Cyclone dust collector

[Brian Rupnow]

As part of my sandblaster build, I am building a cyclonic dust collector system. When I am using the sandblaster, hi pressure air is forced into the cabinet to carry the blasting sand to strip any parts I have in the blaster cabinet. This requires that there be a vacuum line connected to the cabinet to carry away this extra air which is now contaminated with sandblasting sand. Without a cyclone dust collector, the sand carried in this contaminated air would quickly plug up the filter on a normal vacuum cleaner. The answer to this is to have a cyclone dust collector between the sandblasting cabinet and the vacuum cleaner, to separate the sand from the stream of air. The basis for this cyclone dust collector will be a 5 gallon plastic pail, as purchased for $10 at the hardware store.

 

[Sparky_SC]

I plan on building the one with the wood baffle inside. The plans are on the net, even linked in your sandblaster thread as I recall. Reason? Reports say it works better than most 5 gallon commercial ones.

Following to see if you build the same one.

 

[Brian Rupnow]

I will be using a Thien baffle in this build.---Brian

 

[Brian Rupnow]

I don't have a lot to go on here. I have modeled the five gallon pail. I have modelled a flange which fits onto the back of the sandblaster cabinet. Right at the moment all I'm sure of are the pail dimensions and the diameter of the existing hole in the back of the sandblasting cabinet--it's a whopping big 3.68" diameter hole, and I have to fit a 90 degree pipe elbow to it.

 

[ddmckee54]

If you are planning on using standard PVC fittings in your dust collector, get the Sweep Ells instead of the standard Ells. The Sweep Ells have a larger radius and you get a better airflow.

 

[Charles Lamont]

A vacuum cleaner hose will carry a perfectly adequate flow. With my cabinet I have to turn the vacuum cleaner right down to minimum suck to avoid bowing the window too much. It is a while since I last used it, but I am not sure it does not need an air bleed as well. It is sucking through the filter inside the cabinet.

 

[ranger]

On my cabinet, I was advised not to seal all of the seams if using a vacuum cleaner. The reasoning behind this is that unless there is air movement in the cabinet, the dust etc, won’t be sucked out properly unless you put enough air in through your gun to near enough match what your extraction system is taking out!

 

[ddmckee54]

In any dust collection system you need to minimize the leaks, because every place you are leaking air into the system means that much less volume of air that will be removed from where you WANT it to be removed. That means sealing all the joints and controlling where, and how much of, the air is getting into the extraction system.

 

[ranger]

I think the idea was that if you don’t have any air entering the cabinet, other than the time you are actually blasting, if there is no airflow, ie a vacuum, the extraction system can’t remove any dust etc. so the idea was to not perfectly seal the cabinet, but to ensure an airflow to be present. Obviously if you had no extraction system, you would still need a vent somewhere to exhaust the air entering the cabinet from the blasting nozzle!

 

[Sparky_SC]

My harbor freight cabinet has 2 openings. One on the side and another on the rear. The one on the rear is round and ties to a rectangular duct inside that is open at both the top and bottom of that duct. One is for the vacuum the other is a ambient fresh air supply.

 

[HMEL]

I thought I would give my two cents worth on dust collection of having spent most of my career dealing with dust collection systems of all sorts out of necessity. I will start with particle size and ignore its flammable characteristics a criteria essential in dealing with something like grain dust.

Particle size determines carrying velocity. But once you have the particle entrained you have to remove it. With heavier particles cyclones can be used but smaller ones will require a filter. There are such things as impact devices which can also be used.

Air leakage becomes important when the total volume of air can no longer be handled by the fans which are removing it. For sandblasting cabinets most vacuum cleaners have way more air removal then you need.

The extra air can also cause a higher pressure drop across the filter and cyclone which will lower the conveying velocity and blind the filters more rapidly.

There are formulas for carrying velocities, cyclone designs and even filter mesh sizes. However for a person who just wants to sandblast now and then this approach is probably overkill.

