Sometimes it really does come down to “necessity is the mother of invention”, and 3D printers make this possible for nearly anyone willing to invest a little time. Today, I did it again – from design, print, and ready in under 2 hours!

Note that you can click on each picture below for a larger, more detailed image.

The need

I’ve been working on a three tiered plant stand for the back yard, made from mostly 2×4 lumber.  Wanting to stain the finished item, I’ve been sanding each piece before assembly with my DeWalt orbital sander.  While the sander comes with a nice dust catcher, the instructions mention being able to push your shop vac hose onto the output nozzle and reduce the overall amount of dust that escapes from the sanding process.

My shop vac hose will “fit”, but only loosely, and after some experimentation yesterday, determined it would fall off within a couple of minutes.

What other option did I have, but to design and print an adapter!

Measurements

Out to the garage with my caliper, pen, and paper I went. Since the nozzle has several inner fittings, I took all the measurements I thought I’d need. 

It’s possible to push the actual shop vac hose directly onto the adapter I’m about to make, but there’s also a small “tool adapter” that came with the shop vac, so I took measurements of both.

Several possible configurations

You might be able to see here that neither the hose nor the included tool adapter will fit snugly on any of the concentric dust nozzle “ports”.

My initial thought was to fit one end of my adapter to the largest ring of the dust nozzle, and push the shop vac hose onto the other end of the adapter… and forget about the shop vac’s included tool adapter.

Design

I dashed back into the house, where I fired up FreeCAD and fashioned the cylinders to go around the outermost dust nozzle ring (green in the FreeCAD screen shot).

Next I made the cylinders on which to attach the shop vac hose, offsetting it about 30mm from the other end (blue in the FreeCAD screen shot).

Lastly, I made the cones to adapt the sander-end ring to the shop-vac-end ring (orange in the FreeCAD screen shot).

Print

I exported the design into an STL file, which I then ran through Slic3r, using Lulzbot’s provided configuration for fast PLA with a 0.28mm layer thickness, and no support.

I imported the gcode file into Printerface, which estimated2423mm of filament and 1 hour and 3 minutes duration. I fired up the extruder and bed temperatures (200C for the extruder, 70C for the bed), and started the print.

An hour and 5 minutes later, it was a real part!

The part

Here’s the part, in roughly the same position as in the FreeCAD screen shot above. The left-most ring will fit around the outer-most ring on the sander, and the shop vac hose will fit over the right-most ring.

It fits!

Here it is, fully assembled and ready to test! You can see in a previous picture (if you look closely) that the outer-most ring on the sander has a narrow rubber gasket, and the 3D printed part fits moderately snugly over it: easy to go on, and seems like it will hold.

Keep in mind that suction from the shop vac will naturally tend to hold everything together — as long as there is some friction to assist. I would not stay together by suction alone without an adapter.

The shop vac hose is more like “hard rubber” (with some “give” to it, as opposed to “hard plastic”), and it fit over the right-most end with a small amount of effort; it felt “just right”.

How did it turn out?

So in the first couple of minutes of use, guess what happened? The shop vac hose fell off. *sigh*

Turns out there wasn’t enough friction to hold everything together, especially given that the weight of almost the entire shop vac hose was dangling off the end of the adapter. I reached into my shop cabinet and wrapped two long wire ties around the base of the shop vac hose, and grabbed a small bungee cord from my bungee bundle and attached them as you see here.

Ultimately it seems to work fine. I adjusted the positioning of the loops in the wire ties a few times, and I guess sometimes it depends on what angle you’re working at. Still, for “under two hours”, this worked out fine.

Future plans

When I have some “extra time”, I may redesign the sander end to “clip” onto the dust nozzle assembly, and then fashion some sort of tie-down strap to hold the shop vac hose in place. But until then, this works just fine.