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13th April 2014, 01:45 PM #16Woodworker
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Warm Regards, Luckyduck
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13th April 2014 01:45 PM # ADSGoogle Adsense Advertisement
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13th April 2014, 02:42 PM #17.
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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.
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13th April 2014, 04:14 PM #18Woodworker
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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?
Warm Regards, Luckyduck
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13th April 2014, 09:09 PM #19.
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14th April 2014, 09:07 AM #20... and this too shall pass away ...
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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
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14th April 2014, 10:02 AM #21Woodworker
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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.Warm Regards, Luckyduck
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14th April 2014, 01:20 PM #22... and this too shall pass away ...
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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
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14th April 2014, 02:02 PM #23Senior Member
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- Feb 2007
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- Beerburrum Qld
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- 122
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.
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14th April 2014, 05:06 PM #24.
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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.
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15th April 2014, 11:58 AM #25Senior Member
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18th April 2014, 08:02 PM #26Woodworker
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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.Warm Regards, Luckyduck
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18th April 2014, 08:06 PM #27Woodworker
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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.Warm Regards, Luckyduck
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