I'm far from being an expert on this but I feel that in a thin, epoxy-coated body, the internal structure of an infill would act as a kind of constrained layer damping. Wouldn't it? We have full control over the density and structure of the infill, as well over the outer shell thickness.
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I used to own a pair of Oris Horns by BD-Designs. I believe the horn was only about 5mm thick, but I never felt that there were any (audible) issues with them being that thin. Not very scientific: but you could never feel any vibrations or resonances while touching them as they played at loud volumes. That was my experience.
All that being said - if I'm able to successfully print and assemble the current version/design of the A460 horn --- then I am officially moving forward with the build.
It's insane how far along this thread has progressed and how advanced the horns have become. I was hoping more people would have proceeded with developing a full system around these horns but, unless I totally missed it, only a handful have posted to date. For me, the curiosity is killing me.
If I am successful with my print+assembly, then I will proceed with building a 2-way horn speaker with the Peerless driver on the top and possibly the Faital 15PR400 15" or JBL 2216Nd 15" on the bottom. A look very similar to the following:
All that being said - if I'm able to successfully print and assemble the current version/design of the A460 horn --- then I am officially moving forward with the build.
It's insane how far along this thread has progressed and how advanced the horns have become. I was hoping more people would have proceeded with developing a full system around these horns but, unless I totally missed it, only a handful have posted to date. For me, the curiosity is killing me.
If I am successful with my print+assembly, then I will proceed with building a 2-way horn speaker with the Peerless driver on the top and possibly the Faital 15PR400 15" or JBL 2216Nd 15" on the bottom. A look very similar to the following:
I listened to a few combinations during the measurement sessions in a very very crude setup, just quickly EQed with what was probably the worst crossover ever, and could listen to it all day. There's so great potential. Now I only need to give it a nice packaging (and a new listening room).
I think the density and infill and largely irrelevant. Any pla-like material is plenty stiff enough. The only resonance that actually matters is the ringing of the outer diameter. (about 250hz in the a460 I've just made). This can be damped with a single weight at any point on the rim - but I'm not even sure it matters.
Very thin, light and possibly compliant are experiments I'm interested in though.
Very thin, light and possibly compliant are experiments I'm interested in though.
I wouldn't think so. I believe the constrained layer would need a viscoelastic material that does well in converting vibrational energy into heat. Typical filament plastics don't do that well, they act more like a spring then a damper.
The main reason I believe 3d printed horns work well structurally is because of the added thickness and therefore stiffness. Traditional plastic horns are thin walled, because the are injection molded or vacuumformed. Both these manufacturing options don't do well with large wall thickness.
Thickness, as a variable, acts with the power of three on the moment of inertia(bending strength). If you double the thickness you get 8 times the moment of inertia! 3D printing wall thicknesses of horns are not being constrained by the manufacturing method like with the traditional manufacturing options, therefore I suggest using it in your advantage for adding stiffness! No offense to damping, it's also important against resonances, but a lot harder to add compared to thickness.
Thanks, that would explain a lot.
Interesting, how did you find out?
Anyway, I'm giving it a chance 🙂
And I really like the mounting idea shown in #15,721, as it solves more than one problem (for me). It doesn't have to be so thin after all.
I am almost through printing the 6 petals. I still need to print the throat.
One or two additional suggestions:
1) Are the alignment pinholes smaller on one side than the other? If so, I would make them of similar size.
2) I don't know how to describe this modification accurately, but I would make the following feature larger. Modify from RED to GREEN (e.g., if using software like Fusion360, use push/pull tool to push the marked red surfaces below further into the horn).
From my experience, it makes sense first to assemble all the petals and then insert/attach the throat. You would typically do this by laying the petal face down on the floor and inserting the throat from the top, or resting the throat on the on the floor (facing up) and laying the assembled petals from the top. As currently designed, when gluing the horn following this assembly technique, there is more vertical glue space than there is horizontal glue space ----- this has the impact of glue being removed from the two surfaces (if the mating surfaces are too tight) or leaking out (simply due to gravity) if the gap between mating surfaces is too large. If this feature was larger, you would now have much larger glue space in the horizontal orientation and the glue is far more likely to remain between the mating surfaces, creating a stronger bond and provide better gap filling. I hope that makes sense.
