Oneida "Smart" Dust Collector

[Jim Dwight]

I don't know about the merits of a smart vacuum but I do think I understand shop vac setups. I use a Rigid with a filter like this:

http://www.amazon.com/Ridgid-97457-VF6000-5-Layer-Vacuum/dp/B0029NY9XU/ref=sr_1_8?s=hi&ie=UTF8&qid=1457834458&sr=1-8&keywords=shopvac+heap

It pulls through a dust deputy and the vac and cyclone sit on a cart based upon plans from Woodsmith. The HEPA filter is $30. A 6 gallon Rigid vac is about $50. The dust deputy is also about $50. I put an autoswitch on which was about $40 and works even with my 15A table saw. A sheet of plywood is around $30. So for about $200 you can have a very functional shop vac with HEPA filtration. It's noisy but I wear muffs in the shop anyway. Nearly all the tools are noisy. Right now, this is all I use. It won't handle the planner or jointer but works for the other tools. I need the shop vac for the tracksaw and sanders and it works as well as my little DC did for the CMS and RAS and table saw.

I'm not claiming anything about DCs. But effective shop vacs for me start about $200. Not $600.

[Alan Schaffter]

I don't know about the merits of a smart vacuum but I do think I understand shop vac setups. I use a Rigid with a filter like this:

http://www.amazon.com/Ridgid-97457-VF6000-5-Layer-Vacuum/dp/B0029NY9XU/ref=sr_1_8?s=hi&ie=UTF8&qid=1457834458&sr=1-8&keywords=shopvac+heap

It pulls through a dust deputy and the vac and cyclone sit on a cart based upon plans from Woodsmith. The HEPA filter is $30. A 6 gallon Rigid vac is about $50. The dust deputy is also about $50. I put an autoswitch on which was about $40 and works even with my 15A table saw. A sheet of plywood is around $30. So for about $200 you can have a very functional shop vac with HEPA filtration. It's noisy but I wear muffs in the shop anyway. Nearly all the tools are noisy. Right now, this is all I use. It won't handle the planner or jointer but works for the other tools. I need the shop vac for the tracksaw and sanders and it works as well as my little DC did for the CMS and RAS and table saw.

I'm not claiming anything about DCs. But effective shop vacs for me start about $200. Not $600.

Jim, read the Amazon reviews (especially this old one)- despite what the listing says, it is not a true HEPA filter (at least not five years ago). Also, read what people say about it loading up quickly. Also, a shopvac will not provide the CFM needed for a CMS or tablesaw.

[Larry Frank]

I started this thread to discuss dust collector systems and it has migrated to shop vac and for some this is quite useful.

There have been some interesting posts on shop vac systems. As much as possible, I want to use a larger system for dust collection needs. I do not want to give up space for a shop vac, dust deputy system. Also, I do not have a way to exhaust outside.

I do use a Festool CT26 for sanding. I bought it several years ago and while expensive is a HEPA vac, variable speed, quiet and has auto on off.

Joe Jensen's post and article are very useful as he has good info. I am going back to he drawing board and do some estimates of what I need given my shop layout.

[Jim Dwight]

Larry, sorry didn't want to hijack your thread but I guess I did.

Alan, I'll start another thread and see if anybody wants to talk about this.

[David Kumm]

It would be good to know the design differences in the impeller and housing that allow the 3 hp Smart to pull at 23", similar to the high vac Smart, vs the regular 5 hp smart which tops out at more like 15" sp. The high vac provides both high and low end cfm while the normal 5 hp provides more low end and the 3 hp provides more cfm at high pressure. Dave

[Sean Tracey]

It would be good to know the design differences in the impeller and housing that allow the 3 hp Smart to pull at 23", similar to the high vac Smart, vs the regular 5 hp smart which tops out at more like 15" sp. The high vac provides both high and low end cfm while the normal 5 hp provides more low end and the 3 hp provides more cfm at high pressure. Dave

I would think the single speed collector fan curves show only data points taken when the collector is ran at it's single speed.

I would also think that the smart collector curves show what the unit can do in CFM at the most optimum rpm for the particular static pressure shown on the graph. For instance, at high static pressure, the CFM being moved is lower, so the hp required drops which allows the motor to be spun at higher rpm to boost the CFM while still not exceeding the hp rating of the motor at this higher rpm.

I don't think most people understand the highly non-linear relationship of CFM to static pressure at a single speed. And they really don't understand the further non-linear relationship of CFM to static pressure when you increase speed. Then you get people who don't understand how the hp required is related to the CFM moved by the fan rather than the static pressure.

The more air you try to move through a given duct, the higher the static pressure loss. A curve for the duct work can be plotted showing this static pressure vs CFM relationship. This curve will start low on the left side of the graph and curve up.

The curve for the fan can also be plotted on the same graph. This curve starts high on the left side of the graph and curves down. (Because the higher the static pressure, the lower the ability of the impeller to move air in CFM)

The system of ductwork and dust collector will pull the CFM rate that occurs at the intersection of those two curves.

When both curves are plotted on the same graph, then the way the dust collection works makes a lot more sense.

If you really want to understand what is happening in your system, you make a plot for the duct work losses to each machine all on that same graph and you would see where each duct work curve crosses the fan curve and then you could truly understand the benefit of any given single speed vs smart-variable speed collector.

Most people prefer to guess or try to reason it out in their head which is not possible since the systems perform in a highly non-linear fashion.

[David Kumm]

I understand the change in a fan curve relating to rpm but many impellers used in standard collection systems top out after a certain rpm and speeding it up doesn't gain much additional. In addition, a vfd can't really increase much over 60 hz efficiently due to the limit on voltage. I can see an increase in cfm with my radial fan that is rated up to 4400 rpm but there is a limit to how much the motor can speed up within the amp limits. I doubt the Smart is designed to run much over 60 hz, but rather is oversized so when at low pressure runs slower than 60 hz and under high pressure speeds back up. A curved blade impeller by nature won't pull cfm at 23"sp unless sized over 18" in diameter. I have seen pictures of the 5 hp regular smart that operates up to 15" and it is curved so the extra couple of inches must come from the housing design or perhaps a few extra hz. I wonder if the blade design for the high vac models differ and how as most high pressure impellers I've seen are belt driven and radial so as to operate well over 3600 rpm. Dave

[Sean Tracey]

VFD's can be used to spin a motor at some amount more than 60 hz depending on the specific application. Of course, an impeller spinning faster must be balanced to handle the higher speed and the motor must be capable of withstanding the extra forces involved.

Bumping the hz from 60 to 67 hz would give maybe 400 rpm more on a 3450 rpm motor.

I have no idea what oneida has done for each of it's smart systems, but I believe it at least possible that the impellers could be identical to those used in some of their single speed units. They would apply the vfd and then figure out how much performance could be extracted as well as programming in protection against spinning the impeller to fast for mechanical sturdiness, hp limitations, or in a manner that would hurt the flow characteristics.

If results were unsatisfactory, then they would go through the extra expense of designing a new impeller and/or housing.

They could also do a larger than normal impeller and spin it at slower than normal speeds as you stated.

The point is, speed control, applied properly, can be very useful in a device such as a dust extractor.

[David Kumm]

Sean, I agree totally with you. I run with a vfd for that purpose. When I had an Oneida 15" curved blower, I was told to stay within 3-5 hz over 60 and while I got a little more cfm, it wasn't worth the additional noise. I don't remember the actual increase but it wasn't much. I've had better results with my radial when adjusting speed but it is much more loud and the impeller itself is much heavier. What I don't know is how much the housing design and the distance from the blades to the housing affect performance at higher pressure. Dave