Thread: Table saw guards and dust extraction for "non-through" cuts?

I doubt it will make much difference if the black plastic adapter is removed but it can't hurt anything so I would give it a go but you will really need a guard that takes advantage of the 4" ducting.

Originally Posted by BobL

I doubt it will make much difference if the black plastic adapter is removed but it can't hurt anything so I would give it a go but you will really need a guard that takes advantage of the 4" ducting.

Agreed; I'll start planing that soon. Would it be fair to say that the reason why so much dust escapes for edging trimming and non-through cuts is because of the low CFM I'm getting? If I can increase my guard to a full 4" and redesign the dust shroud, again I assume that the increased CFM would help significantly with the dust escaping for these kinds of cuts?

Originally Posted by LuckyDuck

Agreed; I'll start planing that soon. Would it be fair to say that the reason why so much dust escapes for edging trimming and non-through cuts is because of the low CFM I'm getting? If I can increase my guard to a full 4" and redesign the dust shroud, again I assume that the increased CFM would help significantly with the dust escaping for these kinds of cuts?

I personally wouldn't worry about this, instead I would be more worried about the low flow causing invisible fine dust to escape into the shed.

Originally Posted by LuckyDuck

Hi John:

Thanks for your input. I've learned a lot from your dust extraction journey. Ta.

I'm going to give your design a go and see if I can't attach it to my existing Felder arm. Where did you buy your polycarbonate? And do you have approx dimensions you could throw my way please?

Finally, I'm still after your holy grail of having no residual dust lying on undisturbed surfaces. I'm making some headway, but I recognise that trimming timber to width (cutting say 1mm off) and general non-through cuts on the table saw yield more dust than I care for.

Do you get enough airflow overhead to deal with these situations? Would an extra piece extending down one side improve the extraction?

Thanks for your help!

PS. Are you going to the show in May? If so, what day are you planning to attend? It might be good to meet!

Lucky,

Here is a link to the plans I used for my guard. Mine is not exactly as per the plan, which was used only as a guide. http://www.woodcentral.com/bparticle...m_guard2.shtml It was not at all difficult to make. I added the clear rectangular riser, which I like for visibility. The polycarbonate came from Bunnings.

The seam in the front of the guard is a bit of a nuisance. If doing it again, it would look like this.
O'head Blade Guard.jpg

The airflow is good, see http://www.youtube.com/watch?v=X5WE5t-9MqA. However, when taking a trim off the edge of the board where the saw exits the edge, dust is spewed out from under the side of the guard. I am playing with a couple of possible mods for this ... the current thinking is a detachable brush that fits along the side of the guard.

I still get considerable wood dust occasionally, those fine edge trim cuts are one example. The dust velocity is so high I doubt we could get enough airflow to grab it without a mod to the guard. So, sometimes the dust in the shop is grey, and sometimes it is not. The worst dust problem I have is routing for cabinet backs. Nevertheless, the shop is a dream compared to how it was. I checked the shop last night. There is some dust lying around, and some of it is brown. I found a fine layer of dust on top of my duct work, but given that it is now 18 months since the cyclone was installed and the ducts have yet to be cleaned down, this is pretty good. Two years ago I was wading through dust, chips and shavings. You could smell the dust as soon as you walked into my shop, even first thing in the morning. Not pretty.

Also, my new band saw is not yet as clean as the old one ... still working on that in between jobs.

One day ... someday ... I will stop forgetting to open the blast gates. Still do that occasionally; or have two gates open instead of one, which ronboult found hilarious.

I hope to go to both shows, providing my real job does not get in the way. I travel for work, and am often away for a week or two at short notice. So, it is difficult for me to plan these things in advance, but let me know when you are planning to go and we'll see if we can hook up.

Cheerio!

John

Originally Posted by John Samuel

Lucky,

Here is a link to the plans I used for my guard. Mine is not exactly as per the plan, which was used only as a guide. http://www.woodcentral.com/bparticle...m_guard2.shtml It was not at all difficult to make. I added the clear rectangular riser, which I like for visibility. The polycarbonate came from Bunnings.

The seam in the front of the guard is a bit of a nuisance. If doing it again, it would look like this.
O'head Blade Guard.jpg

The airflow is good, see http://www.youtube.com/watch?v=X5WE5t-9MqA. However, when taking a trim off the edge of the board where the saw exits the edge, dust is spewed out from under the side of the guard. I am playing with a couple of possible mods for this ... the current thinking is a detachable brush that fits along the side of the guard.

