hoods for RAS and CMS

[fullmetal]

Hi everyone,
I've recently installed my CV1800 and I'm in the process of building hoods for my RAS and CMS. That's Radial Arm Saw and Compound Miter Saw for those using the search engine.:)

I've been doing some research on the internet and I've found only a couple of solutions. I also ordered "Woodshop dust control" by Sandor Nagyszalanczy, but it hasn't arrived yet.

I have my 6" PVC drops coming into each saw from the ceiling. Right now, I'm focusing on the RAS. I've looked at Bill Pentz website, but his solution isn't overly good for me due to the lack of room between my saw and the wall. Here is his link:

http://billpentz.com/woodworking/cyclone/ducting.cfm#ToolDucting

It shows a topside collection with a sweep of "maximum radius." My craftsman RAS has very little room behind it for this configuration. I don't want to pull the saw too far away from the wall since it will share the table and fence for my CMS. My CMS is on a 16' table. So this solution isn't the best for me.

Before I burn up all my cardboard and duct tape using trial and error, I am hoping that some of you have solved this problem and could post your working solution. If not, I guess I will have to post my humble attempts on this thread so that others will benefit.

Thanks!
Dave

[dwdrury]

Dave,

I trust you've viewed the photos and video of Matt's solution? If not, go to http://www.gallery2.clearvuecyclones.com/v/Misc/Matts-New-Cyclone-Video/ and have a look around. Might give you some ideas.

Regards,

DWD

[Matt]

This is what dad has done on his... I don't think the head swivels on his anymore but i am not sure... http://www.gallery2.clearvuecyclones.com/v/Misc/Matts-New-Cyclone-Video/Planer_2005_011.jpg.html

And This what I have done on mine.. http://www.gallery2.clearvuecyclones.com/v/Misc/mattmorgano/Shop+and+Dust+collector+045.jpg.html

They both work well for cross cutting.....dad's works well for ripping as he stands a board along one side of his tall guard when in the ripping configuration to catch the dust and point it towards the guard. Mine works well up to a 45 on the left side and probably 35 on the right side. Now that i have a table saw i mostly crosscut on it anyway.

Anyway it's hard to get a complete solution for these things because of the wide range of usage. I recently bought a chop saw and all I can say is WOW! It spits dust out everywhere and right now I take it outside because I haven't even come close to even see how I could make a guard for that.

I also managed to find this video of mine cross cutting MDF.. http://www.clearvuecyclones.com/video/RAS.wmv it's 5 megs and should open in windows media player.

I wish I had more ideas to show you but as you said I haven't really seen alot out there.

Matt

I added this to youtube also. http://www.youtube.com/watch?v=Ipv_n_1kk50 I have been meaning to get them on there and to make more/better videos and this is a start with more to come soon.

[fullmetal]

Matt and DWD,
Thanks for the quick replies. I had seen Ed's solution in the gallery, but not Matt's shorter version. I like the modified floor sweep idea since I can still use a topside hookup.

While I don't yet have a table saw, one is in the works. As a result, I will soon be using the RAS for crosscutting only.

Matt, as you face your saw, how is the right side hooked up to the DC? I didn't see any plumbing in the pictures or video. Also, what size hose do you have connected to your blade guard. Does it step down in size at the guard? My dust port on my guard is 1.5". I was going to get the same size hose. Any thoughts on that? I see that Ed has a monster hose connected to his guard.

Does your hood have a simple triangular cross-section? About how tall is the opening at the bottom?

I don't have any PTEG, so I may just use 1/4" luan instead. I guess I should sand and seal it smooth first.

For the CMS, here is the "best looking" solution I've seen yet. It looks like you can slide/pivot it around to best position for the angle cut you are performing.

http://www.woodshopdemos.com/nprod-4.htm

I will base my hood on that design when I get the RAS done.

Regards,
Dave

[Matt]

Hi,

Basically I built one big box and inset the middle but still left an opening from one side to the other. The space at the bottom was supposed to be a little less area than a 6 inch pipe so as to allow enough pressure for that 2.5" line on the guard to still work well which as you know it doesn't work well even with a shop vac on it. Anyway the small hose works well enough to keep that hole from clogging and having clumps of dust fall out otherwise I would have just taped it shut.

