Dust extraction/hoover 3-way valved manifold/splitter

I wanted a way to connect a dust extractor to my Workbee CNC, band saw, and potentially a third tool (e.g. sander) without having to manually plug the dust extractor hose between tools. So I designed this three-way manifold with butterfly valves on each of the three branches.

The manifold entry fits the hose of a V-TUF Mini dust extractor but it should be easy to design an adapter for a different diameter hose. The threads at the manifold exits fit this hose. In hindsight I should have gone with a suppler hose but that's the one I bought and that's the one I'm stuck with (can't be arsed to redesign/reprint everything and spend more money on the hose).

If you want to design your own adapters for use with the valves or threaded vacuum hose connectors, two STLs are supplied ("vacuum hose thread part only" and “half valve housing only”) with only the half valve housing part and only the threaded hose insert part. Their common dimensions (where your own design would start) are 45.8 mm outer diameter and 3 mm wall thickness.

Each butterfly valve uses two 10x2 mm (ID/section) and one 34x2 mm O-rings. I got mine from here and here. Each valve also requires four M3x12 button head bolts and four M3 nuts. Another M3x10 cap head bolt and M3 nut is required for fixing the knob to the valve shaft.

Assemble the valve as shown in the pictures:

• Take one half of a butterfly gate and apply superglue to its middle (not too much, you don't want the large O-ring to get covered in it).
• Place the large O-ring on top. It won't slot into the groove along the circumference of the butterfly gate: this is intentional.
• Place the other half of the butterfly gate over this and carefully compress both parts while massaging from side to side so as to force the O-ring to stretch and fit into the groove formed by both parts of the butterfly. Make sure both parts are aligned and flush.
• Stretch the two smaller O-rings over both ends of the assembly into the slots provided.
• Place the knob on the square shaft and fix with the M3x10 bolt and nut.
• Cover the two smaller O-rings with a generous amount of grease: they will act as bearings and you don't want them to stick. Apply some grease to the large O-ring too.
• Take both halves of the valve housing (one half is part of the manifold, the other of threaded vacuum hose connector) and make sure there isn't too much of an elephant foot effect on the inside of the faces which will connect. File off if there is. If you don't do this, excessive force will be required to turn the valve past the closed position every time.
• Place the butterfly gate into one half of the valve housing and place the other half over it. Turn the valve several times to spread the grease around.
• Use the four M3x12 bolts and nuts to fix the valve housing together.
• Turn the valve several times. This may require a bit of force but the parts will eventually wear in. You don't want the valve to turn too easily or else the vacuum may start opening it.
• The knob locks are provided to lock the knob in either the closed or open position. Place them over the knob and push them into place. They will fit only if the valve is exactly aligned in the closed or open position.

The adapters for the Workbee and band saw fit my particular Workbee dust shoe and band saw vacuum port but it should be easy to design adapters for different diameter ports. Use the “vacuum thread part only” STL supplied for this. Similarly, if you want to use a different hose with the manifold, use the “half valve housing only” STL provided to design your own hose attachment. For both files, the outer diameter of the tube where your design would attach is 45.8 mm and the wall thickness is 3 mm.

Braces are also provided to attach the manifold to a flat surface. You will need additional M3 bolts and nuts, and wood screws for this. To be honest, these braces were a bit of an afterthought and I rushed the design through in about 15 minutes. They do the job but they are quite flimsy…

Supports required for:

• The arched parts of the half valve housings in which the butterfly gate shaft will rotate.
• The perimeter of the half butterfly gates.
• The extremities of the knob wings.

Designed in FreeCAD 0.20, sliced with PrusaSlicer, printed in PLA.