Hi John:

Thanks for your input. Both links were very helpful. The youtube link is VERY informative, in the sense that it is clear that fellow is getting vastly more airflow than I am getting!

The woodcentral link is also very helpful as it gives me a starting point for overall dimensions. I note that they put on a 3" port. I can't remember whether you went with 3" or 4"? If the latter, did you make your guard a little wider than 4" to accommodate?

Would I be correct to assume that the narrower the guard is, the better? Better in terms of bulkiness and moving mitre gauges and fences around it, and better in terms of airflow, as it concentrates the flow directly over the blade? I'm very mindful of Bob's advice about reducing resistance, so I'm wondering whether the 4" width is essential? Perhaps there are plenty of gaps around the base of the guard for airflow anyway?

I appreciate your comments regarding visibility, and the diagram above. I will see what I can do to adapt this kind of guard to my existing boom arm. I'm toying with the idea of pulling apart the vertical (green) portion of my arm, and having a go at increasing its cross sectional area. Will involve an angle grinder and welding -- and I have not done any welding since high school! Could be fun! Failing that, I think I will bring the flex straight down the front and onto a new shroud.

I've gotten way behind on my work as a result of a new dusty and ducting installation -- so won't get to this for a couple of weeks. But...watch this space!

Thanks again to all the guys who have contributed to this thread to date. Much appreciated.

Originally Posted by LuckyDuck

Hi John:

Thanks for your input. Both links were very helpful. The youtube link is VERY informative, in the sense that it is clear that fellow is getting vastly more airflow than I am getting!

The woodcentral link is also very helpful as it gives me a starting point for overall dimensions. I note that they put on a 3" port. I can't remember whether you went with 3" or 4"? If the latter, did you make your guard a little wider than 4" to accommodate?

Would I be correct to assume that the narrower the guard is, the better? Better in terms of bulkiness and moving mitre gauges and fences around it, and better in terms of airflow, as it concentrates the flow directly over the blade? I'm very mindful of Bob's advice about reducing resistance, so I'm wondering whether the 4" width is essential? Perhaps there are plenty of gaps around the base of the guard for airflow anyway?

I appreciate your comments regarding visibility, and the diagram above. I will see what I can do to adapt this kind of guard to my existing boom arm. I'm toying with the idea of pulling apart the vertical (green) portion of my arm, and having a go at increasing its cross sectional area. Will involve an angle grinder and welding -- and I have not done any welding since high school! Could be fun! Failing that, I think I will bring the flex straight down the front and onto a new shroud.

I've gotten way behind on my work as a result of a new dusty and ducting installation -- so won't get to this for a couple of weeks. But...watch this space!

Thanks again to all the guys who have contributed to this thread to date. Much appreciated.

I used a rectangular riser, as seen below, with a PVC transition on top of it to pick up the 4" flexy.

IMAG0229.jpg

The riser has about the same internal cross-sectional area as a 3.5" pipe, so the riser is the restriction. The guard is only about 45 mm wide (internal). I kept it fairly narrow for the reasons you mentioned. However, if you make it too narrow, you may restrict the flow, as BobL suggested. The youtube link shows my saw, so the riser is big enough to get satisfactory airflow. The riser also provided a convenient place to which the arms (also polycarbonate) could be attached (see pic).

Mine is a 10" saw. The guard only just covers the blade and the splitter. The polycarbonate sheets bought from Bunnings were only just big enough to make the guard. The splitter is made from a reciprocating saw blade.

Cheerio!

John

Originally Posted by LuckyDuck

I have recently upgraded my table saw dust extraction. As part of that upgrade, I have installed a Felder overhead guard (taken from a K700S), which has a 3" inlet. I have put on a 4" flex as many Felder guys over the pond report that they get a little more airflow even though they are "not supposed to" as the 3" is the constricting point.

This system works "well" for general ripping.* I can adjust the guard above the timber being ripped by a few mms and I cannot see any dust escape. In other words, the super-fast dust flying off the teeth is hitting the inside of the guard and being sucked away. Presumably all/most of the invisible dust is likewise being extracted? *Note, I have no instruments, so emphasis on the "presumably".

