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3D scanning / 3D printing for old speaker part |
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Hemisphere 
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Joined: 21 April 2008 Status: Offline Points: 2272 |
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 Topic: 3D scanning / 3D printing for old speaker partPosted: 25 July 2017 at 9:40pm |
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It will be for sure.
It's just a matter of time before all the guff we're talking about gets sorted into a convenient arrangement between service providers and customers, and some of the more experimental ideas like piecing together sections or composite shell/core will be more widely understood and hopefully some standard practices established. For some people it's clear enough already, it just doesn't seem to have filtered down towards speaker building/diy communities yet for some reason. Same happened with solar power - everyone was massively sceptical about it's potential for decades, but a few nutters got some excellent creative uses out of it, and now it's pretty mainstream. I honestly don't think 3D printing will ever be the best option if you're talking about 'input idea into computer and hit print'. Same reason you don't use an inkjet printer to print magazines, it's just not the right tool for the job. You'll never 3D print a sub enclosure in solid plastic for the same reason you'd never build one as a fibreglass layup. But if you consider it as just one part of a set of industrial processes it's got loads of interesting potential. You can use it to print moulds for silicone rubber casting, for example.
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Requiem
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Joined: 20 January 2011 Location: Bristol Status: Offline Points: 1805 |
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Posted: 25 July 2017 at 9:16pm |
Robbo, you would be my favourite person for like... the rest of my life. My heads hurting looking at all this stuff regarding 3d printing that I dont understand  That's not to say i'm not extremely grateful to you guys for your input though! Just getting a few replacement bungs will probably be much cheaper. (will probably have the same problem in 3/4 years again, but hopefully 3d printing will be dirt cheap by then
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www.requiem-soundsystem.com
Custom Martin Audio WSX, USB & CSG Soundsystem based in Bristol |
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Robbo
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Posted: 25 July 2017 at 8:03pm |
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I may be able to help here as I have some of the 8" phase bungs and back bowls buried in my garage--all are new and unused.
Bear with me for a couple of days and I will dig them out and have a look. |
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Hemisphere
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Posted: 25 July 2017 at 6:57pm |
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The amount of finishing required with FDM is as much as you specify it to be. It could be a big job applying coats of filler into rough grooves and sanding out crevices, or it could be a couple of spray coats and polish.
 FDM can be as fine as this chess piece, although that will put the price up. There are also finishing services that can be applied to the FDM part by the shop. Even nesting the parts is still going to be quite wasteful with segments of a phase bung. Easily 50% unused, could be 70%. Unless you chop it into really small segments like 16ths. Which could work I suppose! Depends how you designed the bracing structure and assembly stages, but it's all starting to look like a lot of design work for a one off replacement part. You could practically design your own complete 3D printed horn and bung structure if you'll be putting that sort of effort in. Maybe SLS shouldn't be ruled out though. There are services which also offer SLS parts on a 'per cc of material used' basis, or using a a combination formula that accounts for material and bounding box volume. They usually work out more expensive, but are worth a try as they offer immediate online quotes for an uploaded model, so that offers a good benchmark to compare alternatives to. Edited by Hemisphere - 25 July 2017 at 7:06pm |
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RoadRunnersDust
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Posted: 25 July 2017 at 6:19pm |
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If you design it sensibly you could make the join pretty much seamless, especially with the accuracy of printing now...
Just strikes me that having something printed and then having to do so much finishing on it with the potential to bollox it up in the process is a bit much... especially something that the shape and dimensions are fairly critical and hand finishing it would be difficult to maintain I dont see how gluing half the segments together, filling it with foam, repeating with the other half of the segments then sticking the two halves together and a light finishing would be more difficult than hours of finishing for an end product that might then not match the item its replacing |
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Hemisphere
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Posted: 25 July 2017 at 5:39pm |
Assembling the parts of a shell + bracing manually sounds like more trouble than it's worth. It also won't be cheaper, and it won't be higher quality except for having a smoother surface finish, but once you've assembled it from pieces any benefit of surface finish is lost anyway.
Edited by Hemisphere - 25 July 2017 at 5:42pm |
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RoadRunnersDust
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Posted: 25 July 2017 at 5:29pm |
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could you not use the SLS but segment the bung for manual assembly and 'russian doll' the parts in order to use less cubic volume?
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Hemisphere
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Posted: 25 July 2017 at 2:14pm |
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You really don't need 10mm wall thickness for a phase bung.