I guess you could say it's triangular. It's maybe 2 - 3 inches at the bottom then tapers up so that i could plug-in the 6 inch hose. The tapered wall makes an air curtain if you will and just draws the dust in. As you saw in the video mine needs more thought and rebuilt as it's falling apart.

If you decide to go this route I will recommend to make some cuts on wide boards and see where the dust goes for your various set-ups and design around that. I have been using mine as is for about 3 years now and i am still thinking on what I need. LOL

Hope this helps some,

Matt

PS. The 2.5 line on the guard will not help even a little when ripping!

[fullmetal]

Thanks again Matt. I've got the info I need to proceed.

This weekend I will put all this information and some of my own ideas into action and build version 1.0. I will try to get some pictures and video into the gallery. Too bad I won't be able to collect the dust I make building this thing!:)

I guess I'll just have to wheel the RAS over to my overhead door and shoot the dust into the backyard.:p

Dave

[Matt]

you're welcome and I definitely want to see a few pictures as I am getting close to building version 2.0 soon.

Thanks,

Matt

[fullmetal]

Well, I got a start on my RAS hood. After sketching out a plan, I ended up scrapping those plans and starting over. I began with Matt's topside collector as inspiration, but ended up going in a somewhat different direction. My hood will look very much like Matt's though.:)

I didn't want the hood to serve as ductwork since it can be a challenge to reduce the turbulence and improve airflow (at least in my theorizing).:confused: I opted for a under-the-table air plenum to separate the ducting from the hood.

I haven't finished the beast, but if you wish to see what I've done so far, you can view my gallery at:

Edit: The gallery has been moved. The new home is:
http://www.gallery2.clearvuecyclones.com/v/Dust+Hoods+and+Pickups/fullmetal/

More updates to come! I still have another trick up my sleeve...:cool:

Dave

[Matt]

Hi Dave,

It's looking really good so far and it gives me some more ideas as well. With the suction on the bottom it looks like all you would need is the angled piece to direct the dust to your slot as the box just served as a place to connect my pipe to. Maybe not but it definitely gives me a different route to experiment with. Thanks again for sharing and let us know how it turns out.

Matt

[fullmetal]

Matt,
Thanks for the kind words. I appreciate your input into this design so far. Please share any design ideas you come up with. Open brainstorming can lead to great things!

Since you expressed interest in rebuilding your hood, here are some of my ideas. Feel free to share your opinion, or provide additional ideas you may have.

I want to Roundover the extension table along the slot. The theory is that this will clean up the airflow a little. A quick operation with the router.

With a clean transition from the "airbox" slot up along the deflector, I anticipate a nice laminar airflow along the deflector and hopefully some flow along the table. With luck, this will create air-curtain along the the deflector, much like airflow over an airplane wing. You mentioned that effect in one of your posts and I believe your video shows that effect in action. If I get that flow along the table AND deflector, well that would just be a treat.:D I have a thought about using a piece of thin walled pipe, trimmed like one would cut a quarter-round from a wooden dowel. Placed over the slot, this quarter-round pipe could deflect some of the airflow from the slot to pull it along the table. I'll give it a try later should it be necessary. I wish I had one of those smoke tracers like they use in wind tunnels to observe the airflow over aircraft models. That would really help refine the design.

Here's an idea for your consideration...
I plan on having the deflector on the saw side of the hood pivot at the collection slot, much like a door on a hinge rotated 90* with the hinge side down. That way, when I pivot the saw (miter) to the left side, the saw can fully retract (into the hood -against the deflector) and the deflector will move out of the way. It was this idea that led me to build the downdraft collector. I couldn't do that with vacuum behind the deflector for obvious reasons. Of course I will need to get the hood box very square so the deflector can move freely.

