A few questions about dust collection/shop venting...

R

razorhunter

Joined
Jan 27, 2002
Messages
470
Guys,
First off, let me say that I have done extensive reading on this subject, and I have searched and searched.
I am about to get a brand new Bader III grinder, and that will just about complete my shop setup for knifemaking, except for a good ventilation/dust collection system.
Here is my dillema, as well as my two options I have decided MIGHT be the best for this purpose.

1. Penn State Dust cyclone system (or other similar dust collecting system)
Upon viewing these online, am I correct in assuming that these just act like ordinary dust collectors, by sucking up toxic dust at the grinder, and then filtering the air in 5 micron or 1/2 micron bags, and then blowing back into the room? Is this correct? I have always been worried about systems like this, as I'm scared they don't get all the filtering done, necessary to safely breathe the air over and over again. Maybe I'm wrong, I don't know. I would like some opinions on this, before I spend $500 for a system like this. I'm also concerned about how loud these units are. Also, for you guys who use a system like this, are you just running some ductwork to your grinder, with some type of "shroud" under the platen work rest, which sucks the dust up right below the grinding being done?
Finally, I still do not see how these are being used for grinding steel/titanium, which produces fire hazardous sparks. Are you guys just using in line "fireboxes" from TruGrit, OR rigging up some type of bucket with water in it? In other words, WHAT keeps the Penn State Cyclone from catching a spark and then catching on fire?
I would love to see some pics.

2. My second mentioned choice, (and also my PREFERRED, system) is much easier on the pocket.
I have read about guys using squirrel cage blowers from HVAC systems. Upon ALL my searching, I still have not seen any case where someone brought up the fact of all the toxic dust being blown right over the squirrel cages' motor. Is this going to be a problem?
I am still trying to figure the best way to set up a system. Should I just run some metal ductwork to the grinder, and mount the squirrel cage IN-LINE, with it blowing outside? It seems this way, I would not have to worry about any fires or sparks catching fire to anything (for the most part anyway). I would LOVE some tips on doing this type of system. ie - what type of ductwork to use, size of ductwork, etc. Any other tips on this system? Has anyone HERE on this forum actually done this method? I would be FOREVER greatful to anyone who has some pics of a home made system such as this.
My ONLY concern with the "squirrel cage" system, is replacing the air that gets blown outside with new air. I don't want to just crack a window on the other side of the basement, and suck tons of cold air in, during winter months.
What should I do guys? If you guys help me out here, you will surely save the day fellas!! LOL!
 
I'm not sure I can help you, but here's what little experience I do have. I tried disposable masks. They are IMHO better than nothing - but not much better. I have used good quality replaceable filter masks - and these are much better but cumbersome. There is always the temptation to do do "just a bit" without it.

I used a shop vac, which actually wasn't bad but it was obvious that some of the dust was getting past the filter - and it was a pain, moving it from machine to machine.

My wonderful wife apparently isn't ready to collect on my insurance :D because she bought me a 1.5 HP dust collector system. It was the best available for 120v operation and my shop isn't wired for 220 (yet). It is a 4" system, but the pipe kit I bought was 2.5 inch. It does a good job with router dust and any big flakes - and on the other end of the spectrum, it does a good job keeping fine particles out of the air (my major concern). What drives me nuts is that there isn't enough power to keep dust from building up in the machines. My grinder, in particular, has it's dust vent at the rear - a less than ideal placement.

I guess the important thing is that I can now grind for a couple hours and still blow my nose without evidence of black or other contamination.

Oh yes - the 1 micron bag plugs up easily and reduces air flow significantly. Frequent cleaning required.

Don't know if any of this is meaningful, but I thought I'd offer my experiences.
 