What I caution one about is when you sandblast you could be removing toxic materials and if small enough in size can be emitted through the filter systems into the area around the cabinet. That is not good for your lungs.

So what I have done is use a Shop Vac which goes through a cyclone and then the filter on the Shop vac. Also I consider what is on the surface that I am trying to remove from the part. I dont make a living doing this so for as many times I do it which is infrequent it works quite well.

 

[Brian Rupnow]

Today, I am going to start moving forward on my dust collector. On most of the dust collectors that I have seen on Youtube, the pipe inlet that goes into the side of the bucket is glued in place. This looks like it is rather fragile to me---the kind of thing that looks great but breaks about the third time you go to take the hose off and empty the bucket. I have decided to do it a little differently and make that side entrance pipe from wood.--that way I can run screws thru the side of the bucket into the wood to hold it in place. Today I glued up five pieces of 3/4" plywood and set them up in my vice to dry overnight.

 

[olf20]

I've used a dust deputy for about 5 years. It's powered by
a old shop vac that we had laying around. I use it on my
mill / router doing wood and metal.
I'm so impress a what it catches.
Once a year I open up the shop vac to look at the
cloth filter and find almost nothing on it.
The only down side is the noise, but it does a great job.
olf20 / Bob

 

[GreenTwin]

As HMEL mentions about residual fine particle dust going into the shop, I intend to use a cyclone/shop vac in series, and then pipe the output of the shop vac out through the wall, at least when I am sandblasting.
The super-fine particles are the ones you really don't want to breathe, and don't want settling on machine tool equipment either.
My 2-cents on how I am going to set up my sandblaster cabinet, based on all the previous discussions in this thread.

Thanks to HMEL for those interesting comments about dust collection.

.

 

[Robsmith]

In any dust collection system you need to minimize the leaks, because every place you are leaking air into the system means that much less volume of air that will be removed from where you WANT it to be removed. That means sealing all the joints and controlling where, and how much of, the air is getting into the extraction system.

I built a cyclone with a slow motor. Washing machine motor I think. (Gutless and slow but very quiet.) It pulls a reasonable vacuum through a 100mm dia. hose. I have many "leaks". A plate of glass for the viewing window. No seal. The door has a seal but it leaks at the hinges and locks. The small vacuum stops any dust from going out of those leaks and is just enough to remove the blasting dust without moving the abrasive material.

 

[Brian Rupnow]

Woodwork is not my thing, but I can whittle out a shape. Once I get this attached to the bucket, a 90 degree elbow will fit in the outer end for a flexible pipe running up to my sandblaster.

 

[Brian Rupnow]

So, here is a "first assembly" of my cyclone dust collector. The metal tubes are just setting in place for now, as I haven't bought a vacuum yet to run it, and I need a better idea of the pipe size I will require. Good wife and I spent yesterday lunch at a restaurant patio to celebrate our youngest grandchilds fifth birthday. Had the entire family there and a great time was had by all. One kid and one grandkid couldn't be there because they had to work, but it was still fun to get everybody together for a nice meal and birthday presents.

 

[Brian Rupnow]

Today we have a Thien baffle plate carved out. I won't be able to mount it until tomorrow comes----I need to go to the hardware store and buy some 5/16" threaded rod. it's a beautiful warm day here, and I think good wife and I are going to go set at our upper deck and sample some wine coolers.

 

[Sparky_SC]

Brian, a consideration when shopping for a vacuum.... bigger is not better. Too much suction can suck your blast media out of the cabinet and sometimes even suck in the sides of the cyclone barrel. The goal here is to suck the dust only out of the cabinet which does not require a ton of airflow, the media should fall to the cabinet hopper by gravity. You might even get away with a cheap used household vac.

Higher powered vacuums come into play when the cyclone is used for large wood shavings and heavier junk.

 

[Mike Ginn]

Agree with Sparky. I use a domestic Henry which works very well with a Dust Commando cyclone collector which also has an anti crushing valve.
Mike