Finally, if I need to, I will have a light-weight "deflector extension" on top of the hood. I think that would be a good use for some of that cardboard my cyclone shipped in.:D Hopefully, this will have the advantages of your Dad's tall collector with the flexibility of quick removal to allow mitered crosscuts.

I will try to get Version 1.0 done this weekend, but my Wife's family will be visiting. Prediction: 100% chance of fireworks! LOL!

Wishing everyone a happy and safe Fourth of July!
Dave

[fullmetal]

If it isn't obvious -

The "deflector" in my previous post refers to an angled piece of sheet stock to direct dust and chips into the slot. Matt's RAS hood has one made of PTEG. While Matt's "box" is used as ducting to direct the suction, the back of my box is strictly there for structural support.

I haven't cut a deflector yet, but if you look at my photos, you may see some pencil marks showing the anticipated location.

Dave

[fullmetal]

Hi guys,
I've "completed" version 1.0 of the dust hood for my RAS. I must say that I am very pleased with the outcome. I've updated my photo album at:

Edit: The gallery has been moved. The new home is:
http://www.gallery2.clearvuecyclones.com/v/Dust+Hoods+and+Pickups/fullmetal/

Hopefully, the pictures will tell the story. I would have taken a video, but my batteries needed recharging. Perhaps later.

It was great to finally begin using the cyclone. I was gagging on the MDF dust in the shop while making this hood. After I had working dust collection, I buzzed through some MDF cutoffs and the hood works great!

Next I'll hookup my new table saw, then build a hood for the compound miter saw. I'll update this thread as things progress.

Thanks to Matt for the inspiration.

Dave

[dwdrury]

Dave,

Thanks for your documentation on the RAS hood. Don't have a RAS but do appreciate the effort and thought you've put into it. Good to see others' solutions, as they may spark ideas for some future project. For instance, the PVC soup demo....

As I was viewing the photos, though, I had a couple of thoughts. First, you may want to consider moving your gallery from the default, new signups area to the dust hoods album off the main gallery menu.

Second, and too late for this project but maybe for the CMS, the sweep seems somewhat redundant to me. One could attach the newly formed transition directly to the channel, then use either the flex tube or an el to make the turn.

Regards,

DWD

[Matt]

Thanks again for sharing and It turned out nice. I apparently have some default galleriers to delete as it seems alot have signed up and not using them. If you decide to move your gallery and can't let me know and I will look at it again as I may need a gallery for hoods.

Cangrats,

Matt

[fullmetal]

Dave,

Thanks for your documentation on the RAS hood. Don't have a RAS but do appreciate the effort and thought you've put into it. Good to see others' solutions, as they may spark ideas for some future project. For instance, the PVC soup demo....

As I was viewing the photos, though, I had a couple of thoughts. First, you may want to consider moving your gallery from the default, new signups area to the dust hoods album off the main gallery menu.

Second, and too late for this project but maybe for the CMS, the sweep seems somewhat redundant to me. One could attach the newly formed transition directly to the channel, then use either the flex tube or an el to make the turn.

Regards,

DWD

DWD,
I'm glad you found something useful. Thanks for your input! I've used a heat gun on PVC drainpipe before to make small bends. I hoped boiling water would be hot enough, and at ~900' above sea level, it is. Folks living at higher altitudes may not be so fortunate.

I'll move the pic's as you suggest (later, when I have more time). Matt, if I have any problems, I'll send you an email.
Edit: The gallery has been moved. The new home is:
http://www.gallery2.clearvuecyclones.com/v/Dust+Hoods+and+Pickups/fullmetal/

I agree that the sweep is over-engineered. I tend to do that.:o But, it *should* provide cleaner airflow than either a tight radius flex hose or a PVC 90. At least that's my understanding of what I read on Bill Pentz' website. I wouldn't use a PVC 90* because they are quite expensive at my supplier - even more than the wye's! A PVC 90* sweep would have been the ticket, if only I could find one.

Since the CMS hood will slide along the wall and pivot, I don't think a sweep will work anyway. Before I start building the next hood, I'll post a plan so I can get everyone's input before I start cutting.

