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your recommendation for an automatic full-barrel shutoff4/21/13
As in an earlier post, I'm putting together a 7-1/2 Hp cyclone with cartridge filters out of incomplete sets of parts.
I recognize the necessity of a sensor and switch to shut off the system when the dust barrel gets full so I don't blow my filters full of cyclone-extracted crud.
What sensor/shutoff hardware is reasonably cheap, reliable, easy to install, and to transfer from one collection barrel to the next?
There are two basic ways of indicating a full bin.
A 'bindicator' is an arm that floats about the material. As the material builds up, it raises the arm, turning on a light, sounding alarm or shutting down. Tricky to get the arm adjusted right and to have material build with different species, size, etc.
A magnehelic gauge will read the pressure withing the ductwork, and when filters are full, the pressure will drop. This can be linked to a switch that will indicate or you can just look at the gauge.
Thanks for your comments.
C.J., I agree, a design by one of the commercial dust collection companies would be ideal but I reject the idea for two reasons. My shop is a 360 mile round trip from the nearest of those professionals ( I live in Wyoming, a larger than average state with only half a million population) and I'm using a bunch of secondhand components, determined to minimize the cost of this project.
Also, David, could you furnish a brand or type name of the magnetic sensors you refer to? Are these the photo eye devices that shut off your blower or ring a bell or turn on a strobe?
My impression of this type of product is that they are more about the designer/manufacture understanding how to combine cheap components rather than being about excellent hardware. To the degree that assessment is correct, I'd like a recommendation for a reliable, reasonably priced choice if anyone knows of such a product.
On the other hand, I see many new and used bindicators on eBay. I assume they are first-choice, critical-applications hardware. Is that true or are they only obsolete, cold war era stuff?
With regard to accessing the air movement engineers at Oneida Air Systems they can often work from drawings and phone discussions so I wouldn't completely rule that approach out.
Good luck with your dust collector project! I'd enjoy seeing pictures once you've got it all up and running.
I can't say enough good things about Oneida. As a hobbyist who needed dust collection and ductwork but couldn't afford an engineer to design a system for me, they were patient and expert. I worked with Amy Nichols there. Don't be put off that she's a "girl." She knows her stuff!
Mark - The gauges are magnehelic - not magnetic - and work off the pressure differential inside the system vs outside. They need to be sized to the application, with respect to placement and range.
Also, a bindicator is effective if it is placed in the bin correctly. In my experience, shavings will swirl around and pile differently - or pyramid - inside the collection chamber. Wenge dust will fall into the center, heavy and dense, while pine shavings may pile up in a far corner with the air currents, and never trigger the bindicator. This will certainly make bindicator placement a challenge.
I have never seen one in a barrel container, since most barrels are soon overwhelmed and replaced by a more efficient storage.
In my first one man shop, I had a one bag collector that I could fill in 30 minutes of planing. After a few months, I added up all the time I had spent fiddling with bags, hauling bags, all while I was still getting massive doses of fine dust. At my modest shop rate, I had already paid for a dust collector in lost time, I just did not have one.
I contacted Oneida and we worked up a great little system with return filtration that I put into a small closet sized shop addition. The air tight room will hold over 250 c/f of shavings, with a door at truck height so I can empty it easily.
Last word - expect lots of fiddling and perhaps mediocrity with your self made design. There is a world of difference between an engineered system and a cobbled together one.