Prototype SCMS Dust Hood

[Matt Meiser]

I made a prototype hood for my SCMS tonight from some corrugated cardboard. I wanted something that wouldn't need to attach to the saw or the MSUV stand. The permanent version will mount to the wall. It seems to work really good in conjunction with a vac I'd already purchased. One change I'm thinking about is bringing the duct in the bottom instead of on the side. There is some dust gathering in the bottom but from what I can see and smell its doing an excellent job getting the fine stuff. I also plan to put some kind of screening over the inlet to prevent anything that falls in from getting sucked up. Any other suggestions before I build it from something more substantial?

[Darin Higginbotham]

Matt I think if you go through the bottom or side that sloping the bottom torwards the pick-up hose would be a good idea.

[Britt Lifsey]

I also need to build one of those for my miter saw. Several of them I've looked at for ideas have the slopped bottom like Darin mentioned. Also, some had the corners mitered in to direct saw dust. One neat idea was to take a short piece of hose that attached to the dust port on saw and just stick it a foot or so into the big DC hose. This would interfere with your screen idea though.

[Ben Davis]

I might think about adding a small work light. Seems to brighter the better with some of these things. I know miter saws are almost always stuck up against a wall and the lighting can be less than great!

[Brian Kincaid]

Matt,
Nice prototype. Is the top high enough? Seems like when I use mine it shoots a rooster tail up when I plunge the saw.

-Brian

[Joe Chritz]

Unfortunately this is my dust collection hood. The hose only gets about 20% currently.

I will be watching with enthusiasm as I really need to make something a bit more efficient.

Joe

[Matt Meiser]

Ben, this Makita saw actually has a nice worklight.

Brian, I want to do a little more testing but I think it is high enough with the hose on the dust port. However I may raise it a little higher to allow the hose to clear and put a shelf on top similar to one Alan Schaffter posted in another thread.

[Matt Meiser]

I tried out a suggestion to try just hooking the hose to the DC and that works very well. So a trip to Woodcraft today and I came up with this hose arrangement. I'll just put a hole through the side of the hood to route it. The T isn't the best arrangement but in practice it works quite well and need a lot less hose than I'd have with a proper Y.

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Notice that my cardboard and duct-tape prototype is rapidly disintegrating! That duct tape isn't sticking to the cardboard too good.

I also discovered something about this particular saw. There's a rubber flap, which Justin mentioned. Pull a light vacuum on it and its fine. Pull more, say a shop vac or the 2.5" hose with all other blast gates closed, and it sucks itself closed and makes the DC worse than just using the bag. With my arrangement above it won't be a problem but it really needs something to stiffen it up for vac use. I might try to find a piece of thicker, stiffer material to make a replacement.

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[Matt Meiser]

Last Saturday I built the more permanent hood. Then with Saturday night's weather fun the shop didn't have power until late Monday and I worked a 60 hour week so it sat until today. I pretty much stuck to the prototype design because it just worked. I did add some shields on the sides as shown in the photos to reduce the face area and increase the air velocity across there a little. Its all MDF because I had it on hand. To hang it, I just used a plywood french cleat. I made the top from 3/4" stock so I could use it as a shelf. I need to pocket screw a couple hardwood reinforcements underneath to keep it from sagging over time though.

I think its going to work well. Its easy to get the saw in place on the MSUV. The only connection to be made is the top hose which just slips on and off. It does take up a fair amount of room, but a SCMS does anyway. I did pull it out a few extra inches than needed to allow the left side support arm to slide out in front/over the counter on that side.

[Dave MacArthur]

Looks good!
You might consider further restricting the open face, like you did on the right side, with some blocks across the 45 degree corners of the box face. Looks like that would not impact the saw sliding in there or the dust stream, but you could reduce the DC surface area significantly, maybe 30%, and thus increase the airflow/speed a good bit where it counts right around the saw?

Do you get any dust squirting out the bottom side of the saw near the stand also?

Great to see folks designing better dust pickups, bit by bit we're getting this critical part of the DC systems designed, thanks to threads like this and your work!

[Matt Meiser]

I might be able to a little bit, but most of that is needed to accommodate the saw sliding in and out when its set for a miter. I didn't design it to accomodate a compound miter BTW.

However building on that idea--it could be slick to come up with some kind of sliding shutter that could be closed down around the saw. The opening needs to be this wide to swing the saw side to side but at any given time only about 1/2 is needed.

[Dave MacArthur]

Oh that's a good idea--I'd forgotton about angling the saw for mitering lol. I like that shutter idea.

