Is it safe to partition an area around your belt grinder

O

Ome108

Joined
Apr 29, 2014
Messages
224
Hi Guys,
I was thinking to buy several 4' by 8' fire retardant welders partitions sold at mcmaster
My idea is to try and contain my immediate work area for ease of cleaning.
Also being in a basement shop, the boiler at the other end of the room concerns me.
I do not do a lot of work in my shop, but when I do , safety is number one.
I wanted your experience, wisdom, and advice to tell me if I am creating a problem by setting up a partition with these sections of fire retardant vinyl , on 3 sides, there by in increasing the saturation of metal dust that may be missed by what ever method I end up using?
The basement is 3 parts and a separate room at far end.
Size is about 40' by 15' for the middle room with the boiler area at one end.
Ceilings are low and unfinished, 77-78".
Any advice is always appreciated,
Jon
 
Last edited:
The partitions won't hurt, but evacuating the airborne dust is what is most important. With a boiler in the basement you have to make absolutely sure you have slightly positive or neutral air pressure. That means that you bring in as much or more air than you take out. That requires a larger incoming air vent than the exhaust air vent. Usually it is twice the size. Don't just hook up a vacuum line and exhaust it without a return air port somewhere. That would create negative air pressure.
 
One of my favorite things about the GA Guild is that 4 times a year we get to see other makers shops. Several of them have their grinders walled off. The twins have a big fan blowing in at one end and a big one blowing out on the other. I like that setup.
 
Thank you all for any help.
I am going to take your advice and make sure to take your advice.
My windows are very small and the door is not really an option, but would a harbor freight 630 cfm blower for $130. And some 4" flexible ribbed tubing out the window, or which ever port pulls fresh air from outside.
This is the type of blower I was told could also be used to pull small amount of dust and/ or fumes from my mini sanford surface grinder.
So, if I understand you, then when I use a dust deputy or whatever dust collector I get, I should have twice the cfm's of a blower or fan that takes fresh air and puts it in the basement, while the dust collector is pulling dust out of the air.
Is the, "twice as much air in as goes out" proportion the same if the dust collector does not push dust outside but is all inside dumping into a can like the dust deputy?
I just want to make sure I establish this negative pressure in the basement.
Thanks,
Jon
 
If you pump air outside the shop, you need to allow an equal volume to come in. This is called air exchange.

A blower like you describe should do OK for basic air exchange. I assume it is like this one - http://www.harborfreight.com/13-gallon-industrial-portable-dust-collector-31810.html
This one is cheaper and moves a bit larger air volume. (Don't know why, but it looks OK on paper.) - http://www.harborfreight.com/1-hp-mini-dust-collector-94029.html


In a shop with two windows, just have the duct from the exhaust fan go out one and open the other. In a big shop, with a large exhaust fan, a separate blower to bring in new air is often required.


BTW, 4" PVC pipe makes great duct work. No need to glue the joints together for a vacuum system unless you want to. Use the long elbows instead of the short ones. - http://www.homedepot.com/s/4%22%20pvc%20tee?NCNI-52520pvc%20elbow?NCNI-5
same goes form tees, use the ones with curved intake. - http://www.homedepot.com/s/4%22%20pvc%20tee?NCNI-5
 
Hi Stacy, Thank You very much.
I will be taking your advice and putting it into action immediately, for the next time I get to make stuff and have fun.
Jon
 
bladsmth said:
If you pump air outside the shop, you need to allow an equal volume to come in. This is called air exchange.

A blower like you describe should do OK for basic air exchange. I assume it is like this one - http://www.harborfreight.com/13-gallon-industrial-portable-dust-collector-31810.html
This one is cheaper and moves a bit larger air volume. (Don't know why, but it looks OK on paper.) - http://www.harborfreight.com/1-hp-mini-dust-collector-94029.html


In a shop with two windows, just have the duct from the exhaust fan go out one and open the other. In a big shop, with a large exhaust fan, a separate blower to bring in new air is often required.


BTW, 4" PVC pipe makes great duct work. No need to glue the joints together for a vacuum system unless you want to. Use the long elbows instead of the short ones. - http://www.homedepot.com/s/4%22%20pvc%20tee?NCNI-52520pvc%20elbow?NCNI-5
same goes form tees, use the ones with curved intake. - http://www.homedepot.com/s/4%22%20pvc%20tee?NCNI-5
Click to expand...

