hifi.slovanet.sk

[MaBat]

[jzagaja]

Macro for drawing splines:
http://help.solidworks.com/2016/english/api/sldworksapi/Create_2D_Spline_Example_VB.htm

Drawing one quart is enough. Cross sections and guiding curves.

[jzagaja]

And better loft surface body:

http://help.solidworks.com/2012/english/api/sldworksapi/create_loft_surface_body_and_change_into_feature_example_vb.htm

[MaBat]

So how much different would the resulting shape be if I gave you just these four curves (in red)?
As I understand, this is how the surface can be constructed. Right?

https://www.youtube.com/watch?v=fIzEDqL0kUE

[jzagaja]

If you gave me points I will draw splines and compare. Can be coarser set.

I did 7 intersection curves with mesh and surface loft computation was very slow. I couldn't thicken resulting surface.

[MaBat]

OK, these are the points for the four curves shown. Same points as for the STL, you can omit some if you need (beware, the end points repeat).
If this will work, I could then create the splines directly in some script I guess. Maybe also some guidelines in the middle - I don't know about the Solidworks possibilities. The throat could be definitely set as a circle arc, no reason to re-create it from points.

[jzagaja]

This works perfect however I need more curves. Red is your STL and grey is resulting surface loft.

[MaBat]

I think this happened to be different files/horns. These two should match, generated from the same dataset again. Please try it.

[jzagaja]

2cm difference on diagonal.

[jzagaja]

This is what I'm trying to do. Put foam inside.

[MaBat]

What do you suggest? It is obvious that the loft surface has not a constant throat angle accross the circumference. It just leans more directly to the corner. We could either try to specify some "tangent condition" at the throat or add more curves in the middle. It's up to you to explore, I don't have the software. It doesn't have to be exactly the same. You can make a mesh from that and try ABEC to compare. I don't know for sure which one would be better.

That looks promising.

[jzagaja]

Few more curves and match is perfect.

[MaBat]

BTW, what about this?

[MaBat]

[jzagaja]

Exactly.

[MaBat]

So...

[jzagaja]

Perfect Marcel! 3 deg?

[MaBat]

OK, let's say it is good enough. It would be interesting to know the cause of the difference however, because the red shouldn't be seen much from this side, IMHO.
3 deg total. It is hard to measure, isn't it BTW what does CAD say?

One option still left open - the superellipse exponent. It affects how fast the circular throat gets transformed into rectangle. Choose what you like better. The previous was 2.0, this is 2.7. I would maybe prefer the second one, it's up to you (I can make it 2.3).

[MaBat]

SEExp = 2.3 ...maybe a sweetspot.

[MaBat]

Jack, what if I gave you the guide curves for the other direction? Could you try?

[jzagaja]

[MaBat]

Awesome!

- I would definitely connect the front and the back by some sparse grid, otherwise I would be afraid the foam could deform it while expanding. Well, it depends on which foam you are going to use.

[jzagaja]

Suprisingly it doesn't improve - opposite it worsen match by 2mm at diagonals. One must carefully choose guiding curves.

[MaBat]

Thanks.

[MaBat]

Kdyby si chtěl někdo vyzkoušet, jak se dělá v ABEC: https://www.diyaudio.com/forums/multi-way/329476-1-4-2-throat-constant-directivity-horns-actually-buy-post5811562.html

[MaBat]

http://www.at-horns.eu

[MaBat]

B&C DCX464 za 450€. Obávám se, že až se prodá tahle první várka, bude to dál za těch 800€
https://en.toutlehautparleur.com/compression-driver-coaxial-b-c-dcx464-12-16-ohm-1-4-inch-exit.html

Nepořídit před nedávnem ND4015Ti2, asi bych o tom dost uvažoval. Čekal jsem těch 800€ rovnou, proto jsem na to ani nečekal

[MaBat]

K výrobě:
Jedna vrstva pryskyřice LH 330 se skelnou tkaninou 24 g/m² a přes to ještě jedna vrstva samotné pryskyřice udělá na XPS tenounkou krásně hladkou a už poměrně tvrdou a odolnou slupku. Paráda.

To když se přetře voskem, neměl by být IMHO žádný problém to tak odseparovat a pak oddělit. Ale to se teprve uvidí. Ještě si hraju s tvarem samotné horny, je toho na výběr moc, to je spojitá plejáda možností a podle Ath4 a ABEC to všechno vychází hrozně hezky.

[opa]

[MaBat]

To je jen povrchová úprava kopyta: http://hifi.slovanet.sk/bb/viewtopic.php?p=326256#326256
Je to v desetinách mm, ani nevím, jestli má smysl to nějak dopředu kompenzovat na tom tvaru.

Jinak pružné je to asi tak, že ztvrdlý štětec už moc neohnete.