Note: I plugged up the DC port on the RAS blade guard. I doubt I'll make the effort to connect it since it doesn't seem to be needed.


Dave

[dwdrury]

Dave,

Found it, and some additions. Was puzzled about the center deflector 'til I got to the last photo. Then it made sense, quite clever, actually.


...because they are quite expensive at my supplier...


True there is a calculation to be made. I'll sometimes grab whatever's handy or make something that'll do rather than run out and get what might be "best". Don't recall the els I bought at the local Lowe's being that dear. If the major parts for your sweep were from your scrap bin, then whatever the cost of an el is certain to be higher, and only time and other materials enter into the equation. That said, though, I've been known to waste days, months even, cobbling together something just for the sport of it when I could have bought something off the shelf. I have a tool cart that's a prime example. Rather than buy a $200 or $300 one, I made my own, after about 6 months and $600 in parts and supplies. But it was fun, and I have what I wanted. I put a couple of photos of it here (http://www.gallery2.clearvuecyclones.com/v/Misc/Tool+Cart/), basically because Matt & Ed provide a handy place for things like that.

Got a good chuckle out of: Before I start building the next hood, I'll post a plan so I can get everyone's input before I start cutting.
We'll never think of things to say, mods to make, until AFTER you've got the thing built and pictures taken! That's just the way it works.

Regards,

DWD

[Matt]

Love the tool cart!! Didn't even know it was there! I guess if i wanted one it would be really expesive. hehe.

I always have a tough time with time vs. money calls myself. never have enough of either!!:(

Matt

[fullmetal]

DWD,

Don't recall the els I bought at the local Lowe's being that dear. If the major parts for your sweep were from your scrap bin, then whatever the cost of an el is certain to be higher, and only time and other materials enter into the equation.


While we have a Lowe's, I usually buy my drainage from another supplier. I've installed a LOT of drain pipe for my garage/shop project. I should check out the stock of el's at Lowe's - I know for a fact that they don't have 6" SD pipe. The 90's were around $25 apiece at my supplier.


I have a tool cart <snip> I put a couple of photos of it here (http://www.gallery2.clearvuecyclones.com/v/Misc/Tool+Cart/).

Wow, that's a nice cart. You obviously pay great attention to the details. It shows in your work. Great job!


Got a good chuckle out of: We'll never think of things to say, mods to make, until AFTER you've got the thing built and pictures taken! That's just the way it works.

Boy, that's the truth. I have a hope that if I put the design drawings online, you guys might have some creative input before I build. That won't eliminate the 20/20 hindsight syndrome, but it might reduce it.

The next project is hooking up my cabinet table saw. I'm still researching dust collecting guards for that. I may end up with a shark for my sawstop cabinet saw, but there is a long lead time.

Dave

[dwdrury]

Matt, that's probably because I didn't post the photos until last night, primarily to illustrate my point. And because you so kindly provide the opportunity for me to brag. I also wanted to try out how to shorten the link chain with your and Rob's nifty link substitution. Took me a few tries, but I figured it out.

Dave, I checked my records and bought a bunch of 45 els at Lowe's for $8.56 each (about 6 months ago). I've also recently found certain Lowe's carry SDR-35, 6' pipe, for about $34 a 10' stick. Found it at a HD Supply for less, about $22 per 10'. But as I understand it, finding these at Lowe's is hit or miss. Some carry the stuff, some don't.

I agree a full 90 el can be a loss source, especially the small radius variety. But I'm also led to believe you can use a pair of 45s with a short piece of straight pipe between, thus emulating a large radius el, and suffer significantly less loss, perhaps even less than the sweep you made.

Just proves, with apologies to Scooter, our family pet and desk chair thief, that there's more than one way to skin a cat.

Well, no promises on not having 20/20 hindsight, but I'm game to give it a go if you are.

Regards,

DWD

[fullmetal]

Hello everyone,
It looks like this thread lost a message or two after the last server hiccup. Oh well, life in the computer age...stuff happens.

I've been pretty busy with other projects, but I did manage to make the first mock-up of my CMS dust hood. I attached the photos.

