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fonken build
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Old 20th August 2008, 12:43 PM   #1
mantisory is offline mantisory
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Join Date: May 2002
Location: toronto
Default fonken build

Hi all,
Well, I got the FE127EN's from Dave, and am starting to plan out a build of the fonkens...I have a couple of questions though:

1) What are builders of the fonkens doing in terms of joinery? Are straight butt joints good enough, or are you mitering them, or possibly rabbiting (as Dave the Bass did)?
2) The front baffle - it's designed to be 19mm...but the rest of the cabinet is 12mm...since BB is pretty expensive, what are people doing for this one? Using 19mm for these two pieces and then finding other uses for the leftover?
3) on the BB, it comes in 5x5 sheets AFAIK...I have only quickly looked at the plans, but does it take 2 sheets to make a pair of fonkens?
4) Has anyone done any exotic veneers with the fonkens? I am not a big fan of the look of plywood, and, well, the bamboo stuff is 500$/sheet!
thanks all,
B
p.s - once i get back from vacation I will be hopefully keeping a photo log here on the site.
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Old 20th August 2008, 01:19 PM   #2
strider75 is offline strider75  United States
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Join Date: Apr 2008
I went with butt joints on the outer portions of the cabinet but used an 1/8" dado on all sides of the driver brace as well as the top and bottom of the inner side panel.

For the front baffle I picked up a piece of 12" x 30" x 3/4" BB at my local Woodcraft store. It was ~ $12. For the rest of the cabinet I used natural birch 1/2" ply. Couldn't find a sheet of BB, wasn't looking forward to footing the bill if I did!

You might/should be able to make both cabinets out of one 5x5 piece of stock, but it will be pretty close. From memory, I have just about a half sheet of 4x8 ply left over from my build.

Anyway, have fun and take some pictures!
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Old 20th August 2008, 02:18 PM   #3
Jim Shearer is offline Jim Shearer  United States
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I'm in the middle of a Fonken build right now.

One 5x5 sheet of Baltic Birch ply is more than enough for two cabinets.

I'm doing simple butt joints, 'cause that's all I know how to do.

I cut the front baffles from a sheet of 3/4" 'cabinet grade' ply that was relatively free of voids (based on observation of prior use of that particular sheet of ply.)

Cheers, Jim
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Old 20th August 2008, 02:21 PM   #4
mantisory is offline mantisory
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Location: toronto
thanks guys,
Jim, you should start posting some pix and track your build!
Anyway, the woodcraft deal looks pretty decent. even with shipping it shouldn't be more than ~25 bucks (with shipping to canada) for a piece for two baffles...
will keep you all updated!
Byron
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Old 20th August 2008, 02:52 PM   #5
jallenbass is offline jallenbass  United States
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I did mostly butt joints and a few rabbett joints. When I build any future speakers I will do all rabbett joints as it makes glue up a lot easier.
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Old 20th August 2008, 02:58 PM   #6
jallenbass is offline jallenbass  United States
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I did mostly butt joints and a few rabbett joints. When I build any future speakers I will do all rabbett joints as it makes glue up a lot easier.
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Old 20th August 2008, 04:25 PM   #7
schn0354 is offline schn0354  United States
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I am assembling a pair today. With regards to your questions:

1. The joint where the side panels and top/bot meet is naturally a rabbit joint with a huge glue area. Dado slots were made on the baffle and rear using a router with 1/2" mortise to align the brace during glue up. It does not help much with strength, but assures the brace is glued in the right place. Rabbit joints were also made in the side panels where the rear fits into. This again was done mostly to assist in the glue up as everything moves when clamps are applied! Dry assemble everything first. All panes should fit (air tight) with low clamp pressure.

First assume your plywood is not square. I have limited tools and used an MDF sheet as a reference and flush trim bit on two edges of all panels. Mark the 90 degree sides and do not alter it on the table saw. Make all the size cuts at the same time on the table saw for accuracy. For rabbit joints, a trick is to sneak up on a cut using paper shims (.002") on the fence of the table saw. Also, over size some of the panels and trim excess later with a router and flush trim bit.

I find it best to glue up in stages due to having only 10 clamps and limited working time for the glue. However, it is necessary to assemble it as if it were complete, to ensure fit.

2. You can buy 3mm or 6mm Baltic Birch from Ace Hardware or craft stores and glue it to the 12mm baffle. I used two 3mm 12" X 24" sheets glued together, the outer layer was cut with a jig saw for easy flush mounting of the driver. The Fonken cabinet design seems overkill for strength with a driver that has less than 3 grams of moving mass, so I think the thickness on the front baffle has more to do with aesthetics. I actually considered using 6mm for everything except the baffle.

3. I purchased two BB 30" by 60" sheets at $55 total. Accounting for mistakes, I used about 1.5 sheets.

4. Danish oil with a cherry stain looks good on BB. Good veneer is expensive and time consuming.

I have some left over 3/4" Sonic Barrier constrained layer mass loaded vinyl damping material. I would like to use it on the side panel walls only. Would the slight reduction in apparent volume and extra damping be a disadvantage in the Fonken?
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Old 20th August 2008, 04:32 PM   #8
schn0354 is offline schn0354  United States
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Here is the 1st stage glue up of sides, bottom, and rear. You can see the Sonic Barrier in place. It worked well in the prototype, but will it work better with just the 1/2" cotton fiber? Can a ported/near aperiodic design be too damped? Hmmm...
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Old 20th August 2008, 04:42 PM   #9
schn0354 is offline schn0354  United States
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Another picture. Rabbit joints in the rear of the side panels enable clamps to tie the baffle and rear together. This makes cuts more difficult, but results in fewer expletives during assembly!
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Old 20th August 2008, 04:50 PM   #10
schn0354 is offline schn0354  United States
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A 1/2" channel was routed in the baffle and rear for the brace. I do not have the FE127's yet.
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