I'm really surprised that someone with a plastics and rubber manufacturing ability hasn't just jumped all over this "after market dust boots" idea-- you'd just have to design one per saw, then cheap and easy to cast. Every time someone comes out with a new saw, you have a new opportunity to sell more. Everyone would buy one if it hooked nicely to the saw in some kind of shroud setup.

[Ben Bonif]

Looks nice Matt. How deep is the actual box itself?
I have the same saw and love it. Currently it sits atop a large workstation
thats on 5" casters so I swing it where I can pick up the dust best. Only thing I have that isn't tied into the DC setup but I struggle with a suitable permanent location too. Lots of boards exceed 12' and the wall space is tight. This intrigues me as it could be mounted as you do or I could use as a portable type adaptation of sorts too.

I've mocked up a couple times but never have got a good working depth - seems I get some kick/splash out always.

Thanks for input.

[Matt Meiser]

Ben, the sides are 24" but about 5 of that is extra just to push the MSUV out far enough to clear the adjacent counter.

[David Hostetler]

How did you come up with the design? I have a cheapo Harbor Freight 12" slider that just spews dust everyehwere with or without the dust port connected to the vac... I would like to capture this junk, but the sliding capability makes that really tough...

[Matt Meiser]

Purely trial and error, which is why I started with a cardboard mockup.

[james glenn]

Matt I think if you go through the bottom or side that sloping the bottom torwards the pick-up hose would be a good idea.

My thoughts exactly.
I like the design though. good idea.

[David Helm]

[QUOTE=Matt Meiser;1439053]



Notice that my cardboard and duct-tape prototype is rapidly disintegrating! That duct tape isn't sticking to the cardboard too good.

Matt you just learned the "duct tape constant". It only sticks to those things you really don't want it to stick to!

[Bruce Wrenn]

Go over to that other forum and search for "photog's" post on using the Big Gulp, dated 05-09-08. It was also featured in Wood magazine.

[Sean Nagle]

Matt, I built a version of Sam Layton's hoods for my older Makita SCMS. It is fantastic. Can you modify his design for your saw?

http://www.sawmillcreek.org/showthread.php?119650-Chop-Saw-Miter-Saw-Dust-Collection&p=1207891#post1207891

[Jim Andrew]

I have a miter saw like that, and as for the rubber flapper, I just put some duct tape on it to hold it open. And have a vac hooked in place of the bag. Maybe building a hood would contain the rest of the dust. Like your idea.

[Kevin Stricker]

Before spending too much time on the hood try to modify the flap. I have seen a mod where someone took a larger sheet of rubber and glued it to the outside of the existing dust shroud. It was about 1 1/2 to 2 times the size of the existing one. I think they might have glued in a small wire as well in between to keep the flap from shutting. This will get in the way when cutting 4x stock but shouldn't effect you working with up to 10/4, make it a bit big then cut it to size based on what materials you use most.

You also might find that the shop vac gets better collection than your DC with such a small duct size.

[Rick Potter]

Matt, check out the post on Sam Layton's DC hood. Same saw, same general shape, and he worked out all the bugs....it works great.

Rick Potter

[Phil Maddox]

I keep thinking about building one of these myself - I was going to build it out of plywood and use sheet metal or laminate to create a funnel to the dust port(s) - I understand this improves suction quite a bit. Entry loss or something like that.

I have a strong enough DC that I can do 2 - 4" ports - one from each side so I think that, in conjunction with the vac, will get a lot of it. Probably could do 3 but that may be overkill.

Good luck.

PM

[Sean Nagle]

I still have to build a dust hood for my RAS and I'm considering using the airflow technique used by this fellow:

http://www.thewoodnerd.com/workshop/dustCollection.html
scroll to the bottom of the page for detailed pictures of his dust hood and a video of the hood in action.

His DC hose is connected at the top. I'm considering something similar but with the DC hose connected from below.

[Aaron Berk]

I still have to build a dust hood for my RAS and I'm considering using the airflow technique used by this fellow:

http://www.thewoodnerd.com/workshop/dustCollection.html
scroll to the bottom of the page for detailed pictures of his dust hood and a video of the hood in action.

His DC hose is connected at the top. I'm considering something similar but with the DC hose connected from below.

Wow, that was a slick video. I like how he demonstrated the air flow by knocking out his vac filter. Impressive.
My RAS has be begging for proper DC. Right now all I use is the port off the blade guard. :o

I wonder if The Nerds design could be improved by adding a port directly under the miter saw base. Just build a flue into the frame work of the platform and have it connected in with his trapezoid device. Maybe a mini downdraft table design?