What I've learned:
1) At 22 inches wide, this hood is a bit wider than it needs to be.
2) Even with a 6" connection, it fails to draw the dust off the table top, and more importantly, it fails to do anything about the dust collecting under the saw. It looks like I'll be splitting this into two 4" lines, one to draw from under the saw and the other to draw from the hood.
3) I'm not loving the round connection on the bottom of the hood. I'd prefer a slot very much like I did for the RAS. I still want to put the opening on the bottom of the hood. Watching the sawdust fly into the back of the hood and deflected down, it seems to me that the best location for the slot is on the bottom. I've been messing around with google sketchup and I found a nifty transition model online. It may give you an idea of what I'm thinking of for hooking up the hood to a 4" pipe.
4) I could keep the round connection but angle the sides from a wide opening in the front to a narrow back, say 4". Hmmm, PVC soup anyone? Now I'm thinking of a round to trapezoidal transition made of 4" PVC. Clear as mud? Sorry, I'm thinking on the fly here....
5) Sawdust is collecting along the sides of the hood on the bottom. You may be able to pick it out in the pictures. The cardboard is a bit "stained" from dragging drywall across it, so ignore the "chalk marks".
6) Sawdust shooting out of the built in dust port is easily picked up by the 6" line. No need to do anything with the mfg supplied port at this time.

Other random notes:
I've temporarily used my workmate as a stand for the hood. Once I get the hood dimensions settled, I'll decide how to mount it. For now, I have the saw and table pulled away from the wall so I can fuss with the hood.

I've also used a long section of 6" flex hose as a temporary connection. A killer of airflow, but good for this early testing phase.

What I have now works great for 90* crosscuts. I'd like to be able to miter 45* in both directions and have the hood still directly "behind" the saw. That will require some trimming and perhaps some hinged sides.

The dust collection solution for this saw is going to end up being pretty complicated.:( Many challenges to overcome.

Regards,
Dave

[dwdrury]

Dave,

I see progress is being made!

I'm wondering if, instead of having the pipe come in from the bottom, you wouldn't see better chip collection from the table and under if the pipe came in horizontally from the rear. Yes, I know that makes the thing stick out farther from the wall, but might be worth it.

The idea is the air won't have to make the sharp corner to sweep the chips. The tradeoff is that dust higher up won't be as efficiently collected. There may be a "sweet spot" angle that does each job adequately. Like you, I'm thinking on the fly here. You may be able to achieve a similar result by sloping the top down towards the lower rear.

The next question, of course, is how much playing around and experimenting you want to do. At some point, I'm sure you're going to say, "Close enough for government work".

Regards,

DWD

[Matt]

Hi,

That's a project!! I wish I had some input but after using mine I am still at a loss! Have you ever seen a bead blaster where you stick the part in the put your arms into to gloves to do you work inside the box? That's what comes to mind when i make a cut on mine.

Seriously it looks like you are making progress and I think if you keep at it you will find a workable solution.

Thanks for the update and again I am sorry for the lost posts!

Matt

[fullmetal]

Dave,

I see progress is being made!

I'm wondering if, instead of having the pipe come in from the bottom, you wouldn't see better chip collection from the table and under if the pipe came in horizontally from the rear. Yes, I know that makes the thing stick out farther from the wall, but might be worth it.

The idea is the air won't have to make the sharp corner to sweep the chips. The tradeoff is that dust higher up won't be as efficiently collected. There may be a "sweet spot" angle that does each job adequately. Like you, I'm thinking on the fly here. You may be able to achieve a similar result by sloping the top down towards the lower rear.

The next question, of course, is how much playing around and experimenting you want to do. At some point, I'm sure you're going to say, "Close enough for government work".

Regards,

DWD

DWD,
Two things will keep me from using the backside for pickup.
First of all, as you mentioned, space is a premium. Every extra inch out from the wall is multiplied by the 16' table I have the CMS on. Since the RAS shares the table, and fence, it would need to move out too. Add a 90* bend to the inlet and it gets pretty long.

