3D printing of mouthpieces .....

[WoWwYnAtoR]

...Commercial grade printers now seem to uniformly want a surface definition - and that surface must be closed, watertight, and manifold. It must enclose a well-defined solid. Software which comes with the printer will slice this surface model and plan tool paths for the printer. My printers all work by Fused Deposition (stuff comes out a nozzle and stays where you put it). Other printers (esp. those that do metal) work by laying down layers of powder and selectively bonding the powder. It amounts to the same thing in the end. The difference is that some material is easier to melt and other material is easier to make into a fine powder....

[joh_tuba]

It's relatively affordable to have ponoko print your stainless mouthpiece but the finished product would need some refinement.
http://www.ponoko.com/make-and-sell/sho ... less-steel

OR, you can use this company's software(design exactly what you want) and have it machined to your specs, polished, and plated, and shipped to your door: http://www.emachineshop.com/

[sloan]

It's relatively affordable to have ponoko print your stainless mouthpiece but the finished product would need some refinement.
http://www.ponoko.com/make-and-sell/sho ... less-steel

Note the costs. Stainless steel (rough - requiring post-processing) starts at $15 per cubic CENTIMETER. There are 2.54*2.54*2.54 = 16.4 cubic centimeters in a cubic inch. So, about $250 per cubic inch.

I charge my customers about $20 per cubic INCH for ABS plastic.

Some time ago, when my lab was new, an engineer brought me the design for a small box with lots of holes in it and a few stiffeners. He told me (others have confirmed) that he could have it made out of aluminum - but it would take 3 weeks and cost $1000. I made one for him in 12 hours and charged him $150. Three days later, he was back with a modified design. Two months later, he ordered six (6) for training purposes. When it flies to the ISS, it will still be made in aluminum (NASA understands aluminum, but ABS plastic is not on their "approved materials list") - but the plastic versions allowed him to evolve and test the design much faster and much more inexpensively. I think it's the same with mouthpieces - 3D printing is appropriate for fast prototyping (and perhaps customization), but mass production is not (yet) threatened.

For those who want to try this at home: my "industrial strength" ABS printers range in price (just the hardware) from $15k-50k; we have a proposal in to acquire a metal printer - again, just the hardware - $750,000. Don't throw away your lathes (for parts that *can* be made on a lathe!). On the third hand, I believe I could churn out "playable" ABS mouthpieces with a $4k printer (plus hand polishing) for something like $25 in consumables (plus your time for hand polishing). And, the 3D printed versions can include asymmetrical features that can't be turned on a lathe.

Or, you could ramp up to injection molding. Let's see - the first one will cost $10,001. Two will cost $10,002. Ten Thousand will cost $20,000. How many do you need?

[joh_tuba]

Excellent points, of course.

3D printing is obviously the future.

Another alternative, albeit not quite as cost effect as Dr. Sloan is this: http://www.emachineshop.com/
You could potentially have a one off brass mouthpiece turned and shipped for under $50. They'll also polish and plate before shipping for an extra fee.
The cost to do the same design in stainless is a lot more... but cheaper than the price Dr. Sloan referenced for Ponoko.

If nothing else, I encourage everyone to download the eMachineShop software and explore it. It's really too bad that you can't export much because the software is excellent.

[pjv]

We're only talking mouthpieces.
Often brass players wonder how their axe would respond with an alteration in just one part of the horn. This can be very expensive because the brass itself is expensive and shaping conical parts is time consuming and requires skill.
I wonder what the practical applications are of plastic parts for tuba (a mouthpipe for example) with the technical perfection these printers can achieve. Again, for testing purposes.

[sloan]

We're only talking mouthpieces.
Often brass players wonder how their axe would respond with an alteration in just one part of the horn. This can be very expensive because the brass itself is expensive and shaping conical parts is time consuming and requires skill.
I wonder what the practical applications are of plastic parts for tuba (a mouthpipe for example) with the technical perfection these printers can achieve. Again, for testing purposes.

