Dust Collection Question

Dust Collection Question · 07-27-2008, 08:53 PM

I have had my dust collector (2hp Grizzly) set up for three months now and today ran into something that has me concerned. I haven't hard piped the system yet and I am using flexible hose. The hard pipe should be done next week. I have decided not to use a pre-seperator at this time due to space constraints. Anyway, today was the first time I jointed and planed with the dc hooked up. I was milling cypress and the hose plugged solid. I disconnected the hose and there was plenty of suction so the impellor is fine. I unplugged the hose by shaking loose the clog while holding the hose close to the inlet. My questions:

1. Was I taking too thick of a pass while milling?

2. Is this normal for wood like cypress?

3. Am I really making a mistake by not using a garbage can seperator?

DaveO · 07-27-2008, 08:59 PM

I have had that problem big time while planing Maple. I think it has to do with the structure of the wood. I never have that issue with Oak, it's opened pored and I think that the chips break up more before going down the pipe. The closed pore, tight grained nature of Maple causes the chips to stay together in longer pieces clogging the piping. I use a separator, but my clogs happen usually at the blast gate long before the separator.
I wouldn't think that Cypress would be similar in structure as Maple, but it could be.
Dave

Woodman2k · 07-27-2008, 09:10 PM

Geoff,
based on my personal experience with my Delta 1.5 hp unit do yourself a favor and get a trash can lid seperator.You will be a lot happier just taking out that can and dumping it than fooling with those bags on the machine, and they will fill up faster that you would like.The trash can lid seperator is not the top of the line but it works pretty good.I have mine on a 55 gallon can and its mounted on a dolly with casters.

Sanders Woodworking · 07-27-2008, 09:16 PM

I ran a ton of cyprus through the shaper, putting a 1/2" roundover on 5/4" boards. Must have stopped up the ductwork 20 times. It splinters very badly, especially on the shaper. The planer dust tends to wad up too. Mine is hard ducted. Like DaveO said, it was always at a joint, blast gate or Tee.

Dusty Sawyer · 07-27-2008, 11:12 PM

I've had the same problem on other wood when it is not dry enough. For some reason when it is wet it likes to stick together and sit at the bottom. I did get a trashcan separator and have been very happy with the results. How much are you taking off with each pass?

junquecol · 07-27-2008, 11:21 PM

Instead of a trash can separator, why not build a "Phill Thien special as Bas has done. Works much better than trash can separator according to claims of those who have built one. Personally I have no experience as I have a cyclone. When planing cypress, I had no problems.

bguil · 07-27-2008, 11:33 PM

My experience with planer shavings was similar when I had a 1 and1/2hp cyclone, connected directly to the planer with corregated plastic hose (5inch reduced to 4inch at the planer). Now, I have a 2hp pro cyclone piped 20 feet and have no problem with clogs. I think the major points to take away are that more powerful suction sure helps, keep the flex hose to a minimum and be sure that you are maintaining adequate velocity in the pipe (size pipes/hoses properly for your CFM). Also helps to minimize leaks in your ducting and other gates, and maintain velocity by keeping filters clean.

Bas · 07-27-2008, 11:47 PM

Originally Posted by Bigdog72

1. Was I taking too thick of a pass while milling?

Probably not. I've had clogs using my lunchbox planer taking barely 1/64" off a board.

Originally Posted by Bigdog72

2. Is this normal for wood like cypress?

Some woods are more prone to clogging. I've not had any problems with oak or cherry, pine and beech have given me clogs. But it's hardly scientific data.

Originally Posted by Bigdog72

3. Am I really making a mistake by not using a garbage can separator?

A trash can separator is a big help keeping the bags empty and clean. Especially if you add a baffle. This improves air flow and it's much easier to empty a garbage can instead of replacing the bag. But I wouldn't call it making a mistake. More like an error in judgement

I've never had a clog in the hard PVC pipe. The clogs have always been in the flex pipe between the machine and the blast gate. Periodically, you have to clean things out. The self-cleaning blast gates are probably a good idea, but undoing the 6 screws to get inside the gate isn't a big deal. How do you know the hose is starting to clog? For one thing, chips are coming out of the machine.....note to self: this means something.

Anyway, wood species, size of cut, grain, length/ width of board, they're all factors. One something gets caught somewhere (e.g. hose kink) things can build up quickly. I wouldn't worry too much about damaging the impellor. If the intake is constricted, the motor is basically doing nothing. It's much more dangerous to run the DC completely unobstructed (no gates, hose, splitter etc.).

skysharks · 07-28-2008, 06:41 AM

Geoff it's the nature of the wood species.
Like DaveO referred to.
The wood doesn't plane or joint off like Oak does in small hard pieces.
It's more stringy, I guess you could say.
Thus getting hung up in joints, tees. bends, and anywhere else that it can think of hangin up on.

Sometimes just a tiny bit of moisture in the wood will do the same thing in other wood.

JimmyC · 07-28-2008, 10:46 AM

Geoff,

If you're using the less expensive hose (corrugated) with the ridges on the inside, you may want to try a better hose with a smooth inside, they tend to have a lot less problems DAMHIKT

.