First of all you can brace it, and if you're 3D printing there's no good reason not to brace the hell out of it, as it won't add much to your workload. Second is that the surface area just isn't that large to begin with, and the shape is an extremely solid one, geometrically. Just as an example, you mount steel cup bar handles to your subs, right? I know they're not exactly critical structural elements of the enclosure, but if they were vibrating a lot under pressure they wouldn't be fit for purpose, would they? If you put a rubber handle cup in the box you know it would vibrate and have a negative effect, so they're obviously coming under stress, but a lot of them are nothing more than unbraced 1mm steel! And that's apparently good enough for the most expensive touring boxes. Of course the structural integrity of the phase bung is going to be more critical for sound quality, but a 3mm shell braced with 2x10mm braces every 20mm (equivalent material used to 4mm thick unbraced, but much stronger) would still be overkill imo for what you need, and with 3D printing, the only way it's going to be affordable is if you use less material. You could even run full cross braces across the entire length and diameter of the bung, meeting in the middle like a star, and even cross brace that star with a ring in the middle. The less unsupported surface area (and the better supported/more cross-supported each surface is), the less resonance. That's why Mykey's foam core approach worked. The foam is basically an infinite bracing arrangement. The density of the foam will be less than 10% of the density of solid plastic, but it's still incredibly strong. The foam is formed of millions of incredibly thin walls that all link with one another, which gives it strength enough that when the outer skins push on it, there's no resonance. How many mm of glass and resin he applied to the outside of the core I have no idea, but he could have applied 1.5mm and it would have been enough, because of the infinitely braced strength of the internal structure. The quotes you listed are for stereolithography (that's a joke - ancient technology with no relevance to anything besides extreme precision aerospace stuff, but obviously people who still have the machines want to try and sell you their products..), and selective laser scintering (SLS), which is more modern, but has the issue of charging per cc of bounding box, rather than cc of material used. Like stereolithography, SLS is very high accuracy and great for things like jewellery or precision engineering prototypes, but that just isn't necessary for your application. The great thing about FDM (fused deposition modelling) is that the rougher the finish you're prepared to accept, the cheaper the print will be, because it's literally just building up layers of material on top of each other with a nozzle. If you can find a printer with a 3mm nozzle, it'll be much cheaper and faster than one with a 0.7mm nozzle (like 10x faster, many times less electricity used, less damage to the equipment, etc). You'll get a visually rough finish but I presume you intended to finish the bung manually anyway. There are loads of other disadvantages to FDM - it struggles with complex shapes, and that can take the cost and complexity of model preparation way up, but a phase bung doesn't have that issue. You might have better luck on 3D hubs, which can put you in contact with local 3D print shops, who are much more likely to specialise in FDM printing. SLS machines cost like 10 grand minimum, and you could probably get an FDM machine big enough to do your job for about 300 quid - less than what the SLS shop is asking for the entire job! Edit: Actually a phase bung might have the issue I mentioned with regards to FDM printing. It depends if it starts with a flat face on the inside edge or not. If it starts from a curve and ends in a curve then you'll need to print support structures, but that's a function built into all FDM printers and doesn't require extra model preparation.
Edited by Hemisphere - 25 July 2017 at 3:13pm |
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Requiem
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Joined: 20 January 2011 Location: Bristol Status: Offline Points: 1805 |
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Posted: 25 July 2017 at 9:48am |
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Ok thanks for your help.
I was given this quote on facebook, just for the the radially symmetric bung part without the supports/ring. Hollow, 10mm wall thickness: Solid; FAR out of my price range, for something that originally cost £100ish for the entire horn: flare, back bowl & phase bung! I will have to get a more accurate description for the place you;ve linked me, but will get onto it Edited by Requiem - 25 July 2017 at 9:51am |
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www.requiem-soundsystem.com
Custom Martin Audio WSX, USB & CSG Soundsystem based in Bristol |
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Hemisphere
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Posted: 25 July 2017 at 1:28am |
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If the walls were like 3mm you could probably get away with it. The shape itself is structurally strong anyway and you could try bracing it internally as well.
http://3dprintingpricecheck.com/ You can put a file here and get a quote. A 1 inch cube (16cc or so) was quoted as $3.63 from 3dprintuk. EDIT: The quoted figure is with SLS which is actually the wrong sort of 3D printing for your application! You need FDM, which is literally charged per cc of material. SLS charges per cc of bounding box so you would end up paying for the entire solid even if you printed a hollow. Like I said you need to shop around a bit, but FDM is what you need.
That Nylon material is not the strongest though. Not comparable to glass or ABS so you would want to overestimate the thickness needed. At that price you could afford to. Edited by Hemisphere - 25 July 2017 at 1:56am |
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Requiem
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Posted: 24 July 2017 at 11:02pm |
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But as the shell is a closed unit how would i be able to fill it after? There would be no entry point, and i don't really fancy drilling a hole into it to fill it.
Would there be a difference in the sound if it was simply hollow? Yeah the solid resin is too much for the support struts, hence why im looking for this repair. Ive had to do this a few times before but have always managed to discover spares lying around in the past. Looking for a cost effective way to do it, I had someone say that it would cost between £500-1000 on facebook to 3d print this!! Obviously this would be solid resin, I would definitely need a cheaper option and the solid resin as stated, leads to a design flaw with the struts breaking after heavy use.
Edited by Requiem - 24 July 2017 at 11:04pm |
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Custom Martin Audio WSX, USB & CSG Soundsystem based in Bristol |
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Hemisphere
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Posted: 24 July 2017 at 8:31pm |
 ? For the 3D print, I mean. It's a method I've been thinking about a lot recently but didn't have a chance to test it. If foam core works in fibreglass layups why not in 3D printing? Print the shell then fill it with foam after. |
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Robbo wrote: