# Rockler 650 CFM question



## JR-Wrtter (Sep 9, 2021)

I have the Rockler 650 cfm version will I be able to take out the filter and plastic bag and exhaust it outside? I read some dc motors required a certain resistance to work efficiently. The reason is every time my 2 stage 55 gallon drum fillls up the filter gets clog up really bad loosing a lot cfm so I have to remove it and clean it and it’s a pain since I have take out 8 bolts and already cross thread it 2.

thank you


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## DustyDan (Dec 21, 2020)

I’m not sure about motor issues, but that should be an AC motor. Coming from Rockler, their 650 cfm model is a single stage that discharges to a bag. Are talking about removing the drum and bag to spray dust outside?

I think your drum is installed upstream of the fan, right? And you are looking to add hose, pipe or duct to the blower exhaust instead of using the bag that came with the unit. I don’t think there is much resistance on the bag, anyway. Adding discharge pipe or hose to exhaust outside would probably be more resistance then a bag filter.

I think the easiest solution is to keep your drum from overfilling by making it easier to empty. Replacing the stripped bolts seems easier. Or even installing a door on your drum may be easier.


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## JR-Wrtter (Sep 9, 2021)

Yes, sir thank you


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## Kudzu (Dec 23, 2008)

_"I THINK"_ that it would need a little resistance to keep from overworking the motor. But I am sure you can do what you want if you adjust the airflow.

I say this because I have use HVAC squirrel cage fans in the shop. I get them from a buddy of mine that does HVAC repair and he told me to put an amp meter on the power lead to check the amp draw/load on the motor. Then block off some of the opening till the amp reading lowered to a particular load.

The reason being, without the resistance the fan was moving too much air and working the motor to hard. It would eventually overheat the motor and ruin it. 

Since a dust collector is the same basic thing, I think you would need to have some restriction in the air flow to keep the motor from overheating. Removing the filters would allow it blow more air and overwork the motor. I don't think it has anything to do with efficiency, just not overloading the motor. 

A lot of people don't understand that the more air it moves the harder the motor is working. Less airflow, less load on the motor.

If I were you I would borrow an amp meter and check the load as it. Then when you covert it over just introduce some resistance in the ducts so that you have about the same amperage/load on the motor and it should work just fine.


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## DustyDan (Dec 21, 2020)

I edited my comments above. Probably should have replied again.


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## JR-Wrtter (Sep 9, 2021)

Thank you guys I went on ahead and did all the work it works even better I got more cfm also less noise in shop.














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## Kudzu (Dec 23, 2008)

You will get more CFM but if you read my previous post you may overwork and fry your motor too.


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## DrRobert (Apr 27, 2015)

✔ I don’t think you’ll have a problem, there enough resistant in the exhaust hose.

I have one dedicated to my miter station & router table also exhausted directly outside. I’ve heard about the resistance thing, but never seen it. My bigger unit is exhausted outside 5 years nothing burned up. 

Not all can do it, but bypassing the filters makes a huge difference in performance.


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## BigCountry79 (Jun 2, 2021)

You also have significant resistance on the input side.


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## Kudzu (Dec 23, 2008)

BigCountry79 said:


> You also have significant resistance on the input side.





DrRobert said:


> ✔ I don’t think you’ll have a problem, there enough resistant in the exhaust hose.


Not trying to beat a dead horse but if you don't measure the load how do you know there is enough resistance? Your just guessing. 

Not my problem but he said he got more CFM so the load has increased on the motor. To much? No way to now without measuring it somehow.


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## woodnthings (Jan 24, 2009)

DrRobert said:


> *✔ I don’t think you’ll have a problem, there's enough resistant in the exhaust hose.*
> (and suction hoses, my added opinion)
> 
> I have one dedicated to my miter station & router table also exhausted directly outside. I’ve heard about the resistance thing, but never seen it. My bigger unit is exhausted outside 5 years nothing burned up.
> ...


You can measure the amperage with a "Kill a Watt" meter:








KILL A WATT Electric Monitor


Amazing deals on this Kill-A-Watt™ Electric Monitor at Harbor Freight. Quality tools & low prices.




www.harborfreight.com





That's an induction motor and runs on AC from the looks of it. The bag was the biggest source of resistance, as far as I know. Then the ribbed intake and exhaust hoses are next. The bag is gone, so less resistance. As an experiment, cover the suction end with a flat plate or board and listen to the change in the motor RPMs. It shouldn't speed up radically. Then plug the motor into the Kill a Watt meter and do the same again. If the current drops, that's better than increasing. If the increase is just 1 AMP or so, I don't think there's an issue, but I'm NOT an electrician either.


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## Tool Agnostic (Aug 13, 2017)

I wonder what the area in, around, and outside that flapped outlet vent will look like after a few weeks of woodworking?

When we were young and didn't bother with dust collection or protection, a huge pile of sawdust and chips would accumulate behind our radial arm saw. The sawdust pile could easily build up to a cubic yard (cubic meter) of sawdust and chips behind that one tool alone. (Note: I would never allow that today, but we were very young, naive, and too busy/lazy at the time.)

I realize that a lot of finest sawdust will blow away, but wonder what will happen to the exhaust port in general over time. Around here, a loose pile of sawdust outside the home would attract both subterranean and drywood termites.


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## BigCountry79 (Jun 2, 2021)

Kudzu said:


> Not trying to beat a dead horse but if you don't measure the load how do you know there is enough resistance? Your just guessing.
> 
> Not my problem but he said he got more CFM so the load has increased on the motor. To much? No way to now without measuring it somehow.


Well, you can return it or buy a new one if it breaks. Honestly, there's no telling how it will react even if the load goes up. A lot of these just die on their own too.

Use it with the bag for an hour. Feel how hot it gets. Try it without the bag for 15 min. It's it hotter?

I think we are over analyzing


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## woodnthings (Jan 24, 2009)

BigCountry79 said:


> Well, you can return it or buy a new one if it breaks. Honestly, there's no telling how it will react even if the load goes up. A lot of these just die on their own too.
> 
> Use it with the bag for an hour. Feel how hot it gets. Try it without the bag for 15 min. It's it hotter?
> 
> I think we are over analyzing


A "hybrid" solution is to collect the dust and chips in a container to dispose of or compost later, once a week maybe? rather than blow them around into the neighbor's yard, that would be the best solution. That's different than a restrictive filter bag, so more efficient. That little 650 CFM blower will be straining no matter what to suck enough CFMs regardless. The recommend volume for a table saw is 350 CFMs minimum according to the duct collection Wizard, Bill Pentz.
I do like the Kill a Watt meter for many purposes.


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## JR-Wrtter (Sep 9, 2021)

It’s working great the chips and big stuff lands in the 55 gallon drum the fine dust that the filter doesn’t really filter it gets thrown outside instead of inside the shop update I got the 4in Dust Deputy wow I can actually fill up the whole 55 gallon drum before it starts shooting wood chips outside before I was using the double elbow method half way the drum it would start shooting chips outside now with the dust deputy you can fill it all the way to the top highly recommend dust deputy.


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