Jimmy

Bigdog72 · 07-28-2008, 10:55 AM

Originally Posted by JimmyC

Geoff,

If you're using the less expensive hose (corrugated) with the ridges on the inside, you may want to try a better hose with a smooth inside, they tend to have a lot less problems DAMHIKT.

Jimmy

I am going to finish the hard pipe and reduce the amount of flex. I am also thinking of using one of these: http://cgi.ebay.com/Cyclone-Separato...QQcmdZViewItem
I kind of wish that the garbage can seperators were a little easier to use.

JimmyC · 07-28-2008, 03:18 PM

Originally Posted by Bigdog72

I am going to finish the hard pipe and reduce the amount of flex. I am also thinking of using one of these: http://cgi.ebay.com/Cyclone-Separato...QQcmdZViewItem
I kind of wish that the garbage can seperators were a little easier to use.

I've been looking at getting that seperator also for my Grizz 2hp. DC, but I'd have to go with a filter set also, to maximize the suction. Right now I'd use one of the homemade Garbage can seperators ilke Bas's but I'm not sure that design would work with the 6" hose instead of 4".

Jimmy

Bas · 07-28-2008, 04:39 PM

Jimmy, I can't give you any first- or secondhand experience here, but in my opinion, it should work. In terms of pipe size, my 1.5HP Harbor Freight unit ("2 HP") would be happier with 5" than with 4", but you can't get PVC in that size. 5" would be pretty close to an optimal trade-off between velocity and volume. With 6", the velocity drops too much and I get clogs. For a true 2HP unit (i.e. 220V), 6" would be fine.

You can make your garbage can separator with 6" fittings, the principle should be the same as for 4". You won't find too many examples of that on the web, since most people that have 220V and go beyond the typical 1.5HP DC (JET, Delta, HF) jump straight to the 3HP/ 5HP full-blown cyclone (Oneida, ClearVue, Penn State). That doesn't mean a trash can (with or without baffle) won't work. And it's not like it's a big investment of time or money.

A canister filter is definitely better than a bag, no question.

Alan in Little Washington · 07-28-2008, 05:30 PM

Originally Posted by Bigdog72

1. Was I taking too thick of a pass while milling?

2. Is this normal for wood like cypress?

3. Am I really making a mistake by not using a garbage can seperator?

Oh, where to start . . . .

There are too many unknowns to give you a good answer. To really answer we need to know what size impeller on the Grizz? How long are your (flex) runs? What diameter is your flex? What size planer? What size is the planer's DC port? What type of DC filter do you have- bag or cartridge? and how clogged was your filter?

Unless you have a screen or other restriction (which should be removed) in your DC intake, a quick answer is that the flex is probably the culprit. It is likely compounded by a number of factors like blower size (too small), filters (clogged or too small), flex size/shape (interior should be smooth), bends (every bend affects air flow) in the flex, etc. etc. Flex should be used sparingly in a well designed DC system. No flex is best but likely impractical for most, since it is easier to connect machines to your duct work with a one or two feet of flex. Cypress is not likely the problem, there are other more fibrous woods.

Frankly, a properly designed DC should be able to handle anything any woodworking machine can throw at it, dust and chip wise. Remember, DC's are, or should be, designed to accomplish two things. One is general cleanliness and convenience and the other is environmental health safety- (1) remove dust and chips from your machines and collect it in a central location (2) capture as much free air, fine, dust at the source AND NOT allow it to return to the air because of poor filter design.

(1) Requires a certain level of airflow (CFM) and velocity which both depend on the blower RPM, motor hp, ducting (diameter, length, number of bends), and filters. You must maintain a certain air flow to keep the chips and dust in suspension as it travels through the duct work.

(2) Requires even more flow to ensure most dust is captured at the source. It also demands a quality filter that traps particles down to .5 microns. The problem with using a DC without a pre-separator, is that too much dust will clog the filter, reducing flow. The old DC's with bag style filters, typically only filter particles down to 5 microns, and some only to 30 microns. These bags are actually designed to filter/filter better when they are caked with dust. There is a point, however, where the caking reduces air flow too much.

While some folks have had reasonable success with trashcan separators- the performance (separation of fine dust, reduced airflow resistance, etc.) of a cyclone far exceeds that of a trashcan separator.

As far as the cyclones being sold on Ebay- I've said this before- they will work to a degree, like a trashcan separator, but do not work nearly as well as a well designed cyclone like one based on the Bill Pentz design (either homemade or a ClearVue.) The cyclones being sold at the Ebay link are based on an old design published in Wood Magazine (8 - 10?) years ago, and have significant design deficiencies- specifically, bad inlet geometry, lack of neutral vane, lack of spiral inlet ramp, etc. but they are the cheapest ones available.

Frankly if I wanted the best and cheapest I would build a Pentz design (which I have done). It cost less than $100 in sheet metal and MDF, and is arguably the best home cyclone available anywhere at any price.

I suggest you spend some time reading the wealth of info on Bill Pentz site.

(The best DC system is one with a monster blower (3 - 5 hp motor and 14" - 15" impeller), large diameter (6" - 8") duct work, that discharges outside with no filter backpressure.)