Thread: Cyclone separator into open bag, no filters on external exhaust.

PM sent.

I received the PM, do not think the criticism therein is helpful, but for the record, I am thankful for the replies, have thanked others in this thread and don't appreciate the suggestion I have not been adequately appreciative. Frankly, whether or not you intended it as such, I found your PM to be of an unbecoming snarky tone. If I had more time perhaps I wouldn't be feeling so overwhelmed with/by the sheer volume of information presented in this forum and could pick through and soak it up, but I don't so if I miss something, it's because I haven't the time or lack the mental capacity to take it all in. Shoot me, or bite me. Either way, it is what it is.

The next time you've got something private or derogatory to say to me send me a PM. Don't post it on a public forum! I've sent you another PM that, I hope, explains why a bit of 'self help' is in order.

Originally Posted by dropstix

At the rate things are going, I'll have to buy at least an ammeter and make incremental changes one at a time and read what the motor is telling me. i think this dust collection part of this forum ought to come with some sort of "rabbit hole" warning that flashes and users have to click a "I've been warned" button to keep reading.

I have posted my total work in progress for a full modification of a genetic 2HP DC in the Genetic 2HP thread. I, like you, fell down the rabbit hole I even ended up buying a Hotwire Anemometer to get accurate measurement of airflow in the ducting. I also built a manometer to look at pressure changes in the ducting.
I took ammeter readings and decibel readings.
All these readings are in the thread and also in my WIP thread. I even have before and after readings.

The object of the exercise was to take a cheap 2nd hand 2HP DC ( tests showed it was more like a 1.5hp) and make modifications, one at a time, to see what changed in the system - did it stay the same, did it improve, did it get worse? I was always going to plumb my shed with 6" PVC pipe and ended up with approx. 7m of solid pipe and 2m of flexy at the end of the PVC to the table saw. I can always upgrade to a 3hp unit and won't have to change the plumbing. Besides, I like a challenge

The end result was an increase from 456cfm with just a modified inlet (125 to 150mm) to 733cfm with pump inlet, outlet and the dust separator inlet all opened to 6" and table saw connected. With the outlet from the pump disconected so there was no dust separator or filter, the flow went up to 833cfm.
The point is, that anything in the system be it a filter, a cyclone whatever, is going to drop the flow.

i'd love to add a cyclone on my system but I know it will drop the flow significantly with the DC I currently have.

What you need to do is to go overboard with the DC then even when you add components, you have reserve.

JMT

Originally Posted by Lappa

The object of the exercise was to take a cheap 2nd hand 2HP DC ( tests showed it was more like a 1.5hp)

The HP assessment of the generic 2HP DC in the sticky was done using current and voltage measurements which are not very reliable. Eventually I did put the motor from that 2HP DC onto my HP measuring rig and found it was a true 2HP (actually 2.3HP) motor. I also measured another motor from an old but similar to the generic 2HP DCs and it measured 2.1 HP. The 3rd 2HP motor I measured I bought on Gumtree and I was told it was from an unbranded 2HP DC and that was also 2.1HP.

Thanks for that Bob. So much for all the derogatory comments about 'Chinese HP'. Now we just have to hope that the motors last!

Originally Posted by aldav

Thanks for that Bob. So much for all the derogatory comments about 'Chinese HP'. Now we just have to hope that the motors last!

I' getting up to the ~25 motor mark for HP testing (mostly 3 phase but around 1/3rd? are single phase) and have yet to find a single motor that did not meet their stated HP rating.
The method I use is raw measurements of torque (force x radius) and RPM. The measurement gear is easily calibrated/checked and I know I am operating at less than +/- 5%.

There is one thing I must add about any cheap motors and that is that they do seem to have poorer temperature control. Some get relatively hot even under zero load, let alone when used for a long time at maximum load as found on dust extractors. As you can imagine this does not sound like a good thing to be happening near a bag of dry sawdust. Some of the poor control is due to poor capacitor performance, especially over time as they always (even good caps) will degrade. Usually the Caps just blows and the motor stops but a DC7 we had at the mens shed we got when it was near new and it ran for ~ 3 years before its cap went slightly off-key, overheated the motor and it ended up seizing a bearing. I'm still scratching my head as to how they let it get that bad - I guess most older blokes are pretty deaf?

Originally Posted by Lappa

The end result was an increase from 456cfm with just a modified inlet (125 to 150mm) to 733cfm with pump inlet, outlet and the dust separator inlet all opened to 6" and table saw connected. With the outlet from the pump disconected so there was no dust separator or filter, the flow went up to 833cfm. The point is, that anything in the system be it a filter, a cyclone whatever, is going to drop the flow. i'd love to add a cyclone on my system but I know it will drop the flow significantly with the DC I currently have.

wow, that's one heck of a change in flow. Given the cyclone I pictured above has a 5" inlet it'll be interesting to see if it chokes things up too much. Sounds like it will. I think I'll build everything else around 6" and if the suckyMotor isn't enough or the cyclone too restrictive, I'll have to tweak/replace when time and $ allows, which will be a while given the state of finances.

Originally Posted by BobL

The HP assessment of the generic 2HP DC in the sticky was done using current and voltage measurements which are not very reliable. Eventually I did put the motor from that 2HP DC onto my HP measuring rig and found it was a true 2HP (actually 2.3HP) motor. I also measured another motor from an old but similar to the generic 2HP DCs and it measured 2.1 HP. The 3rd 2HP motor I measured I bought on Gumtree and I was told it was from an unbranded 2HP DC and that was also 2.1HP.

Seeing you quoted me, I must respond as you misread - I was referring to mine, not yours BobL, and you didn't put mine on any measuring rig

Originally Posted by Lappa

Seeing you quoted me, I must respond as you misread - I was referring to mine, not yours BobL, and you didn't put mine on any measuring rig

Sure I realized you were referring to yours. I was referring to my posts in the sticky where I also said it was less than 2HP but I later found that only by putting it onto a HP rig where it can be fully loaded could I really measure the HP.

Why quote me then? Why not just refer to the sticky!