Confused by DC

[Matt Mattingley]

I know I don't have any obstructions in my pipes, plus since right now only the wide belt is hooked up, I have gates on the openings where the other pipes will go eventually. I had both of the gates partially open to minimize the pressure on the system.

It is highly likely that the seal on the collection bin (plastic can) is not solid as it starts to collapse. That explains the dust in the filters. Knowing that there is a significant suction on the can, I am thinking I will get a metal can so that isn't a problem in the future.

Sometimes the obstruction is the pipe itself. What diameter main trunk are you using? How long is it?

There should be negative pressure inside a cyclones drop bin. With all my gates closed I am pulling 20 inches water column at the intake of the cyclone. This is about 0.7 pounds of force per square inch. My DC would crush a Rubbermaid trash pale. I would have almost no problem picking up a 16lbs. bowling ball with 5 inch pipe.

You do want to illuminate as many leaks as possible, between the trash bin and blower side of the cyclone. If you don’t the finest dust Will make it through to the filter.

[Mark Blatter]

Sometimes the obstruction is the pipe itself. What diameter main trunk are you using? How long is it?

There should be negative pressure inside a cyclones drop bin. With all my gates closed I am pulling 20 inches water column at the intake of the cyclone. This is about 0.7 pounds of force per square inch. My DC would crush a Rubbermaid trash pale. I would have almost no problem picking up a 16lbs. bowling ball with 5 inch pipe.

You do want to illuminate as many leaks as possible, between the trash bin and blower side of the cyclone. If you don’t the finest dust Will make it through to the filter.

Right now the main line is 6" and is about 10' long. The end splits with a Y running with two 26" long sections of 6" tubing. Those run into splitter boxes from Clear Vue where they split into two 4" lines each. The now four 4" tubes run about 22" to the top of the wide belt.

[John K Jordan]

Mark, I just saw this thread. I didn't have time to read all the posts so forgive me if what I have to say has already been covered.

I have the 5 hp ClearVue and it works well, actually, amazingly well. The bin collects even talcum-fine dust and after several years of hobby use there is probably not more than two tablespoons of dust in the cleanout box - I've never cleaned it out.

The way these cyclones are designed there will always be suction (negative pressure) in the collection bin. In fact, everything in front of the impeller is under negative pressure, ducts, separator cone, and bin, otherwise no dust will be picked up. If the blast gates are all closed, the negative pressure will be lower ( or "higher" for those who think that way), stronger suction. (This would be different for dust collectors that have the impeller/fan in front of the cone and bin such that all the dust gets pushed through the impeller and into the collector - in that case the entire separation and collection part of the system would be under positive pressure and an unsecured bin lid would pop off.)

If there is a leak anywhere past the inlet to the cone (in the bin, the bin lid, in the cone-bin lid coupler, or somewhere in the cone) then the separation will not work correctly and dust won't spiral down and fall into the bin as designed. Instead, dust can be carried by airflow up through the impeller and into the filters. The loss of efficiency will depend on the location of the leak - the worst is if the leak is in the bin.

From the ClearVue manual:
"Leaks in the collection drum or at the bottom of the cyclone are a major problem. Such leaks will cause an up-flow of air through the cyclone and prevent the dust from entering the collection drum."

My system is tight - I use a metal 30 gallon trash can and lid and a home-made 6" flange connected to the bottom of the cone with a short piece of flex and good clamps. I sealed everything with AlexPlus clear silicone caulk. The suction at the duct openings is amazing. The suction (negative pressure) in the cone and drum was so high the first trash can I tried collapsed immediately, caving in the sides with a loud metallic sound! I blame this on the lower quality of manufactured trash cans available these days. I substituted an can bought above 5 years earlier and it's heavier gauge steel. It has worked very well. I used a 1" wide strip of soft self-adhesive weatherseal about 3/8" thick around the inside of the lid so it presses against the rim of the trash can. Suction inside the can pulls the lid tight.

During initial testing I tested for leaks with smoke from some incense sticks.

BTW, if the system is working properly there should never be a need to partially open any blast gates unless you are somehow getting too much suction at a machine. The suction from the impeller will lower the pressure of the entire inside (ducts, cone, and bin) towards a vacuum. If you put an amp meter on the motor leads you can actually watch the current decrease when the blast gates are closed since the impeller can run easier in a partial vacuum than when moving air. In normal use resistance in the ducts and machine is enough to keep a lower pressure in the entire system. In fact, this is the reason the ClearVue instructions warn against even testing the until completely assembled - moving too much air will cause the motor to work the hardest, increasing the amperage and possibly causing damage. From the ClearVue manual: "Do NOT turn the motor on until the system is completely assembled, including the collection drum. Doing so may cause the circuit breaker to trip, physical damage to the system and/or bodily harm."

