bp-355 bandsaw dust collection newbie question

sorry for the real newbie question,

i've got a bp-355 bandsaw. Up to now i've had no dust collection on it, but i've managed to get hold of a 2HP unit. The 4" air outlet on the bandsaw is about 80% obstructed on the inside by a thin metal plate.

That plate is held on with small welds, am i meant to cut through those welds and remove the plate, thereby opening the air outlet up to the full 4" in size, or is that plate there to baffle the air for some reason or for some other purpose, by design ?

Just wondering if anyone else knows before i go taking a dremel to my bandsaw and cut a bit off that's meant to be there. I was thinking maybe its there in case you dont have a dust extractor on the saw (like i've been using it) but surely if that were the case it would 100% cover the opening, not only 80% or so ?

Definitely cut the plate out to collect dust from the cabinet.

BUT

Cabinet dust collection generally does poor job at collecting dust from a BS.
Most of it spills out from under the table before it even gets to cabinet.

I found I get better dust extraction by extracting from directly under the table like this.
I also collect from the two existing cabinet ports, one is on the lower cabinet and the other one visible in the photo.
The second port is also supposed to collect from under the table but does very little.
Attachment 425994

interesting. i did plan ahead to do something like that so there's a Y before it gets to the bandsaw and a blast gate on both exits so i can balance the flow but it's reduced down on one to a 50mm hose (which i haven't purchased yet). I'll see if 90mm is doable, but the entire room is only 10m2, so getting a 2HP collector in there with a 14" bandsaw has been.... interesting. I dunno if i can afford the space for that much hosing.

I have the same saw and a 2 HP dusty also. At first I was just using a shopvac and intended to remove that plate but when I got the dusty I find the plate is perhaps there to to do something afterall like direct the suction around the cabinet. As BobL says a suction under the table is the important one so I better get the finger out and make one of those like I been intending for too long.
I always wheel my dusty outside to use it as it will be giving off fine dust and I would rather not share a closed in space with it.
Regards
John

well, that turned out to be a total pain in the butt ! I went to get the dremel in to cut the small welds but it wouldn't fit with the lower wheel on. Whoever put that wheel on did it like it was the cure for cancer, because the bolts wouldn't budge, and then using a breaker bar it rounded the Allen head over. I ended up having to remove the entire lower wheel assembly, mount and all.

After taking the skin off my knuckles doing that, and spending 45 minutes with a dremel, the plate is finally removed. Gawd damn ;-/ I'll see if i can sort out the under-table collection tomorrow.

I have what is probably the model before yours from Hare and Forbes.

The bottom plate is there because the bandsaw blade itself, along with the driving wheel, are easily touched if you put your hand inside the dust extraction hole.

That aside, removing the baffle may be done in a home environment at your risk, just don't stick your hand in and expect compensation. Removing that baffle in a workshop situation, I assume is not a good idea.

I have done under table as well, this is my version. The yellow rectangular funnel is screwed to the timber which is chamfered to ensure the long edge of the funnel is hard up on one of the tabletop webs to catch as much dust as possible. This has been far more successful than I thought it would be. The 101.6mm junction piece with the 63.5mm take-off is available from HAFCO, not from Carbatec; works a treat.

Mick.

Quote:

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Originally Posted by BobL

Definitely cut the plate out to collect dust from the cabinet.

BUT

Cabinet dust collection generally does poor job at collecting dust from a BS.
Most of it spills out from under the table before it even gets to cabinet.

I found I get better dust extraction by extracting from directly under the table like this.
I also collect from the two existing cabinet ports, one is on the lower cabinet and the other one visible in the photo.
The second port is also supposed to collect from under the table but does very little.
Attachment 425994

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Hi Bob, where do you get those bell mouth ends?.

A few thoughts that may be worth contemplating - or not.

IMHO when Bandsaw manufactures say "good dust collection design - dual ports blah blah" what they are really saying is "good chip and visible dust extraction FROM THE LOWER CABINET" - just think about those last four words for a few seconds.

This is completely different to efficient dust collection for the operators health and workshop environment. You have only got to look at the typical YouTube video where they test dust extraction efficiency by opening the cabinet door and show only 1" of chips and dust instead of the normal 6", and then tell you how great the improvements are on this model - well yes, they are - for the lower cabinet - but never mind the dust all over the floor from below the table and above the lower guides or the bad stuff that the operator breathed in.

As BobL posted, under table dust extraction around the guides, blade and table blade opening is the absolute KING when it comes to a BS. There are a number of ways to setup under table extraction and it may depend on the room available and the flow path around and across the lower guides. IMHO exactly how much flow you need at this point for effective dust capture is influenced by two things - 1: how close you can get to the guides and 2: how well you can funnel / enclose the space between the table opening and the top of the cabinet, that's the area around the blade and lower guides, this funnel effect can restrict dust from escaping in the first place, thereby allowing you to focus all available flow through the enclosed tunnel surrounding the blade and lower guides.

My testing has shown that the lower cabinet ports and lower cabinet dust extraction is just wasting your available system flow rate for virtually little gain. The question I asked myself was this: Am I trying to keep the lower cabinet clean? Or am I trying to keep the dust out of the workshop? They are not the same thing.

Lower cabinet extraction is used by manufactures because they provide no under table extraction. Once you add effective under table extraction do you really need that much extraction from the cabinet? There are other ways to keep the cabinet clean that don't waste precious vacuum and flow rate.

