# Dust Collector Shutoff Delay?



## Crashcup (Feb 11, 2015)

Now I wish I could remember where I read it, but someone said that many of the dust collector manufacturers recommend that it doesn't get shut off and restarted frequently. In other words, avoid shutting it off if you're just going to turn it back on a minute later. If this is true, I would assume it's for the protection of the motor.

But what have you all seen? Do you have a DC where the manufacturer makes this recommendation? Or maybe the DC has a built-in shut off delay?

I'm designing my DC system now, and I want to switch it from the blast gates with a solid state relay. But I'm trying to decide if I need a shutoff delay.

It's not too bad to include one, there are many options to add a delay circuit so that when the switch is opened, it waits a predetermined time, like 3 min or 5 min, before shutting off. (The forum at All About Circuits is awesome). But if it's really not needed, why bother.

Thanks
Keith


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## Sparks500 (Jun 30, 2017)

If you just use low voltage switching, put a microswitch on your biast gate. As long as its open, it's on. Simple.


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## Crashcup (Feb 11, 2015)

> If you just use low voltage switching, put a microswitch on your biast gate. As long as its open, it s on. Simple.
> 
> - Sparks500


Right, that has been my plan. Have the switches, have an SSR, have an old wall wart to provide 9VDC to drive the relay. But I saw a comment somewhere about limiting how much the DC switches on and off, so I was curious if you guys have seen that… or your opinion on the need for a delay so that if I close a blast gate at one machine, walk right over to another and open that gate, the DC stays on during that time. (My system will be one machine at a time only - will need to keep only one gate open at a time).


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## Sparks500 (Jun 30, 2017)

I guess it's just something I've never given much thought to. If I go from machine to machine quickly, the dc is still winding down and will start back up easily. 
I'm curious as to why an ssr? Most ssrs that I've had experience with were designed for variable heat loads. I just used a 24v ac relay, rated for 30a, with a 24v transformer all mounted in a junction box. Mounted speaker quick connects on the outside of the box for the microswitches.


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## Crashcup (Feb 11, 2015)

> I m curious as to why an ssr? Most ssrs that I ve had experience with were designed for variable heat loads. I just used a 24v ac relay, rated for 30a, with a 24v transformer all mounted in a junction box. Mounted speaker quick connects on the outside of the box for the microswitches.
> 
> - Sparks500


I'm not sure there's a driving need for an SSR. If I had a regular coil type relay around, I'd use that. But I had to buy something, and a 25A SSR was only 12 bucks, so it seemed like that might be more reliable. Oh, and no clicking sound. Not that that's a deal breaker.

So, with the handle Sparks, are you an electrician?


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## AZWoody (Jan 18, 2015)

That was probably me you were referring to.

I did at once time have an auto start switch hooked up to a relay to run my dust collector. When I bought the Clearvue, the person who gave me all the information said that it could cause the start capacitor to have a short life. It wouldn't be a problem for the motor but just be a $20-$30 purchase sooner than normal.

I was ok with that but the more I was working in there, I found it was just easier to switch the dust collector on and let it run. I also have it in another room so the noise issues isn't as bad as having it in the work area.


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## Bill_Steele (Aug 29, 2013)

My Oneida Mini-Gorilla (an older model) recommends starting and stopping no more than 4-10 times per hour (page 12).


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## bonesbr549 (Jan 1, 2010)

I have the Greengate system, and in the beginning it was 30 sec delay and it was a tad annoying, but so be it. Now it's set to 10 seconds, and thats fine, just to clear the line after the tool goes off and then the gates close.

www.grngate.com


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## BikerDad (Jul 16, 2008)

The purpose of the delay is to capture whatever may be created during "rundown" after the power to the tool is shut off but the "cutter" (sander head/saw blade/jointer head/etc) is still spinning. Furthermore, the delay gets most/all of what is in the line. You want a delay. How long of a delay is really dependent on how long your lines are. Portable dust extractors with auto-on/off, i.e. glorified shopvacs like Festool, Fein and others make, have a few seconds because their lines are pretty short. If, on the other hand, you've got a big shop with 30' of piping across the ceiling and the 7' down to the tool, if you cut off early you'll be dropping "content" back down your piping to the tool.


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## Crashcup (Feb 11, 2015)

> That was probably me you were referring to.
> 
> I did at once time have an auto start switch hooked up to a relay to run my dust collector. When I bought the Clearvue, the person who gave me all the information said that it could cause the start capacitor to have a short life.
> - AZWoody


This sounds familiar, Woody. Might be what I was thinking of. So far it doesn't seem that there's an overwhelming feeling that a delay is necessary for the motor's sake. 
I wonder if the guy from Clearvue exaggerated a bit. Some situations you could see a definite problem… say it's an air compressor where the startupans cutout pressure switches are set wrong and the motor has to keep starting up every minute. 
But it's hard to imagine a home shop DC starting up that frequently.


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## Crashcup (Feb 11, 2015)

> The purpose of the delay is to capture whatever may be created during "rundown" after the power to the tool is shut off but the "cutter" (sander head/saw blade/jointer head/etc) is still spinning.
> - BikerDad


Good point, thanks. It is probably a good idea for that reason alone.


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## Sparks500 (Jun 30, 2017)

> I m curious as to why an ssr? Most ssrs that I ve had experience with were designed for variable heat loads. I just used a 24v ac relay, rated for 30a, with a 24v transformer all mounted in a junction box. Mounted speaker quick connects on the outside of the box for the microswitches.
> 
> - Sparks500
> 
> ...


Yep. Retired after 43 years. Now, I play in my shop and chase grandkids around.


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## Sparks500 (Jun 30, 2017)

I'll be interested in hearing how your ssr works out. They are sturdy little things, I've had one connected to a pid controller running my smoker for about 10 years.


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## Crashcup (Feb 11, 2015)

> Yep. Retired after 43 years. Now, I play in my shop and chase grandkids around.
> 
> - Sparks500


Cool. I have a lot of respect for the trade. I've done some electrical work on our house addition/remodel, and while I can get the job done, it takes me an awful long time planning and double-checking to make sure everything is right. But I sure like electrical work more than plumbing!


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## Sparks500 (Jun 30, 2017)

Well, I gotta admire anyone who wants to keep Clyde Crashcup alive and well…...


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## Crashcup (Feb 11, 2015)

> Well, I gotta admire anyone who wants to keep Clyde Crashcup alive and well…...
> 
> - Sparks500


Ha! Somebody who knows who that is! Clyde Crashcup is actually just a bit before my time, but was one of my dad's favorite cartoons, and Clyde was his nickname for me when I was a lad.

Now I've got work to do… 3D printing my blast gate design, and going to start with my current Penn State 1 1/2hp DC and just 3 drops. I'll try to remember to post something when I have it up and running.


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