3-D printing of a horn or a lawn dwarf

[pos]

Lee, to what compression driver would you like to mate this horn?

The thin printed skin + damping material it appealing indeed.
This is what Rich did for his H9800 clone, using sikaflex (albeit no 3D printing there...).

[Lee in Montreal]

Lee, to what compression driver would you like to mate this horn?

The thin printed skin + damping material it appealing indeed.
This is what Rich did for his H9800 clone, using sikaflex (albeit no 3D printing there...).

I have some 2440, 2441 and 2445. Aluminum, titanium and Radian diaphragms. So, 2" throat.

BTW The drawings I linked in the first post are Yuchi's A290 from his own website. He also did an A290S and A290FL. And many others.

[pos]

Ok so maybe that would be a good idea to modify the title, as there is nothing related to the TH4003 here

Interested to know what you end up with though...

[JeffW]

Will your lawn dwarf have 1.5" or 2" throat?

[grumpy]

Not sure I like where this is going...

[Lee in Montreal]

Will your lawn dwarf have 1.5" or 2" throat?

I dunno, but lawn dwarves are known to have big mouth when you walk away...



Back to topic

In order to reduce the cost of plastic and "printing" time, as well as shipping costs, why not "print" an hollow shell with, say 1.5mm (1/16") walls, and fill it with epoxy or any dense material when received? Fill it on the evening, allow the night for catalysing. Basically, the vanes would remain solid, but everything else would be hollow.

[grumpy]

as long as the whole process (printing/"drying"/filling/curing) allows for reasonable dimensional stability,
that sounds pretty much along the lines of what I was thinking (and saves building an external mold)

[Lee in Montreal]

My friend currently produces automotive headlamp buckets using ABS in his printer. So far, there will be limitation in size, but for the experimental purpose, I don't mind outputing a half sized unit. Just to see if it works, and test the process. For strength before fill up, the horn can have the cavities ribbed to hold the shell.

One 1kg (2.2lbs) roll of ABS filament seems to run $25.00/$30.00. So, making a hollow shell makes sense if it weight 1kg, costs $30.00 in material + printer time. Then fill with catalysed automotive bondo. Maybe rubber, but have no experience with liquid rubber.

[Mr. Widget]

In order to reduce the cost of plastic and "printing" time, as well as shipping costs, why not "print" an hollow shell with, say 1.5mm (1/16") walls, and fill it with epoxy or any dense material when received? Fill it on the evening, allow the night for catalysing. Basically, the vanes would remain solid, but everything else would be hollow.

I'd suggest building in a network of internal supports so that the hollow horn (or gnome) doesn't distort when you back fill it with a casting resin. Also realize many casting resins have an exothermic reaction and may heat your plastic to a degree that it distorts.

All that said, I think with a bit of experimenting this could work.


Widget

[Lee in Montreal]

All that said, I think with a bit of experimenting this could work.

Experimenting is indeed the key word in this thread. BTW I've read good reviews on Yuichi's A290 and A290S (flat sides) as well as luke warm apreciations of the TH 4001. So, some A290S might reproduced. Sorry guys, no lawn dwarves

[dr_gallup]

I've had lots of rapid prototypes made for work and there are definite size/strength/resolution/speed/cost tradeoffs. The fused deposition material machines material costs the least, cheap stuff is about $20/lb. High end material can cost ten times that. Most of the inexpensive desktop printers are limited to a 6"x6"x6" build volume so a big horn is going to have to be made from a lot of little pieces and glued together. There are big build volume machines but they cost a lot. While I love the technology and it's going to keep getting cheaper and better, I think most of the predictions are way overblown.

[Lee in Montreal]

I've had lots of rapid prototypes made for work and there are definite size/strength/resolution/speed/cost tradeoffs. The fused deposition material machines material costs the least, cheap stuff is about $20/lb. High end material can cost ten times that. Most of the inexpensive desktop printers are limited to a 6"x6"x6" build volume so a big horn is going to have to be made from a lot of little pieces and glued together. There are big build volume machines but they cost a lot. While I love the technology and it's going to keep getting cheaper and better, I think most of the predictions are way overblown.

Yup. Seems correct. Size is the first limitation I can see. I will still proceed to make a CAD drawing of an A290S. Then maybe look for another production method, maybe involving 3 axis CNC, if 3D printing goes nowhere.

[srm51555]

Has anyone tried to print out a horn adapter such as a JBL 2328. When I built my 2397 Smith Horns (Big Thanks to Mr. Widget!!), I found the adapter was just as challenging to build as the whole horn. It is the first thing the sound wave travels through.

[Lee in Montreal]

There are plenty of those adapters available used. Priced from $20 to $200... You have to be there at the right time and at the right place. Very often, JBL 2350 horns are thrashed and their adapters along. ;-(

[tomee]

Hey Lee,
Nice project! I've been thinking similar thoughts lately as co-workers are using 3Dprinting for prototype work. The prototypes are very strong and rigid and need minimal sanding and smoothing. The process is not cheap - maybe $500 to $5000 per part depending on the time in the machine. It seems the material cost is not such a big deal as the time in the machine. There are many on-line companies that will return quotes if you send them the design files.
Do a half size prototype model and you have a 1" throat, and you use/test it with 2425 etc! Best of luck - I admire your initiative in getting out and doing this!!