Dust collection for machine cabinet

[cncmadness]

Hello, I am working on building a cabinet for my machine and would like to get some help/ideas on adding a dust collection system to my machine.

First I will state what I have tried so that we can save some time on ideas that I have already done and no longer work for my situation. First I used a vacuum hose and followed the bit as it cut removing the dust as it went along, this didn't work so well and I got tired of standing at the machine. Next I made a dust boot to contain the dust with the vacuum line attached. This worked well, but as I found that my bits were over heating and breaking, I have since added and an air nozzle to the machine which blows compressed air on the bit. This has solved my problem of the bits breaking from the heat, but now here is where I am stuck. The air is now blowing the dust out of the boot and making a big mess in the shop.

I have now built a box around the machine with plexi glass windows so that I can see the machine working. I have removed the dust boot and am allowing the dust to be blown to the back of the cabinet that now covers the machine. But I am stuck on how to add a dust collection system to it. I have one idea tat I have been working on and would like some input. I have been doing it all in 3D models and have attached what I have done with what I have been thinking about for a dust collection. As you can see, I have created a slot at the back in which the dust can fall into. As this is where the suction will be coming from, it will also help pull the dust into the box below the table top. I plan on adding some sloped plates to help guide the dust to the hole. I have then created a sloped piece inside the box which will help prevent large pieces from entering the fan by creating a change in direction in the air flow and causing the large pieces to fall to the bottom. The fan will then take the air with some small particles and force it though a cyclone to remove any remaining dust. The dust free air will then be blown out the side of the cabinet and into the shop again. This will complete they cycle of the air through the machine. My first problem seems to be trying to figure out how big of a fan to place under the cabinet to create enough air movement to be able to pull the dust out of the cabinet. I have tried connecting a 1HP dust collector to the collection box and I don't feel like it is crating enough suction though the slot in the table. From what I have found, the dust collector I am using is doing about 570 CFM. I am looking at getting a 2HP dust collector and removing the motor and squirrel fan and placing it under the machine. This new fan is able to move 1500CFM.

So,do you think that this upgrade to a larger motor and fan is enough to do the required task?
Is this a route that will lead to success or should a quit now an move to a different idea?
Do you see a way that I could improve in what I am doing?

One other thing that I have also considered is to blow the clean air after the cyclone back onto the front of the machine to assist in dust removal and to help direct the air over the table to the back of the machine.

I have attached several pictures of the project so you can see what I am doing. Here is a link to a video of the machine so far.



Please let me know if you have any questions or need a picture with a different angle so that you can understand what I am doing.

Thanks for having a look and providing any input.

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[cncmadness]

Just received the new dust collector. Hoping the increased air movement will improve the suction of the dust. I have been looking at the design, and was thinking about the cyclone. Would it be better to have 3 smaller cyclones or one larger one. I am thinking of a Dyson vacuum cleaner and it has several on it. Looking for any thoughts

[ger21]

Typically, the air exits the cyclone into a filter or filter bag. I guess you could recycle it through without using filters, but then you'd be filling your cabinet with really fine dust, which would get everywhere.

I don't see anywhere for fresh air to enter the cabinet.
Perhaps a box with 2-3 4 inch hoses on the opposite end of your suction, to get airflow across the machine.

My preference would be a good dust boot in addition to the cabinet. If your cutting mainly flat stock, you should be able to collect 90-95% of airborne dust at the source. I cut a lot of MDF on my machine, and the dust shoe get's virtually all the airborne dust. But I don't have an air blast on the tool.

I would think that if you need an air blast to keep from breaking tools, that you should revisit your choice of feeds and speeds.

[cncmadness]

I have played with the feed speeds and the air seems to be the best solutions to keeping the bits to last. I am cutting carbon fiber and its much harder then MDF. The dust boot idea worked until I started to use the air as it now blows the dust out of the boot. When I did have a dust boot, it did a good job on getting most of the dust. As this isn't an option anymore, I need to find a better solution. As for fresh air into the machine, the front of the machine will have a window on it that will slide and I can leave open a bit. This will also allow me to reach in and remove the finished parts. If I recycle the air and have it blow across the table top, the air should be clean as the cyclone should remove the dust before it gets returned to the machine. This is where I got thinking of using more then one to help in the removal of the dust. They dyson and other vacuum cleaners what use cyclones are bag less as they remove almost or all of the dust. As most of my cutting is carbon fiber and fiberglass, I need to find a better way of handling the dust.

[rocketflier]

Did you play with the angle of the air nozzle? Get the material to bounce/reflect to the dust port instead of out the side?

[cncmadness]

I did. There was a second problem and that is that the dust wasn't removed fast enough. When the Z axis went up, the air would again blow the dust out. Overall, I found no way to contain the dust with out building a cabinet. I just did a test with the new dust collector. It has a lot more suction then the previous one. I covered the front door with cardboard and left a slot about 6" tall. I could feel the air being pulled though the front. There is no way that the dust will be able to come out into the shop now. I cut several lines on the CF using air from the nozzle as well as not using it. I found that when I didn't use it, the dust still moved a little across the table. Not much but it was there. When the air nozzle was in place, I was able to remove the dust and the suction in the back seemed to take away a good part of the dust. I was only able to hook up one of the 4" line to the machine as I don't have a second hose. I hope that once I have the second hose hooked up I will get more suction yet. For this test, the hose was just connected to the back collection box though the side.

[cncmadness]

one more thing about changing the direction, because the dust collection happens on the front of the machine, this would mean that the air nozzle would have to point straight down or towards me. I couldn't go straight down as there wasn't enough room, and as for facing me, this would blow and remaining dust at me and into the shop which is the last thing I need. I already wear a mask, but having it blow at me would be much worse.

[ger21]

If you have enough CFM at the dust shoe, and the dust shoe brushes form a seal to your table, you should be getting nearly 100% of airborne dust at the shoe, even with an air blast.

A cyclone will not be 100% efficient, and finer dust will get recycled back into your cabinet. I would want to collect dust at the source, rather than having it inside a cabinet, where it will get on your screws and rails, and make keeping them clean difficult.

[cncmadness]

I could still include a filter. Its just what to do with the air after its clean. I could put it back into the room or back over the machine to help with removal.

[hojpoj]

I could still include a filter. Its just what to do with the air after its clean. I could put it back into the room or back over the machine to help with removal.

Cyclone separation efficiency is based on a number of factors, but you can safely assume that you'll be cyclonically separating the larger dust particles. Adding a filter will help to get the finer particles, but even then there's a limit to that separation efficiency and I imagine you'll be clogging the filter in fairly short order. All these additional separation steps will reduce the pressure and flow in the system, so what might be 1500 cfm now could easily be reduced to 600 cfm when all is said and done.

I would not advise blowing the treated (note I did not use the term 'clean') air back into the shop as the finer particulates of the materials you're cutting are likely severe respiratory hazards- I'd vent that outside. I know this doesn't answer your question, but you only get one set of lungs... safety first!