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Old 18th October 2020, 05:42 PM   #21
hifijim is offline hifijim  United States
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First pic shows the driver cut outs with the flange recesses. The tweeter terminal dog-ears have not yet been cut, and the chamfer on the backside of the mid has not yet been cut. This baffle was a composite layup of 3/4 inch solid wood and 3/4 plywood. I unfortunately cut the flange recess for the mid driver too deep, so I had to add a small chamfer on the front side... It could have been a real F**K-up, but I managed to salvage it and in the end, it looks good.

Second pic shows the backside 60 degree chamfer. Tweeter terminal dog-ears have been cut.

I am not sure how I would machine this hole on a assembled cabinet.
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Old 18th October 2020, 06:26 PM   #22
planet10 is offline planet10  Canada
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Quote:
Originally Posted by puppet View Post
I've seen this several times and still wonder why people rebate a driver prior to veneering.
This is the way Chris built all our loudspeakers. Veneer before the rebates.

And to address Calís query, Chris used an actual exact-knife.

dave
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Old 18th October 2020, 07:54 PM   #23
chrisb is offline chrisb  Canada
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FWIW, not all my many builds over the years followed exactly the same procedure/sequence or used the same tools, and of course there’s more than one way to skin a cat, but in no particular order of merit, and to correct a couple of Dave’s assertions:
- I almost exclusively used flexible paper baked veneers in full 4x 8’ (sometimes larger) sheets, and post veneered after assembly completed. I found them much cheaper per square foot, and a full sheet could easily finish several small pairs of boxes and allow for alignment and mirror image / book matching of grain patterns - which on some species can be very dramatic.

- Yes a laminate trim router with a down spiral can do a perfectly fine job of trimming even across the grain, but I generally did at least all the latter by hand, with a cheap thick bodied Stanley 2” chisel, in a series of arcing downstrokes.

- Most of my builds with with smaller diameter “full range” single drivers with chamfers on rear side of through hole, and many of those with rebates shallower than the bearing and nut clearance on flush trim bits - even on something as small as the Amanda 3/16” . That, and the fact that I had access to a CNC routing machine that allowed for matching of all the cut outs and rebates even on multi-ways in a single operation determined my build and assembly sequence.
Driver, terminal and vent cut-outs were done by highlighting /lightly scorching the edges with nose of the iron and trimming with a utility “box cutter” knife (generally an Olfa L-5, to be precise), then sanding at a slight angle with 150/220g paper before sanding the rest of the enclosure.
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Last edited by chrisb; 18th October 2020 at 07:56 PM.
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Old 19th October 2020, 12:05 AM   #24
solarfish is offline solarfish  Canada
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Quote:
Originally Posted by hifijim View Post
This baffle was a composite layup of 3/4 inch solid wood and 3/4 plywood.
That looks great but I would be a bit concerned at having real wood that thick glued to plywood. The solid wood is going to want to move with seasonal changes in humidity and the plywood is going to remain at the same dimensions. You may end up with joints failing or the panel delaminating. Recommendations I've seen are never to go more than about 3/8" thick for a veneer.
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Old 19th October 2020, 12:41 AM   #25
prairieboy is offline prairieboy  Canada
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I would agree regarding no thicker than 3/8" (or 1/4"). Besides the stability issue, using 3/4" is a waste of 'good' wood.
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Old 19th October 2020, 03:09 PM   #26
hifijim is offline hifijim  United States
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Well, what is done is done, and no splitting so far Actually I don't expect any trouble. In modern epoxy-fused wood boat building, it is a common practice to laminate solid wood to plywood in this same way, or to encapsulate plywood within solid wood. The joints between bulkheads and stringers, and between hull and bulkhead, often resemble the kind of construction seen in my baffle. You can also see this kind of construction in fully-glued-up butcher block table tops.

The reason I needed such a thick layer of solid wood is that I wanted to deeply profile my baffle, and I lack the veneer skills to do it with veneer. So I needed a solid wood edge of 1.5 inches thick
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Old 19th October 2020, 03:54 PM   #27
Joel Wesseling is offline Joel Wesseling  Canada
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Lovely, hifijim!

Using solid wood has been discouraged by woodworkers but so far haven't had a problem. I have a walnut front panel 2way that's about 5 years old and haven't noticed any changes. This 3way has a poplar front panel and bottom section is joined to side ply panel with a tongue and a groove. But the Bin primer works so well at sealing that I'm now thinking about layering BB and profiling it and the bin primer will perfectly seal the exposed end grain-will see!
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Old 19th October 2020, 08:02 PM   #28
prairieboy is offline prairieboy  Canada
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Well, every rule can be broken, but there's generally a reason for them. If you need a baffle an inch and a half thick, I'd use, for example, a 3/4" plywood, or MDF, core faced on each side with 3/8" thick solid wood. Alternately, 1/4" solids on an inch Cote.
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Old 19th October 2020, 09:38 PM   #29
solarfish is offline solarfish  Canada
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First off jifijim and Joel, that's some incredible work you have there and I absolutely understand the desire for thicker solid wood for that sort of profiling.

As I've been posting in my very first speaker build thread, I added a solid wood 'picture frame' border around the baffle so that I could add some profiling to the front. It won't allow me to do anything as significant as your designs but I will have something interesting I hope.

I had a look at a wood shrinkage calculator and put in the following assumptions:
Wood: yellow poplar
Width: 10 inches
Initial moisture content: 5%
Final moisture content: 10%
Shrinkage: 5/32 inch

This is a big assumption as I don't know the variation in moisture content where you are. The thick paint will also definitely help and a little more than 1/8" movement might not even be noticeable.

Doing the same for cherry ( I think that's what hifijim's gorgeous baffle has )
Wood: cherry
Width: 10 inches
Initial moisture content: 5%
Final moisture content: 10%
Shrinkage: 1/8 inch

Again it might well be fine, especially as in both cases we are talking about movement of the front of a panel rather than at or against a joint. I can tell you though that I have a couple of cherry picture frames on my wall where the mitres are not as tight as they were when I made them. I also have a cutting board that uses a mixture of cherry, walnut and maple, it was perfectly smooth when I made it, now I can feel ridges at the joints because the species have moved different amounts.

Of course the great thing about woodworking and I guess the same applies to diy audio, is something does break or deteriorate in some way, then you should always be able to fix it. Having seen your two excellent examples of baffle contouring, I may well use solid wood for my next baffle!
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Old 27th October 2020, 12:29 PM   #30
Joel Wesseling is offline Joel Wesseling  Canada
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Thanks, Solarfish. I have never looked at a shrinkage calculator.

I had some poplar logs milled 3 weeks ago and the boards are stacked and drying. I had one thin 1/2 inch off cut that is drying inside the warm house. The piece is down to 12% moisture. I planed it a few times during the drying process. Its very stable with no splitting or checking and nice and flat. FWIW, poplar appears to be a good choice for Front Panels.
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