DC Question: Blast Gate on a Branch?

[Paul Kierstead]

I am designing my DC system...well, OK most of the design is done. Alas, I have a wimpy 1 HP Delta DC which I hope works out. It is the typical PVC 4" system.

From the DC, there are essentially 2 branchs; a "main" branch, with the TS, planer, jointer & chop saw and a "side" branch, which is quite long (goes to other side of the shop) for router, bandsaw, DP, and misc. One question I had is: Is it work putting a blast gate at the beginning of the side branch? There are likely to be 2 or 3 gates off the side branch. I am not cementing the system (too likely to change), so I expect some losses. A gate *might* reduce the losses in the side when it is not in use...for that matter, I could gate the main like (after the branch of course) too, to "optimize" the side branch.

Thoughts?

One other question: Since I am not cementing the joints, any thoughts on minimizing the losses in a non-permenant, non-work intensive (I'd prefer to be working wood!) way?

Paul Kierstead

[Gary]

I've got a 1 1/2 horse system. I don't gate my branchlines but I put a separate gate at each tool. Unless you're talking industrial quality DC stuff, you'll need to do that to get any meaningful air flow at each tool. Putting a blastgate in front of a blastgate (by gating the branch which then has gates at the tools) would probably be overkill. A few moments of running will build up the pressure in the system as long as you don't have a lot of leaks along your side branch. I don't think you need to cement (assuming you're talking PVC), but it's easy enough to just put a wrap of duct tape around your joints and still give you the flexibility to change later.

Gary

[Pounds on Wood]

All blast gates leak, so there is a theoretical benefit to gating a branch. But for 2 or 3 or even more branch circuit blast gates I think it is overkill. Instead, spend your time maximizing flow in the lines by using loooong sweeping elbows (2 @ 45 deg in place of any 90 deg), sanitary tees (instead of any right angle tees). Use irrigation fittings from the borg, which fit over the pipe, instead of any woodworking store fittings, which fit inside the pipe (cheaper too). You should only need a few adapter type fittings from the official dust collector fitting series.

No cement needed, just wrap with duct tape. Any place you think a fitting might slip due to gravity or whatever, pin it with a single pop rivet. These don't leak, don't extend inside to restrict flow, and are easy to drill out if you want to change the layout.

I just did my second shop, using the ideas/mistakes above from the previous shop.

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[Mark & Juanita]

If your system has enough loss that gating the branches is needed, you have a more basic problem that needs to be fixed, rather than band- aided.

If you are using PVC, cementing should not be that big a deal, if you want to make changes, you can always cut the pipe and use a coupler to re-splice your changes. If you are using metal pipe, you could use things like duct tape, but that will deteriorate over time and come loose, so you will find yourself repatching the whole system, this time with dried-on tape residue (DAMHIKT).

Really, the fastest (in the long run) way to do it, is to do it right and seal your ductwork. Those leaks will eventually rise up and bite you. In my case, to the tune of having to replace planer blades when a duct clogged and the shavings forced a planer chip breaker screen into the way of the rotating blades.

[Bob Davis]

Use the metal foil duct tape (not the cloth or plastic type).

[Paul Kierstead]

That was my feeling, but it is nice to hear someone to back it up.

All I am using from "DC" are blast gates. I am mostly using Y tees which may or may not be better since it ends up being more pipe, possibly negating the positive effects of using Y. I guess we'll see. I have ended up with one 90 degree, necessitated by space constraints. Not bad, I think. I am also trying to minimize the amount of flex hose to get to a machine, as well as the bends in the flex hose.

The pop rivet idea is a great one!!! I was going to use screws, but wasn't sure how big the initial hole had to be, etc. Riveted them, works great. Will duct tape later...well, I hope I will. Shop projects tend to stay status quo. Made a cabinet for the shop with 8 drawers; intended to put drawer fronts on them, 2 yrs later, still no drawer fronts...

Thanks for the help!

[Paul Kierstead]

I expect that you are right...just my first time, and I tend to be a "designer" and sweat the details a little too much.

I know that you are right, but I am currently fooling around with shop layout a lot trying to get it right; notably, enough room around the bench to work comfortably yet breathing room for the TS, jointer and planer. Not to mention I would love an assembly area and a spray booth. Yeah, right. So until I nail an arrangement that I like or build so much accessories around the equipment that it becomes impractical to rearrange it, I will be very unhappy to cement it.

I have had DC problems twice with a planer and once with a jointer. In the case of the planer, I spotted it early since at least with my planer, you start seeing excessive shavings coming out of the planer right away; normally the escaped shavings amount very very close to zero. In the jointer case, I can hear a different sound; it sounds kind of odd when shavings build up. As soon as one of my machines sound different, I stop and check. This is with my equipment, others will be different. So I am not *too* worried.

Thanks for the help.

[Paul Kierstead]

You confirm my suspicion, but I wanted to check...

Thanks! Haven't done this before and having never used one, I was never really sure how well it will work. Hope it works well, as I really don't want to buy another DC; I prefer to spend my money on materials.