Blast gates

murphy · 26 Jan 2017

I suppose some of you have made your own blast gates, I thought I would post this just in case it might help someone, I made these about a year ago after forever unbocking the plastic or metal ones, and have had no problem at all with them, no more blockages as they are self cleaning, and easy to make from scrap 18mm MDF, these are 4"
Pat

chill · 1 Feb 2017

Very neat Murphy, I will pinch this idea if thats ok, as I need a couple for my new extraction(4"domestic waste pipe) system,
Cheers
Chris

sunnybob · 1 Feb 2017

There is a way of curing the plastic gates of jamming open.
The gate slide pushes sawdust into the back of the slot that the slide runs in. Eventually this builds up so that the slide can no longer close.
If you hacksaw a 1/4" triangle off the back moulding on each side, then the slide just pushes the sawdust all the way through and out.
I've done this on all 5 of my gates, and havent had a blockage in the almost 2 years since I did it.

This how far they used to jam open.

This is the cure

You dont actually need to cut as much as that pic shows, it was my first protoype. As long as you cut through the plastic it works.

ColeyS1 · 1 Feb 2017

That's a smart looking blast gate Murphy !
Sunnybob, won't you lose suction through the holes you've made ?

Coley

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sunnybob · 1 Feb 2017

Not to take anything away from murphy's gates,if youre starting from scratch you could most likely save money making your own. But if you already have plastic ones and dont want to go to those lengths my mod will work.

Remember if you have multiple blast gates, when they are closed, theyre closed, and the cuts have no effect.
When they are open, yes, the air is sucked in through that gate only, but the total is smaller than a single badly fitted hose, a negligable amount. Remember I said that pic showed excessive cuts, you can get away with half that opening.
There is an unexpected but useful side effect... if the suction hose blocks, the holes produce a strong whistle, immediately alerting you to the problem, where you might take much longer to know something is up with a normal blocked hose.