But I have two observations:

When I trim the width of something, where the blade is not trapped in a kerf, but is running along the side of the timber (say taking off 1mm), lots more dust escapes because the guard is not adjusted flat against the table, but only flat against the stock. Consequently, plenty of dust leaks out the side (left side, with the right sided fence). I've wondered whether it would be helpful to position a piece of timber or some kind of curtain on the side of the guard to try to trap this dust?

Second, when make non through cuts, say grooving a piece of timber to take a panel, or working on tenons with the mitre guage, again plenty of dust is emmitted from the groove or from the underside of the tenon. Not sure what to do here?

Consequently, I would say that my guard is dust "effective" only for "properly" through cuts. All the rest yield sub-optimal results.

You guys must have come across this? Any solutions?

Thanks.

I like your idea of sliding sides for the guard. They would not need to be the full height of the guard sides as they are only going to extend the depth of the timber being cut. You may even be able to use a rubber sheet with tiny brush like cuts in the bottom.

Another aide would be to construct an elongated rectangular funnel with rare earth magnets on the bottom edge. It should be about the full length of the table and placed fairly close the the edge of the timber being cut. The magnets would bold it in place and a 6" flexible hose to a junction in the ducting should collect most of the dust thrown.

Originally Posted by shedman

I like your idea of sliding sides for the guard. They would not need to be the full height of the guard sides as they are only going to extend the depth of the timber being cut. You may even be able to use a rubber sheet with tiny brush like cuts in the bottom.

Check this out
https://www.woodworkforums.com/f200/bristle-guard-edges-dust-collector-hoods-guards-165892

Another aide would be to construct an elongated rectangular funnel with rare earth magnets on the bottom edge. It should be about the full length of the table and placed fairly close the the edge of the timber being cut. The magnets would bold it in place and a 6" flexible hose to a junction in the ducting should collect most of the dust thrown.

I would be worried about any unfixed hard metal in the region of the TS blade, ally and brass would be OK. It would just take a knock from a piece of wood being cut to possibly move the metal into the blade and then watch out.

Originally Posted by BobL

Check this out
https://www.woodworkforums.com/f200/bristle-guard-edges-dust-collector-hoods-guards-165892



I would be worried about any unfixed hard metal in the region of the TS blade, ally and brass would be OK. It would just take a knock from a piece of wood being cut to possibly move the metal into the blade and then watch out.

I agree Bob it is my sloppy writing I was thinking in terms of a perspex funnel with the magnets set back from the front edge.

Originally Posted by BobL

Check this out
https://www.woodworkforums.com/f200/bristle-guard-edges-dust-collector-hoods-guards-165892

Hi Bob:
I saw your "brushes" idea previously, and it is a great idea. Funny, I never really thought about the brushes on various semi-trailers when I'm driving about. Now, I drool over them when pulling alongside at a set of lights!

Incidentally, I was using one of those yellow magswitch feather boards to hold some sticks I was trimming to length...the feather board was located just in front of the blade and provided a physical barrier for the stream of chips/dust shooting out the side towards my belt line, such that most of the chips went up the overhead extractor. This shows, I would think, the importance of the physical barrier to combat the "super-fast" chips/dust coming off the blade.

Still doesn't help with the cloud of invisible dust I'm sure is coming off the blade though. I'm busy with a couple of handcut dovetails on some drawers I'm making...but the time is coming when I will address my poor overhead TS extraction!

Hope you all have, and are having, a great Easter break. Cheers.

Originally Posted by shedman

I like your idea of sliding sides for the guard. They would not need to be the full height of the guard sides as they are only going to extend the depth of the timber being cut. You may even be able to use a rubber sheet with tiny brush like cuts in the bottom.

Another aide would be to construct an elongated rectangular funnel with rare earth magnets on the bottom edge. It should be about the full length of the table and placed fairly close the the edge of the timber being cut. The magnets would bold it in place and a 6" flexible hose to a junction in the ducting should collect most of the dust thrown.

Hi Shedman:

I like your idea of using the rare earth magnets. I'm pretty settled on an overhead TS design in keeping with the ones made by BobL and John Samuel. They make theirs out of clear material. I would think some magnets could be set into the bottom edge of the shroud might be useful for an extra piece of plastic...although I do like Bob's "brushes" idea which he posted a link to...

Cheers.