Announcement

Collapse
No announcement yet.

Dust collector system

Collapse
X
 
  • Filter
  • Time
  • Show
Clear All
new posts

  • Dust collector system

    How do you go about sizing a new system when you never had one before? I don’t know horsepower or anything? Where do we get more in depth details?
  • Thread Continues Below...

  • #2

    Re: Dust collector system

    Bill Pentz is considered one of the gurus on the subject.
    http://billpentz.com/woodworking/cyclone/
    billh

    Comment


    • #3

      Re: Dust collector system

      Originally posted by billh View Post
      Bill Pentz is considered one of the gurus on the subject.
      http://billpentz.com/woodworking/cyclone/
      billh
      Thank you however I find that just as confusing if not more than before.

      Comment


      • #4

        Re: Dust collector system

        It depends on your goals, size of your shop and the work you anticipate doing, the machines you have/may get and the budget.

        If you want to just get the shavings and sawdust you see flying off the machine to avoid sweeping up, then a smaller system will do fine as long as you always wear a mask while and for hours after cutting. If you want to get the fine, invisible to the eye (under 10 micron) dust that is a health problem, then you need a bigger system that moves a lot of air.

        A small shop, working with small projects doing a lot of hand work and minimal machine work is again going to work with a small system. A bigger shop with larger machines and large projects needs a bigger system. A shop in the basement rather than stand alone needs better dust collection to keep the dust from moving throughout the house.

        A smaller system can get by with 4" ducting as long as the flex hose is kept to a minimum. It has three times the drag that a smooth pipe does. A 4" smooth duct can only move at most 400cfm no matter what DC it is attached to. 6" can flow three times as much air as 4" and is needed if the goal is to get the under 10 micron particles because you need lots of flow to capture the finer stuff (800cfm minimum at the machine pickup). Machine ports need to be opened up to accommodate the bigger pipe and possibly open more of the machine to allow the airflow through it. Dust can't be sucked up if the air doesn't move.

        A word about DC airflow specs. Most DCs can only deliver about half the claimed airflow. The reason being they test the motor impeller with a short test duct and no piping or filters after the impeller housing. The test is done with a measurement of the centre of the airstream where the air moves the fastest. That gives a nice high flow that looks good in the specifications. It would average lower if they took readings across the duct but that doesn't look as good. With ducting, hose and the machines hooked up to the upstream side plus the piping and filters on the downstream side of the impeller you get approximately half the claimed airflow. So the 1,200cfm DC will only flow 600cfm and if you use 4" ducting you are limited to the 400cfm, probably less, that it can flow. Adding a small cyclone or separator to a small DC will further reduce the airflow as they have their own internal drag.

        It is all in the Pentz site but you have to take the time to read it from start to finish, a section at a time over a period of days from one end to the other and maybe a second time at a later date. There are repetitive parts throughout because people come in for a quick read and cherry pick so it is presented to put the info in front of them.

        If you post the info about your goals, size of your shop, machines in it and the work you do we can suggest more.

        Pete
        Last edited by QC Inspector; 10-16-2020, 11:42 AM.
        Wood Grower likes this.

        Comment


        • #5

          Re: Dust collector system

          Originally posted by QC Inspector View Post
          It depends on your goals, size of your shop and the work you anticipate doing, the machines you have/may get and the budget.

          If you want to just get the shavings and sawdust you see flying off the machine to avoid sweeping up, then a smaller system will do fine as long as you always wear a mask while and for hours after cutting. If you want to get the fine, invisible to the eye (under 10 micron) dust that is a health problem, then you need a bigger system that moves a lot of air.

          A small shop, working with small projects doing a lot of hand work and minimal machine work is again going to work with a small system. A bigger shop with larger machines and large projects needs a bigger system. A shop in the basement rather than stand alone needs better dust collection to keep the dust from moving throughout the house.

