Phil Thien's Baffle and Bill Pentz

[David Hostetler]

...
All that said, I own an underused HF DC with Wynn filters and an air filter and intend to add your separator, I just don't delude myself that that's as good as it gets, and will continue to wear a mask while sanding.

Very well said, that setup isn't as good as it gets, but for some of us, it is as good as we can manage... And for a good number of us, better than some can manage. (You'd be suprised how many guys are running the HF 1 HP DCs due to budget!)...

BUT... To be honest, if you want to be TRULY safe, doing those sanding operations even with a full on Clear Vue, and the best hood designs, you will still want to wear a good quality respirator... Just because you captured that additional bit of dust, doesn't mean you got all of it, and if you want to be truly safe, you avoid the exposure entirely...

Now for the wrench in the works.... Can you ever be 100% truly safe? I mean a jet engine could break off of a passing plane, smash through your roof, and kill you before you are done reading this...

[Phil Thien]

In Alan's scenario, he's assuming that you just entered the shop after the heat was shut off for a very long time and everything is very cold. Now, your heating system must heat up the shop, warm its contents and also heat the make up air ejected by your dust collector as you work in the cold shop.

Oh, that explains it!

Sorry.

[Randy Klein]

I mean a jet engine could break off of a passing plane, smash through your roof, and kill you before you are done reading this...

Ha, finished reading.

[Mark Engel]

Can you ever be 100% truly safe? I mean a jet engine could break off of a passing plane, smash through your roof, and kill you before you are done reading this...

Whew, it missed me!

[Alan Schaffter]

So leaving the 30 micron filter bags on the DC is a better option if outside exhaust cannot be used?

First, if it were me, those 30 micron sieves would be gone in a flash.

You will need to decide what is worth it to you. If outside exhaust is not an option, you need to check prices, expected life, benefits, and disadvantages of a cartridge filter vs a high efficiency bag filter of the same rating, like one from American Fabric Filter, etc. Frankly, whatever filter you decide on, I would build or buy a cyclone or other pre-separator.

[Mark Engel]

The DC I am using now is an old Reliant 3hp, 4 bagger. I replaced the original cloth bags with needle felt bags rated at .5 micron. The bottom 2 bags are clear plastic. The needle felt bags are much larger than the old cloth bags. In addition I have a Thein separator sitting on (in) a 40 gallon Rubbermaid Brut trash can, on wheels.

The only thing that drops down into the plastic bags is very fine dust. Since I built the Thein separator over 2 years ago I have never had more than an inch or two of dust in the plastic bags.

I also have a JDS 750 air filter suspended from the ceiling.

[Bruce Wrenn]

I have a Wood magazine cyclone that I built. It doesn't have a neutral vane (yet). I have seven 6" X 65", 0.5 micron filter socks on it. But it is located in the back corner of my shop. I use my planer (15") and jointer on the slab in front of my shop. I got tired of sending the shavings to the cyclone, and then having to haul them back to the front for disposal, so I built a Phil Thein Baffle. I was, and still am amazed at how well the baffle gets the shavings, and most of the dust. As an experiment, last week, I cleaned out cyclone dust bin, including brushing it clean. I ran six 5/4 cypress boards through both jointer, and planer, reducing them to 3/4". I collected two 30 gallon cans of shavings at the baffle, and not one piece in the cyclone, only some fine dust. For some pictures of my baffle, and results, google Phil Thein, and look for my post "Another Vote for Phil Thein's Baffle."

[Dan Friedrichs]

Have you done any tests with your baffle with and without the back-pressure of a filter? Do you see any change in pass-through?

I have a Thien baffle to separate chips and vent the rest outside.

I haven't done a quantitative evaluation of back-pressure, but qualitatively, I can tell you that the Thien baffle didn't seem to reduce my airflow, the 5micron bags had very low air flow, 30 micron bags had moderate airflow, and venting outside with the Thien baffle in place had significantly more airflow than I had even with the 30 micron bags.

$0.88/hr in the worst climate (-5F) reasonably imaginable. If you ran it an hour a day, every day, for 5 years, you'd just be getting to the cost of an Oneida cyclone....

[Alan Schaffter]

I have a Thien baffle to separate chips and vent the rest outside.

I haven't done a quantitative evaluation of back-pressure, but qualitatively, I can tell you that the Thien baffle didn't seem to reduce my airflow, the 5micron bags had very low air flow, 30 micron bags had moderate airflow, and venting outside with the Thien baffle in place had significantly more airflow than I had even with the 30 micron bags.

$0.88/hr in the worst climate (-5F) reasonably imaginable. If you ran it an hour a day, every day, for 5 years, you'd just be getting to the cost of an Oneida cyclone....

