Thread: Minimax token dust collection, how to fix?

My CU300 5 inch port isn't cut in half like yours! The main worry I have is when I don't put the vc on the top and/or are using the scriber. Let me know if you find the solution!

Originally Posted by richmond68

As for the shroud, is it worth modifying it to get a decent cross section of flex on it, or just dispense with the flex and build an enclosure within the cabinet connected with rigid duct to the new port?

The latter.

Makes sure the enclosure IS NOT totally enclosed but can grab air from somewhere. The more air it can grab the greater the cloud of fine dust it will pull. As long as it does not interfere with operation a few chips sneaking out o the enclosure and back into the cabinet is no big deal.

Its one thing to pay $1000 for a contractor saw with pathetic dust extraction but another to pay top $ for a machine and see that sort of thing going on.

What sort of a DC are you using?

Modifications to a Hammer slider Table saw port/pickup upgrade WIP

Thanks Bob, that is the direction I am leaning towards. I was thinking it'd need to be shaped like a hopper bin and open at the top, I've still got to have access for blade changes so airflow shouldn't be a problem. The challenge will be fitting it in around 3 motors and belt paths. But what's life without a few challenges.

DC is a holytek 3hp 2 bag, similar to the H&F DC-80. I'd like something better, but it'll have to do for now.

Ok, after putting this in the too-hard basket for a number of years and being reminded by Sunnycoaster, I've decided to have another look at it. Taking into consideration all the accessibility issues of doing anything else, it looks like modifying the existing shroud or fabbing a replacement is about the best I can do. So I took the blade shroud out to get your ideas and feedback.
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I think this is a large part of the problem, if air can't get in it can't get out. The limited cross section at the top combined with the limited cross section of the outlet and further restrictions with the internal ducting of the saw, I hate to think how little flow it has.

So, I'm thinking of doing something like this:
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The idea is to cut off the base of the shroud, and weld on as large a diameter pipe as I can fit to remove the outlet restriction. I have mocked this up with 100 PVC just to get an idea of size. Front of the tube (on left) to be open, possibly with a bell mouth and the socket end on right would connect with flex to a new outlet mounted higher on the back of the machine (some CU300 smart had a 120mm outlet there, about as large as would fit). This would make the ducting as straight and horizontal as possible.

Thoughts from all the dust collection gurus?

I think this is a large part of the problem, if air can't get in it can't get out. The limited cross section at the top combined with the limited cross section of the outlet and further restrictions with the internal ducting of the saw, I hate to think how little flow it has.

Its pretty typical of most machines.

This may have been answered before but why can't the shroud be completely removed and just extract direct fro the cabinet with a 6" duct ?

That's what I did on my simple TS and it works a treat.

If it were that simple Bob, these kinds of questions would not arise! Typical table saws tend not to have more than a cubic metre of space inside, with 3 separate motors, belt paths, spindle moulder mechanism etc. And don't forget that sliding table is 2250 and breaking down a 2400 sheet requires its full travel, so the start of the cut is like leaving a door open and then closing it as you move through the cut, and opening another at the end of the cut. Without the shroud I suspect it'd quickly fill the workshop with fine dust because it's not contained. Dust that settled elsewhere inside the cabinet could be stirred up again when I switch to planing or moulding. So capturing as much as possible as close as possible to the source is my preferred approach.

Originally Posted by richmond68

If it were that simple Bob, these kinds of questions would not arise! Typical table saws tend not to have more than a cubic metre of space inside, with 3 separate motors, belt paths, spindle moulder mechanism etc. And don't forget that sliding table is 2250 and breaking down a 2400 sheet requires its full travel, so the start of the cut is like leaving a door open and then closing it as you move through the cut, and opening another at the end of the cut. Without the shroud I suspect it'd quickly fill the workshop with fine dust because it's not contained.

Containment is not an issue provided enough air is collected which is THE problem with enclosed cabinets so I would not worry about the large gaps created by the slider. Lathes and belt sanders can make a lot more fine dust than a table saw and are completely open to the shed and their fine dust can be prevented from getting into the workshop is high air flows are obtained with the help of BMHs. 1250 cfm is about 20 CubicFts which is equivalent to a sphere of air 2.2m in diameter being removed per second from the inside of the cabinet. I wouldn't worry about the gaps - they help to let the air in so the dust can get out. A 6" BMH on the outside of your cabinet opposite these major openings should take care of the fine dust.

However chip collection will be an issue so in addition what you suggest should help especially if a BMH is used. On a small diameter pipe like this may add as much as 20% to the flow.

Ok just to clarify, you are saying I need a 6" inside the cabinet for fine dust, plus the modded shroud for chip collection, which is probably limited to 5", plus a 4" connection to an overhead guard?

