When I kickoff set up my dust collection network, I purchased some of these blast gates.  The blast gates were used to control air catamenia by sliding the gate in a runway, either assuasive or blocking air flow.  I closed gates to cake airflow to tools not existence used, thus increasing the suction to the tools in use.

At get-go, they worked well.  Then, as dust accumulated inside, the move of the sliding gate became impeded and the gate would not close.  This meant that the blast gates were unable to effectively control air flow – their sole purpose.

What's more, i broke.  The blast gate consisted of three parts – the gate and two halves glued together.  Well, the glue failed.  Now, the good thing about that broken boom gate was that I was able to make clean it out thoroughly and hands.  Since I didn't take whatsoever spares, I clamped it together with four C-clamps (double-sided tape didn't work).

The blast gate on my table saw wouldn't close completely.  I didn't think this was a problem until I hooked up my DeWalt planer.  The planer's blower used to articulate fries pressurized the dust drove system and blew fries through the hoses and up out of my tabular array saw, raising a big cloud of fries and grit.

I'm going to supercede the plastic blast gates with metal self-cleaning blast gates.  They price twice equally much, but I'm convinced they will be worth it.

As shown on the Lee Valley Tools Ltd. site, the design of these self-cleaning blast gates avoids the problem of the plastic ones.