fixing dust collector leaks

[skamath]

hi,
i feel like my HF DC setup leaks. (i have the wynn filter on top with a plastic bag.)

the bag itself seems to be fine (i couldn't see visible leaks), maybe it is the joints.

the plastic bag used to release dust where the strap left a seam. i could make those out because the dust spray was visible. to fix that problem i put a masking tape and it looks well sealed now.

also i put couple of layers of masking tape where the hose goes (at the DC end) so the hose is clamped on something softer rather than hard plastic. (it secures it better.)

any comments/suggestions on how to detect and fix leaks?

thanks!

[dbhost]

DC leaks will be pretty obvious because, well dust will be around where the leak is, just check where there are joints, or components like the handle, and upright bars mount, light colored wood dust shows up really well against that green...

Almost all bag type DCs will leak where the bags mount.

I would also check where the tube that hose you taped up, goes into the inlet ring. That CAN leak but doesn't do it often. If it leaks, clean it, and run a thin bead of clear silicone around the joint. Same thing with where the two halves of the DC impeller housing meet.

I had the same leak problem with the bag mount, and fixed it with some thin foam weatherstripping tape.

[LCHIEN]

the leaks are easily found as you already know by the dust trails they leave.

The plastic catch bag is slightly larger diameter than the ring it mounts to so there's a couple of pleats where the excess is captured under the metal band and you can see it leaks a tiny bit there.

I'm sure that the total cross section area of this leak is infinitesimal compared to the four inch minimum diameter of all the holes and plumbing thae air goes though so the total loss is much much less than 1%, probably much less than .1% so I'm not particularly worried about it except for cosmetics.

Your approach is probably satisfactory along with the suggestion to use some silicone caulking where appropriate to provide a more compliant landing.

[skamath]

thanks for the replies!

i don't have dust trails just fine dust collecting over the DC. maybe it is inadequate collection at the table saw. (i do have the JDS overhead air cleaner.)

i am also reorging my machines around the DC. i am tired of having to plug in/out the machines and DC hose. so what i am doing is use the two inlets, one permanently on the table saw and the other on one of the other machines.

will this setup be OK for the HF DC? the other thing i could do is connect couple of Y fittings on each of the two inlets and hook up all the 4 major machines: table saw, planer, jointer and bandsaw. would i definitely need blast gates for this setup. maybe i only need the blast gates for the other machines.

thanks again! (sorry to pile on to this thread.)

[phi1l]

DC leaks will be pretty obvious because, well dust will be around where the leak is,

... ummmm .. well since DC piping is mostly under negative pressure this isn't exactly true. you need to get a smoke puffer ( http://www.professionalequipment.com...s/?source=pegs ) & use it at the joints to find any leaks.

But it sounds like your system just isn't efficient enough for the small particle sizes. It's a funny thing about air filter systems, though, they get more efficient the more they are used. So I would clean up the existing dust, a few time & see if the performance gets better, before I made any changes.

[LCHIEN]

... ummmm .. well since DC piping is mostly under negative pressure this isn't exactly true. you need to get a smoke puffer ( http://www.professionalequipment.com...s/?source=pegs ) & use it at the joints to find any leaks.

But it sounds like your system just isn't efficient enough for the small particle sizes. It's a funny thing about air filter systems, though, they get more efficient the more they are used. So I would clean up the existing dust, a few time & see if the performance gets better, before I made any changes.

true about negative pressure, but leaks into the duct system are of little concern. I think he's talking about leaks on theoutput of the impellor to the bags which is under positive pressure.

SKAMATH, if you are getting fine dust all over the machine with no trails, then you don't have pinpoint leaks but your filtration is passing fines or they are not getting picked up in the first place. If your filter is too coarse (liek 30 micron bags) then you will get a fine layer of fine dust all over the shop - this is not good and you need to go to 1 micron or so filter canisters, which, if you have the wynns, they should be.
That leavs the other, not picking up fines at the source. this is symptomatic of a), not enough air flow at the source due to excessive longs runs and pressure drop in the ducting or hoses. or b) suction inlet too far from the source allowing the fines to scatter before being picked up by the air flow. Actually b is a case of a.

