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3D printing a leadpipe for Jinbao contrabass trombone in F #3
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Hi Jean, it should be a measurement in millimeters. However, it's a radius, not a diameter, so you should divide the value by 2. It's very possible there are more issues with that specific script, since I've only used that file to create a specific alto leadpipe. It's only a few lines of code, so should be easy to fix, but I can't test it right now. |
looks good! Leadpipes seem to be the hardest part to 3d print and to get right of the entire trombone. Let me know how it works :) |
I doubled the wall thickness to 0.8 mm. The tech said that 0.4mm came out too fragile with the 3D printer using PLA. Hope to try it out Monday. |
0.4 should be printable, but breaks rather easily unless you're very careful when inserting the mouthpiece. But for an alto thicker walls wasn't really an option :) 0.8 should work fine for a contrabass though |
I just opened the original file. Wow, I made that a bit messy :) I cleaned them up a bit, so you can download the new version. What I changed:
You can now set the wall thickness by changing:
Which will not change the mouthpiece receiver inner shape. If you make it too big, it will just not fit your inner slide at the beginning of the mouthpiece receiver. If this happens you can compensate by making the You can change the mouthpiece taper with:
That means you should be able to change everything you want to change easily now. Except for the spokes - nice idea. My leadpipes printed fine on my prusa i3 mk2 so I didn't add anything, but I did something similar for a mouthpiece: https://www.thingiverse.com/thing:1697510 . I relied on the support generation of the slicer to add a scaffolding below the horizontal disk you see there. |
Here is the code for making the support spokes
|
Hmmm. The leadpipe I printed with 0.8mm walls (using the previous commit of the leadpipe code) is too stuffy due to the walls being so thick. The part of the leadpipe that goes into the inner slide is less than ~15mm in diameter (0.587"), and the inner diameter is 1.6mm less than the outer diameter simply due to the wall thickness of 0.8mm. So, I am going to try 0.4mm wall thickness. |
A few things that might be worth a try as well, instead of the 0.4mm wall thickness, since 0.8mm has clear advantages over 0.4 in terms of breaking easily:
Also now the leadpipe is just a conical piece of tubing down to the venturi, then a conical piece down to the end, plus a mouthpiece receiver. I have not checked if that's the shape a leadpipe should be. That could also be the cause of the stuffiness. |
I am pretty sure the design is close enough to leadpipe-like in shape. I’ll try the 0.6mm walls as you suggested. I think the venturi size is okay - it translates to 13.26mm or 0.522”. As far as I know a 0.562”bore bass trombone has about a 0.500” venturi, so a 0.522” venturi for a 0.587” bore contrabass seems reasonable. Probably could also try a 0.542” venturi or so. |
The distance of the venture from the mouthpiece receiver is also something to play with of course :) |
As an update, I did some more sanding on the leadpipe with 0.8mm walls and 0.522" venturi, and I doesn't seem so bad afterall! In fact, I will use it instead of the original leadpipe for now! I am going to reprint this leadpipe with 0.8mm walls at the mouthpiece receiver and 0.6mm walls for the rest of the leadpipe and try 3 different venturi sizes (0.512, 0.522, and 0.532 inches). Not sure if the 0.6mm walls will make it too fragile, so I might revert back to 0.8mm walls for the whole leadpipe. |
In the new jinbao leadpipe scad file, the |
Good to hear it works. Did you sand the inside of the leadpipe, and did it make much of a difference? For mouthpieces, sanding to get a smoother surface improves the result quite a lot. Thanks for finding that issue. I'll fix it. |
I sanded the inside of the leadpipe where the mouthpiece goes in and that made a big difference! |
I was playing around with the leadpipe openscad file and modified it to produce and outside shape that is cylindrical but an inside shape that is conical (like real leadpipe shape)
Not entirely convinced I implemented the code properly as the leadpipe on the left is from the original (conical design), and the one on left is with a cylindrical outer shape. What do you think? Does this produce the same inner shape as the original code but creates an outer shape that is cylindrical? Not sure this really influences the sound much or not? |
The code looks right. Render doesn't really look the same indeed. You can at least get rid of the first I've tried making the outside shape cylindrical. However, it was much easier to get a smoothly printed leadpipe with a constant wall thickness. To print a subtly variable thickness wall, your slicer needs to be able to calculate variable layer widths to make the transition from one to two walls smooth, or you end up with ridges. At least Slic3r and Cura can in fact do this, but when I tried it, it wasn't as good as just printing with a single wall in spiral vase mode. However, that was a while ago, and slicers have progressed, so it may work now. |
So, any news on your leadpipe project? :) |
So, I made 3 leadpipes with 15mm gap and either .532“,.522“, or .512“ venturi. I have also made three other pipes with 0.522“ venturi and 0,30,or 45mm gap. All leadpipes have 0.6mm thickness with the cylindrical outerwall shape. So far the 0.522“ venturi and 15mm gap is my favorite. I am printing the pipes at 230mm long in two pieces on a Prusa i3 MK3 with .15mm PLA layer height then using crazy glue to connect them. |
Hi,
I am trying 3D print a leadpipe for a Jinbao contrabass trombone in F. The bore is approximately 0.589" in the slide, so I would imagine a venturi for the leadpipe would be 0.522" or so. I edited https://github.com/pieterbos/PrintBone/blob/master/jinbao_leadpipe.scad to the following:
line 57
leadpipe_length=199;
was changed toleadpipe_length=222.25);
and
line 73
shank="small";
was changed toshank="large";
and
line 67
leadpipe_venturi_radius=(10.7-0.8)/2;
was changed toleadpipe_venturi_radius=13.26;
but, changing the venturi to 13.26 (0.522") had an unexpected change in size
Here's with the original venturi

(10.7-0.8)/2
Here's with a

13.26
venturiI am guessing that this value for venturi is not a measurement in millimeters exactly, but it is used in a calculation?
Best,
Jean Elbers
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