Secondly, the "rooster tail" of sawdust moves as the saw cuts and hits the back of the hood at different heights. The current hood back is curved so that the stream of sawdust tends to hit the back at a right angle. The dust then just drops down into the inlet. Cardboard works good as a backstop since the sawdust doesn't bounce much. I doubt it would work well long term since it is likely to erode quickly. Perhaps if it was sprayed with truck-bed liner? I don't plan on using cardboard long-term anyway, I'm just thinking out loud for the benefit of any lurkers.:) Cardboard is easy to fabricate with after all.

Using a downdraft design, I hope to get a laminar airflow along the backstop, which will help draw the dust into the DC.

I suppose a hood that resembles a funnel turned sideways would work fine if space was not a consideration.

How much experimentation am I willing to do? Like you said, until it gets close enough for government work.

Stay tuned for cardboard v2. Flared sides, narrower opening and wings for miter cuts. Also, 4" inlet formed from PVC soup and perhaps the bottom will be angled down also. Gotta love those compound miters.

Matt,
Yes I have seen those spray booths. My Dad has one for etching glass. He doesn't do that anymore so he wants to give it to me. Good deal. I don't plan on using it for the CMS though.:) Come to think of it though, the mask material he uses on the glass would make a great coating for the dust hood. At least along the backstop.

Not to worry about the lost posts. I once was a system admin and I understand fully how stuff can happen.;) Thanks for your efforts keeping this forum running. I'm sure it helps a lot of woodworkers.

Dave

[dwdrury]

Dave,

While wandering about the web in search of other things, I happened upon this item (http://www.woodcraft.com/family.aspx?familyid=5206)

Granted, only a 4" port, and exits to the rear, but possibly with the addition of your flexible side shields, might do the job. At $20, price seems steep for what it is but reasonable considering building your own.

Regards,

DWD

PS: Found essentially the same thing at Woodworker's Supply, here (http://woodworker.com/cgi-bin/FULLPRES.exe?PARTNUM=120-053&search=Dust%20Collection%20-%20Plastic%20Hose%20&%20Fittings)

PPS: And at Amazon, here (http://www.amazon.com/PSI-Woodworking-DBGULP-Gulp-Dust/dp/B0000223WV/ref=pd_cp_hi_2?pf_rd_p=413863601&pf_rd_s=center-41&pf_rd_t=201&pf_rd_i=B001399UTO&pf_rd_m=ATVPDKIKX0DER&pf_rd_r=1JBM20PMGQ9S6D7CHR79) for much less

[Jim O'Dell]

Thanks for keeping the updates coming. I've been contemplating how to do the pickup for my Hitachi slider. Just boggles the mind. :D I originally built my cart with the pickup coming from underneath, then was going to decide how to to the hood. The more I look at it, the more I think I will change this, though I do agree that the collection port being at the bottom instead of at the top would be best.
I have a 24' long wall, with 10'+ long, 24" deep cabinets on either side of a 3' wide box bay window. This gives me some extra depth to be able to play with and not take up any more room in the shop. Originally built with the idea of a normal slider that sticks out farther in the back. I ended up with the Hitachi that doesn't require so much space behind as the Makita I really wanted. I have a 6" pipe coming out of the ceiling, down the wall, and going through the back of the cabinet. The back 10" is raised to make a "fence" with the front part about 13" deep. This front part will also act as my infeed/outfeed for the lunchbox planer. Multiple tools will be on carts that will roll into this spot, and use the same DC hook up. I'm building the planer cart right now. Need to finish the bondo, sand and put the laminate on this weekend. Then move the Herc-U-Lift from the jointer stand to this one. Then build a hood for it. But I digress....
I'm thinking I can build a hood into my box bay window area for the SCMS, collect at the bottom, and just leave it there. Now, what to use the 6.5 hole in the top of the cabint for?? :rolleyes: Jim.

[fullmetal]

DWD,
Thanks for the info. If that bit doesn't make it into my CMS hood, it may find a home on another machine!

