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DIY Joinery

Discussion in 'Amps and Cabs [BG]' started by 4Mal, May 2, 2005.

  1. 4Mal

    4Mal Supporting Member

    Jun 2, 2002
    Columbia River Gorge
    Been playing with Rabbet style joinery for a while. Which approach A or B from the 'drawing below' is the better approach when building with 3/4 ply. Thanks, Mal

  2. Just from a physics pov, i think B is more structurally sound/solid just by nature, thats all i can say :s
  3. Both work well. I think JBL prefers the 2nd approach. Both will be splinter-prone with plywood.

    IMO, both are over kill. I do a butt joint + full cleat, glue+screws, and haul it all over everywhere without any separation.

    If you have the jointing tools, go for it. If not, put some time into rib bracing and it's all good.
  4. billfitzmaurice

    billfitzmaurice Commercial User

    Sep 15, 2004
    New Hampshire
    Owner, Bill Fitzmaurice Loudspeaker Design
    They're both good and as noted both overkill. For the most part butts with screws and glue are adequate, but if you want a splined joint do it with biscuits. Fast, easy, and very strong.
  5. 4Mal

    4Mal Supporting Member

    Jun 2, 2002
    Columbia River Gorge
    Not a problem that I've been having. I suspect that is for 3 reasons. Very high quality and clean router bits, teflon 80 T and negative hook angle saw blade with stabilizer, better grade (read mucho dinero) plywood.

    I have a majorly slick table saw router table setup from JoinTech that I'm learning to use. I'm planning on building a furniture grade 'built in' to complete a kitchen remodel later this year,so I'm busily scrapping wood as I learn how to rabbet & dado, dove tail and finish in general. A couple of bass cabs will, uh, enhance my learning ...

    I'm going to do an old style Fender 2x12 sealed Bandmaster style with finger joints after a bit. I need to get the planer dialed and also my glue up technique. I'm planning on using 3/4 pine strips, t&g'd with my router and glued up to form the 11.5 inch wide boards necessary. Total overkill but, it's a learning experience. (and it will look totally cool under my Pro Reverb guitar amp!)

    Hopefully I won't end up as the only 3 fingered bassist in town ...

    Carpenter's handshake aka Fisherman's handshake...

    1. Hold right hand out, thumb extended at 90 degrees to palm, 4 fingers extended.

    2. Fold middle and ring fingers* back towards the wrist.

    3. Shake hand up & down ...

    * middle or ring for faster learners ...
  6. K Dubbs

    K Dubbs Just graduated from OSU, Go Bucks!

    Mar 16, 2002
    Toledo, Ohio
    I usually use simple butt joints on all edges with the sole exception being the edge where the speaker baffle joins with the top, bottom, and sides. On those edges I use a dado. In addition, for any empty boxes over 40 lbs, it might be a good idea to use cleats, but most of the rigidity of the box should come from straight cuts, proper gluing and piloted screwing, and cross bracing.
  7. 4Mal

    4Mal Supporting Member

    Jun 2, 2002
    Columbia River Gorge
    So the speaker baffle is something like 3/4 wider and longer than the interior dimensions of the box allowing for 4 sides of 3/4 by 3/8ths dado (assuming 3/4 material where a 3/8's deep dado would make sense) ?
  8. Mo'Phat

    Mo'Phat Supporting Member

    Oct 1, 2003
    San Diego, CA, USA
    Dovetail that bizzatch.
  9. K Dubbs

    K Dubbs Just graduated from OSU, Go Bucks!

    Mar 16, 2002
    Toledo, Ohio
    I prefer making small and light boxes using 1/2" thick baltic birch (i think its 9 ply). I glue 2 pieces back to back in a sandwich for a 1" total baffle and use 1/4 inch deep dados. The dados are pretty useful in keeping things stuck together if you've gotta assemble the box by yourself

    Keep in mind that commercial cabinet makers have most of the pannel cutting process automated and consistent. When you have that degree of consistency and precision to work with, designs can afford all sorts of additional goodies like interlocking joints, rabbets, etc.

    When working with a single table saw (a decent table saw with a steady locking guide is essential) you'll be adjusting for different cuts and keeping consistency is difficult enough. Adding complication will likely render you with less overall rigidity/strength than using simple cuts, simple joints, screws and quality glue. If you want added strength to the edges, glue in some wooden strips on the inside edges.
  10. Munjibunga

    Munjibunga Retired Member

    May 6, 2000
    San Diego (when not at Groom Lake)
    Independent Contractor to Bass San Diego
    I use the double rabbet (A) glued with Gorilla Glue and 1-inch #6 or #8 screws about every 8 inches. Overkill? Hell yes! Will it come apart? Hell no!
  11. 4Mal

    4Mal Supporting Member

    Jun 2, 2002
    Columbia River Gorge
    Kdubbs - I like the light weight idea. I'm prototyping at the moment working on a 4.5 ft2 box for an E140. When I arive at the apropriate box, I'll move to higher quality wood. I was going for 3/4 marine as it is certified void free but I'll have a look at the 1/2" instead. It certainly can't be more expensive than the marine stuff! Even in Portland where there is actually 'marine' that stuff is dear.

    I definately like the idea of a rabbett/dado joint on the speaker baffle.

    I like the rabbett option B the best I think. I've worked with A and I suspect 1 person alignment will be easier in B. B also has an additional glue bearing surface if I'm thinking correctly.

    I find that the consistency angle is largely a matter of having good tools and taking time. If I rush, it doesn't come together very well at all.
  12. That is an awfully large box for an E140.

    I know this tuning is recommended in the JBL Enclosure Guide (4.0 at 40 Hz), but it generates a huge EBS cabinet and a nasty GD spike at 40 Hz. FTR, I've not heard one in this tuning.

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