Bill Tarbell

Blast gate box for dust collection

13 posts in this topic

I had made one of these for my own dust collection system about 6 weeks ago.  A friend saw it and said he liked it so i figured i'd make him one as a gift.

 

The idea was to centralize the blast gates for the shop.  This makes it easy to see which are open and quick to change the active line.  I didn't think to take pictures until it was mostly completed, but it's fairly straightforward.  The 6-port side has a layer of 5/8 plywood, then 1/4 ply strips to create the blast gate chambers, and a full-size 1/4 sheet to complete the sandwich.  It's important to put the thicker sheet on the outer-most side so that you have enough material to screw the dust ports to without having the screws block your sliding chambers.  I made the 6 ports closer to the back wall so that the gates didn't have to pull as far out to turn on the port.  This also allots more area for the gate to sit without falling out.  

 

The glue joints are all just butt joints.  Since it's a sealed box it ended up being plenty sturdy without any advanced joinery.  The back panel is glued flush to all of the sides.  The front panel is glued flush to the mitered sides, but not the 6-port piece (the 6 port piece is 1/4 wider than the rest of the sides to accommodate this).  This saves from having to cut slots in the front panel to allow for the gates to slide in and out.  I added a little 2" strip to give it something to glue to under the 6 port side.  In the picture, the strip has a squiggly line so i knew which sides i had jointed.  The gate slides are 1/4 ply that i hand planed down a bit so they would comfortably fit the slots.

 

For the finish on mine i did 4 or 5 coats of shellac.  The one in the picture got a couple coats of semi gloss poly.  Due to the low-grade plywood, one side of each piece was a lot rougher than the other.  Since it just goes in the shop, I put the rough side on the outside so that the vacuum area had the smooth side.

 

I'm still working on laying out my basement shop, so my box is just laying flat on the floor as of now.  It works nicely, but it does get a bit of pileup on the opposite side of the box.  Switching ports immediately cleans it out and i've yet to have any jams.  Having it so the single port side is facing downward should eliminate the accumulation due to the slanted walls funneling it down to the port.  I couldn't detect any vacuum leaks with the wooden gates.  I'm guessing that some suction power is lost due to the large size, but you likely make up for it by having the blast gates closer to the collector rather than at each tool.

 

Excuse the mess in the basement - it drives me crazy, but i'm just getting started and the shop is still in an infancy stage.

 

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Great idea Bill and well executed.

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Thanks guys.  In case anyone is interested, the 2.5" ports were purchased from amazon for about $2.25 each.  out of the 13 i bought, none of them had any defects and fit the hose i bought nicely.

 

ports:

http://www.amazon.com/gp/product/B00AX5I9X2

 

The hose i used is from peachtree.  it's a soft, pliable rubber hose with a metal coil:

http://www.amazon.com/gp/product/B001JBANYM

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What tools do you intend to support with this DC system?  What type of dust collector are you intending to purchase?

 

I ask because most DC systems I've seen use larger, smooth pipe for the ducts and not 2 1/2" flex hose. The main concern it to minimize the resistance to air flow in the duct so there is enough volume and velocity to carry the chips through the ducts without settling out and clogging.  Spiral flex hose provides significant resistance and will degrade airflow. Sharp bends and irregular shapes will also cause turbulence and restrict airflow.

 

The typical system is usually built around a main duct with Y's tapping off at each tool. The ducts are either sheet metal or PVC and the smallest taps that go to stationary power tools are 4 inch diameter. The main ducts are preferably larger.

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The blast gate box i made for myself has 5 lines.  I have a 6" jointer, table saw, planer, soon to be router table, and one line free for floor cleanup.  I use a shopvac and have a 55 gal thien separator between the vac and gate box.  It works great and neither the planer or jointer clog up even though they have a 4to2.5 reducer on them.  A couple runs are about 10 feet and the other 2 are about 15'.  It's currently all full flex tube. 

 

I also questioned if it would work effectively or not.  Thankfully, it works wonderfully.  I initially had a metal trash can for my separator and it was constantly caving in on me from the suction.  I ended up upgrading to a 55 gal plastic rain barrel and that's able to withstand the suction.  I think one contributing factor is that my lines are short and only one of my lines has suction at any time.  On typical systems all lines have suction up to the blast gate near the tool.  I don't know how much loss that causes, but it does seem like it'd eat up at least a little bit of the suction.

 

This is the shop vac i use.  I bought it used from an auction for $60.

http://www.amazon.com/dp/B0029NY9VW

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Now there's a project that really... wait for it... sucks...

Get it?
Ah, I've still got it.