Jim,
I have a friend who is looking at a 12" Hitachi SCMS (C12LSH) for possible purchase at Lowes. Which one do you have and how do you like it? I've heard it is pretty heavy. My friend doesn't have a dedicated shop, so he will be moving the saw around every time he needs to use it.

Thanks for the feedback guys! Hopefully I'll get enough time this weekend to work on the CMS hood. I'd like to be able to show some progress.

Dave

[Al T]

Hi everyone, I have been following this tread for awhile now and figured that I would discuss come of the things I have done with my sliding CMS since many of the things I have done are being discussed in this thread. I have provided a link below to my gallery pictures I just put up. First, my saw is located next to a wall adjacent to and at the same height as my RAS and part of the workbench surface. I have approximately 22" from the CMS cutting fence and the wall in back. This did not leave much room for the dust collection but since my shop is in a portion of a small double car garage that is all I was willing to allocate. As you can see from the photos my dust collection consists of a fixed rear clam shaped collector shield, a Rockler big gulp 4” dust collector port with a wire mesh screen located in the bottom rear, an under the saw 4 inch port, and a 2 ½ inch port located on the original Porter Cable saw dust collection port. In usage, I generally partially or fully close off the under the saw 4 inch port with a plywood board to direct the airflow to the other two ports.

So how does it work? Well in general I would give it a fair rating. In general it picks up most of the very fine dust and a fair amount of the larger chips that fly off the saw blade and go back to the rear port. How well it works depends on the type cut I make. If the saw is in a typical chop saw mode with the blade locked at the full front position a considerable amount of the sawdust hits the back of the saw and drops onto the table without being directly captured. However, in a cut where the saw is slide forward and then back using the sliding motion the sawdust typically falls behind the machine most of which is captured by the rear port. Additionally extreme angle cuts have the saw dust fly back with a large amount missing the rear port. Basically at the end of a cutting period I typically take my air hose and blow the remaining sawdust into the rear port or the underneath dust port.

I think there is a need for improvement here but I have not come up with any planned changes that would fix all the issues. The main problems are:

1. The large cutting range of the saw makes it difficult for the fixed collector shield to direct the sawdust to the rear dust port.
2. The rear of the Porter Cable saw is flat and causes the sawdust to be diverted away form the collection ports as it bounces off.
3. It is difficult to close the top of the fixed dust collection shield due to the large cutting range of the saw (both miter and compound angle positions coupled with the sliding motion).
4. Optimum dust collection for a sliding CMS should be behind the blade up where the sawdust typically is projected after the blade cutting action. Unfortunately collectors in this area are dependent on the design of the factory dust collection port. On the Porter Cable Sliding CMS I have the port is in the right position but is two small and the flat back support design interferes with the dust collection.
5. The port under the Porter Cable saw is ineffective during operation because most of the sawdust in this area bounces onto the top table surface and does not drop below. Additionally, the flat areas around this port tend to hold much of the sawdust that does drop below.


Well that is it. I have included my design to let people know what I have tried in the hope that it might help them make better decisions on there CMS dust collection. My pictures are in the gallery under the "Dust Hoods and Pickups" section under "Al T Sliding CMS Dust Collection" Here is the link:

http://www.gallery2.clearvuecyclones.com/v/Dust+Hoods+and+Pickups/Sliding+CMS+DC/

[Matt]

Hi Al,

Thanks for the pictures and sharing. I like the fact that your saw has a pickup on the blade guard and that you have enough room to sweep around the saw for what doesn't get picked up! Excellent Job on the pickup and Your workbench is really nice also!

Matt

[fullmetal]

Al,
Thank you very much for sharing your design. You certainly set the bar high! I'm very impressed, especially with your workbench. It is very similar to what I've been thinking of doing with my CMS and RAS. All in good time.:D

It's great to see what you've done with your dust collection. Sharing what works and what doesn't is very helpful to me. I will try something different for collection under the saw, for example.

It is unfortunate that for the most part, dust collection for these saws appears to be an afterthought by the manufacturers. By far the best SCMS saw I've seen for dust collection is the Festool Kapex. It is also the most expensive SCMS I've looked at. Perhaps that tool will foster innovation from other saw manufacturers and good dust collection will become more standard.

