp the 1X2 in a workmate and everything will be secure when making the cut. Also, shim the workpiece up with a couple of scrap pieces of plywood save the top of the workmate.

- A 14V cordless drill really doesn't have enough torque to drill a 1/2" hole.

- Masking or blue painters tape protects things as well as waxed paper, but doesn't move around.

- Set up and verify you clamps before applying glue.

All add more as I come up with them, but this is a start.

- PL doesn't stick to the cheap plastic putty knives available everywhere

- PL squeeze out can be scraped off with the cheap plastic putty knives if you do it about an hour after putting the joint together.

- Plan for one easy and one difficult glue joint at a time, that way you have a place for the PL ooze out.

- Everytime I put a glue joint together, a variation of the Bruce Springsteen lyric "Tenth Avenue freeze-out" is changed to "Tenth Avenue squeeze-out" and runs through my head. :x

Here's a new one I knew already, but forgot tonight.
- When using the circular saw cut guide, the piece you want to keep goes under the guide, otherwise the the piece will be short by the saw kerf. (Time to find another piece of 1/8" ply).

Hope they help.

Rob
Last edited by lowbob on Tue Aug 09, 2016 9:06 pm, edited 2 times in total.
No matter how many times I cut it, it's still too short.

Optimist - The glass is half full.
Pessimist - The glass is half empty.
Engineer - The glass is twice as big as it needs to be.

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LelandCrooks
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Re: Things I've learned building a J12L

#2 Post by LelandCrooks »

Isopropyl alcohol. I think that's probably the only thing I've never tried. Thanks!
If it's too loud, you're even older than me! Like me.
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Bill Fitzmaurice
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Re: Things I've learned building a J12L

#3 Post by Bill Fitzmaurice »

LelandCrooks wrote:Isopropyl alcohol. I think that's probably the only thing I've never tried. Thanks!
I prefer ethanol, applied internally. :clap:

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lowbob
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Location: North of Bob's Country Bunker

Re: Things I've learned building a J12L

#4 Post by lowbob »

Bill Fitzmaurice wrote:
LelandCrooks wrote:Isopropyl alcohol. I think that's probably the only thing I've never tried. Thanks!
I prefer ethanol, applied internally. :clap:

Leland, at work we call it IPA, but I thought I'd save you the embarrassment of washing up with something you should be drinking, :D

I'll bet Bill drinks rainwater and pure grain alcohol. :D

Thanks Guys.

Rob
No matter how many times I cut it, it's still too short.

Optimist - The glass is half full.
Pessimist - The glass is half empty.
Engineer - The glass is twice as big as it needs to be.

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James Champer
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Location: BF Builder - Indianapolis
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Re: Things I've learned building a J12L

#5 Post by James Champer »

I like the painters tape tip. Surprised I hadn't thought of that yet :P
Retired Authorized Loudspeaker Builder - Indianapolis, IN

NukePooch
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Joined: Mon Jun 30, 2014 8:07 pm
Location: Berea, Kentucky

Re: Things I've learned building a J12L

#6 Post by NukePooch »

Bill Fitzmaurice wrote:I prefer ethanol, applied internally. :clap:

:loler:

Sheesh...what'd I do last night? This thing's like 3/4" out of square and glued hard as a rock!
Built:
4 Jack 112L- 3012HO, melded array
17.5 wide AutoTuba with Infinity 860w
6 Wedgehorn W6 w/ Panel Mount Piezos
2 T48 Slims (15" wide) with 3012LF
4 T48 Fattys (32" wide) with 3015LF

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