That's pretty cool. This would considerably save time on printing. How would the petals attach to the throat?
OK, understood. Which one do you prefer? -
(The one on the right would be a lot easier to sand down if necessary.)
The holes are nominally the same (⌀1.95 mm) but the first few layers typically get smashed a bit, so the holes get smaller. A drill should do.
I'm not sure if decreasing the bed temperature would improve this. In slicers there are also compensation settings for this (can't recall the name), I've never really experimented with it much.
(The one on the right would be a lot easier to sand down if necessary.)
The holes are nominally the same (⌀1.95 mm) but the first few layers typically get smashed a bit, so the holes get smaller. A drill should do.
I'm not sure if decreasing the bed temperature would improve this. In slicers there are also compensation settings for this (can't recall the name), I've never really experimented with it much.
I would say definitely the one on the right. Too much precision (at the printing level and the glue level) would be required for one on the left to work out..
This is what I did. You can tune the with of the small parts separately and print trials quickly. Then you can even dry fit them. This allowed me to use CA glue which I prefer over the slower gap filling glue and the need for the glue clamp part is gone. End result is also cleaner and needed less sanding.
Sure, I already have this in another kit. This time I thought I'll make it simpler and good enough...
For me, the pinholes worked were just fine. A small (1/8") drill was used to get a sufficient opening to insert 1.75mm filament on both sides with a little bit of pressure. I sometimes stretch the filament with pliers to get it a little thinner.
I also like your idea above, as long as it's a spline system and not a tongue-and-grove system. It would also help, as @Tom Kamphuys suggested, to tune the smaller parts to be ever so slightly smaller than the opening. Can the cavity be designed so no supports are required during printing? Otherwise, it would be nearly impossible to clear the cavity sufficiently for perfect insertion of the spline.
All that being said, the pinholes did work out just fine for me.
Sure, spline joint, no supports. I'll add several widths in a fine step so a perfect fit can be achieved.
OK, so hopefully this is the last one. I like the dry-run possibility, seems like a good idea.
Maybe the spline joint could be deeper. This look good to me -
OK, so hopefully this is the last one. I like the dry-run possibility, seems like a good idea.
Maybe the spline joint could be deeper. This look good to me -
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I cannot tell you guys how much time I wasted on this goofy parameter.
I was this close to just uninstalling EVERYTHING and going back to making waveguides The Old Timey Way.
Literally every attempt I've made at creating a waveguide, for MONTHS, has suffered from really dramatic peaks and dips in the response. I tried:
1) using a small roundover
2) using a large roundover
3) increasing the sampling frequency
4) increasing the density of the mess
5) increasing the granularity of the frequency response
Nothing worked. Turned out it was "Mesh.SubdomainSlices"
I think this could work out well. I wonder if the spline system would also work well for adjoining the throat to the petals. I really like the throat+petal joinery as is - and I think the mod you already made should take the bond to the next level. But I'm just curious if a spline system would work equally well. For the spline to work between the throat+petal - you would need (I) near perfectly circular glue up of the petals or (ii) the spline to be thin enough to allow for reasonable tolerance.
Thank you very much for creating such a nice piece of software. I was wondering if there was a way to automatically run the generated .abec files and save the simulation results (instead of clicking on the files and running the simulation manually). So via something like a command line interface for abec. Is there a way to do this? I have looked in the abec help file but found nothing.
Here is a Part 1 update after the full petal modification only (and not other mods discussed in the last few posts).
Here is a glue up of just the petal --- overall, far better than the first go around. I glue there petals together and then glue to two halfs together. Of the total six glue joints between the petal, these are my results:
1) Excellent
2) Excellent
3)Very good
4) Excellent
5) Excellent
6) 3/4 very goog, 1/4 poor. (the joint section closer into the throat connected better than the other rim of the horn). So I just poured some extra superglue and sprayed with activator. I think once sanded and painted, it would be less obvious to tell.
The three petal glue together really well. Then when attaching to two halfs, once side glues together really well but the other side requires a lot of force to pull together.
I'll update again once I attach the bass. Note the base being printed is prior to the modifications discussed in post 15,728