I know what you mean about the lid not needing to be locked down becasue the suction will pull it down, but I wonder whether the more important issue is whether the 2nd stage collector (or pre-collector) is airtight. Especially as you are down on HP, I would have thought that there is quite a fair chance that some of your “suck” (tech term) is escaping around the edge of the lid.
A quick test would be to compare performance in the current configuration with performance with the led sealed to the bin with (typically) duct tape.
Good point – will look into it. I don’t think it will be a problem, because the lid has a foam ring under it which assists in providing the seal, and that appears to be making good contact all the way around. But hey, it won’t be hard to test both scenarios to see if my hypothesis holds up.
Greetings from the States. Love your site. I’m a dust collection newby. In your 2nd stage DC system, you showed us what it looked like under the trash can lid. However, can you tell me which is the inlet and which is outlet? I’m guessing that the straight pipe is the inlet and the elbow is the outlet but please confirm.
It is a good question, and obviously I haven’t given enough detail on the lid! It is actually the other way around – the curved section is the inlet (ie the side that is connected to where the dust is being collected from). The short straight bit is connected to the dust extractor.
It is this way around, so the dust as it enters the collector is encouraged to spin, creating a bit of a vortex inside the collector. This throws the dust wide, and hits the sides of the bin where friction slows it down, dropping it out of the airflow, so gravity can drop it to the bottom. The air then reverses direction so it can then exit via the short tube, and again, this is a very hard path for the dust to follow, so again it is encouraged to fall out of the airstream.
The principle is the same as actual cyclonic dust collectors, but is much more budget (and still works well enough for my workshop so i don’t have to go to additional expense). You don’t even need a special lid – the plumbing supplies are enough to turn a standard bin lid into this concept. (But it is easier with the one specifically designed to have 4″ hose attached!)
Hello from the states, I’m a new fan, love the site. How has the paper barrel worked out on the dust collection system in episode 35? Or, was that just for test purposes? It looked like the side of the can where the material hit had already started to wear from the abrasion.
Been going very well. There is some loss in suction, but that is a trade-off between performance of the collection system and ease-of-operation of the system.
There is no wear inside the barrel, if it looked like that it may just have been dust remaining (temporarily) stuck to the inside.
It has gone through a few changes since then, and is now been cut down in height so it can fit directly under the motor on that side of the duct collector itself – saves floor area. This was necessary because I have chosen to move the dust unit back into the main shed – increases suction, makes for easier on/off/emptying/filter cleaning.
Still, the principle remains valid – pre separation is a successful method to be incorporated in a dust collection system.