I mentioned this YouTube video by “DIY Wood Guy” about stretching dust collection pipe to form glue-less connections to fittings : Dust Collection Ducting That's Cheap and Easy? - YouTube It’s a great general overview of systems, but take a look specifically at time stamp 3:43 thru 5:00. I have used this technique with a cheap HarborFreight heat gun, not a propane torch, and it works GREAT!
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Hal, I missed this some way.
There are a couple of things about this video I would like to comment on.
- Reducing the size of the main runs down to 4" from the source is drastically cutting his air flow. He should be running 6" all the way to his machines and then reducing to 4"/or 2 1/2" at the machine.
- The difference between Dust collection and Vacuum cleaners is that in dust collection the air velocity is slower and quantity of air is larger, In a vacuum system, the air velocity is greater and the volume of air is smaller.
- When the volume of air is reduced from a dust collector, i.e. choked down from 6" to 4" to 2 1/2" on a dust collector, the amount of air being sucked is almost nothing.
- From my own experience, there is a dramatic fall in air movement in smaller diameter main runs.
5, Flex also cuts down on air flow if the ribs are on the interior of the hose. - I have seen U-Tube videos of shops piped with 3" main runs, and the owner can’t figure out why his air flow is so poor. To move sawdust the air flow is the most important factor.
- If that was a high velocity vacuum system, then that would be a different story.
Herb
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agreed on what you said Herb…
using a torch on plastic also off gases some seriously lethal gases…
PVC does actually catch on fire, the fumes coming off the pipe at 158 degrees Fahrenheit are hydrogen chloride gas and dioxin… a heat gun will cause off gasing also…
hydrogen chloride, which is a corrosive, highly toxic gas that can burn skin and cause severe, permanent respiratory damage; and dioxin, the most dangerous known man-made carcinogen, which will persist in the environment for a long period of time…
use metal for your DC piping and control the static while yur at it…
anybuddy priced PVC lately???..
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let’s add static discharges to the safety issue of DC piping…
Static in Dust Collection.pdf (59.2 KB)
can I add some design information to what you said Herb???
Air_Handling_Design_Guide.pdf (1.9 MB)
Installing your air handling system.pdf (281.8 KB)
Dust Collection System Design 10 April 09.pdf (274.6 KB)
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A couple of comments I would like to make about dust collection.
- Static Electricity charges. I have built 2 systems using 6" white PVC main piping runs. When I used my planer and the drum sander I got huge zaps from the static elec., These were not life threatening or a fire hazard. They were just startling and could under the right conditions cause unsafe reactions from the operator. How I dealt with these is to take a bare #12 copper wire about 3feet long and wrap one end around the pvc DC pipe and ground the other end to the machine. The machines are self grounded by the 3rd wire in the electrical cord, this solved the problem.
- when I connected the pipe to the fitting,I ran 2 , 1/2" long self tapping sheetmetal screws through each side of the conection to hold them together. Then I wrapped the connection with that shiny metal duct tape you can buy at Lowes. It seals the joint and to make changes in the system in the future, just remove the tape and the 2 screws and it comes easily apart.
Herb
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