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Now there's a project that really... wait for it... sucks...

Get it?

Ah, I've still got it.

a regular ol Johnny Carson

Nice project Bill.  It will serve you for a long time.

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Thanks, It's working nicely, but i did recently learn that it has the flaw of getting clogged by long sticks.  Typically if you suck up a 4-6" cutoff sliver on accident it will just slip through the hoses.  The box, on the other hand, has that big empty space in the middle where the sticks can orient themselves across the face of the outlet hole.  This causes a backup fairly quickly.  I've only had it happen once so far, but it resulted in about a 3" bed of debris on the bottom of the box before i noticed there was something wrong with the suction.  

 

You could probably put a door on the side of the box so that you could check for clogs and fit your hand in to clean them up.  I think It would be relatively difficult to get a good long-term seal on the door that wouldn't be affected by the dust when you open/close, so i don't think i'll be adding one. Another thought to consider is having one of the walls be made out of plexiglass instead of wood so you can observe the inside of the box easier.  I'm not sure how long the glass would stay clear.  My guess is that the interior side of the plexi would get coated with dust to the point where it would eventually become rather opaque.  Though, it may stay clear enough to at least notice when it has accumulation due to an obstruction.

 

All-in-all, i'm very happy with how the box performs and the convenience it adds.  My shop is only of medium-ish size @ about 20x20'.  If it were larger then i think it would be more convenient to have the gates at each machine instead of centralized.

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I think a door could be leak free, if you use rubber or foam weather stripping and design it so the suction pulls it tight.  When you open it, wipe down all the mating surfaces before closing it, so the dust doesn't interfere with the seal.

 

This may be getting too fancy, but if you put an LED at the bottom and a window on the top, I think you could tell whether there was something covering the LED, even with a lot of dust on the window. 

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I like it. I'm going to use a bigger version of that idea in my shop. I have 2 blowers I want to hook together going to various machines.

 

thumbs up.gif

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On 8/10/2014 at 1:17 AM, Bill Tarbell said:

I had made one of these for my own dust collection system about 6 weeks ago.  A friend saw it and said he liked it so i figured i'd make him one as a gift.

 

The idea was to centralize the blast gates for the shop.  This makes it easy to see which are open and quick to change the active line.  I didn't think to take pictures until it was mostly completed, but it's fairly straightforward.  The 6-port side has a layer of 5/8 plywood, then 1/4 ply strips to create the blast gate chambers, and a full-size 1/4 sheet to complete the sandwich.  It's important to put the thicker sheet on the outer-most side so that you have enough material to screw the dust ports to without having the screws block your sliding chambers.  I made the 6 ports closer to the back wall so that the gates didn't have to pull as far out to turn on the port.  This also allots more area for the gate to sit without falling out.  

 

The glue joints are all just butt joints.  Since it's a sealed box it ended up being plenty sturdy without any advanced joinery.  The back panel is glued flush to all of the sides.  The front panel is glued flush to the mitered sides, but not the 6-port piece (the 6 port piece is 1/4 wider than the rest of the sides to accommodate this).  This saves from having to cut slots in the front panel to allow for the gates to slide in and out.  I added a little 2" strip to give it something to glue to under the 6 port side.  In the picture, the strip has a squiggly line so i knew which sides i had jointed.  The gate slides are 1/4 ply that i hand planed down a bit so they would comfortably fit the slots.

 

For the finish on mine i did 4 or 5 coats of shellac.  The one in the picture got a couple coats of semi gloss poly.  Due to the low-grade plywood, one side of each piece was a lot rougher than the other.  Since it just goes in the shop, I put the rough side on the outside so that the vacuum area had the smooth side.

 

I'm still working on laying out my basement shop, so my box is just laying flat on the floor as of now.  It works nicely, but it does get a bit of pileup on the opposite side of the box.  Switching ports immediately cleans it out and i've yet to have any jams.  Having it so the single port side is facing downward should eliminate the accumulation due to the slanted walls funneling it down to the port.  I couldn't detect any vacuum leaks with the wooden gates.  I'm guessing that some suction power is lost due to the large size, but you likely make up for it by having the blast gates closer to the collector rather than at each tool.

 

Excuse the mess in the basement - it drives me crazy, but i'm just getting started and the shop is still in an infancy stage.

 

20140718_152753-a.jpg20140718_152902-a.jpg20140718_153012-a.jpg20140718_152915-a.jpg20140809_235643-a.jpg20140809_235748-a.jpg20140809_235931-a.jpg

this would be a good solution for my new dust collection setup. I can essentially do one simple blast gate bank right next to my separator

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