Band saw port grills

**BobL** · 20th November 2012, 12:06 PM

Bandsaws may be one machine where multiple 4" ports might make some sense since BS seem to generate / distribute dust in a number of places and hence need a number of ports or collection points. If all of these are 6" ports the air speed at any one port will be too low unless a true 2500 cfm DC is used. Of course larger BS could still be constructed with 6" ports and 4" adapters and those that have a high capacity DC could then utilise the bigger ports.

Given that about the most a standard 3HP DC with 6" main ducting can pull is 1250 cfm then 800 cfm on one 6" port and 400 cfm on one 4" port would be about the most one could expect. If 3 collection points are used then 3 x 400 (4") cfm is a reasonable alternative. However, it would be good if the ports were 100mm and not 95 mm.

Apart from size and obstructions, another problem with all BS ports is that they are not well located so their overall dust collection efficiency from a BS operation is poor.

1) We have already discussed the port located at the bottom of the lower cabinet and the need to improve the air flow to this port.

2) Even worse than 1) is the port located at the top of a BS cabinet since this is usually so starved for incoming air that making that port a 6" port would be a waste of time unless the saw structure is opened up. A complete redesign of this area of a BS is required. I note some folks have tried to open this part of the cabinet up but it may be better to do what is described in 3)

3) I reckon neither ports 1) nor 2) are very effective and despite improving 1), my particle detector confirms what others have already observed and that is a substantial amount of dust spills out from the area around bottom blade guides before the blade enters the bottom cabinet. As others have done I find jamming a 4" flexy up under the table at this point does more for dust collection than ports 1) or 2). I only did a quick and dirty test with the particle counter and need to repeat this in a more systematic fashion. For example, it may be better to forget completely about drawing from port 2) and direct all that air flow to 3). Another reason for doing this is that to a certain extent ports 1) and 2) are connected and hence complete with each other for the same air.

4) Despite the improvement obtained using under table collection another place I measure invisible dust is above the table and work - this is caused by air currents resulting from the blade moving down fluffing invisible dust dust up off the work. This is why BP recommends a duct located above the work. BP recommends a 3" port at this point but I reckon if there is one point where a 6" port makes sense it is here, provided of course the DC has the capacity to deal with this size port.

**chambezio** · 20th November 2012, 01:46 PM

It's an interesting topic that will not be fixed by the manufacturers tomorrow
Does anyone have a dust port pickup design that we can modify our own machines?
I had a cursory look at my Toolmac". Below the table where the lower guides are 2 contentious areas. The boy of the frame is cast iron- so cutting decent holes is a no no, then at the front of the machine we have the sheetmetal cover with the "Water Tap Refugees" holding it in place. A modification here (not much room) will be tricky because I reckon that the dust pickup point should be free of the front cover to make blade changing simple, without having to grapple with an unwieldy dusty pipes.

I have seen somebody shove a pipe through the sheet metal cover right below the bottom guides, but I think that would only help minimally

Any thoughts any one?

**Chris Parks** · 20th November 2012, 03:57 PM

Originally Posted by BobL

2) Even worse than 1) is the port located at the top of a BS cabinet since this is usually so starved for incoming air that making that port a 6" port would be a waste of time unless the saw structure is opened up. A complete redesign of this area of a BS is required. I note some folks have tried to open this part of the cabinet up but it may be better to do what is described in 3)

Bob, that is certainly not my experience with a JET 18" BS. It is a 4" port just under where the blade enters the lower cabinet and with adequate air entry I would say it picks up at least 99% of the dust, in fact I would say more as after a very extensive firewood wood cutting session of at least one hour only a handful of dust was present in the lower cabinet floor. I am guessing the port drags the air across to blade as it enters the lower cabinet and sweeps the dust straight into the port. if I were to modify the cabinet I would put an opening opposite this port but maybe half a port diameter lower so the air was drawn upwards to help pick up the debris that are on the blade and drag them up to the port. Mind you the open door method works so well I have not bothered.