Stacy,
How would I go from a 12" or 8" and reduce to a 4" to increase the static pressure in the duct.
I got 2 blowers cheap with 1400cfm and 3000 cfm. Also the ducting is flame retartent and 8@ and 12" diameter and 16' long
Any advice would be helpful
 
You don't really need to worry about static pressure in a air exchange duct. That is more of an issue in dust and particle extraction for a collector/filter. In an air exchange, the larger and more free flowing the air path the better.
 
Stacy,
Thanks, I did get these two blowers of different size ducts and cfm for air movement and exchange, but could I use one of these blowers, the lowest is 660cfm compared to shop vac at maybe 200 cfm, instead of using a shop vac for the dust deputy or separator?
The HF DUST Collector with out the bag, has two connections for sucking and blowing, but no filter.
Much more powerfull and uses 4" duct for exhaust and 4" to 2.5" for the sucking at grinding site.
The 4" exhaust will go out the window into a garbage can.
Thanks Stacy for all the info you always share with me.
Jon
 
Yes, you can use the smaller blower as a dust exhaust. As you said, just pipe it in and out. Use 4" duct in and out for the max airflow. While metal duct is obviously the best choice, 4" PVC works well, too. Avoid using corrugated flex tubing except for vacuuming up the bench and floor. It greatly slows airflow by creating turbulence.

Where people get confused in planning air systems is confusing air flow with air speed. They are inversely proportional in many ways. For suction, increase air sped by decreasing the size of the intake duct. For air flow, decrease air speed and increase air flow by increasing the duct size. In a knife shop setup, air flow is far more important.
 
This is the Clift Notes version, for the full story read Bill Pentz's website on dust collection. It's mostly geared to wood dust, but the basic physics are applicable to collecting metal dust too.

When it comes to dust collection air flow and air speed are both important. If the air is moving too slowly through the duct, the dust will settle out and stay in the duct. For wood dust 4,000 fpm velocity through the duct is usually recommended, for metal, 5000 fpm. To get a 5,000 fpm velocity through a 4" duct you will need an airflow of about 440 CFM, which the Harbor Freight dust collector blower might be able to do, depending on how long, smooth, straight or curved the duct is. The faster the airflow through the duct, the more energy it takes to move that air. The resistance to the airflow is measured in inches of water pressure. Airflow for dust collection blowers is generally spec'ed at 0" of pressure (free air flow), and some manufacturers will publish the fan curve showing airflow at different amounts of static pressure. Dust collection blowers less than 5 Hp generally stop moving air at somewhere between 8" and 16" of pressure. Contrast this with vacuum cleaners which have blowers designed to move less air, but at much higher pressures, eg., 120 CFM max or 70" water max.
 
Thanks for the information. I have been reading Bill Pentz, awesome amount of technical info.
I do find it confusing though, hearing from people about there positive experiences with much smaller in every aspect.
According to the data that Bill Pentz collected, these systems that people are using should not work at all.
So, I just got a Partiiculate counter, which is amazing, instant knowledge of the particulates in the air.
So, I can experiment and find what works best. Just by putting a small 10" window fan in a 8" basement window, made an almost instant difference.
Then adding a 20" box fan with a .3 micron box filter 19.6" and 1" thick, duct taped to the fan.
I will be ducting the exhaust out the window with the large 12 amp shop vac with about 220 cfm, which has more suction than the HF dust collector. I still have to come up with a good way to send it thru water when vented outside.
The one thing Bill Pentz mentions pertaining to corrugated flexible duct to be a avoided, except for vacuum hoses for cleaning dust up.
That is a tough one, most of us Hobbyists use the clear flexible heavy duty duct with out any problems, according to alot of people and a limited use by myself.
When the TW90 comes, i hope to have a metal cyclone system waiting, along with some other aids to help clean the air and create positive pressure in the basement shop.
Thanks,
Jon
 
You will find PVC pipe easier to use and far cheaper, and greater at dust and air transfer than corrugated flex tubing. You don't even have to glue up the joints everywhere unless needed. A good whack with a rubber mallet makes a nice snug joint. Use long elbows and curved entry Tee's when possible. Sharp angles impede air flow a lot. In the same way, the most direct path from pick-up to discharge is the best path. Use as few bends as possible.