          A smaller system can get by with 4" ducting as long as the flex hose is kept to a minimum. It has three times the drag that a smooth pipe does. A 4" smooth duct can only move at most 400cfm no matter what DC it is attached to. 6" can flow three times as much air as 4" and is needed if the goal is to get the under 10 micron particles because you need lots of flow to capture the finer stuff (800cfm minimum at the machine pickup). Machine ports need to be opened up to accommodate the bigger pipe and possibly open more of the machine to allow the airflow through it. Dust can't be sucked up if the air doesn't move.

          A word about DC airflow specs. Most DCs can only deliver about half the claimed airflow. The reason being they test the motor impeller with a short test duct and no piping or filters after the impeller housing. The test is done with a measurement of the centre of the airstream where the air moves the fastest. That gives a nice high flow that looks good in the specifications. It would average lower if they took readings across the duct but that doesn't look as good. With ducting, hose and the machines hooked up to the upstream side plus the piping and filters on the downstream side of the impeller you get approximately half the claimed airflow. So the 1,200cfm DC will only flow 600cfm and if you use 4" ducting you are limited to the 400cfm, probably less, that it can flow. Adding a small cyclone or separator to a small DC will further reduce the airflow as they have their own internal drag.

          It is all in the Pentz site but you have to take the time to read it from start to finish, a section at a time over a period of days from one end to the other and maybe a second time at a later date. There are repetitive parts throughout because people come in for a quick read and cherry pick so it is presented to put the info in front of them.

          If you post the info about your goals, size of your shop, machines in it and the work you do we can suggest more.

          Pete
          Hi yes thank you for a better answer to help understand. I think it would be ideal to collect as much as possible of all dust and chips. I have been thinking the cyclone would help achieve this by preventing a lot of filter jam up.

          I am in process of starting up machines. Thus far I have jointer, planer, scroll saw, sander, and bandsaw. I have yet to get going shaper, table saw, lathe. I am pretty sure that is all the machines I have. I am going to need some tooling still for these machines still as well.

          I am thinking the machines for the most part have nothing in way of having dust collection. So probably I'll have to fabricate some different ways to hook up the dust ports. I don't have an incredible amount of space, but at some point I would like to build a new incredibly larger sized shop.

          Also I consider the budget to be what is required for the job to be done correctly.

          I have thought of running wheels on machines to move but in the future I'd really enjoy having them in a more fixed position. I would like to have a setup for time savings instead of spending it all moving everything around.

          Thank you.

          I hope this explains a bit more about my situation.

          Comment


          • #6

            Re: Dust collector system

            Originally posted by QC Inspector View Post
            ...

            A smaller system can get by with 4" ducting as long as the flex hose is kept to a minimum. It has three times the drag that a smooth pipe does. A 4" smooth duct can only move at most 400cfm no matter what DC it is attached to. 6" can flow three times as much air as 4" and is needed if the goal is to get the under 10 micron particles because you need lots of flow to capture the finer stuff (800cfm minimum at the machine pickup). Machine ports need to be opened up to accommodate the bigger pipe and possibly open more of the machine to allow the airflow through it. Dust can't be sucked up if the air doesn't move.

            ...
            Pete
            Hi Pete,
            I don't want to derail the thread, but I have a question about the statement above that I marked in bold. Where did you get your information about the limit of 400cfm for a 4" pipe? The amount of air moved is going to depend on the velocity and if you can get enough velocity through the pipe, won't you be able to get larger values than 400cfm?

            If my calculations are correct, your 400cfm number equates to a velocity in the pipe of about 4600 ft/min which is around the recommended range of airspeed for a wood dust collector. If I have a large enough collector that can generate twice the speed of air in the pipe, won't I also get twice the CFM?

            I'm asking because I have taken air speed measurements on my system and they are well above 4600 ft/min for some of my 4" pipes. I'm not suggesting to use 4" ducting (most of my system is 7", 6" and 5"), but I want to be sure I understand what you are saying.

            Thanks,
            David

            Comment

            • Thread Continues Below...

