Thread: Question re Carba-Tec Dust Extractor

Originally Posted by TORB

I have a Carba-Tec 1HP Dust Extractor and it generally does an OK job.

Where the sawdust etc enters the extractor, before the fan, there is a guard to stop large bits hitting the fan blade and potentially damaging the blades. (It has a circle in the middle and four spokes coming off it and going to the outer edge of the opening.)

Every time I use my jointer, the shavings quickly block the hole. When that happens there is not enough suction to pull the chips/shavings into the hose and the waste just shoots out the machine.

Anyone else have the same problem, and has anyone removed the guard?

Yep I recommend removing it, and as well as not getting blocked it gives you about about 20% more airflow as well.

However you will need to watch out for stuff like rags and sticks that will then be able to get into the impeller. Things like rags can wrap themselves around the impeller and they can be a right PITA to untangle.

A more significant problem with 1HP DCs is they just don't have enough total flow to grab fine dust at source so your shed will fill quickly with invisible (ie more dangerous) dust. Ideally the DC should also be outside your shed - then you could run it for a while after your last dust making activity to help vent the shed.

Thanks Bob. I will remove the guard. I keep things pretty clean and organised so the chances of sucking up something like a rag is pretty remote. However, I will have to keep an eye out for little bits of wood when I am vacuuming.

I don't have a dust problem as my "shed" is an open deck with a covered roof.

I found the same blockage occurring when using the thicknesser. I removed the guard and have not had any problems. I'm just careful as to what I put near the hoses.

Originally Posted by TORB

Thanks Bob. I will remove the guard. I keep things pretty clean and organised so the chances of sucking up something like a rag is pretty remote. However, I will have to keep an eye out for little bits of wood when I am vacuuming.

Very good

I don't have a dust problem as my "shed" is an open deck with a covered roof.

While this is much better than operating inside, It's far from a fool proof method. I have measured dust levels outside while operators were using routers and also an arbortech, and dust levels will go above above OHS within 2 minutes. I lost my sense of smell for 6 weeks with a couple of days of sanding MDF outside using an ROS.

I would make up a small Thien separator which collects everything, so nothing much goes through to the DC. They work well.

Originally Posted by Dengue

I would make up a small Thien separator which collects everything, so nothing much goes through to the DC. They work well.

How can something collect everything and then still allow something thru to the DC?

No dust or chip collector, cyclone or Thien collects everything, to do that they would have to catch and hold all the air they collect. Most small cyclones and chip collector connected to low power/volume flow are pretty useless at collecting the finest dust which is the one we should be concerned about for our health. To work effectively a cyclone needs to be well designed and well made otherwise all it does is reduce the pressure available for dust collection meaning it grabs less air and in turn that means grabbing less dust.

Originally Posted by BobL

Very good
While this is much better than operating inside, It's far from a fool proof method. I have measured dust levels outside while operators were using routers and also an arbortech, and dust levels will go above above OHS within 2 minutes. I lost my sense of smell for 6 weeks with a couple of days of sanding MDF outside using an ROS.

Interesting, but ignorance was bliss. Thanks for bursting that bubble.

Seriously, when routering, sanding etc, I use a dust mask. I learned very early on that if I didn't use a dust mask, I copped a bad hit of hay-fever for a few days.

Originally Posted by TORB

Interesting, but ignorance was bliss. Thanks for bursting that bubble.

Sorry

Seriously, when routering, sanding etc, I use a dust mask. I learned very early on that if I didn't use a dust mask, I copped a bad hit of hay-fever for a few days.

I'd wear it while using the jointer as well.

I would make up a small Thien separator which collects everything, so nothing much goes through to the DC. They work well.

Sorry, wasn't being pedantic enough

Should read " collects nearly everything except fine invisible carcinomerous dust"

Originally Posted by BobL

Sorry



I'd wear it while using the jointer as well.

Bob, I should have mentioned that I mainly use hardwood and don't often use MDF.

Ric

I can't remember if you have a pleated filter on your DC, if not I would start there. Remove the guard and add a chip separator Dust Separator Lid : CARBA-TEC.

The pleated filter and removing the guard will impove the performance, the chip separator will decrease it. Bob will know the figures I can't remember what mine were and since then I replaced my 1hp with a 2hp DC-6.

Gary Pye use to have the Jet separators which looked a little more efficient than the CT ones but I have not tested one.

Ross

Originally Posted by Ross

Ric

I can't remember if you have a pleated filter on your DC, if not I would start there. Remove the guard and add a chip separator Dust Separator Lid : CARBA-TEC.

The pleated filter and removing the guard will impove the performance, the chip separator will decrease it. Bob will know the figures I can't remember what mine were and since then I replaced my 1hp with a 2hp DC-6.

I have not measured the flow efficiency differences between different filters - something to add to the list.
According to BP if a DC system can generate 12" of static pressure then
- cloth bag filters will consume around 20% of that pressure (I question this and need to do some testing)
- needlefelt bags will consume around 8% of that pressure
- Pleasted filters between 2 and 4% of filters
- chip catchers can consume up to 40% of that pressure

The elephants in the corner are thus cloth bags and chip catchers. but there are diminishing differences after that.

One thing to bear in mind is, that once filters are conditioned (ie have a fine layer of dust covering their insides) filters are not usually the rate limiting step to flow especially if 4" ducting is used.
If 4" ducting is used the maximum flow possible using a 2HP or bigger DC is ~400 cfm and its all downhill from there - on a 1HP it's about 350 cfm.
If 6" ducting is used the maximum flow possible using a 2HP or bigger DC is ~1250 cfm and its all downhill from there.
Adding a pleated filter will retain the maximum flow for longer but I do not know for how much longer. The other advantage with pleated filters is they can be cleaned without removing them.

Placing a chip collector in line will not only drop the pressure differential and reduce flow BUT it also changes the composition of the dust that then coats the inside of the filter. The resulting composition seems to block all filters including pleated filters equally badly and quicker than not using the chip collector. Form what I can tell most people using chip collects use them so they don't have to empty the DC collection bag but it appears that the DC filters may need to be cleaned MORE often than if a chip collector is not used.

There does not appear to be that much difference between the dust filtering efficiency of Pleated filters and needlefelt bags. As to be expected, cloth bags are generally inferior but not as much as might be expected. The achilles heel on all systems is LEAKS. Most DCs I have looked have leaks, especially those on wheels that are moved around to different machines. This is the main reason why DCs should be outside.

Bob, Phil Thien will be after your hide. His views are very contrary to what we believe to be best practise.

Originally Posted by Chris Parks

Bob, Phil Thien will be after your hide. His views are very contrary to what we believe to be best practise.

I guess he can join the queue along with the vacuum cleaner sales people.

That aside I'm thinking of dragging out the small (40L) chip collector I made last year for testing purposes and/or buying a vacuum cleaner for the shed. SWMBO has started rock/glass polishing and cutting in the shed and currently she has her own 4" DC flexy line to keep things tidy but I'm worried about glass fragments in the DC.