Some of the tests I carried out included blocking off the cabinet dust ports and running just two dust extraction points - DE 1 is below table and DE 2 is the important above table. This resulted in minimal dust in the lower cabinet, dust there is mainly from chips that release from the gullet as the blade bends over the lower wheel, and a few chips that are pulled in by the suction / down draft effect caused by the high speed blade running into the lower cabinet, which is the dust that gets past under table extraction.

In the end I settled on a single small 80mm pipe into the lower cabinet with a small 60mm opening added in the door opposite the cabinet dust port, a grill over the door intake is fitted for safety. This port allows a small amount of air to flow across the blade to remove some of the dust following the blade, it also reduces cabinet vacuum at the blade entry slot from fighting below table suction - they are on opposite sides of the lower cabinet blade slot and WILL fight each other, now it may be a small effect but I don't want to PULL dust into the lower cabinet, I need only remove some of the dust that comes in with the blade air flow, and if your below table extraction is working correctly then there should be minimal dust in the cabinet. There should be NO dust underneath the table or anywhere between the table and the cabinet, the only dust on the floor will come from handling the timber and depending on the type of work, any large dust particles that fall from the top of the table.

Restricting flow into the lower cabinet allows more system flow / vacuum to be used for the two main extraction points. The above table pick up is positioned above the timber and close to the blade and ends up being not far below the operators head line, the idea is to grab any dust ejected by the blade as it enters the work etc, thus helping to keep this dust from your lungs, it's not really there to capture any dust sitting on the top of the table.

After each cutting session I vacuum up any dust in the cabinet and remove any sticky crap form the tyres while I'm at it, it takes all of 15 seconds. I have a vacuum cleaner mounted in a cabinet on the outside wall - a must - or vent the VC outside. I use a long flexible hose (the good stuff) that connects to a through wall fitting and a mini cyclone with a BIG dust bin, the hose reaches just about everything in our small workshop, the hose is always connected and hangs on the wall. A flick of a switch and it's all ready to go. This setup along with strong cross flow ventilation keeps out small hobby workshop spotless, the dust collection results are verified with a particle counter, and my extreme sensitivity to wood dust and the fact that I no longer need to wear a mask in the WS - well except when I clean / empty the filter bags from our externally mounted DC.

i get what you're saying, but bear in mind up to now i've had no dust extraction on it at all in a 10m2 room, so i'd have to stop sawing every 5 minutes or so because the dust in the lower cabinet would be about 3 inches deep. So much of it that It would go up the blade into the top cabinet too.

I'll get a semi-rigid scoop for under table collection like optimark has done as i've just seen where i can buy that from, and then i'll save my pennies to get a room air filter which has been on the shopping list for a while at the wife's demand :-). It's such a small space that (on paper at least) it should be able to change the room's air about 40 times an hour :o

Quote:

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Originally Posted by artful bodger

Hi Bob, where do you get those bell mouth ends?.

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I "roll my own", See, https://www.woodworkforums.com/f200/i.../3#post1996096

During the last year I have made about 50 each of 100 mm and 150 mm sizes. A few spares have been given away to men's sheds while most have been sold to other folks but it's not something I want to be doing on an regular basis. My prices, plus the postage are such that it hopefully encourages others to also make their own but I realize not everyone has access to a lathe.

For anyone that is interested in purchasing these, shoot me a PM and I'll send you details and if you are still interested I can put you on a list. I tend to make them in batches when I get some spare time which is not very often so don't expect to get them too fast.

Quote:

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Originally Posted by sirex

i get what you're saying, but bear in mind up to now i've had no dust extraction on it at all in a 10m2 room, so i'd have to stop sawing every 5 minutes or so because the dust in the lower cabinet would be about 3 inches deep. So much of it that It would go up the blade into the top cabinet too.

I'll get a semi-rigid scoop for under table collection like optimark has done as i've just seen where i can buy that from, and then i'll save my pennies to get a room air filter which has been on the shopping list for a while at the wife's demand :-). It's such a small space that (on paper at least) it should be able to change the room's air about 40 times an hour :o

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This is an old photo so forget the other hoses. A simple pick up made with a few dollars of 100mm pipe, the fitting and elbow pull off from the side connection DE pipe, it doesn't get in the way and the connection to the DC is at the rear. This pick up will remove almost everything before it gets into the lower cabinet, however with a 2HP DC you may have to focus on just this one extraction point to do that, but this is a starting point - you will be surprised how well this works, because it forces air to rip across the underside of the table slot, it helps remove a lot of the dust from the table area around blade slot - as small as that may be it makes a difference.

There is a little more to the pick up in that it forces most of the intake air to flow between the table supports and take a path that engulfs the lower guides and blade.

http://www.brisdance.com/Wood/LongerPickup.jpg

http://www.brisdance.com/Wood/DChoodOn.jpg

This assembly pulls off from the side fitting which is bolted to the bottom of the table.

http://www.brisdance.com/Wood/NewHood.jpg

The bottom of the opening sits level with and against the top edge of lower cabinet, that's right at the base of the lower guides and is almost touching them. The top of the opening sits against the bottom of the table, the uncut sides of the opening rest against the table supports trunnions, the timber end piece completes the intake path and forces the intake air from the back of the underside of the table and between the trunnions to rip across the guides, blade and blade slots. There are aspects of this fitting that go against the normal thinking for size, shape, turbulence and flow resistance theory, however this thing works brilliantly. It takes 2 seconds to remove or fit and it cost virtually nothing as it was made from scraps.

Once you get something working you can experiment with above table pick up using a bell mouth, you may be able to balance the flow rate for best performance with the available DC.