Larger parts are mostly limited by the build envelope of the printers. Large size and fin precision are difficult to get at the same time. My largest printer can do 8"x8"x12".

I could, perhaps, do a piston valve set...that doesn't come apart. Probably not practical, but "interesting".

[joh_tuba]

Alright, let's go down the rabbit hole.

For those that want to design their own stuff, what are some of the design conventions one should generally adhere to?

What I've gathered:
Total Length: 3 7/8"
Outside largest diamter: 1 7/8"
Throat: generally around 1/3"
Shank tip diameter for American shank: According to Bach .519"
Euro shank tip: ?????
Shank length: 1 3/4"
Morse taper for shank: 1.4321 degrees OR 0.05/in
Cup diameter: generally 29-33mm
Safe wall thickness at shank tip for machining: ???

Is that all correct? What is a common cup depth to the smallest part of the throat? Conventions for shaping entry into the backbore? Conventions for shape of backbore?

[joh_tuba]

https://drive.google.com/file/d/0B2QfbI ... sp=sharing

Link is to an eMachineShop file describing a mouthpiece I just whipped up based on limited knowledge and my personal aesthetic.
Specs:
.323 Throat
Bach American shank
cup depth 2 1/8"
Cup width 1 3/8"
Flat rim 1/4" wide

Pretty sure I'm describing a pretty wide, deep funnel cup with a sharp rim and Laskey sized backbore on an american shank.

I encourage folks to visit http://www.emachineshop.com/ and download the software to see it for youself. You can view a 3D rendering of the finished product and get instant cost estimates to have it made in various materials with different finishes etc. An unpolished stainless steel 416 version will set you back $122 after shipping with the price dropping dramatically the more you produce. Raw unfinished brass is about $80 and you could polish it up at home and have it plated locally after you decide you like it.

Also, looks like DXF and STL files can be exported but I've not experimented with that. Might be helpful if you want Dr. Sloan to give it a try in plastic first.

Feedback?

[sloan]

Alright, let's go down the rabbit hole.

For those that want to design their own stuff, what are some of the design conventions one should generally adhere to?

I recommend starting with the Bach mouthpiece brochure (Google is your friend) - which
has a lot of useful "standard" dimensions.

First, define a standard shank (for extra credit, parameterize it) and outside shell.

That takes you from the tip of the shank to the lower boundary of the rim. Add a parameter for the radius of the rim.

Next, work on the inside - starting at the tip of the shank. Inside diameter at the tip is pretty much nailed down by your standard shank. The next point to define is the end of the (straight line?) inner surface through the shank.

Now, you get to work on the detailed shape from the shank, through the bowl, and around the rim. The only constraint is that you join up with the outer shell (just under the rim) and the entry to the inner shaft of the shank. Use your favorite method of defining smooth curves to get from A to B. You now have a polygon that defines (one half) of the cross-section through the axis of the mouthpiece.

For a rough sketch, perhaps as few as 10 points (x,y - from where the shank enters the bowl to he outer edge of the rim) should be enough. On the cheap, you could build a mouthpiece from this. For a little bit more, interpolate the non-straight-line portions of the polygon. "fit a spline to it"

To turn the polygon into a solid model, you rotate it about the axis. Programs such as OpenSCAD provide this as a single operation. You can easily produce more triangular patches than ABS plastic can resolve, so all (unwanted) sharp edges can be smoothed out.

Now - if you want asymmetric features (an oval rim, or a rim that changes thickness as a function of angle), the problem becomes slightly more complicated. The easiest way is to repeat the process above for n different angles around the axis. Then, you can either use those radial cross-sections directly, or interpolate. If that's too simple, you'll have to move up to a real 3D CAD program.

All of this can be done with 2D drafting tools, plus some fairly easy processing to turn the 2D drawing(s) into a solid model.

If you can't hack the last step, most people working in the area can probably get you there on the cheap. For example, I'd be happy to accept n radial cross-sections and print from that. Writing the program to read in n radial cross-sections and spit out a model suitable for printing is probably a 15 minute task. An hour, if you want documentation.