I was in a friend's shop one time and we caught his shop vac on fire. Had worked for some time with no problems, but that day we had to drag it outside and get the bag out. Fortunately we noticed it before it became a problem.
My system uses a blower from a hot air heat system. I cut a hole in the wall under my grinder and lined it with flashing (to prevent any sparks from going down inside the wall), I went to lowes and bought a funnell shaped reducer that fit the opening on the side of the squirrell cage, and some flex metal pipe about 4" diameter to fit the reducer. I got a floor register and mounted that under the front of my grinder (where the bucket of water would normally go), and hooked the pipe op to it.
It seems to work pretty good. I can grind antler without stinking pu my shop. I don't worry about sparks setting a bag on fire. But it could use some tweaking. I'm thinking the tubing is way too big. The =register is probably too big as well. I've got a hole in my wall about 10" square, and I really should put a hinged flap on it to help keep out the cold. Druing the winter, condensation tends to form on the very cold metal of the fan housing and drip onto the floor (or actually into a bucket now that I noticed it). I have noticed lately that it seems to be out of balance which is probably from wet steel dust collecting on the fan blades (perhaps I forgot to turn it on once). I need to take it apart and brush the fan down.
I don't have pics of it, but if you really want I can take some tomorrow. Let me know.
Ed
 
Well, have you noticed ANY problems with the dust and grime getting all over the motor? I thought this was the problem with squirrel cage blowers that have the motor right in the line of the dust/grime???
I'm really hoping to get some good bites on this thread, cause right now I'm on the fence about what to do, and just can't decide....
I just want to be able to grind and not worry about killing my lungs or setting my shop on fire....
 
Try thinking on this a little, I got this idea from a set up I saw in IG's shop. Kind of a poor man's air cleaner.

I'm currently building a wall to separate my shop area from the furnace/well tank/HW tank area of the basement. What I plan to do is purchase a couple of large square-cased ~28 in. floor fans and mount them on/in the wall outside the shop - probably I'll frame them in with a header above so I have one big opening the size of two fans. The fans will sit side-by-side blowing out from the shop. On the inside of the shop my grinders will be mounted directly in front of the fans, with 3 or 4 furnace filters on the intake side of the fans.

I'll probably end up experimenting with types of filters - maybe even a coarse in front of a fine (ie 3m Filtrete), and hopefully not experimenting with different fans. I'd rather err on the side of purchasing something too strong - and expensive - than buy two cheaper ones and have them be inadequate so I end up buying two more. I'm also considering a single "whole house" fan - the kind you would install in an upstairs ceiling - and mounting it sideways. That way I could play change-the-pulley-games for variable speeds or even go for a bigger motor.
I'll have a huge opening at the end of the wall so return airflow is not a problem.

I'm still studding out the wall, so I haven't gotten too far with this idea yet. In the nicer weather there are two windows I can open, one on each side. I'm not sure if I'll be able to do much about smells in the winter, there's no heat in that part of the basement but it stays well above 50 as long as I don't open a window.
 
Bill H,
When you say "I'll have a huge opening at the end of the wall so return airflow is not a problem."
I'm not quite sure what you mean.. What kind of HUGE opening? A HUGE window that can be opened?
What are you going to do in the deep cold winter months, when return air flow will be freezing temperatures?? LOL! This is my dilemma! Thanks for your help!
 
I'm considering one of these units, and I would like to hear from anyone who has one. http://www.pennstateind.com/Merchant2/merchant.mv?Screen=CTGY&Category_Code=CY
How do you keep these from catching on fire from grinding sparks????? Do you have to put one of the Tru Grit "Fire Suppression Boxes" in line, before the dust reaches the cyclone unit????
I REALLY don't want to spend $400-$500 for one of these, but I just don't know what else to do!
Hopefully someone can help!
 
The wall doesn't turn the corner at one end of the shop, so the air can go around the end of the wall and re-enter the shop that way. I'll be recirculating air in the winter, and I have two windows at opposite ends for a good air replacement setup in the summer.