Originally Posted by richmond68

Ok just to clarify, you are saying I need a 6" inside the cabinet for fine dust, plus the modded shroud for chip collection, which is probably limited to 5", plus a 4" connection to an overhead guard?

Yep, because sure as eggs the shrouded 5" won't be picking up much flow , probably less than a 4" (say 350 CFM) , and a 4" OH guard won't pick up anywhere near the max flow of a 4" (say 300 CFM) so you have plenty of unused flow left over (600 CFM) so why not direct that to the cabinet to pick up any escaped fine dust?

Well, I thought I had nothing to lose by testing it, so I gaffa taped the PVC to the shroud, hooked it up to some 4" flexi and did some test cuts. No surprise it was an improvement, and it gave me some idea of what's going on that makes the saw so bad.

What BobL has said about the 6" inside the cabinet picking up the fine dust would be right, judging by what the open end on the 4" PVC was picking up - you can see it pulling visible dust from behind the blade to the inlet, and from several inches in front of it. What I didn't previously understand was what was happening with the heavier stuff that caused it to go everywhere inside the cabinet - despite the shroud being ducted out of the machine, the planer motor that sits underneath the saw would get covered in piles of sawdust, as would the spindle motor. As it turns out the spillover from the top of the shroud is ridiculous - just leaving the hinged section open made a noticeable difference in the amount of swarf deposited inside the machine. The gap on the motor side between the top of the shroud and the underside of the table is also a problem, because swarf hits the belts which throws it toward the front of the machine, except for the stuff that hits the belt for the scriber which runs the opposite way and throws it to the back of the machine. The tube did improve scavenging in the shroud, with visibly less swarf exiting the back past the riving knife, which shows just how restrictive the existing duct was.

While the tube made an improvement in chip collection and scavenged better inside the cabinet, extracting it at the rear of the machine is problematic because of the height winder for the spindle moulder, which restrict both the diameter and the ability to tilt the saw. So I am back to the drawing board. BobL is correct (again) that it'd be better to get rid of the shroud, but having something to contain the heavier swarf so it doesn't get flung to the far ends of the cabinet is definitely needed because you'd use the planer or spindle and all the swarf that deposited on them from sawing would get stirred up again. And for safety reasons there would need to be some guarding put in place if the shroud is removed.

As Arnie says, I'll be back.

Great thread. Thanks for kicking this off. I've got the same model Cu300. So poor is the designers token attempt at chip extraction on the table saw that i'd suggest it looks even more ridiculous in real life than the photos here suggest. I've long considered going in with a 125 or 150mm duct above the existing 120mm which provides a clear run to the saw underneath the spindle height adjuster. Almost identical to what you suggest here Richmond68. What's interesting to me though is the notion of making this an open bell mouth hood with supplemental collection up closer to the blade. I would have voted with Richmond on this being ineffective but the science suggested here makes sense on reflection. I'll look forward to doing some testing as I upgrade my dust extraction system in the next couple of months and I'll also watch this thread with great interest. Thanks again.

Originally Posted by Flindersia

. . . . . . What's interesting to me though is the notion of making this an open bell mouth hood with supplemental collection up closer to the blade. I would have voted with Richmond on this being ineffective but the science suggested here makes sense on reflection. . . . .

Originally Posted by Flindersia

I've long considered going in with a 125 or 150mm duct above the existing 120mm which provides a clear run to the saw underneath the spindle height adjuster. Almost identical to what you suggest here Richmond68. What's interesting to me though is the notion of making this an open bell mouth hood with supplemental collection up closer to the blade. I would have voted with Richmond on this being ineffective, but the science suggested here makes sense.

To clarify, it's not that I think it would be ineffective, but that the situation is more complex because the machine itself is more complex. There are multiple air pathways inside the machine, lots of surfaces and corners which create low pressure areas, Coandā effects etc. Ideally, a large diameter duct underneath the front of the saw blade would pick up the vast majority. But you can't have it follow the tilting arbor because of the shape of the cabinet. On a 45° bevel cut, the swarf would be thrown out about 350mm on an arc away from where you'd put the bellmouth for a 90° cut. And placement under the blade is restricted by the position of the motor for the planet/thicky. So there is need to provide some means to direct the swarf, but whatever you put in needs to be easily removable for access for servicing.

From my last test, I've pretty much ruled out the port on the back of the machine, and am back to a port exiting in front of the thicknesser. I'm convinced the shroud has to go, but that means some guarding is required under the slider. I'm looking at perforated sheet for that, but the best I can get is 60% open so how much it affects air flow into the cabinet will have to be determined. There's plenty of other places it can get in so I don't expect it to be a problem but you don't know until you try.