So...just to make this concrete, here's a file format:

N - number of radial cross-sections
n0 - number of x,y points in the first cross-section
x0,y0 - n0 x,y pairs
x1,y1
...
n1 - number of x,y points in the second cross-section
x0, y0 - n1 x,y pairs

x,y should be Real numbers, in either mm or inches (please specify - mm preferred)

By convention, the polygon should proceed counter-clockwise.

for example, here's a pipe that has an inner radius of 10mm, a length of 100mm, and a wall thickness of 2mm:

=============
1
4
0,10
100,10
100,12
0,12
=============

I'll bet that a quite reasonable (radially symmetric) mouthpiece can be specified in this format in fewer than 100 lines. If you want asymmetry, multiply that number by 128.

You create the file, I'll print it (and send a bill...). Let the games begin!

[sloan]

Also, looks like DXF and STL files can be exported but I've not experimented with that. Might be helpful if you want Dr. Sloan to give it a try in plastic first.

Feedback?

STL is *exactly* what I prefer for vanilla print jobs. Please check with something like "netfabb" - it's free - to be sure the STL actually defines a closed, watertight, manifold surface.

but, see my previous post for people who want to try out a mouthpiece idea who own only a pencil and graph paper.

And....when it can be "machined", that will probably always be the technology of choice. The fun starts when the machinist starts shaking his head in disbelief. Want to see a functioning Rubik's cube, printed as one (no assembly required, no dis-assembly allowed) piece? Or, the iconic sphere-within-a-sphere-within-a-sphere-within-a-sphere-within-a-sphere?

For tubists, consider the possibility of a complete piston valve assembly - that does not come apart. You probably would not be happy with the tolerances (you'd need really heavy oil...) but it could be done.

[sloan]

If nothing else, I encourage everyone to download the eMachineShop software and explore it. It's really too bad that you can't export much because the software is excellent.

My loyal staff tells me that eMachineShop does NOT do a good job of exporting STL (our preferred format) - but it does export (more competently) a couple of formats that can be read by freeware (we like "netfabb") that will not only verify (and repair as needed) the design, but also then output excellent STL. I *think* we are almost at the stage where I could consider taking an eMachineShop file and printing from it. [nominal extra charge for doing the file format conversion for you...]

[waiting patiently for reports on the tuba mouthpieces I have printed for TubeNetters recently...some of the designs look, um, "interesting"]

[joh_tuba]

I am guilty of an 'interesting' design and plan to write a very thorough review of my observations very soon.

Short version observations:
1) Apparently if there is a big end and a little end it'll probably play like a mouthpiece.. even if it's 'interesting'.. in fact it might work better than most in it's own 'special' aka not general purpose way.
2) A hollow shell of a mouthpiece made of ABS plastic feels, plays, and sounds just like a metal one.
3) 3D printing is a cost effective quick way to test ideas but probably not a great solution for a refined production product
4) I sent an STL file exported from eMachineshop that at the time Dr. Sloan said looked fine.. maybe not?

[sloan]

4) I sent an STL file exported from eMachineshop that at the time Dr. Sloan said looked fine.. maybe not?

Your STL was fine. Apparently, stl export is "in beta". For you, it worked.

Alas, I was misled about the "other formats might work" part. eMachineShop enthusiasists are stuck with "in beta" export, which may, or may not, be adequate. Note that the main reason for the eMachineShop design tool is to get you to submit the job to eMachineShop for printing. I'm not sure how motivated they are to make "export to stl" work perfectly.

But - as you demonstrated - it can be done.

When I try to process your .ems file, I get a "WARNING: export does not include 3D data". That kept me from spending any more time on it. Perhaps it's the "WARNING" that is in error. This is why I prefer to have the customer produce the .stl file - I have a hard time getting up to speed on the 100 or so design programs out there, each with their own internal format.