Hmmm let me try to explain it better...
Standing at the grinder, there's a wall on my right. There's a wall way behind me with a window. On the far wall of the room on the opposite side of the fan (which is in front of me) is another window. Grinder is in front of me, the new wall with the fans in it is behind the grinder. Dust comes off belt, either falling into my water bucket or getting sucked into the filter that's only 2' away. On my left side is a partial wall -- it does not go all the way to the corner to meet up with the new wall. So with the windows closed air goes through the filters, then the fans, then through the utility room which is 3 sided. Out the opening where the 4th wall isn't, then back into my room through the opening where my partial left wall is only halfway to the new wall.

With the windows open, air comes in the window behind me, past me to the grinder then the filter, then the fan, then across the utility room and out the window there.

I could get away with not even using filters in the summer, but I'd rather they catch the dust than have to keep cleaning the fans.

The trick to this whole thing is 1.) having good filters before the fan to avoid blowing all the dust through the fans and all over the utility room, and 2.) having a strong enough airflow to get all the fine dust to the filter. I'm not worried about the heavier pieces that'll just fall to the floor or in the water, I have a broom for that (not that I ever actually use it ;) )

Let's not forget I'm still in planning mode here... but I think this will work.

In the deep cold winter months (if you're in Atlanta you don't have this problem) I'll be recirculating the filtered air with the windows shut, so I'll have to avoid grinding stuff with really bad odors. If that turns out to be a problem I'll have to figure out a way to steal some heated air from upstairs or add a piece of radiator. Or say the hell with it and take a nap :D
 
The Penn State Cyclone will do the job by itself in sucking up all the crap in a wood shop, or when grinding handle materials.
When grinding metals, you do not want to suck it straight into a dust collector, as it's a fire hazard looking to happen.
I run a metal collector inlet (like a range hood, only smaller) down to a four inch metal hose to a little trash can cyclone lid on top of a metal garbage can with some water in it, then off to the dust collector.
For the really fine stuff that gets through the dust collector, I have an air purifier I built similar to the Delta AP200.
There are a number of manufacturers of these, mostly found in the woodworking tools sites.
I still need a mask, though, as I cannot immediately capture everything that comes off the grinder.

Howie
 
I have to admit, I'm still using combination of cartidge respirator and safety goggle/glasses. When to eye protection starts to fog up, as it always does, it's usually the lung protection that goes unless I get some pretty good ventilation going. I've got a shop vac set up hooked into dust ports on my machines, and I don't feel it's adequate. In fact my wife KNOWs it's not adequate as I work out of a shed in our yard where she also stores her good china and christmas stuff. It's always fun cleaning 11 months of wood, micarta and metalworking crud off of the ornaments and good plates.
I dunno, loss of sight really frightens me (hospitalized with typeI (JUVENILE)diabetes at 35 years of age - really messes with your vision - but the black boogers are just gross.
 
I realize Atlanta has better weather than you Northern guys, but I promise you there is ice everywhere outside right now, and limbs are falling all across the state. Ice, Ice, Ice.
I don't want 20-30 degree weather coming in my shop. That's just too cold.

Hey Howie,
If you buy a TruGrit "Fire Suppression Box" that TruGrit sells, then you can suck the dust right into the dust collector. Just as long as the firebox is mounted in between. That's what they're made for.
I like your sytem too... Thanks fellas! Keep em coming!!
 
Hey. I was a woodworker before getting into knifemaking and have been through several configurations. The best I have come up with so far is a 1200 CFM collector sitting outside (no bags) with a five inch port through the wall that is located about headhigh on the side of the shop where I create the most of my airborn waste...disc sander, bandsaw, drill press, surface grinder, BIII, etc. I necked the the 5" port down to two 4" ports just inside the shop wall and attached a 10' rubber flex hose to one of them. I move the end of the flex hose from operation to operation as needed. I crack the shop door on the other side of the room for flow-through when collector motor is running. The door-length opening keeps the flow-through from being turbulent. It moves everything outside except what's so heavy that it falls to the floor. It is the safest and most effecient yet. I have a well insulated 20X24 shop that's heated with an oil radiator heater that is on low most of the winter months. The ambient temperature of the interior and the furnishings are pretty constant and will bring the air temperature back pretty quickly even after running the collector for a couple hours at a time in low temperatures.
With the combination of materials that we work with, I am of the opinion that an in-shop bag system cannot be made safe enough to protect your health or to protect you from the spark that will eventually find it's way to the bottom of the bag.
 
