Why would my cyclone stop diverting dust?

[mrFinpgh]

This afternoon, I was jointing some southern yellow pine to build a stand for my midi lathe.  This wasn't a lot of material - less than 100 sf of material before ripping/crosscutting/etc.  By the time i got to the last 8 or so pieces, I noticed the 'problem light' on my Metabo vac flashing, indicating an issue with suction.  My jointer is an 8" benchtop model, and I typically take light passes.

After checking the hose for obstructions and ensuring my dust deputy was not full, I checked the vacuum itself and found the inlet fully clogged. Further investigation uncovered that the fleece bag was completely full!

I have a fair number of bags, so I'm not too worried about wasting one, but I am not sure why this would be happening. The dust deputy generally performs like a champ, and I've been using it for four or five years now without issue.  I did build a new 'bucket' for it, so I can go longer between emptying it and place a liner in so I can bag up the dust rather than dump it out. 

Once I get a new bag in there, I'd prefer it if this doesn't happen again. Does anyone have any suggestions about what I should investigate for the reason it would be failing to divert as much dust as should?

 

[woodferret]

I've had occasion where the dust manages to build itself a skateboard ramp back up the walls of the bin.  When that happens, jailbreak!

 

[Michael Kellough]

Could be simply because jointer chips have a much higher ratio of surface area to mass (compared to saw dust) so maybe they don’t fall down the cyclone fast enough to be captured below.

 

[MikeGE]

If there is a break in the seal between the cyclone and the bin, the chips and dust will most likely be diverted to the vacuum bag.  This happened once on my large shop extractor, and I didn't recognize the symptoms until it was too late.  It took me hours to dismantle the air plenum and clean out the filters.

This will also happen if the collection bin is full, or the cyclone outlet to the bin is clogged.  I know this from experience as well, but that time I caught it in time.

 

[jeffinsgf]

Quick question about your bucket liner...do you have a relief hose running from the bottom of the bucket up to your inlet? If not, it's likely the bag is being sucked up, closing off the bottom of the cyclone and diverting the chips to the vacuum. Just turn it on and look through the top of the bucket...if the bag is being sucked up...there's your problem.

Interesting timing on your post. I've been running a Dust Deputy for a few months, almost exclusively on the top blade guard of my SawStop and on a SCMS the rest of the time. I looked in the bucket (no liner) and was disappointed with the amount of chips in there. Opened the vac and found the fleece bag had far more in it than the bucket. Not sure why, but I am guessing it is the light weight of the majority of the load??

 

[ChuckM]

Snip.

Interesting timing on your post. I've been running a Dust Deputy for a few months, almost exclusively on the top blade guard of my SawStop and on a SCMS the rest of the time. I looked in the bucket (no liner) and was disappointed with the amount of chips in there. Opened the vac and found the fleece bag had far more in it than the bucket. Not sure why, but I am guessing it is the light weight of the majority of the load??

Something must be wrong there.

I use two DDs for the Kapex and drill press/sanding station. This is what the vac bucket (for the Kapex) should look like when the DD bucket (no liner or bag) has been close to full TWICE or more:

[attachimg=1]

In addition, the chip/dust size doesn't seem to affect the dust collection in my case:

[attachimg=2]

 

[Crazyraceguy]

If there is a break in the seal between the cyclone and the bin, the chips and dust will most likely be diverted to the vacuum bag.  This happened once on my large shop extractor, and I didn't recognize the symptoms until it was too late.  It took me hours to dismantle the air plenum and clean out the filters.

This will also happen if the collection bin is full, or the cyclone outlet to the bin is clogged.  I know this from experience as well, but that time I caught it in time.

Any kind of issue with the big units is a compound problem for sure. We had a single bag fall off of its connection in the bag house once about a year ago. It put about a foot of dust all over the inside of the house. All of the bags had to come out and the whole thing needed cleaned out. Major PITA, because it shuts down all of the big equipment until it's back in service.

 

[mrFinpgh]

If there is a break in the seal between the cyclone and the bin, the chips and dust will most likely be diverted to the vacuum bag.  This happened once on my large shop extractor, and I didn't recognize the symptoms until it was too late.  It took me hours to dismantle the air plenum and clean out the filters.

This will also happen if the collection bin is full, or the cyclone outlet to the bin is clogged.  I know this from experience as well, but that time I caught it in time.

So the cyclone is attached to the lid of the bin w/ a gasket. I have two latches that pull the lid tight to the bin, with a gasket running the perimeter of the lid. Interestingly, when I turn the cyclone on, if the latches are free, it will suck the lid tight to the bin and compress the gaskets on the bottom of the lid

Thankfully, this is only on a shop vac type unit, so worst case is I change the bag and mess around with the cyclone.

 

[mrFinpgh]

Quick question about your bucket liner...do you have a relief hose running from the bottom of the bucket up to your inlet? If not, it's likely the bag is being sucked up, closing off the bottom of the cyclone and diverting the chips to the vacuum. Just turn it on and look through the top of the bucket...if the bag is being sucked up...there's your problem.

Interesting timing on your post. I've been running a Dust Deputy for a few months, almost exclusively on the top blade guard of my SawStop and on a SCMS the rest of the time. I looked in the bucket (no liner) and was disappointed with the amount of chips in there. Opened the vac and found the fleece bag had far more in it than the bucket. Not sure why, but I am guessing it is the light weight of the majority of the load??