Until then, I'll keep fussing with my setup until it becomes adequate.

I have another hood mock-up put together. This one has a 4" connection. I haven't gotten it tied into the DC yet, so no report on how well it works. It is capable of pivoting with the saw on it's full range of miter angles which is +/- 52* from a crosscut.

Photos to come after I get it hooked up. Perhaps tomorrow. After this prototype is tested, I'll be moving on and setting this project aside. I need to begin finishing the interior of my shop. Cold weather is coming so by the end of the month I want to pull down all the duct work so I can insulate and drywall. I'll take this opportunity to move the cyclone as well. Perhaps I'll start another thread for that project and explain why there. Needless to say, it may be awhile before I will get back to working on the CMS hood. When I do, I'll post on this thread again.

Random thought of the day::rolleyes:
Air compressors, leaf blowers, shop vacs and even a properly plumbed clearvue cyclone can blow air. It is relatively easy to direct compressed air where you want it and keep it concentrated in an open area. It is very difficult, if not impossible to direct air in suction over an open area. Using both together may make for a better dust collection solution.

Just thinking outside the box. Another thing to ponder while finishing my wiring, insulating and hanging drywall.:)

Dave

[fullmetal]

Hello everyone,
I've gotten version 2 hooked up. It needs some refinement, but that will have to wait. I have begun on completing the shop wiring, so this dust collection project is officially on hold.

I've attached a few pictures.

This hood has a 4" line and uses 10' of 4" flex hose for a temporary hookup. Obviously, airflow is greatly reduced from the previous edition with a 6" hookup. I made a trapezoid to round transition out of sheet metal. I was in a hurry and it was quicker than building a form and stretching PVC pipe with boiling water. It works ok for a prototype. It is good I didn't invest too much time in this transition since it will get scrapped.

I was going to split a 6" line into two 4" lines, which is roughly 50/50. The other line would collect under the saw and potentially from the saw's supplied dust collection port. After some testing, I've concluded that I need to devote more of the airflow to the hood. Perhaps 60/40 or 70/30. This version of hood needs the saw's port hooked to the DC or a shop vac. The previous hood didn't.

The dust that spews out the back port hits the hood's back and is easily consumed by the hood's downdraft inlet. But, this hood doesn't collect the chips as well as version 1. I think version 2 is too narrow. I will need to extend the sides and top toward the operator so that more of the saw's output is captured.

I hope you enjoy the photos!

Dave Zeigler

[dwdrury]

Dave,

Yeah, that's sort of what I envisioned. Pity it doesn't work as well.

Viewing the photos, I found myself wondering if more of a bellmouth, ala a trumpet end, might work better. In other words, curve the top the other way, wider at the top, narrower at the middle.

Also was wondering if your trick flex panels might not help the side capture situation.

Yeah, I also know we engineers have a nasty habit of wanting to play in a sandbox. Had a boss once who's favorite motivational tool was to say, "Eventually you have to either fish or cut bait."

Regards,

DWD

[Al T]

Dave and Matt thanks for the compliments on my dust collection and my work bench. Both were very time consuming but the effort is starting to pay off.

Dave I found your random thought of the day comment about directing the air around a suction port interesting. My experience certainly confirms your thoughts. And in regards to using a combination of a blower and the suction port I have actually considered that for my SCMS setup to force more of the sawdust back into the shield area and the duct collection ports. But have note seriously decided to pursue it yet.

I did not mention it in my initial post but I have tried to put a flat cover over the two dust ports in the workbench surface with spacers to elevate the boards up slightly to allow the airflow to be directed throw a smaller area around the perimeter of the board with the thought it might increase the velocity of the air going into the dust ports and hopefully increase the suction in these area’s to capture more sawdust but my attempts so far have not prove beneficial. I know it was a crude try but it was quick and thought it might be worth the effort.

Dave, I look forward to hearing about your improvements to version two when you get back to it. I have really enjoyed this thread's contributions so far. Thanks to everyone for putting their efforts into it. :) Al