Improving dust collection from Kapex SCMS - Need help with overkill method

[Jim Becker]

Calculate the approximate open area around the saw and compare that to the area of the DC port inside the box. If it's less, you'll want more air from somewhere. If it's more...fagetaboutit.

[Chris Parks]

Shouldn't I want the inlet flow from the dust collector, and by extension the front of the shroud to be as much as the dust collector can produce?

Alan, in all honesty your guess is as good as mine. I think the ideal might be to maximise the air flow where the blade is cutting the timber but the chances of doing that are most probably zero because these saws have so many inbuilt impediments to good dust collection. In the end I think we have to accept that ideal dust collection is not going to happen. Most users simply don't have the air flow available to achieve any more than a token effort but any effort is better than none. I did an installation using a 17" impeller at 60hz and while it is better the mitre saw dust collection is saw 1 dust extractor nil in the sense that it is not perfect.

[Alan Lightstone]

OK. Looked at the system, and decided on one more modification (LOL, I'm sure there will be others.)

The gap over the top of the Kapex's arm had to be pretty big, and is clearly not useful for collecting dust during sawing. It just will reduce the CFM going through the important areas. But it has to be kept open for the saw's arm to move.

So I took some CNC dust boot I had left over from using it on the Overarm dust collector for my SawStop and glued it to the inside of the box, allowing the saw to move, but effectively cutting down the airflow through that area when the saw is cutting. Time will tell if this helps, but I figure it seems like a good idea and can't hurt.
CNC Dust Boot Addition to Miter Saw Shroud 1.jpgCNC Dust Boot Addition to Miter Saw Shroud 2.jpg

Still debating slightly enlarging opening on both sides at the bottom near the zero clearance insert. If I hadn't glued those pieces on, I would have already done that. As is, it's a handsaw operation.

[Jim Becker]

Good idea to use the "Hula Skirt" material for a "no seal seal" situation like that.

[Alan Lightstone]

Still tinkering because, well, that's what I do.

I thought there is too much dead space on the top half of the shroud. A more direct path for air/chips should help things, cut down turbulence, and hopefully improve air flow.

Looking at the box, I attacked the right side first, closest to the air intake from the dust collector. Again, having to keep the ability to maximally rotate the saw, I made a triangle box with the slope going at 45 degrees from the front of the box to the dust chute. Hard to explain.

Time will tell if this helps things.

Right side triangle box.jpg

Left side box (easier build) likely to follow. Still debating whether to make those diagonal cutouts near the zero clearance insert.

[Alan Lightstone]

Well, I measured and built a second internal box to cut down on the dead space inside the shroud. It's amazing how much I had to decrease the size of these to allow the saw maximal movement from side to side for angled cuts. I could have just settled for 45° angles instead of the larger amount the saw allows and made those larger, but I didn't want to decrease the capacity of the saw.

Finished Kapex Shroud without Front Covers 1.jpgFinished Kapex Shroud without Front Covers 2.jpg

As it turns out, it was absolutely necessary to make those angled cuts at the bottom of the enclosure to allow the saw to make those cuts also. I'm hoping those increase the efficacy of the dust collection. I think they will.

Now, in retrospect, I think those inside boxes will prevent some beveled cuts, which I very rarely make, so probably not an issue. And I could always make those on my table saw. And they are removable with two screws, so I could always temporarily remove them.

As far as how well this works... I'll test it out sometime. No question that the dust collection is more effective with the two holes for the clamps closed up. And it was a mistake using 1/2" magnets. Way too strong. You can easily get your finger caught while it slams shut. 1/4" magnets would have been a better choice. The shroud itself doesn't collect all the dust on the bottom. A bunch stays in there. But that's not stuff that you breathe, and to a certain extent, "Out of sight, out of mind". And, every once in a while I can vacuum inside it.

[Scott Winners]

Alan, you are on a mission. And I know you are checking your particle counts in the shop space. I wish you the best of luck and hope you make a million dollars off your successful build.

[Alan Lightstone]

Alan, you are on a mission. And I know you are checking your particle counts in the shop space. I wish you the best of luck and hope you make a million dollars off your successful build.

Thanks, Scott. Not ever going to be sold, just me following a thought to its ridiculous ending. Ah, OCD...

And yes, most people would kill for the particle counts in my shop. And my lungs love me for it.