Thread: Placement of Blast Gates

I don't believe 'dead' ducting has any affect. Having them near the machine is most convenient and does allow some time in the future to actually have the extractor turn on/off when you open/shut a gate.
That is what I have done - having them near the machines - the auto turn on/off will come later - maybe - sometime -------
Cheers

I am no expert on "dead" ducting but in order to improve the suction to some machines I am relaying one long main duct line and splitting it into two and using bast gates as stop valves.

I am placing the blast gates close to the main lines near the machines and using stopvalves ( blast gates) to shorten the line.

This seems to work better.

Regards

Peter

A consideration is that if you place the blast gate close to each machine do you then have to walk to another machine to turn a blast gate off. If all the valves were placed in a central location this would negate this.
A way around this is to always shut the blast gate on a machine when you switch the machine off.
cheers,
Rod

I wondered about the same thing when I laid mine out, and after a few less than scientific experiments, I deduced that it didn't make any difference where you put the gates in terms of suction. Geoff's point about auto on/off is something to consider.

All,

From all that I have read and found out, dead ducting does not really matter. As for placement of the blast gates, mine are near each machine which I do find Ok as I have a compact workshop so it's only a few steps to most of the gates when a change is needed. Having them all in one spot (ie near the D/C) would be nice but would get quite costly for the separate pipe runs to each machine.

As for auto gates - have you ever seen the price of Auto systems! ECOGATE, sold by Greg Machinery, is priced at $1,675.00 for:
* Four x (4") blast gates
* Controller - greenBOX
* Four sensors
* Remote switch
* wires, and user guide
http://www.gregmach.com/equipment_ca...ms/ecogate.htm

I have seen a few sites on the web were guys have made their own auto gates but they are fairly tricky to make. Also probably prone to breaking/stuffing up/etc. imho. If I can find the link, I'll post it up.

Putting switches on the blast gates is another idea:
http://members.cox.net/jfrantz/shopweb/blastgate.htm

As well as using remote switches to turn on the D/C
http://www.studio1304.com/silca/cyclone/electrical.htm

HPM make an Infrared remote switch for $40 which I have thought about - supposed to support up to 10amps but I am not
sure they mean it to switch a big electric motor on/off
http://www.dse.com.au/cgi-bin/dse.st...uct/View/M7215
http://www.hpm.com.au/products/Produ...r=59&Group=318

Well, that lot should keep you all busy.

The simplest way I have seen is to put a 12 volt contactor on the extractor. Place read switches on each blast gate (those little magnetic switches that are used in burglar alarm systems). These can be used to control the contactor.

The nice bit about this is that only the fitting of the contactor should be done by an electrician - or at least somebody with the necessary experience.

The placing of the switches and the wiring of the switches should be within the capabilites of anybody who can use a saw or chisel!
The wiring to the switches can be any old insulated twin wire that might be available. As things grow or change the owner can make the changes.

The 12v to power the setup can come from a plug pack, or even the shed burglar alarm (if it has one).

Cheers

A good techo could probably devise a simple system that uses HED's - Hall Effect Devices. These measure current in a line. When current is detected the device would activate a solenoid starting the dust extractor and powering the appropriate gate open. A delay in powering up the extrtactor would avoid a surge on the circuit by bringing the motors on line seperately. Motors draw their maximum amperage on start and settle down to a lower drain after start.

Switching the machine off would have the reverse effect, isolating the solenoid and allowing the gate to close and the extractor to power off.

Just a thought!

Redneck - yep, that type of idea is used but it bothers me a little. You need to turn your machines off/on frequently to move a fence, change a bit etc. The extractor can be left going. As you say, motors pull max current at start - and it is a lot more than running current, so leaving it going can be the cheaper option, it is also better for the motor. Constant stop/start is not good.
It also does not give time for the extractor to clear the last of the dust from the lines rather than leaving it settle in them.
Cheers

I came across a US site that specialises in dust extraction. They have a good bit of information in the design section of their web-site. You can also download a 4 page PDF (Adobe) document from there which is a handy reference guide.

www.airhand.com/designing.asp

As an electronics engineer by trade I would suggest that either a 6V or 12V system using micro switches ( dust-proofed) be fitted to blast gates back to a contactor on the extractor rather than some of the other methods discussed. Anything else become overly complicated and more prone to beakdowns as well as a lot more costly. Even if the micro-switches clog up etc it is only a couple of dollars to replace them. Obviously the intial cost of the contactor setup is going to be considerably higher than that.

Ruffy - that is almost exactly what I suggested except, rather than using microswitches, which need dustproofing, use read switches and magnets as used in burglar alarm systems. Totally dustproof and not much dearer than non-dustproof microswitches.
Cheers

Hi GeoffS,

Yes I agree with you and I should have "quoted" you. The prime reason I was considering micro-switches is that they are a lot smaller and less obtrusive than the reeds and magnets..

But the dust-proofing could be an issue. I might try both when I get around to doing mine.

Whatever happened to the KISS principal? And just how large are your workshops that it is a problem to walk over to change a blast gate? Must be much larger than the standard two car garage!:confused:

Wouldn't it be simpler to have the blast gate next to the machines that are connected to the dust extraction system? Before you turn that machine on open the gate. When you are finished using the machine, close the gate. Then when you are at another machine, do the same. Seems to me that complicated circuitry and remote controlled devices sound good in theory, but if you ask me, these are just something else to maintain and keep me away from woodworking!

I could not agree more !

Aw gee - some people just want to spoil all our fun!!!
No seriously though, in a small cramped workshop the extractor is probably in a corner or behind something (after all, you don't work at it) and getting to it, with a workpiece in hand, can be a menace.
For us more technical types maintenance of this sort of system is not a problem, in fact properly designed it shouldn't need any.
Also for those who think of moving the extractor from machine to machine, in a cramped workplace that could be a disaster in the making.
I know, I'm an opinionated old fool but I reckon at my age I'm allowed to be -
Cheers