Blast Gate Discussion

[Rick Moyer]

OK, from my reading, I understand that a blast gate is basically a sandwich with removable cheese. The "bread" which the plumbing pcs connect to; and the "cheese" that fits between the bread and slides in/out allowing air flow (or not). I guess we should call it swiss cheese because it has one large hole in half of it to allow air to flow thru. Now this bread has to be fastened together on two or three sides and the cheese either slides in from one side bottoming out on the third sealed edge, or slides thru (self-cleaning) to allow either the flat solid part (white american) or the hole (swiss) to be in line.
So, my questions are:

1. Is it better to be able to slide the cheese all the way thru (self-cleaning)?
2. Is the "white American style fine (as long as you trim the corners to self clean)?
3. Do I have to make my own sandwiches? I have read (and seen) that Clearvue makes 6" gates that will fit astm2729 pvc. I have also read that the popular ones Lee Valley have require some work to fit well. I don't mind trying to make some, but I want to know if the store bought ones are as good or not.
4. Anybody now hungry?

[Paul Stoops]

In my previous shop I made my own blast gates for thin wall 6" PVC ducting using 1/2 of a coupling on each side glued to 1/2" Baltic Birch ply. I used 1/4" thick HDPE for pass thru gates (overkill!). However, the pass thru type are heavier and take up more space due to the long gate. They worked well, but were bulky. I think Alan Schaffter has a better design which was documented in one of the recent American Woodworker magazines, using two thicknesses of laminate for the gate.

I purchased some of the new injection molded 6" blast gates from Clearvue. They are self cleaning and of very high quality. They fit the 6" thin wall PVC ducting very well. In fact, the end of the ducting nests into a stop at the inside end of each gate support half, making for a fairly smooth interior. They are listed on the Clearvue website. In the $20 price range, I highly recommend them.

[Alan Schaffter]

My article is in the June/July 2010 issue, #148 of AWW. Like Paul, I use a 1/2 of a coupling on one side, but a piece of ASTM 2729 pipe on the other- so I have a male and female side, but use whatever you need.

I lined the inside faces with laminate and constructed the slide from two layers of laminate- they seal great yet slide effortlessly with laminate against laminate.






Actually, I don't have manual gates anymore, I converted them all to autogates- but I made all of them the same way.

[Al Barale]

Like Alan I made my own also, I made mine from sheet metal, and they work great, I custom made mine to fit my ducting and flexible hose.

[Dave MacArthur]

Hey, I have that AWW magazine, and enjoyed that article--it's in my "DC" pile! Didn't make the author connection--Dang and here I've been reading you "realtime" and all, this is better than a book-signing!

The bad thing is I was serious. I probably shouldn't look into that too closely...

[Rick Moyer]

Thanks for the responses and congrats Alan on the article publishing.

1. Now, how does everyone cut the hole for 6" gates?
2. Also it seems as though the ClearVue ones are nice if I wanna pay the price, but are they better or are the homemade ones generally better, or is there no difference? I don't want to get/make some and later find out I'd rather have the other. I don't intend to use automatic ones. too much effort/expense for my limited use.

[Matt Meiser]

I've always used through ones but had a few places recently where that wouldn't work due to the extra space needed when they are open. I made some non-through ones and they've been working out great. I'll make them all that way from now on.

I bought one of the aluminum ones from Woodcraft for my Shark Guard because I wanted something quick and needed to attach a hose directly to it. I'm not impressed.

[Alan Schaffter]

Thanks for the responses and congrats Alan on the article publishing.

1. Now, how does everyone cut the hole for 6" gates?
2. Also it seems as though the ClearVue ones are nice if I wanna pay the price, but are they better or are the homemade ones generally better, or is there no difference? I don't want to get/make some and later find out I'd rather have the other. I don't intend to use automatic ones. too much effort/expense for my limited use.

1. Not sure which hole you mean but if it is the hole in the gate, that was really easy. First I cut a holes in the MDF with a jig saw- they don't need to be perfect. Second, I covered one face of each MDF square with laminate (free scraps from a counter shop.) Then I glued in the connector (coupling or short piece of pipe) using polyurethane glue which expands to make a good seal. I drilled an access hole in the laminate and used a router with flush trim bit to open it up. The bearing rides against the inside of the pipe/coupling to make a perfect hole (see pic in my previous post). I used double stick tape to hold the slide on a gate half and made the opening in that the same way. The last thing I did was to join the gate halves together at the edges using the slide and one layer of tape to establish a gap.

Use a flush trim bit to make the opening (I couldn't find the bit when I took this photo- for the article, the AWW art director inserted one using Photoshop ):



Making the opening in the slide the same way (slide is taped in place):

This is one of those situations where you need to weigh cost and convenience and determine your own needs. I originally wanted my gates so I could mount them anywhere in my ducting, hence the male/female sides. By making my own gates I saved a little money, but, more importantly to me, I ended up with gates that operated more smoothly than any commercial ones I had seen and fit my needs perfectly.

[Anthony Whitesell]

Alan,

When you say 'laminate' you are speaking of the high pressure laminate such as Formica, correct? I wouldn't have thought that stuff would have the strength or be too fragile to hold up well as the gate.

[Alan Schaffter]

Alan,

When you say 'laminate' you are speaking of the high pressure laminate such as Formica, correct? I wouldn't have thought that stuff would have the strength or be too fragile to hold up well as the gate.

Yes, Formica type stuff. The surface is very durable and laminate adhesive is very strong. The first gates I made over 10 years ago had slides made from only one layer of laminate, but worked well. I only had a problem when I dropped a gate- the exposed slide broke. In my later versions I used two layers for the slide, laminated back to back, but i did that just so the slide would stay flat. The laminate on the gate interior faces has held up well also, with absolutely no signs of deterioration or delamination. I used 3M waterbased laminate adhesive.

I used four 10 year old gates from my old shop when I built my new shop six years ago. They work as well as the newer ones. I switched to an easier way to assemble the gate halves, but everything else - MDF body, laminated faces and slide, pipe/couplings, is the same.

[Anthony Whitesell]

ahh...two layers, that sounds better.

[Dan Friedrichs]

To cut the hole, I'd highly recommend a circle/wheel cutter on the drill press, instead of jigsawing the holes like Alan did. Much, much faster and more accurate...

[Matt Meiser]

Only problem with the circle cutter is that its hard to find one big enough for 6" PVC. most go up to 6", but you need something like 6.25". I found one when I made all my original gates, probably paid $30. It worked great, but when I went to use it last time the set screw ended up stripping out and now its useless. If you buy one, it might be worth swapping out the setscrews for good quality ones.

[Dan Friedrichs]

Matt, I bought this one (after finding out, as you said, few others that went >6"):
http://www.amazon.com/gp/product/B00...ef=oss_product

It seems very high quality, made in USA, only $20, and will go to almost 8".

[Matt Meiser]

Yep, that's the one I bought. General. Do yourself a favor and buy some high quality setscrews. The one on mine that stripped is the one that locks the beam.

Good price, maybe I'll replace it after all.