Shopsmith Forums

dusty wrote: ↑Thu Jun 17, 2021 5:31 pm I have a 36" hood and it fully inflates (for whatever that is worth).

What would I gain by changing to a 42" hood other than the claim that it captures smaller particles.?

What is lost by having a taller hood that does not fully inflate.

Does the cake that develops in the hood help or hinder and how? When I change collection bags, I've been knocking all that cake off.

dusty wrote: ↑Thu Jun 17, 2021 5:31 pm I have a 36" hood and it fully inflates (for whatever that is worth).

What would I gain by changing to a 42" hood other than the claim that it captures smaller particles.?

What is lost by having a taller hood that does not fully inflate.

Does the cake that develops in the hood help or hinder and how? When I change collection bags, I've been knocking all that cake off.

RFGuy wrote: ↑Thu Jun 17, 2021 6:11 pm

dusty wrote: ↑Thu Jun 17, 2021 5:31 pm I have a 36" hood and it fully inflates (for whatever that is worth).

What would I gain by changing to a 42" hood other than the claim that it captures smaller particles.?

What is lost by having a taller hood that does not fully inflate.

Does the cake that develops in the hood help or hinder and how? When I change collection bags, I've been knocking all that cake off.

Dusty,

Yes, the taller 42" filter hood filters down to 1 micron supposedly. Where did you get a 36" filter hood? Did Shopsmith sell it at one point in time because they no longer do. As long as the filter hood isn't so small to restrict the blower (motor + impeller) by back pressure then there really is no difference between the different filter hood sizes except for the fact that the taller one filters down to 1 micron. Of course, having a larger filter hood means you can go longer for maintenance, e.g. not having to knock the cake off because of reduced airflow. According to Shopsmith website the 24" filter hood only filters down to 5 micron and the 12" hood only down to 7 microns.

Well, a filter hood that doesn't fully inflate indicates an anemic blower...it means that the airflow is lower than it should be.

Cake in the filter will limit airflow, but it improves collection efficiency. I don't know the filter specs for Shopsmith's filter hoods, but let's say as an example that it is 96% efficient at collecting 1 micron particles. This is ONLY true after there is sufficient cake built up, so a brand new filter with no cake may only be 80% efficient at catching these particles. Once there is a sufficient layer of cake built up then the collection efficiency rises. Just throwing numbers out based on other filters I have seen in the past, i.e. there aren't published numbers for Shopsmith's filter hoods other than them giving the micron rating. Whenever airflow drops too low, the filter cake should be knocked off or at least reduced to improve airflow.

DLB wrote: ↑Thu Jun 17, 2021 6:24 pm For each increase in hood size, they show a decrease in particle size and an increase in CFM: "Advantage of the 24" filter hood on DC3300 is that it increases airflow 30% or from 330 to 430 CFMs. 42" hood CFM range 695-890 hose is 2 1/2". Diameter plastic end makes it 2 1/4"." From: https://www.shopsmith.com/mediawiki/ind ... Filtration

algale wrote: ↑Fri Jun 18, 2021 10:55 am Excuse my ignorance, but is the cited document from an official Shopsmith site or official Shopsmith info?

I have never seen the claim that increasing hood height increases CFM. Intuitively, it does seem plausible to me that if made of the same material (i.e. same pore size) a larger filter will offer less resistance to the impeller pushing air through it and might increase CFM. But, if porosity is smaller in the 42" hood and the hood has achieved maximum filtration efficiency (i.e. has a built-up cake of sawdust) a larger filter might actually decrease CFM in operation.

algale wrote: ↑Fri Jun 18, 2021 10:55 am Excuse my ignorance, but is the cited document from an official Shopsmith site or official Shopsmith info?

I have never seen the claim that increasing hood height increases CFM. Intuitively, it does seem plausible to me that if made of the same material (i.e. same pore size) a larger filter will offer less resistance to the impeller pushing air through it and might increase CFM. But, if porosity is smaller in the 42" hood and the hood has achieved maximum filtration efficiency (i.e. has a built-up cake of sawdust) a larger filter might actually decrease CFM in operation.

DLB wrote: ↑Sat Nov 28, 2020 7:17 pm I guess I'm a bit skeptical. Two things I would not expect in a modernized portable Dust Collector at this price point are 2-1/2" ports (only) and a 12" hood style filter. I don't see any way that it can perform well compared to other systems available that offer comparable power, 4" ports, and large filters. But that is based more on physics than skepticism, Shopsmith does not make a lot of performance claims that would cause one to be skeptical. Despite any of that, I would be a likely buyer if a reasonably priced upgrade to the 3300 is made available.

- David

JPG wrote: ↑Fri Jun 25, 2021 6:30 pm well the 'upgrade' is official.

I wonder if it will allow rereleasing the 4" port upgrade?

$279 is tempting!

RFGuy wrote: ↑Fri Jun 25, 2021 8:40 pm

JPG wrote: ↑Fri Jun 25, 2021 6:30 pm well the 'upgrade' is official.

I wonder if it will allow rereleasing the 4" port upgrade?

$279 is tempting!

Yeah, I just saw the email. That is great news. So, I wonder if the motor is the only change for the DC-6000 or if the impeller is modified as well. In other words will upgrading the motor on the DC-3300 also yield 600CFM or will it be slightly less.