When running mine, if I need to pause making dust for a few minutes I simply close the blast gates and let the cyclone run.

If you do go with a steel can instead of the plastic and you can't find one strong enough, you might consider getting a used 30-gal steel drum, not as common as the 55 gallon drums but still available. You can find them with removable lids which would make things easier. However, if the height is too much for your installation (about 29"-30" I think) if you have welders and such another option is to get a 55-gal steel drum shorten it, and reweld the rim on the top. Even a closed drum without a removable lid would work - lots of people build a flat lid from MDF which can be sealed against the drum rim.

JKJ

I know I don't have any obstructions in my pipes, plus since right now only the wide belt is hooked up, I have gates on the openings where the other pipes will go eventually. I had both of the gates partially open to minimize the pressure on the system.

It is highly likely that the seal on the collection bin (plastic can) is not solid as it starts to collapse. That explains the dust in the filters. Knowing that there is a significant suction on the can, I am thinking I will get a metal can so that isn't a problem in the future.

[Mark Blatter]

John and All, thanks for the replies and info. I have more work to do, but had to get it up and running so I could get some things sanded for a customer. I will give in and pick up either a 35 gal or 55 gal steel drum to collect in. I have the height just didn't want to go the 55 gal drum due to the weight. Will look for a smaller one.

I will have to work on sealing the whole system better after Christmas.

[Matt Mattingley]

Right now the main line is 6" and is about 10' long. The end splits with a Y running with two 26" long sections of 6" tubing. Those run into splitter boxes from Clear Vue where they split into two 4" lines each. The now four 4" tubes run about 22" to the top of the wide belt.

Hey Mark. What are the exhaust ports from the top of the wide belt sander?

Ideally a clear view 5 hp DC gets aboat 1500-1900 CFM I believe the intake on the Clearview has about 40 in.³. You want to try to maintain this in a main trunk if over apming isn’t a problem. This would be a 7” dia. main trunk (38 in.³). From the 7 inch main trunk you can reduce to 2=>6 inch Y. At this point you are CFM will be cut in half but with very little restriction. If you take off the 6 inch with 6 inch flex and reduce to the major diameter machine exhaust ports you will get optimal extraction.

The 2=>4 inch flex lines are choking you a little bit(about 15-20%) and your main trunk is choking you a little bit(about 35%).

End result is you’re gotting about 50% of the suction you could getting.

I’m using a 60 gallon semi transparent chemical plastic bin,which I cut one 3 off the top of (height restrictions). My bin with the fine shavings/dust can weigh close to 50 pounds.

[jamie shard]

Great post John, thanks for taking the time to write all of that!

[John K Jordan]

John and All, thanks for the replies and info. I have more work to do, but had to get it up and running so I could get some things sanded for a customer. I will give in and pick up either a 35 gal or 55 gal steel drum to collect in. I have the height just didn't want to go the 55 gal drum due to the weight. Will look for a smaller one.

I will have to work on sealing the whole system better after Christmas.

A 55-gal drum would be too heavy for me too unless I could haul it outside on a cart and use the tractor to haul and dump.

If the thicker 30gal trash can I tried hadn't worked, I considered reinforcing it since it did fit nicely in the 9' high space I had - perhaps make a few bands from something like aluminum channel, bent into rings and fastened inside the can, perhaps even a cage of sorts that could simply set in place. Or tack weld rings of 1/8 steel inside. Seeing just how the can had caved in I'm pretty sure reinforcing would have worked.

I do like the handles on the can, but it would be easy to make handles for a 30-gal drum or a shortened 55-gal drum.

JKJ

[ChrisA Edwards]

I have this 55 gallon drum ($75 from Amazon). It's very sturdy and easy to take the top on and off with the clamp.

I use Home Depot contractor trash bags in the bin. The only negative, with the top slightly tapering in, it can be hard to get the bag out if I let it get too full. When removing, I usually tie the top of the bag shut and lay the bin on its side and roll it a little, side to side, while pulling the bag out. This shifts the contents of the bag as it comes past the taper.

Eagle 1656MBBG Straight-Sided Drum with Metal Band and Plastic Lid with Bungs, 55 gal, Blue

[John K Jordan]

Great post John, thanks for taking the time to write all of that!

Thank you! It took longer to decide what to say than it did to type it (I learned to type like a maniac from 15 years in software development!)

JKJ