New designs for Curvy Bruce

[planet10]

I know you guys have probably thought of this, but it would be nice to see the CNC plans/templates/whatever they are called designed to minimise waste. We have enough waste in this world as it is... Looking side-on, would breaking the design into 3 or 4 pieces help reduce waste? This would also allow a smaller packing size. Just thinking out loud...

With the execution of Andrew's CB 2 the straight back section could be a piece of plywood... it would not only be a material saver, but would be stiffer than the translam.

As to the support leg, i'd graft on a single separate metal leg on the back, and perhaps mirror that with a set of outboarded points on their own metal bit out front.

dave

 

[chrisb]

Some lay-person suggestions:

1. BR chamber - extend into the voids, then use deeper peaks and valleys to break-up lower freq. (I think). Could Schroeder (sp?) calcs be used? Hmmm, perhaps the space in the BR chamber would be too limited and pressurised for those types of calcs to have any effect?

2. Aesthetics - I prefer the leg style of the top right in P10's drawings; the Curvy Bruce 2 legs make it look somehow dumpy, tho may look okay if painted in strong primary colours for a 'modern' look.

3. If it is going to result in a practical material saving, I prefer Curvy Bruce 2, because it lacks the rear voids. It also keeps the weight down to a minimum.

I know you guys have probably thought of this, but it would be nice to see the CNC plans/templates/whatever they are called designed to minimise waste. We have enough waste in this world as it is... Looking side-on, would breaking the design into 3 or 4 pieces help reduce waste? This would also allow a smaller packing size. Just thinking out loud...

Cheers

Unless you can obtain endless hours of CNC time at zero cost, no matter how efficiently you nest the patterns for a design such as this, the machine run time would be considerably more costly than the most commonly used sheet good materials (i.e. MDF or plywood) .

Breaking larger pieces such as the layers of the back wall of outer shell would substantially complicate the fabrication as well as weaken the complete assembly, particularly if aesthetically slenderized legs are included in those layers.

edit: we haven't been in direct communication on this subject, but I see that Dave essentially addressed the same point in his post above



MDF has many great properties as a panel product , but my well documented and herein acknowledged personal bias for the sound quality of high count plywoods aside, once machined to parts of these sizes, MDF is very brittle, and requires very careful handling during assembly, and sealing .

As a flat-pack kit, this would be very expensive to package and ship, not to mention the headaches involved in replacing parts damaged in shipping or during assembly.

 

[atilsley]

Dublin78

Well done on that laminating....I've thought about those thin layers for component platforms....very nice look.

For the Carfrae Little Big Horn I built, I applied a fibleglass resin to the internals. I built the large horn in 2 cross sections to provide access to the narrower sections. Still a pain.

The same technique for my C-Horn....glue in 2 or 3 stages...sand as you go.

My Big Fun Horn was not sanded inside...and it sounds great...

Andrew

 

[planet10]

I applied a fibleglass resin to the internals

For MDF i'd expect that (or similar) would absolutely be required.

dave

 

[atilsley]

For MDF i'd expect that (or similar) would absolutely be required.

dave

Never again! Awful smell, awful on hands, awful to finish smoothly. I'd prefer a thick style undercoat/sealer....almost like that thick paint you paint garage floors with...eg has a semi gloss finish and is really thick.

For the large mouth opening on the Carfrae, I applied wood filler/bog and sanded it out evenly. Worked well. Then it was painted....this is just the internal part that you can see when seated...not the whole horn path. The upper horn path was fibreglassed.

 

[planet10]

Never again! Awful smell, awful on hands, awful to finish smoothly. I'd prefer a thick style undercoat/sealer....almost like that thick paint you paint garage floors with...eg has a semi gloss finish and is really thick.

With the MDF it is important to create a very stiff layer in the surface of the MDF. I doubt paint/sealer would not do the job. (reason why its probably easier/cheaper just to start with plywood) -- the fiberglass is just a bandaid on the issues with MDF.

dave

 

[dublin78]

Unless you can obtain endless hours of CNC time at zero cost, no matter how efficiently you nest the patterns for a design such as this, the machine run time would be considerably more costly than the most commonly used sheet good materials (i.e. MDF or plywood) .

You are correct; my CNCing work cost more than twice as much as the BB plywood (best available quality) sheets.

It is good to avoid waste, but in this case it is irrelevant. Perhaps you could make some funky sculptures from the leftovers?

 

[dublin78]

Don't forget about weight.

All my baffles and internals were 50mm thick. I did this for rigidity, and because I could. The NET result was extremely heavy cabinets that I can barely move on my own - pretty solid though.