            • #7

              Re: Dust collector system

              Originally posted by DGB_WAT View Post

              /snip/

              If my calculations are correct, your 400cfm number equates to a velocity in the pipe of about 4600 ft/min which is around the recommended range of airspeed for a wood dust collector. If I have a large enough collector that can generate twice the speed of air in the pipe, won't I also get twice the CFM?

              /snip/
              The dust collector is sucking, and the atmospheric pressure is pushing the air into the pipe, so you won't get more air into the pipe than is pushed in by the atmospheric pressure, no matter how hard you suck.
              Wood Grower likes this.

              Have fun and take care
              Leo Van Der Loo

              Comment


              • #8

                Re: Dust collector system

                What you are describing puts you in a 2 car garage equivalent or bigger space, if not now, eventually, and if you want to collect the fine dust you want a larger DC system. In that case I would suggest you look into a Clear Vue (Stockroom sell them) or Oneida 5hp cyclone. They have longer cone cyclones that are more efficient at separation and have or can have more filter area. The short cyclones like the Laguna are not as efficient at separation so more goes to the filters, which is why they have to have the automatic cleaning paddles. Problem with that is at some point they will start to wear holes in them and they do not have a large area of filter. Clear Vue have 600 square feet. The only plus to one is they are shorter and can fit under lower ceilings but there are ways around that. They are, at least here, more expensive than the Clear Vue. The downside to any large DC is the noise so if you want to converse with someone while it is on you'll need to enclose it in a soundproof room/closet with a labyrinth or other muffled air return to the shop. With warm weather you can bypass the filters and vent directly outside.

                You are going to need to run 6" ducting (possibly bigger) all the way to the machines with elbows of 1r or larger. Some will tell you two 45 degree elbows with a short straight section is more efficient than a single elbow but that is incorrect. Look at page 54 of http://www.lorencook.com/PDFs/Catalo...ok_Catalog.pdf and you will see the straight duct length equivalents of elbows of different types. Here is a calculator that you can play with to see how much variations in layout or elbow choices can change the static pressure losses and affect the velocities in the ducts. Hose will need to be calculated separately and added to the type of rigid duct you pick. http://www.freecalc.com/ductloss.htm

                The forum with the best section on dust collection I have found is Australian. The stickies at the top have a lot of good info as do the threads through out. https://www.woodworkforums.com/f200

                Others will have different opinions so it is up to you to do the research and make your choices.

                Pete

                Comment


                • #9

                  Re: Dust collector system

                  Originally posted by DGB_WAT View Post

                  Hi Pete,
                  I don't want to derail the thread, but I have a question about the statement above that I marked in bold. Where did you get your information about the limit of 400cfm for a 4" pipe? The amount of air moved is going to depend on the velocity and if you can get enough velocity through the pipe, won't you be able to get larger values than 400cfm?

                  If my calculations are correct, your 400cfm number equates to a velocity in the pipe of about 4600 ft/min which is around the recommended range of airspeed for a wood dust collector. If I have a large enough collector that can generate twice the speed of air in the pipe, won't I also get twice the CFM?

                  I'm asking because I have taken air speed measurements on my system and they are well above 4600 ft/min for some of my 4" pipes. I'm not suggesting to use 4" ducting (most of my system is 7", 6" and 5"), but I want to be sure I understand what you are saying.

                  Thanks,
                  David
                  Leo is correct. I have read it in various places like Bill Pentz's site, the Aussie forum I linked above and others. The Aussie forum is moderated by a retired university professor that designed the clean rooms and laboratories in the university. You can get more through the pipe if you can increase the static pressure to the levels you get in a shop vac (100 to 140+ inches of water column) but that is almost impossible to achieve with a high velocity low pressure duct collector we all use. They are generally at best 15" or 16" of static pressure and much less in smaller DCs.

