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Blast Gates Because I didn't want to wait.

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Project by Zonker posted 04-05-2020 12:19 PM 1444 views 3 times favorited 18 comments Add to Favorites Watch

I am in the process of building a sanding center for the shop. It is almost done and just waiting on the cash for the last machine to be added. In the process of working out dust collection, I decided on PVC plumbing for the machines, and recognized the need for blast gates. Since I couldn’t find 1 1/2” gates, and didn’t really feel like waiting for 2’ blast gates to arrive in the mail, I decided to fashion my own. Materials are tight grained mid eighties reclaimed waterbed (2×6 scrap), 3/16ish plywood scrap from a pallet and pvc pipe (2’ and 1 1/2”). I started by drilling out the holes for the pipe in the wood blocks, 2 3/8” for the 2’ pipe and 1 3/4” for the 1 1/2” pipe. The pipes are cut to leave enough outside the block to attach an appropriate sized connector. Then I glued them in with Gorilla glue so the expansion of the glue would help form a seal between pipe and glue. I then “ripped” the blocks in half on the bandsaw. After that I cut the plywood to form the gate and plywood strips as fillers for each side of the opening. They got glued and nailed together, then the gates took a little surface sanding to allow them to slide smoothly. And as an after thought I notched the gate, and added a latch to hold the open. So far they work rather well and seal tight enough to collapse the Lowes bucket on the sanding center. All told I think I have a couple hours invested in making the three blast gates and a good chunk of that was spent scratching my head and mumbling to myself. Thanks for looking.

-- Larry A. - I've made a small fortune with my woodworking. The trouble is, I started with a large fortune.





18 comments so far

View Zonker's profile

Zonker

153 posts in 1100 days


#1 posted 04-05-2020 12:41 PM

This is what happens when you turn on the vacuum with the blast gates closed.

-- Larry A. - I've made a small fortune with my woodworking. The trouble is, I started with a large fortune.

View TDominy's profile

TDominy

205 posts in 3791 days


#2 posted 04-05-2020 01:55 PM

I like it and will copy it. Did you use PVC for the lines around the shop? If you did, did you ground them? And if you did how?

TIA

-- By hammer in hand, all things do stand.

View woodchuckerNJ's profile

woodchuckerNJ

1525 posts in 2883 days


#3 posted 04-05-2020 02:58 PM

I made a relief valve.
my gates are wired so the vac turns on, but before I did that, I would use a remote. I destroyed a metal can, sucked it right in.

So I made the relief valve. It has 2 dampers to prevent a hysteresis. one being the brass tubes which have a plug in the end and a small hole.. it acts like a shock absorber. The other is a straw around the spring to prevent the spring from vibrating… this way it doesn’t vibrate and cause the hysterisis.

https://imgur.com/6lQtejl

-- Jeff NJ

View hutchmp's profile

hutchmp

89 posts in 4201 days


#4 posted 04-05-2020 07:29 PM

TDominy…..If you run a bare copper wire inside the length of the PVC and attach (screw) it into metal connected to the vac motor it will ground through the plug of the motor.

-- Hutch

View TDominy's profile

TDominy

205 posts in 3791 days


#5 posted 04-05-2020 09:30 PM



TDominy…..If you run a bare copper wire inside the length of the PVC and attach (screw) it into metal connected to the vac motor it will ground through the plug of the motor.

- hutchmp

Awesome, Thanks!!

-- By hammer in hand, all things do stand.

View Zonker's profile

Zonker

153 posts in 1100 days


#6 posted 04-05-2020 10:23 PM

TDominy, It is not grounded. The photo below ids the extent of plumbing for the sanding center. As soon as I get around to purchasing and installing a 12” disc sander, I’ll post more photos of that build. It’s functional now, just not finished.

-- Larry A. - I've made a small fortune with my woodworking. The trouble is, I started with a large fortune.

View robscastle's profile

robscastle

8282 posts in 3453 days


#7 posted 04-05-2020 11:43 PM

Very interesting concept
maybe some internal bracing, otherwise it looks like a real blast to me!

Actually pressure pipe is it not?

Grounding yep watch it!

https://www.lumberjocks.com/robscastle/blog/30085

-- Regards Rob

View Andybb's profile

Andybb

3330 posts in 1853 days


#8 posted 04-06-2020 12:43 AM


TDominy…..If you run a bare copper wire inside the length of the PVC and attach (screw) it into metal connected to the vac motor it will ground through the plug of the motor.

- hutchmp


From everything I’ve ever read there has never been a documented “incident” because of a DC not being grounded. Urban legend??

-- Andy - Seattle USA

View Madmark2's profile

Madmark2

3106 posts in 1837 days


#9 posted 04-06-2020 12:55 AM

Yes. The ductwork isn’t large enough to sustain a flame front. You can always install a flap type dryer outlet that will vent any positive pressure.

-- The hump with the stump and the pump!

View doubleDD's profile

doubleDD

10718 posts in 3292 days


#10 posted 04-06-2020 01:11 PM

This is a awesome quick set up for any size blast gate. I like it.

-- Dave, Downers Grove, Il. -------- When you run out of ideas, start building your dreams.

View hutchmp's profile

hutchmp

89 posts in 4201 days


#11 posted 04-06-2020 04:36 PM

I would disagree: https://www.woodshopnews.com/features/boom-the-dangers-of-wood-dust

This was a sawmill explosion that killed 2 and injured 20. I understand we are talking home shops here but for the cost of thin copper wire and a screw, it’s a good investment. This biggest benefit is not getting a big static shock from your system every time you touch it.

People also said that COVID-19 was no worse than the common Flu…...urban legend?? I don’t think so :)

-- Hutch

View Madmark2's profile

Madmark2

3106 posts in 1837 days


#12 posted 04-06-2020 04:47 PM

It was a saw mill not a woodshop.

It’s like saying don’t make popcorn because of a grain silo explosion.

And again a flap type dryer vent will automatically release any positive pressure.

-- The hump with the stump and the pump!

View TDominy's profile

TDominy

205 posts in 3791 days


#13 posted 04-06-2020 04:58 PM

You do not have to convince me.

If you want to do a little experiment to see what happens…get a cardboard box about 1 foot cube. Put a dixie cup with dust in it with and a small hose that goes from the bottom of the cup out the side of the box and a long ways from the box. Put a candle it the box and close it. Get back and blow into the hose!

As kids we use to grind up one saltine cracker as fuel.

-- By hammer in hand, all things do stand.

View Madmark2's profile

Madmark2

3106 posts in 1837 days


#14 posted 04-06-2020 05:27 PM

Try the same stunt in a 4” hose without a candle and see what happens – nothing. You can even use your arc burner as an ignition source and nothing will happen. The 1000 cm or so air volume prevents ignition.

The examples shown are with high volumes and little airflow. Home and small shop dust collection systems simply don’t explode. If they did, no one who purchased a DC would be able to get homeowners insurance. Call your insurance agent and see if they need elaborate grounding on your home system to mitigate the explosion risk.

-- The hump with the stump and the pump!

View TDominy's profile

TDominy

205 posts in 3791 days


#15 posted 04-06-2020 05:36 PM

You might be correct, but I wear belts and suspenders.

-- By hammer in hand, all things do stand.

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