[skamath]

thanks Loring and phi1l!

the hose is 5 ft and the table saw is 22124. it is probably case b (typical cabinet saw dust collection.) i guess i could trim the hose down somewhat since the DC is going to be pretty close to the table saw. that should help significantly some.

[phi1l]

A couple other things you might try:

1) I have the Sears BTS21 clone, which has notorious bad dust collection. I found that & could correct the problem nearly entirely by taping a piece of thin cardboard to extend the blade enclosure up to (or nearly up to the table top. THis works as long as you are making 90deg (or nearly) cuts. (for severe bevels the cardboard gets in the way.)

2) Another thing that will improve dust collection is a zero clearance insert.

And, yes, get a more efficient filter bag if the efficiency doesn't improve to acceptable levels soon.

[dbhost]

A couple other things you might try:...

2) Another thing that will improve dust collection is a zero clearance insert.

And, yes, get a more efficient filter bag if the efficiency doesn't improve to acceptable levels soon.

A Zero Clearance Throat Plate will only keep more of the dust on top of the saw, instead of allowing it to get pulled below the table. ZCTPs are great for preventing tearout on the back of a cut, but do nothing positive for dust collection... However punching breather holes in a ZCTP will help...

And since the OP has the Wynn cartridge filter, I doubt it is filtration level problem... Rather dust not getting picked up, or blown around...

On the negative pressure issue. Before the impeller housing, unless it is a HUGE leak, I wouldn't worry about it because it is under below ambient pressure (Dust collectors aren't powerful enough to create TRUE vacuum.). So the negative pressure is negative relative to ambient... On the output side of the impeller housing however, you are dealing with greater than ambient pressures, and this is where I would expect to have a dust collector leaking dust from. Which is why I mentioned what I did in my first post... Sure a smoke puffer will tell you where a dust collection system is taking air in where it shouldn't, but air coming in to the system is not the problem the OP is addressing...

Along with what Loring mentioned in his last post, I would take a look at insufficient dust hood at the tool. For example if you have a saw with a 2.5" port and open bottom, expect you are not going to get much dust collection actually done at the table saw, and a fine layer of dust all over everything...

Since you mention that the table saw is a 22124, I would look at the top side of the saw... A Shark Guard, and a ZCTP with breather holes will likely help alleviate your problem...

[Iansaws]

A Zero Clearance Throat Plate will only keep more of the dust on top of the saw, instead of allowing it to get pulled below the table. ZCTPs are great for preventing tearout on the back of a cut, but do nothing positive for dust collection... However punching breather holes in a ZCTP will help...

I have a similar problem with dust coming off the top of my BT300. I have installed a ZCTP and as you predicted it made the matter worse. I also installed bottom side DC and use the standard rear DC port as well. Regarding breathing holes in the ZCTP..how many, how big and where should they go. Can I expect this to eliminate the need for a top mounted dust collector arm for my TS?

[dbhost]

I have a similar problem with dust coming off the top of my BT300. I have installed a ZCTP and as you predicted it made the matter worse. I also installed bottom side DC and use the standard rear DC port as well. Regarding breathing holes in the ZCTP..how many, how big and where should they go. Can I expect this to eliminate the need for a top mounted dust collector arm for my TS?

I have only been experimenting with mine thus far, but I have 3 3/8" holes drilled into the ZCTP, and it helps. It doesn't get everything, but it is awfully close.

[Iansaws]

I have only been experimenting with mine thus far, but I have 3 3/8" holes drilled into the ZCTP, and it helps. It doesn't get everything, but it is awfully close.

Any chance you could post a picture of this? Location of the holes would be crucial I assume.