Thread: a vac for shavings?

Hrae&forbes are selling a large shopvac type unit for $99, i tried to link to it but as is the norm these days their website is down

I use a vac marketed by ridgid here in the states. a cheap single stage 185 cfm vac, hooked to a 35 gallon garbage can with another hose coming out of that.

If the shavings are very large and coarse, I shovel them up by hand first after brooming them into a pile (and put those in a large 55 gallon drum liner), and vacuum the small stuff everywhere else with the shop vac. If your aim is to do all shavings, I'd want 4 inch hose without interruptions or catches in it. Various aspects about the shavings make them a pain to vacuum.

Originally Posted by D.W.

I use a vac marketed by ridgid here in the states. a cheap single stage 185 cfm vac, hooked to a 35 gallon garbage can with another hose coming out of that.

The claims made by US suppliers of vacuum cleaners are just wrong.
There is no way a cheap (or even expensive) vacuum cleaner can pull 185 CFM.
The power requirements to pull 185 CFM at the sorts of pressures that a vacuum cleaner operates at would be in the >5 real HP range which at 110V would mean around 35A of current.

The so called 5HP motors in US vacuum cleaners only draw ~10A (that is even stated in their product description)
10A x 110V makes it about 1100W or about 1.5 real horsepower.

A cheap vacuum cleaner with a clean new filter, unblocked hose, not collecting any dust and all the planets aligned draws about 100 CFM, while a higher end unit might get to 130 CFM
Not long after being used when the filter partially blocks etc they draw about 70 CFM.

Units that can collect a real 185CFM are invariably low pressure dust collectors

Originally Posted by BobL

But if your impeller is inside the shed and as the hose connects to the impeller then there should be no need to take the hose outside??
Or am I missing something?

Hi I have attached a couple of photos as it better illustrates what I am saying.
The impeller unit has been detached from the original unit and mounted above the olive drum.
The drum acts as an interceptor and any larger debris falls into this.
Smaller particles are light enough to be drawn into the impeller and ejected into the filter unit and bottom bag outside the workshop.

Originally Posted by mark david

Hi I have attached a couple of photos as it better illustrates what I am saying.
The impeller unit has been detached from the original unit and mounted above the olive drum.
The drum acts as an interceptor and any larger debris falls into this.
Smaller particles are light enough to be drawn into the impeller and ejected into the filter unit and bottom bag outside the workshop.

OK I get it.

A few problems with this setup are;

Using the DC outside the shed creates a slight vacuum inside the shed so all the fine dust that comes through the DC filter bags and various leaks (they always leaks somewhere) will come straight back into the shed. The finer the dust the more of it will come back into the shed. To minimise this effect the DC must be located outside the shed on a wall opposite the biggest opening in the shed so that air is preferentially drawn in a far away as possible from the DC filters/

Adding extra flexy between the impeller and the filters/bags increases the resistance to flow.
Drum interceptors do the same thing and can reduce flow by as much as 25%.