                  I will bet dollars to donuts you did your testing with a fan/propeller type anemometer. Am I right? They are not suitable for reading small ducts like we use in DCs. The air has to speed up to go through and get around them so the readings can be up to 50% higher. That Bernoulli guy from high school that I slept through. ;) They could be used if you exhausted the air out of the wall and measured the air coming in to replace it through a large window. Readings at the mouth of a duct are not accurate either because the flow into them is disturbed by the fan and that is why it is so hard to get consistent readings. The better instrument to use is a hot wire or pitot static anemometer in a test duct, taking multiple readings across the duct to get an average. The test duct, if memory serves, should be about 6 diameters in front of the probe and 4 or 6 after to ensure the flow has smoothed out. A hot wire anemometer can be had for between $100 and $200, a little more money than the fan type. That Aussie site has more info on testing. The US Bureau of Mines found that out ages ago and published a procedure on it. https://www.cdc.gov/niosh/mining/use...dfs/ri9061.pdf.

                  Pete
                  Wood Grower likes this.

                  Comment


                  • #10

                    Re: Dust collector system

                    Originally posted by QC Inspector View Post

                    Leo is correct. I have read it in various places like Bill Pentz's site, the Aussie forum I linked above and others. The Aussie forum is moderated by a retired university professor that designed the clean rooms and laboratories in the university. You can get more through the pipe if you can increase the static pressure to the levels you get in a shop vac (100 to 140+ inches of water column) but that is almost impossible to achieve with a high velocity low pressure duct collector we all use. They are generally at best 15" or 16" of static pressure and much less in smaller DCs.

                    I will bet dollars to donuts you did your testing with a fan/propeller type anemometer. Am I right? They are not suitable for reading small ducts like we use in DCs. The air has to speed up to go through and get around them so the readings can be up to 50% higher. That Bernoulli guy from high school that I slept through. ;) They could be used if you exhausted the air out of the wall and measured the air coming in to replace it through a large window. Readings at the mouth of a duct are not accurate either because the flow into them is disturbed by the fan and that is why it is so hard to get consistent readings. The better instrument to use is a hot wire or pitot static anemometer in a test duct, taking multiple readings across the duct to get an average. The test duct, if memory serves, should be about 6 diameters in front of the probe and 4 or 6 after to ensure the flow has smoothed out. A hot wire anemometer can be had for between $100 and $200, a little more money than the fan type. That Aussie site has more info on testing. The US Bureau of Mines found that out ages ago and published a procedure on it. https://www.cdc.gov/niosh/mining/use...dfs/ri9061.pdf.

                    Pete
                    Thanks Leo and Pete for your responses. Pete - you are correct that I am using the fan type anemometer and if I recall, it was quite hard to get a consistent reading which matches your explanation. I'll look into the Ausie site that you mention when I have some time.

                    David

                    Comment


                    • #11

                      Re: Dust collector system

                      Originally posted by DGB_WAT View Post

                      Hi Pete,
                      I don't want to derail the thread, but I have a question about the statement above that I marked in bold. Where did you get your information about the limit of 400cfm for a 4" pipe? The amount of air moved is going to depend on the velocity and if you can get enough velocity through the pipe, won't you be able to get larger values than 400cfm?

                      If my calculations are correct, your 400cfm number equates to a velocity in the pipe of about 4600 ft/min which is around the recommended range of airspeed for a wood dust collector. If I have a large enough collector that can generate twice the speed of air in the pipe, won't I also get twice the CFM?

                      I'm asking because I have taken air speed measurements on my system and they are well above 4600 ft/min for some of my 4" pipes. I'm not suggesting to use 4" ducting (most of my system is 7", 6" and 5"), but I want to be sure I understand what you are saying.

                      Thanks,
                      David
                      Remember you are drawing a vacuum and not building pressure through the pipe, you would likely need an insane system to generate higher flows than stated to create a larger pressure drop on the sucking end of the pipe. You might not be talking about a motor and a blower any longer.... Your blower fan will only create so much negative pressure before it gives up trying. You'd need probably a vacuum pump instead of a blower. I kind of think that's where he was going with a stated maximum flow.