I had a dust collecting unit hooked to my grinders with the plastic hoses. I use my KMG for wood and metal, well the wood dust caught on fire and melted the hose I was very lucky. Now I have a hose dumping into a 5 gallon bucket with water in it is right under the KMG.
I use a box fan 2' X 2' with furnace filter on both sides. This works well and is cheap. After using my surface grinder you can see all the dust that it picks up and then I just vacuum off the dust on the filter.
 
Well I cant tell you what to get but if you have any scrap wood and various other materials on this site I would try this before spending bukoo cash.home made :D
Im always in to what works and cheap. About the noise issue is ther any way to have the unit in a little shed outside of the shop to keep out of the weather?
 
Direct venting to the outside is the simplest and cheapest way.Remember to have some way for new/fresh air to enter the shop (vents,window,open door,etc,)The motor in many squirrelly cage blowers is outside the housing.Mine is a pulley shaft run by a separate motor.You are right to avoid an internal motor unit.If using a dust collector,you will have to install a fire trap - a water trap is best.All of these do not remove the requirement to wear a good quality filter/respirator.There is much more toxic dust/gas created than goes down to the exhaust vent.-SA
 
Dear Mr. Gene Ingram,
I am with you on this. I have decided that I would MUCH rather vent this stuff outside.
Would you mind explaining exactly what kind of "1200 CFM collector sitting outside " you are using?
I have decided that I am going to use some kind of "blower" to pull/suck this stuff outside. I don't want to fool with filters, or worrying about breathing air that has been filtered.
I just need to find some type of blower, that doesn't run the dust/debris right across the top of the motor.
Also, what do you guys think about this?
I could just put my BaderIII DIRECTLY in front of a window, and buy a HIGH POWERED fan, that would fit in the window, and blow this stuff out. I THOUGHT that if I buy a HIGH POWERED fan, then it might just suck up everything, if the grinder is DIRECTLY in front of it. I could even build some type of "shroud" from the window to the grinder, to help keep suction directly over the grinder....
What do you guys think? Anybody got some detailed pics of their systems?
 
I attached a picture of the blower. I got a secondhand 2HP Grizzly for not too much money, but if I were buying new, I would consider something a bit smaller...probably 600-750CFM.
 

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I see Gene,
So you just took the blower out of the Grizzly, and then ran a single tube/pipe to your grinder? Do you feel that your system sucks most of the debris out, or is there a lot of airborne particles left in the air inside, when grinding micarta, woods, carbon fiber, etc?
I'm not as concerned about steel, as I am the toxics. Although I don't want to breathe the steel dust either!
 
I was fortunate to locate a twin motor vac. that a car wash was replaceing with new ones. 25 dollars cash and carry. wow! Watch for these they are fantastic. The filter bags in these are positioned upside down, inverted ice cream cones. The grindings from my kmg fall to the bottom of the collection tank below the three filter bags. No fire as of this post.
One thing I find usefull; where the hose actually intercepts the grindings coming off the machine, I want to be able to move the end of the pick up hose to many positions depending on where I make contact with the belt. By makeing this flexable you will be able to pick up agreater proportion of the waste. I run a 4inch flex pipe under my machine, over a rubber bunji cord.
It works well for me. Good luck Fred
 
I attached a 4" flex hose that is long enough to move anywhere it's needed. Can also connect several pieces for go anywhere in shop vacuum for floor and worksurfaces. 1200CFM theoretically turns air in shop over about every 5 minutes, but probably something less than that. I position the end of the hose directly under the tool rest on the BIII, buffer wheels, band saw, etc.
 
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