Salad Bowl Speakers

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Ray P
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#31 Re: Salad Bowl Speakers

Post by Ray P »

Some more progress yesterday.

I tested using threaded inserts and T-nuts for the speaker mounting on some scrap material but found that the Acacia wood is a little 'brittle' so for installing the drive units I have epoxied in some rivnuts - they're fluted/serrated so shouldn't twist when the drive units are bolted in place.

I've started glueing in strips of 1.5mm birch ply to make a flange to align and strengthen the join when I glue the front and back bowls together.

I've ordered the port tubing and have revised the 'deflector' for the rear panel and two are currently being 3D printed.
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Ray P
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#32 Re: Salad Bowl Speakers

Post by Ray P »

Played bowls again this morning, so some pictures

I'm glueing thin ply strips to make a flange for joining the bowls
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Busy with the sandpaper.
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And a couple of pictures of two bowls temporarily assembled,
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brig001
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#33 Re: Salad Bowl Speakers

Post by brig001 »

Looking good
Looking forward to the measurements too - want to know if the reflector idea could help my salad bowls. Not sure if 1cm is too small to have any effect at audio frequencies, but will wait and see

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#34 Re: Salad Bowl Speakers

Post by Ray P »

brig001 wrote: Mon Nov 06, 2023 9:51 am Not sure if 1cm is too small to have any effect at audio frequencies, but will wait and see
Thanks Brian. These are a quite a bit bigger than your IKEA bowl speakers, as I recall, and somewhat more barrel shaped.

Not sure either as I'm not an acoustics expert but if nothing else drawing the deflectors was a satisfying exercise in starting to learn Fusion 360.
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Ray P
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#35 Re: Salad Bowl Speakers

Post by Ray P »

A little more progress - cutting the port tubes ready to glue them in.

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Greg
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#36 Re: Salad Bowl Speakers

Post by Greg »

Are you glueing them in before you experiment with port length/tuning?
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Ray P
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#37 Re: Salad Bowl Speakers

Post by Ray P »

Greg wrote: Sun Nov 12, 2023 12:10 pm Are you glueing them in before you experiment with port length/tuning?
No, there's a sleeve that will be glued into the bowl. I've cut the tubing to the longest straight length I can accommodate in the bowls though.
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Ray P
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#38 Re: Salad Bowl Speakers

Post by Ray P »

I've been making sawdust this afternoon!

I glued an extra 20mm layer of acacia wood to the base of the rear pair of bowls with the intention of making the speakers a bit more egg shaped. I''ve just been shaping the extra layers, blending it into the bowl and rounding off the port opening.

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I rough shaped with my power plane, then refined with a surform before working down through the grades of abrasive.
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Ray P
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#39 Re: Salad Bowl Speakers

Post by Ray P »

Some more progress today, the 'deflectors' are now epoxied to the rear panel and I've 'painted' the inside surface of the rear bowls with low viscosity laminating epoxy to seal the surface - once it has cured I'll be ready to glue the front and rear bowls together.
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Ray P
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#40 Re: Salad Bowl Speakers

Post by Ray P »

The project is coming together nicely.

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I've finished coating the insides of the bowls with low viscosity epoxy and then used the same to glue together both pairs - 24hr cure at room temperature so patience required now.

I've noticed that the bowl rims vary by up-to a millimetre or so, so a some sanding will be needed to fair them together before finishing.
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Ray P
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#41 Re: Salad Bowl Speakers

Post by Ray P »

I've been making sawdust again today, sanding back to bare wood and fairing the joins. To completely fair the joins is going to entail removing too much wood so I have to think of how to disguise them without detracting from the wood finish.I have some very thin carbon fibre sheet so I'm thinking of glueing a strip over each join but open to any suggestions..

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simon
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#42 Re: Salad Bowl Speakers

Post by simon »

How much is too much out of interest Ray?
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#43 Re: Salad Bowl Speakers

Post by Ray P »

simon wrote: Sun Nov 26, 2023 4:05 pm How much is too much out of interest Ray?
To get down to a completely flush join, probably 1-2mm, but over quite a large area because of the barrel shape - the bowls themselves match up pretty well but the problem is the join is recessed because of the rounded over edges of the bowls.

I've now decided on the solution and made a start on implementing it - I've mixed some filler and added it around the joins then, after I've cut the filler back, I'll glue a strip of veneer around around the middle - I've ordered a small piece of sycamore veneer, which, being light, will make a good contrast to the acacia - the veneer is only 0.6mm thick so will be quite subtle.
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#44 Re: Salad Bowl Speakers

Post by simon »

Mmm tricky. A jointer would probably do the job, but I'm guessing you don't happen to have one of those laying around :lol:.

Perhaps 4? sheets of 60 grit (maybe 40 to start) stuck down to a flat surface, then slide the bowls' rim back and forth. But no guarantees, and you have a decent, more reliable solution already.
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Ray P
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#45 Re: Salad Bowl Speakers

Post by Ray P »

Not sure about the jointer idea, the tops of the bowls are very flat and they mate together very well, it's just that there's a shallow V groove all around the join.

Anyway, I've applied the filler so let's see how it turns out after it's sanded flat.

Incidentally, I didn't have any wood filler to hand so mixed up some slow Araldite and lightweight fairing compound I have for my model boat builds - I've used it before and it works well as it makes a paste stiff enough to stay put but still with very good adhesion and I know it sands to a feather edge very well.
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