                      Comment

                      • Thread Continues Below...

                      • #12

                        Re: Dust collector system

                        Originally posted by QC Inspector View Post
                        What you are describing puts you in a 2 car garage equivalent or bigger space, if not now, eventually, and if you want to collect the fine dust you want a larger DC system. In that case I would suggest you look into a Clear Vue (Stockroom sell them) or Oneida 5hp cyclone. They have longer cone cyclones that are more efficient at separation and have or can have more filter area. The short cyclones like the Laguna are not as efficient at separation so more goes to the filters, which is why they have to have the automatic cleaning paddles. Problem with that is at some point they will start to wear holes in them and they do not have a large area of filter. Clear Vue have 600 square feet. The only plus to one is they are shorter and can fit under lower ceilings but there are ways around that. They are, at least here, more expensive than the Clear Vue. The downside to any large DC is the noise so if you want to converse with someone while it is on you'll need to enclose it in a soundproof room/closet with a labyrinth or other muffled air return to the shop. With warm weather you can bypass the filters and vent directly outside.

                        You are going to need to run 6" ducting (possibly bigger) all the way to the machines with elbows of 1r or larger. Some will tell you two 45 degree elbows with a short straight section is more efficient than a single elbow but that is incorrect. Look at page 54 of http://www.lorencook.com/PDFs/Catalo...ok_Catalog.pdf and you will see the straight duct length equivalents of elbows of different types. Here is a calculator that you can play with to see how much variations in layout or elbow choices can change the static pressure losses and affect the velocities in the ducts. Hose will need to be calculated separately and added to the type of rigid duct you pick. http://www.freecalc.com/ductloss.htm

                        The forum with the best section on dust collection I have found is Australian. The stickies at the top have a lot of good info as do the threads through out. https://www.woodworkforums.com/f200

                        Others will have different opinions so it is up to you to do the research and make your choices.

                        Pete
                        OK good to know information about the height of the cyclone. I wasn't overly aware there was a large difference there, but I suppose the more swirling you do the harder it is for dust to hang on for the ride and drop out. I will have to add this into considerations! Thank you.

                        Comment


                        • #13

                          Re: Dust collector system

                          Clear Vue cyclones have been mounted on an angle to get them to fit in low ceilings or in an attic space. There are companies making horizontal cyclones but I don't think they are quite as efficient as a vertical and they are a lot more money. I asked a salesman and when he found out I was comparing to a Clear Vue he wouldn't quote. https://www.dustcollectorhq.com/dust...ust-collector/

                          Pete

                          Comment


                          • #14

                            Re: Dust collector system

                            Lots of good info here.

                            Bigger is usually better, certainly 5hp Oneida or Clearvue systems would future proof all a typical hobby shop might ever want. If I bought a cyclone today, without budget or height constraints, that is what I would buy.

                            That said there are some very good cyclones in the the slightly smaller range which can be utilised effectively and reasonably well with planning in a typical hobby shop. I'm thinking a 3hp or possibly 2hp Oneida. Somewhat cheaper to buy and run, and depending on model possibly smaller. Felder RL series dust collectors could be worth looking at too if cyclone height didn't fit in your space. I believe they are 4hp.

                            So if you decide the 5hp models don't work for you for whatever reason, there are other good options. I would avoid at all costs the typical felt bag, chip collecting, dust pump though.

                            Good luck.luc
                            Jerome likes this.

                            Comment


                            • #15

                              Re: Dust collector system

                              I run my 600 sq foot woodworking shop with an older Oneida cyclone with a 3 hp blower.
                              20” planer, 14” jointer shaper, bandsaw & table saw.
                              I also have an edge sander and spindle sander.
                              I have never bothered to hook up drill press, lathe or mortiser.

                              5” mains with 4” drops.
                              My machines are grouped together to make dc and electrical runs simpler.

                              Chop saw and sanders get hooked up to a shop vac.

                              Nathan
                              Wood Grower likes this.

                              Comment

                              Working...
                              X