**BobL** · 20th November 2012, 06:48 PM

Originally Posted by Chris Parks

Bob, that is certainly not my experience with a JET 18" BS. It is a 4" port just under where the blade enters the lower cabinet and with adequate air entry I would say it picks up at least 99% of the dust, in fact I would say more as after a very extensive firewood wood cutting session of at least one hour only a handful of dust was present in the lower cabinet floor. I am guessing the port drags the air across to blade as it enters the lower cabinet and sweeps the dust straight into the port. if I were to modify the cabinet I would put an opening opposite this port but maybe half a port diameter lower so the air was drawn upwards to help pick up the debris that are on the blade and drag them up to the port. Mind you the open door method works so well I have not bothered.

From what I have seen the 18" Jet bandsaw is a better design even though it looks like it has only one port in the back top of bottom cabinet just under the bottom rollers.

I'm not that worried about what sticks to the blade or ends up in the bottom cabinet. I'm more concerned about the invisibles that spill out from under the table. I will do some measurements to better quantify this.

**John Samuel** · 21st November 2012, 12:35 AM

I guess every bandsaw is a bit different. The cabinet port for mine is right at the bottom of the cabinet.

Before I built the dust extraction system for my saw, I cleaned it up and made a bunch of sawdust, just to see where it would gather. What I found was that a lot of dust was accumulating immediately under the table but above the lower cabinet, in the region of the lower guides. A bunch more was reporting to the lower cabinet, and a little was being carried around by the saw to the upper cabinet and back to the workpiece.

So, I cut a 90 degree PVC elbow to fit as closely as possible to the blade between the table and the lower cabinet (very similar to Bob, who used flexy), used the existing cabinet port (just to see if it would work) and connected a flexy to the upper guide to draw air from the top of the workpiece and nearby surrounds. None of these ideas are original. I plagiarised them from Bill Pentz, BobL et al.

Essentially, the system is three 90 mm pipes, because that is the size PVC used. because I am using a ClearVue, I am getting pretty good airflow from all three, and I am very happy with the results. In particular, the area under the table but above the lower cabinet stays spotlessly clean, and this has always been very dusty in the past.

I thought this would be a difficult job, but it wasn't. A bit fiddly in places, but not tough. The only issue seems to be that to do a good job we need plenty of air flow, and it seems that Bill Pentz was right when he said that to do the job really well we would need a 3HP dusty or a 5HP cyclone. Sadly, it puts effective dust collection beyond the means of many hobbyists.

Perhaps we should run some trials to determine what is the best way to collect dust from a bandsaw if all we have is a 1HP dusty. That way these discussions can help more people do a better job. My guess is that something like a 75 mm line to the lower cabinet and a 50 mm line to the blade around the lower guides would be a good start for many, but I am guessing.

Finally, many thanks to BobL, Chris and many others who have helped me understand dust collection. A couple of months ago I was completely ignorant, but now I have a pretty good system approaching practical completion.

**John Samuel** · 7th December 2012, 12:22 PM

Took my own advice and ran some tests to see which of the 3 ports on my band saw collected dust the best when only one port was operating.
IMAG0036.jpg

No doubt about my machine ... at all ... BobL was right (at least for visible dust). The port that draws air from between the table and the cabinet (around the area of the lower guides) does the best job by itself.

When drawing air from the cabinet port only, I get lots of dust collecting around the lower blade guides. It seems likely that I am getting a lot of invisibles exiting from this area as well.

So, if I was using a 1HP dusty for my machine I would connect the air to this location, and not to the port on the cabinet.

What does that say about the design of the original dust collection on my machine? Your machine may be different, but I reckon this result will be common for many machines.

Thread: Band saw port grills

Thread Tools

Search Thread

Similar Threads

For port lovers

Port Macquarie

USB port not working

Grandfather Port

port barrel

Tags for this Thread

Posting Permissions