As for passing the blast through water outside, that is a bad idea. Ignoring the problems of a barrel of water filled with crud stinking up the place as well as breeding mosquitoes, it will be hard to keep the water in the barrel. It is better to just have the blast directed into a 18" wide barrel where the dust can collect. The air blast should come into the side about 2/3 of the way up. No down-turn is needed or desired. This makes the air stream suddenly loose speed and pressure by entering a much less restricted environment. The larger particles will just fall to the bottom, and the lighter ones will drift out the top. Cut a 12" square opening in the barrel lid and put a 1/4" screen over it. It would be good to build a small "roof" over the barrel that will allow air flow, but keeps out rain and critters. This is easiest by making a shallow pyramid in plywood or sheet metal and setting it directly on the barrel top. For an 18" wide barrel, make the pyramid with a 24" base.

The best setup I have seem was a fellow who's shop was in the field behind his house. He had been given a HF dust collector, and found it useless for use inside his shop ( probably why it was given to him). The bag just let too much dust back out in the shop, and it made a lot of noise. He took off the blower, and threw the rest away. He installed a 4" PVC pipe with curved entry Tee's as pick-up ports at each grinder. A metal "funnel" collected the grinding dust and sparks. Each "funnel" had a simple wooden "cap/plug" that sealed it up when that grinder was not in use. The pipe went straight down the underside of the bench and out the wall. He had a PVC reducer on the end of the 4" pipe that had a 2" PVC gate valve and a stub of 2" PVC pipe on it. He had clamped a vacuum hose to this and merely opened the valve to use the hose when cleaning up. He put the blower outside the shop on the end of the PVC manifold pipe. There was a PVC elbow and 12" of PVC pipe on the blower exhaust.The dust and grit just blew out the blower exhaust port and fell into the grass. He had a little "dog house" over the blower to keep the rain off the motor. He said his whole setup cost him less than $100. His only problem with it was when sparrows tried to build a nest in the blower while he was away for a couple weeks...it ended badly for the sparrows when he turned on the grinder and blower!
 
bladsmth said:
You will find PVC pipe easier to use and far cheaper, and greater at dust and air transfer than corrugated flex tubing. You don't even have to glue up the joints everywhere unless needed. A good whack with a rubber mallet makes a nice snug joint. Use long elbows and curved entry Tee's when possible. Sharp angles impede air flow a lot. In the same way, the most direct path from pick-up to discharge is the best path. Use as few bends as possible.

As for passing the blast through water outside, that is a bad idea. Ignoring the problems of a barrel of water filled with crud stinking up the place as well as breeding mosquitoes, it will be hard to keep the water in the barrel. It is better to just have the blast directed into a 18" wide barrel where the dust can collect. The air blast should come into the side about 2/3 of the way up. No down-turn is needed or desired. This makes the air stream suddenly loose speed and pressure by entering a much less restricted environment. The larger particles will just fall to the bottom, and the lighter ones will drift out the top. Cut a 12" square opening in the barrel lid and put a 1/4" screen over it. It would be good to build a small "roof" over the barrel that will allow air flow, but keeps out rain and critters. This is easiest by making a shallow pyramid in plywood or sheet metal and setting it directly on the barrel top. For an 18" wide barrel, make the pyramid with a 24" base.

The best setup I have seem was a fellow who's shop was in the field behind his house. He had been given a HF dust collector, and found it useless for use inside his shop ( probably why it was given to him). The bag just let too much dust back out in the shop, and it made a lot of noise. He took off the blower, and threw the rest away. He installed a 4" PVC pipe with curved entry Tee's as pick-up ports at each grinder. A metal "funnel" collected the grinding dust and sparks. Each "funnel" had a simple wooden "cap/plug" that sealed it up when that grinder was not in use. The pipe went straight down the underside of the bench and out the wall. He had a PVC reducer on the end of the 4" pipe that had a 2" PVC gate valve and a stub of 2" PVC pipe on it. He had clamped a vacuum hose to this and merely opened the valve to use the hose when cleaning up. He put the blower outside the shop on the end of the PVC manifold pipe. There was a PVC elbow and 12" of PVC pipe on the blower exhaust.The dust and grit just blew out the blower exhaust port and fell into the grass. He had a little "dog house" over the blower to keep the rain off the motor. He said his whole setup cost him less than $100. His only problem with it was when sparrows tried to build a nest in the blower while he was away for a couple weeks...it ended badly for the sparrows when he turned on the grinder and blower!
Click to expand...

