3D printed waveguides

[DanP]

Why would it be any more difficult to print? If you mean in wood, that may be, you and TNA would know better than I.

I was addressing your comment that this project could result in easy to build waveguides. I thought you were saying that your requested deviation from tangent at the mouth would result in an easy to build waveguide. I must have misunderstood.

Dan

[augerpro]

Easy to build because anyone can print one, no special skills needed. Not that I'm not interested in developing wood ones along with this, but at the end of the day any wood guide that is promising I would want to turn into a 3D printed version.

EDIT: I've misunderstood your misunderstanding No, my comment about changing the mouth was't to make fabrication easier, just wanted to capture some variations in a standardized way so we Know any final designs that result will be the best possible.

[TN Allen]

Augerpro,

Do you have a place near you where you can print guides inexpensively? If so, I can send you a .stl file this morning that you could print. I'd send it to anyone else who wants to try printing. It can be a small round or oval guide with a flange.

It probably would be a good idea to test out this aspect of the project, that is that with an appropriate file people with access to a 3D printer can print their own guides. There may also be 3D print services online that could be used.

The file I'll provide is for a small oval or round guide, and I'll make the throat opening whatever is wanted. I'll use a contour similar to one Ryan Bouma tested a few years ago and liked, and that Takitaj also tested and said achieved what many guides do not, that is that it did not fall off at 10k. The round guide can be similar to the 8-8.5" diameter guide 2" deep, or whatever configuration is wanted. Within reason, I'd do various openings and contours.

These files are easily produced, and if printed could provide guides for testing, and some sense of how practical it may be to print guides in various parts of the country.

If the printers and printing services available are as easy to use as the MakerBot I used a few years ago, and I am given the correct file format to provide, there could be a proliferation of guides fairly soon.

[johnnyrichards]

Augerpro,

Do you have a place near you where you can print guides inexpensively? If so, I can send you a .stl file this morning that you could print. I'd send it to anyone else who wants to try printing. It can be a small round or oval guide with a flange.

It probably would be a good idea to test out this aspect of the project, that is that with an appropriate file people with access to a 3D printer can print their own guides. There may also be 3D print services online that could be used.

The file I'll provide is for a small oval or round guide, and I'll make the throat opening whatever is wanted. I'll use a contour similar to one Ryan Bouma tested a few years ago and liked, and that Takitaj also tested and said achieved what many guides do not, that is that it did not fall off at 10k. The round guide can be similar to the 8-8.5" diameter guide 2" deep, or whatever configuration is wanted. Within reason, I'd do various openings and contours.

These files are easily produced, and if printed could provide guides for testing, and some sense of how practical it may be to print guides in various parts of the country.

If the printers and printing services available are as easy to use as the MakerBot I used a few years ago, and I am given the correct file format to provide, there could be a proliferation of guides fairly soon.

Please send me the file, the oval version if you would. jr at midwestaudioclub dot com

[Face]

I believe some UPS Stores also have 3D printing available.

[TN Allen]

Please send me the file, the oval version if you would. jr at midwestaudioclub dot com

What will you need for a throat opening diameter?

[TN Allen]

Please send me the file, the oval version if you would. jr at midwestaudioclub dot com

Message and file sent.

[augerpro]

TNA> I'm right in the heart of downtown Denver, so I *should* have someone close that can print them. But let me figure out the baffle first this weekend. I'm still deciding on a standard insert design. Then I'm going to Woodcraft and get all starry-eyed when I buy the Festool track saw

[TN Allen]

I think I have found the file I used to print the wg in the photo amidst the group of photos I posted earlier. I suggest I send it to you, then you can take it on a jump drive to anyone you think might print a file for you, and ask if it is compatible with their system, and if the scale is correct for their machine. As I recall I had to scale the part file to reconcile the inch dimensions I used in the design, with the metric dimensions used in the MakerBot I used for printing.

There will be problems, what I suggest is a way to work through these toward producing suitable guides, minimizing the frustration and wasted time and energy digital technology seems to occasionally involve when beginning a new project.

I'll need an email address to which I can send the file and a few photos from the printing process.

[johnnyrichards]

Email received. Thank you.

[augerpro]

I have the inverted dome Tang Band 25-1983 and a RS28A on the way. Anyone have other tweeters worth looking at? If someone has some Scanspeaks I'm sure those would be appreciated.

TNA> PM sent. BTW would it be difficult to add a phase shield to your design?

[augerpro]

There were some requests earlier for a way to generate the curve in, say, excel to be imported into the CAD program. I don't know if anyone looked at the info I posted here: https://www.dropbox.com/s/q9wcxxqdd1...uides.rar?dl=0 but there is one file "OS WG 2.xls" that shows the x,y coordinates generated.

[TN Allen]

I have the inverted dome Tang Band 25-1983 and a RS28A on the way. Anyone have other tweeters worth looking at? If someone has some Scanspeaks I'm sure those would be appreciated.

TNA> PM sent. BTW would it be difficult to add a phase shield to your design?

It might be interesting to add this tweeter to the mix, but later: http://www.parts-express.com/peerles...eter--264-1016

If you can post or link to a photo, I'll look into a way to add it.

[augerpro]

It's certainly popular, but I lived with XT25's for 8 years in my home theater and they're not my cup of tea. That said, I'm just the measurement guy, if someone wants to make a guide for that and supply the driver I'll measure it.

[Pete Schumacher]

I guess I didn't mention the angle at the mouth is assumed to be 180 degrees. This leaves only one radius that can connect the mouth at 180 degrees and the throat at some residual angle.

Now if you wanted an 8" waveguide that was 8" deep, you'd have to move to a variable radius, but I think this becomes outside the range of what is useful in home hi-fi. It's actually kind of lucky that the useful (to us home DIYers) range for these combinations falls into such an easily defined set of parameters.

I have actually purchased the hardware and designed most of a waveguide cutting jig based on TN Allen's post a while back, because what he just posted is true: the easiest and cheapest way to do a round guide with a constant radius profile is to mill it right into the baffle. In order to simplify the mechanism, I will be fixing the radius at 2" + the baffle thickness. So all you'll have to do is choose the throat opening dimension and the depth - the radius and mouth diameter will be automatic. This ratio of baffle thickness to profile radius will always be in a good range to provide useful waveguide loading.

With those assumptions you won't be able make a 8" WG that's 1" deep, nor a 5" WG that's 3" deep, but I don't think those are as useful as 8" dia x 2" deep or 5" dia x 1" deep (numbers may not jive, just examples).

Dan

I just completed the design of my final RS28A/8BG51 two way. I changed the guide from the original 2" deep 7" wide guide to an 8" wide by 1" deep guide machined into the baffle via CNC. Took 10 minutes to sand the tool marks out by the way. The result is excellent. Still great pattern control and acoustic alignment but better top octave liveliness for lack of a better descriptive term.

While the amount of low end boost is less, it is still quite respectable (~10dB). Current XO is at 1000Hz LR4.