Nautilus speakers
Prototyping services for your business

Monthly Archives: March 2015

Nautilus speakers

I printed these as a gift for my father.  He’s not an audiophile, but he does appreciate good music and certainly understands what makes speakers sound good.  These were printed in halves, solvent-welded together, smoothed with autobody filler & sandpaper, then painted with gloss black spraypaint.



Hardware parts list (everything was from Parts Express):

  • 2x Part # 091-1245
  • 2x Part # 240-676
  • 2x Part # 296-717

The frequency response was surprisingly wide.  The nautilus shape is hollow all the way back, and creates a relatively large enclosure for the speakers.  I haven’t measured it, but I wouldn’t be surprised to know these 3″ drivers were reproducing down to 100hz.

Turning printed parts into metal parts (part 2)

As shown in the previous post, we needed to step up the game strength-wise for this set of parts.  Fortunately, the shape is immanently castable, and with next to no modification of the part itself (only some post-processing) it’s ready to turn into solid aluminum.  I printed the parts again in the same orientation, but in natural PLA, which I unfortunately didn’t get pictures of.  The parts do have to be scaled by 103% to account for shrinkage in the aluminum after it cools.

Afterwards, the parts were sprued and vented with wax and 3mm PLA, respectively.  You can see them here looking like little upside down bugs in the lower-right of the picture:


The fat blocks of wax are used to flow the aluminum in, and the spindly bits of PLA are used to vent air out.  I placed the parts in a steel tube, capped with wax.  The tubes are shown below, the wax-capped versions are not:



From that, I covered it with jewelers investment, vacuumed the air bubbles out, and allowed it to cure:


The resultant plaster-filled tubes were baked in a searing hot kiln for 10 hours to turn all the plastic into … nothing, and prepare the molds for the equally searing hot molten aluminum to be poured in:


The remainder of the process happened quickly, and was instead captured on a pair of rather uninteresting videos (they were a lot more intense actually being there):

After the parts came out, some cleanup to remove the aluminum sprues, and beadblasting, and they were ready to ship:


And, finally, here they are installed:



The process of being able to cast aluminum parts directly from printed parts meant my customer didn’t have to redesign his part at all, and we could avoid expensive billet CNC work.  While the CNC would have produced a prettier part, the extra expense was wholly unnecessary in his case.  In addition, the pre-casting blanks were able to be used to verify dimensions, allowing for much quicker turnaround on designs before committing one to metal.

Turning printed parts into metal parts (part 1)

Here’s something I’ve wanted to do for awhile, and my customer was kind enough to give me permission to do so.  This will be a two-part post.

I had a commissioned project to produce some skateboard parts. This has surprisingly pushed the limits of what I’ve been able to do, as skateboards are very demanding pieces of equipment. We start with the customer’s parts for the trucks (the part that holds the wheel assembly to the frame):



From here, a high-infill part printed out:



And promptly broken:



Clearly, we must go stronger

Repairing an outboard boat motor with 3D printing

Recently, my father in law came to me with an interesting problem. The pull-starter gear on his auction-purchased outboard motor had been stripped out pretty badly (he thinks somebody pulled the cord while it was running).

Step 1 was to start with some simple measurements, and SCAD:

$fn = 60;

difference() {
union() {
cylinder(r = 22.22, h = 2.30);
cylinder(r = 15.00, h = 11.10);

for(r = [0: 25.71: 360]) {
rotate([0, 0, r])
hull() {
translate([19.50, 0, 0])
cylinder(r = 1, h = 11.00);

translate([16.00, 0, 0])
cylinder(r = 2.1, h = 11.00);

translate([0, 0, 0])
cylinder(r = 5.00, h = 11.00);

translate([0, 0, -0.05])
cylinder(h = 11.20, r = 7.50);

gives us:

From here, we can plate a few up (in case one isn’t up to snuff, he’ll have extras), and print them out in solid ABS. Shown below is the finished plate (still on the printer) with the original gear next to it for comparison.

And here it is installed:  (it’s taken a bit of a beating, that’s why I printed 4 though!)



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