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Old 7th March 2017, 08:39 AM   #231
jcx is offline jcx  United States
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Join Date: Feb 2003
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I liked Creo free version - just old style enough to have actual text and examples in the help, maybe cumbersome but easy to grok ribbon menus

Fusion 360 however is likely better for freeform design - and full functionality is free for hobby use, but without Creo's free version limits
but the developers, most of the community seem to think hundreds of few minute videos constiutes documentaiton
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Old 21st November 2018, 07:35 AM   #232
sugercube is offline sugercube  Australia
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Join Date: Jan 2009
Quote:
Originally Posted by onni View Post
xrk was asking for a STL for 1" compression drivers. Here's a few 90x60 horns that have the following parameters:
W_total: 210 mm
H_total: 130 mm
D_total: 95 mm
R_throat: 12.7 mm
R_vert: 20 mm (vertical roundover at mouth)
R_hor: 50 mm (horisontal roundover at mouth)
Alpha_vert: 30 degrees (vertical coverage = 60 degrees)
Alpha_hor: 45 degrees (vertical coverage = 90 degrees)
N: 1.5 (superellipse)

The geometry has been simplified according to suggestions from andy19191. The mounting holes are 76 mm apart and 6.5 mm diameter (should suit M6). Calculated printing time for 3 shells and 30 % fill is 5.5 hours with my printer.

The throat angle differs according to file name.

7 deg should suit BMS 4550 and B&C DE250.
12 deg should suit CDX1-1445, CDX1-1440, BMS 4552, B&C DE12.

I have not tried printing any of these. I recommend low printing speed for the first layers as the overhang angle is large initially but will quickly decrease.

I can easily make other similar waveguides (other dimensions or angles), just ask me if you feel like printing one

Here is what the geometry looks like:
Click the image to open in full size.

Click the image to open in full size.

/Anton

Hello Onni, I was trying to get hold of SEOS-12 & SEOS-15 waveguides from diysg but they have been out of stock for months and months and there are no local Autotech re-sellers for for these horns in Australia (I am very late to the party). Perhaps you could modify your example to something like those horns so i could try and 3D print those instead (I am guessing the SEOS ones have a much larger horizontal roundover in the mouth.

I have a couple of DE250s waiting without a mate for a few months and has driven me to look at 3D printing route.
Attached Images
File Type: jpg waveguides.jpg (148.0 KB, 231 views)
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Old 19th October 2019, 06:55 PM   #233
altie is offline altie  United States
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Join Date: May 2010
Location: Portland, OR
Quote:
Originally Posted by jcx View Post
you can generate a OS surface by rotating a section of a hyperbola about a axis

may have to enter the hyperbola as a spline thru calculated points

I have used literal conic section construction - rotate triangle to get a cone, slice the cone with a plane offset but parallel to the axis, project the cut face/edge hyperbola to a construction plane and then rotate about a new axis for the OS waveguide shape

I tried this method and it turned out to be much, much easier than previous attempts I had made. Tracing a spline to an image exported from someone's Excel spreadsheet with oblate spheroid equations in it can sort of work. This is better though.

Attached is a Fusion 360 file with a history timeline showing how to do it. I also created three different offset planes in order to see how the different generated hyperbolas would compare. It turns out that as you get further from the midplane with your cutting plane, the generated hyperbola has a softer bend to it. I guess it would probably take some ABEC or COMSOL modeling to figure out which of those hyperbolas works out to be optimal for a given throat exit angle and frequency range.


Oh, and on that note, I'll go ahead and document something I found here while working with an EV ND6 driver (probably equivalent to the often talked about DH1A). If you trace the EV ADH-6 1.4" to 2" throat adapter shown on the EV ND6 data sheet, it comes out to about a 10.6 degree exit angle. I haven't seen that info written down anywhere else.
Attached Files
File Type: zip radially symmetrical oblate spheroid v1.zip (92.8 KB, 7 views)
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Old 22nd October 2019, 02:03 AM   #234
altie is offline altie  United States
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Join Date: May 2010
Location: Portland, OR
Default An attempt at a 1.5 inch throat imitation of the QSC HPR152i/PRV WG35-25-B

Is there a more active thread I should be posting about 3D printed waveguides in? This one's got good information about using the oblate spheroid curve, so I'm updating here unless someone tells me not to...

Attached is a .zip with the .stl and .f3d (Fusion 360 file including history) for the quarter-horn I've generated mimicking this guy: PRV Audio WG35-25-B 1" 90 x 60 ABS Waveguide 2-Bolt. I have a couple of drivers I'd like to try with it.

The geometry on the back side is kind of a mess since I haven't figured out a good workflow yet for creating an object of constant thickness. Maybe that's my next step... anyway...

The specific model of the horn attached right now doesn't have a flange attached yet but has been cut off for a compression driver with a 10 degree exit angle (a few steps earlier in the history, the oblate spheroid profile was generated from a symmetrical hyperbola giving a 0 degree throat angle, so I drew some tangent lines and made a cutting plane about half an inch from the base to give a 10 degree throat that's about 1mm/0.04 inches larger than the 1.4 inch throat I started with).

About half way along the depth of the horn, the profile changes. At the throat, it's a radially symmetrical oblate spheroid profile. At the half way point that surface is lofted to the 14"x10" mouth of the horn, with splines matching the angle of the OS curve along the vertical and horizontal border.

I went with this approach because a previous attempt in Fusion 360 to loft along rails for the entire oblate spheroid curve for a horn with a superellipse or rectangular mouth gave these weird dents on the diagonals that looked oddly like the JBL M2 waveguide. This made me wonder if a workflow like this may have accidentally led someone down that path. If I ever figure out what I'm doing wrong that creates those, maybe I'll redo this with a workflow more like what's shown in Creo in the rest of the thread. Until then, the radial-to-rectangular loft seems to look pretty nice. Maybe I'll play around in ABEC if I can figure that out. If you're reading this and you know how to use it though, could you give it a try?
Attached Images
File Type: png QSCish rectangular horn with oblate spheroid throat v1.png (58.5 KB, 79 views)
File Type: png accidental knuckles.png (163.3 KB, 79 views)
Attached Files
File Type: zip QSCish rectangular horn with oblate spheroid throat v1.zip (1.92 MB, 9 views)

Last edited by altie; 22nd October 2019 at 02:05 AM.
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