Bottom line: if "netfabb" (free download) likes your .stl file, I probably will, too. And, if netfabb blesses it, and it has no tiny features (smaller than 1mm), and it fits in an 8"x8"x12" build envelope, I can print it.

[Ben]

some of the designs look, um, "interesting"]

I will post some results on Tuesday when I recieve a 3x2 matrix exploring sinusoidal rim depth VS ovular cup radius. While my design template is flawed - I am isolating rim features that I suspect are critical to tone and response.

[Ben]

Any updates on your mouthpiece generation project? Inquiring minds want to know!

[sloan]

Care to put some hard numbers on that? Start with the capital investment costs you claim were ignored. Please show me where they were ignored and what they should have been.

[joh_tuba]

I'm SUPER thankful to Dr. Sloan for working with me on the prototype mouthpiece. I learned a tremendous amount from the experience. Most important lesson: how little the dimensions and materials matter for a mouthpiece to still work just fine.

That said, the other VERY large takeaway was that prototyping mouthpieces on a 3D printer isn't the best way to go about it in terms of either accuracy or cost efficiency. I had to sand quite a bit before it was comfortable to play and the final dimensions were close to what I intended but unlikely to be consistently reproduce-able.

eMachineshop can prototype a mouthpiece in raw brass for less.. you can modify it all you want once it arrives and then plate it to your specs. Total cost for a single custom mouthpiece in brass doesn't have to be much more than a high end off the shelf model.

ALSO, you can never scale 3D printing up for mass production.

Cost and accuracy not competitive for prototype OR mass production = not a strong alternative at this time.

Counter argument!!
1) For complex or difficult to machine shapes the calculation could quickly change!
2) In a production environment where the act of prototyping means STOPPING production on a machine, resetting, and then running a small batch, 3D printing might make a lot more financial sense.

Time will tell!!

[Kevin Hendrick]

... you can never scale 3D printing up for mass production.

Well, it's not a tuba mouthpiece, but SpaceX seem to be having some success with this:

http://en.wikipedia.org/wiki/SuperDraco ... ufacturing

http://www.spacex.com/press/2014/05/27/ ... o-thruster

[sloan]

Care to put some hard numbers on that? Start with the capital investment costs you claim were ignored. Please show me where they were ignored and what they should have been.

I apologize if you feel put on the defensive. Maybe more to the point is another series of questions:
1) A post in this thread mentions the actual cost of the capital equipment. Assuming the accuracy of the equipment cost as reported, that is a valid data point. But unless it is usefully related somehow by say, seeing its relation to the cost of the prototyped object, the data is meaningless because it is disconnected in relation to the subject (the cost of making the stuff using 3D print technology.)
1a) Data is not information unless it is useful.
It would be useful to tie the cost of the equipment used in fabrication into the cost of the product fabricated.
2) A post in this thread says the engineer with the frame prototyping for a NASA space station project was charged 150 bucks.
The perceived allusion that this was an inexpensive way to avoid traditional setup costs for machining is an illusion,
because it has not been tied into the cost drivers that define setup/prototype costing
(primarily overhead, which in this discussion includes the capital equipment.) Follow?

Finally the obvious, and sadly emotionally-charged (but in business, emotionally indefensible) questions:

"who paid for the printer?" "who paid for your time?" and "who paid for the materials?"

These resources did not just drop out of the sky like manna from heaven.
Now I don't have a horse in this race, so-to-speak.
I am also not a machinist, but I am very much a respecter of tradesmen and (frankly) reason.
If you have a 3D print lab at a college or university and are not compelled by the university to recover the cost of your capital equipment when costing your deliverables, great. But to intentionally avoid disclosing that fact promotes the technology (which is your horse in the race) without illuminating the true cost of manufacture (a profound dis-service to students, and readers here on tubenet.) I guess I understand why you sounded a bit defensive.

-30-

Care to put some hard numbers on that? Start with the capital investment costs you claim were ignored. Please show me where they were ignored and what they should have been.

[sloan]

crickets....