Please download this model from the Printables 3d model repository: Print 137801

Update 03Apr22
Please download this model from the Printables 3d model repository: Print 137801

20May20
Marius-Bloemhof requested the CAD files:
(https://cad.onshape.com/documents/5425e358a4e266ea950b034e/w/fb495421e309359b374e4475/e/07ed980bcf8592c544c8964f)

Update 24Aug20
I've posted a new design for a blast gate based on a ball valve: thing:4578649

Update 03Jun20
I've posted a 100mm version of this blast gate based on a ball valve: thing:4422842

After having unclogged the groove, in the commercially available blast gates in my workshop dust and chip extraction network, for the umpteenth time so that the gate closed fully, I decided that there had to be a better design. Naturally, I looked on Thingiverse but didn't find anything that seemed quite right (it doesn't mean that there isn't anything, just that I didn't find it!). I set to in Onshape with an idea, which, as I drew it, developed into two ideas, and then into two finished 3d printed objects. They both seem to work without clogging, and each has its own advantages and disadvantages.

This is the second idea, based on a butterfly valve, throttle-like assembly. This takes up less space than the sliding blade of the first design and is more of an anti-clog arrangement than the self cleaning action of the first design (the first design is thing 4298421)

Both designs are nominally for a 63mm (2½" ) rigid tube system, as shown in the photographs, but flexible hose of the same nominal size also fits.

In addition to printing filament you'll need 4 short M5 bolts of some kind and 2 short socket head M3 x 6mm and 1 socket head M3 x 10mm or 12mm bolts. The M5 bolts should self-tap their own threads into the holes printed into the Tube_1 frame, or you could use an M5 tap (or any other thread size that fits the hole). Likewise for the M3 bolts. The longer M3 bolt is used to hold the lever on the butterfly shaft. The holes may need to be eased with a suitable drill bit.

The lever has an arrow-like shape at it's tip, which shows which direction to rotate it to open the gate.

You need to print 2 tubes, the 2 halves of the butterfly (Butterfly_1 and Butterfly_2) and 1 lever for each gate.