When I first tried my bin with liner approach, I did run into what you describe - it sucked the green liner right up into the cyclone part. I thought about the relief hose but ended up putting in a complex system of a cross brace (scraps) and a tube (scrap ram board, taped end to end) to hold the liner open. 

Now that you mention this.. one thing is occurring to me. I think I also put some heavier scraps in the liner before.  It could be the case that the liner is collapsing more now than it was before I changed it out.  I will need to check this and put some offcuts in there.

 

[mrFinpgh]

In addition, the chip/dust size doesn't seem to affect the dust collection in my case:

[attachimg=2]

Chuck, this is basically my 'normal' experience with the cyclone.  Almost everything typically ends up in the bucket and my bags were lasting a very long time unless I started working on projects around the house. 

My best guess is that the issue is with the liner somehow collapsing and reducing the impact of the cyclone, despite my efforts to keep it more fully open.  It seems like that would have the same net effect as if the bin was overly full.

I had to stop milling today so I could glue things up. Tomorrow I'll change the bag and see if I can get the liner to stay open.

 

[luvmytoolz]

When I first tried my bin with liner approach, I did run into what you describe - it sucked the green liner right up into the cyclone part. I thought about the relief hose but ended up putting in a complex system of a cross brace (scraps) and a tube (scrap ram board, taped end to end) to hold the liner open. 

Now that you mention this.. one thing is occurring to me. I think I also put some heavier scraps in the liner before.  It could be the case that the liner is collapsing more now than it was before I changed it out.  I will need to check this and put some offcuts in there.

When I started using bags in my DD they would always get sucked up and block immediately, I ended up cutting a bunch of waste mdf sheet into circles and placed one inside the bag so it held it open and stopped it being sucked up.

 

[Steve1]

Any chance you accidentally swapped the inlet and exhaust hoses to you Dust Deputy ?

 

[jeffinsgf]

Any chance you accidentally swapped the inlet and exhaust hoses to you Dust Deputy ?

Thank you, Steve! I can't believe I put that together wrong and ran it wrong for 4 or 5 months. Amazing...when you have the right hoses going to the right places, it works just like the online videos.  [big grin]

 

[ChuckM]

Onedia's fault!

Better (arrow) markings on the cyclone indicating the outlet and inlet will prevent that kind of mistake from happening.

 

[jeffinsgf]

Onedia's fault!

Better (arrow) markings on the cyclone indicating the outlet and inlet will prevent that kind of mistake from happening.

Jeff's Fault!

Should have read the instructions more thoroughly and/or scratched my head when it didn't work as advertised.

 

[ChuckM]

The reason I attributed the fault to the manufacturer is that we woodworkers are infamous for not reading user manuals or reading them poorly (thanks to many many poorly written manuals), and clear markings on the product would help. In fact, every time I disassemble the DD unit to clean the shop vac's HEPA filter, I have to make a mental note of the inlet and outlet ports.

 

[squall_line]

The reason I attributed the fault to the manufacturer is that we woodworkers are infamous for not reading user manuals or reading them poorly (thanks to many many poorly written manuals), and clear markings on the product would help. In fact, every time I disassemble the DD unit to clean the shop vac's HEPA filter, I have to make a mental note of the inlet and outlet ports.

To this point, industrial design, UX, and other philosophies should seek to make the user's life easier, or at least not unnecessarily complicated.  Printing/relieving/embossing in and out arrows is fairly trivial at the design phase and incurs no extra cost if incorporated directly into a mold.  And it makes the manual shorter and less necessary.

I tell my techs all the time when I'm building automations and processes that "if something I've changed has made your work harder or more confusing, it's the wrong thing to do. Please tell me so that I can make it better, not worse."

Absent a proprietary hose and keyed inlet and outlet ports, including clear design elements to assist the user in working with the product in the correct manner without instructions or a "cheat sheet" is the right thing to do.

To wit, the CT VA-20 has an embossed dust collector pictograph above one port, and an embossed hose pictograph above the other.  It makes it fairly trivial to know/remember which is which.

 

[luvmytoolz]

The reason I attributed the fault to the manufacturer is that we woodworkers are infamous for not reading user manuals or reading them poorly (thanks to many many poorly written manuals), and clear markings on the product would help. In fact, every time I disassemble the DD unit to clean the shop vac's HEPA filter, I have to make a mental note of the inlet and outlet ports.

What are these "manuals" you speak of? ;-)

 

[Steve1]

  Printing/relieving/embossing in and out arrows is fairly trivial at the design phase and incurs no extra cost if incorporated directly into a mold.

Perhaps.  Depends on where the mold is split and the direction it opens/closes.
But where there is a will, there is a way.
The 6" diameter top cap could definitely have some added text,  "--> to vacuum" beside the top center port.

Yes, there should be indication on the unit showing the direction of flow.  My solution involves a black marker. 

[attachimg=1]

 

[ChuckM]

Snip.  My solution involves a black marker. 

[attachimg=1]

Your marking is exactly what Oneida should've done...but in a more elegant manner, of course.

The use of arrows or directional signs is nothing new to help users do it right without trial and error:

[attachimg=1]