That is good to know! What kind of deposits do you get outside? Are you in a neighborhood or in the woods? Does it build up on the grass, or mainly blow away. Have you ever over-filled your dust bin and if so what kind of mess does it make outside?

For the reasons stated in my post, I honestly think you have the best setup to maximize CFM and minimize all the hassles with filters and dust escaping back into the shop AND the least expensive! And, if you limit your DC operation to the times you are actually creating dust, the cost of additional cooling or heating will be minimal and the benefits well worth the expense.

[Dan Friedrichs]

That is good to know! What kind of deposits do you get outside?.

Absolutely nothing. No wood flour or anything. My vent points down to the ground, about 8" above the ground.

Are you in a neighborhood or in the woods? Does it build up on the grass, or mainly blow away. Have you ever over-filled your dust bin and if so what kind of mess does it make outside?.

In a close-in suburban neighborhood. The vent noise is probably about 4x louder than a dryer vent, or maybe 1/3 as loud as a shop vac. I've never had any complaints.

Nothing at all appears on the grass, and I've never overfilled the bin (yet!)

For the reasons stated in my post, I honestly think you have the best setup to maximize CFM and minimize...

I agree! I don't have an instrument to measure airflow, but by holding an index card in front of an open gate, then measuring the angle that it deflects (my very high-tech airflow measurement set up...), I see a huge difference between venting outside and using 30 micron bags.

I think anyone considering this should try taking the bags off their DC and "feeling" how much more airflow they get.

[Nathan Callender]

Not to get too far OT, but...

If we're removing 70F air and replacing it with -5F air and enough energy to reheat it to 70F, why do we care about the thermal mass?

If some of the energy to reheat the -5F air to 70F comes from the thermal mass, then that energy will have to be replaced by burning the gas we didn't use to heat the air.

In any event, it looks like we'd have to spend $.88 to reheat the conditioned air for one hour of running an 800-CFM DC exhausted outside (assuming the national average of $13.68 per 1000 cubic feet of natural gas).

And yes, I agree that an hour is a long time. I figured it was at the very top end of what someone may do during a fairly busy weekend day in a shop.

Seems like a no-brainer, provided you take care of any CO issues.

I bet if you were using radiant heating, (like the overhead kind) this would even be less of a problem as the air temp doesn't really matter all the much if you are standing under one of those things. This could actually make the 'venting outside' thing workable in the winter.

As for summer, I think running this with and A/C would be very problematic you would need a machine that can match the output of the DC. But, maybe if we run the numbers, it might still make sense. However, I can deal with a hot workshop better than a freezing cold one!

I work in a garage, so whenever it's not freezing outside, I can open up the door and set up a fan and get the best air cleaner ever. :-) So, the DC is more for chip collection than anything else, but in the winter it becomes a problem.

Venting outside does force someone to go to a stationary DC and ducts - this definitely adds cost so that's the downside to it, along with a neighbor that might complain.

[Phil Thien]

As for summer, I think running this with and A/C would be very problematic you would need a machine that can match the output of the DC.

That was a concern. My air conditioner is a two ton (24k BTU) and runs a lot more to keep the house comfortable in the summer than my furnace runs (even on the coldest days) in the winter.

[Mark Beall]

That was a concern. My air conditioner is a two ton (24k BTU) and runs a lot more to keep the house comfortable in the summer than my furnace runs (even on the coldest days) in the winter.

Could an air-air heat exchanger be added to recover some of the heat (cooling) loss? I really have no idea if the pressure loss of one of those would make the idea pointless. I do recall (it's been a while since I looked at this) that they can deal with the humidity issue to some extent in the summer also.

Just a thought,

mark

[Dan Friedrichs]

As for summer, I think running this with and A/C would be very problematic you would need a machine that can match the output of the DC.

If you vented inside, all the power that goes into the DC motor gets turned into heat. 5HP DC = 3.7kW of heat that you also have to remove.

[Alan Schaffter]

If you vented inside, all the power that goes into the DC motor gets turned into heat. 5HP DC = 3.7kW of heat that you also have to remove.

Good point, unless you have the DC outside. You also have some heating due to air friction, though I don't have a feel for the amount. We have one of those bubbler tubs in our master bath that uses a very high velocity fan to heat the bubbler air via friction, there are no electric heating elements.

If you looked at my video (link at prior post in this thread) you will see I have a very efficient and nice DC with a true 3 hp motor, 14" impeller, 3D cyclone, and twin (parallel) 300 sq. ft Farr-type 9L300BL filters returning air to my shop. I also have a high dust alarm to prevent disastrous back-ups. But . . . near the top of my "to do" list is to add an outside discharge/filter bypass blast gate. I plan to use my DC in the filter-bypass mode most of the time, unless the weather is at one extreme or the other.