ThAnks Stacy,
Since I wont be grinding daily, I was hoping to create a water trap outside with a cover, that I could empty at the end of the grinding session. We have no grass, but lots of landscpe trees and bushes, so I want to trap all dust coming outside thru the vacuum exhaust off the cyclone inside.
I am not sure how to release the pressure crom the exhaust outside so as to not loose any dust to the outside.
I was going to use a small plastic garbage can with cover and drill a hole for the exhaust 2.( 25 or 5) as you mention, and thats as far As I have thought out.
Still need a way to keep pressure from exhaust from blowing the top off the garbage pail with all the dust blwing around
Thanks for all and any help,
Jon
 
You can put water in the can if you wish, but remember to dump it.

There is no way to keep ALL the dust in the barrel without putting a filter bag over the top. Honestly, that isn't necessary. The fine dust that would drift out of the barrel top isn't a significant problem unless you are a large volume shop or running woodworking equipment like drum sanders and jointers. The heavier particles will fall into the barrel. The larger the barrel, the better the retention. A big "Rain Barrel" would work well.

OK, here is what you could do if you ant. Make a lid for the barrel. It doesn't need to be tight fitting unless you want it to, just something that will cover the top. A 24" square of 2X4s would work fine.Cut it out and put a piece of cotton or muslin over the cut out. This will effectively make a filter top that will slow down the dust enough to make it stay in the barrel. You will have to bang off the filter occasionally. If your have ( or buy) a filter bag for a dust collector, you probably could rig a way to stick that over the barrel top.

To understand why there is not a problem with the "pressure" from the exhaust, realize that a 4" tube is entering an 18-24" barrel. The change in area makes for a twenty to forty fold drop in pressure ( 18"= 20 fold, 24"=40 fold), due to the difference in area of the cross section. If it is coming out the 4" pipe at 20PSI, that would drop to less than 1PSI out the barrel top.
 
bladsmth said:
You can put water in the can if you wish, but remember to dump it.

There is no way to keep ALL the dust in the barrel without putting a filter bag over the top. Honestly, that isn't necessary. The fine dust that would drift out of the barrel top isn't a significant problem unless you are a large volume shop or running woodworking equipment like drum sanders and jointers. The heavier particles will fall into the barrel. The larger the barrel, the better the retention. A big "Rain Barrel" would work well.

OK, here is what you could do if you ant. Make a lid for the barrel. It doesn't need to be tight fitting unless you want it to, just something that will cover the top. A 24" square of 2X4s would work fine.Cut it out and put a piece of cotton or muslin over the cut out. This will effectively make a filter top that will slow down the dust enough to make it stay in the barrel. You will have to bang off the filter occasionally. If your have ( or buy) a filter bag for a dust collector, you probably could rig a way to stick that over the barrel top.

To understand why there is not a problem with the "pressure" from the exhaust, realize that a 4" tube is entering an 18-24" barrel. The change in area makes for a twenty to forty fold drop in pressure ( 18"= 20 fold, 24"=40 fold), due to the difference in area of the cross section. If it is coming out the 4" pipe at 20PSI, that would drop to less than 1PSI out the barrel top.
Click to expand...
Thanks Stacy,
Will it matter If I end up using the 2.25 or 2.5" exhaust hose crom the shop vac that is connected to the metal dust deputy, the Ir will be moving faster?
Thanks Stacy
Jon
 
My sizes were for example. Use whatever size your system uses. The point I was making was the larger the piping, the lower the static pressure and the higher volume of air extraction.
 
Stacy's right, venting outside into a big barrel is a good choice, unless of course the vented air will blow right back into the shop... Steel dust and grit from belts is mostly big heavy dust. Unless you are working wood or other handle materials you won't see much fine dust coming out of the barrel. If you are still worried, run the airflow through a cyclone appropriately sized for your blower, and vent it outside, the dust in the exhaust will be too small to see.. If you use the shop vac, and the dust deputy, the large dust will fall out in the dust deputy and the fine dust will go through the the shop vac. Put a HEPA filter in the shop vac and you will stop the fine dust. Consider that metal dust can be flammable, chose and locate your collection drum accordingly. The water in the bottom of the drum can cause more problems than it solves, especially if you grind any aluminium and are not diligent about cleaning between types of metal. Ignoring the thermite issue and the mosquitoes, warm standing water can also harbor legionella bacteria...something to think about if you use a dip pot while grinding too.

Dust collection is like anything else, each incremental improvement takes disproportionately more money, time, and equipment. You can get by with undersized equipment and get a lot of the visible dust. You can get better equipment and get almost all the visible dust. But to really get the invisible dust takes lots of airflow, good hood design, and good filtration or outside venting.
 
You must log in or register to reply here.
Back
Top