Thanks Phil

[JakesDad1]

I setup my current shop a couple of years ago. I moved from the basement with no dust control to the garage. Again with no dust control and too cold to work in the winter. So I convinced my wife that if I bought a shed to move my shop to, I would not be tracking sawdust into the house. She bought it!!!

After spending a ton of money on the shed and wiring it, I was not in a position to spend $$$ on a cyclone. I found this website and am very thankfull for it!!! I 've started using the shop quite a bit lately and I just can't get over how nice it is to not be constantly buried in saw dust. I used several peoples ideas and then modified them to my situation.

I started with the HF setup. I bought their filter. Then I took a 35 gal. trashcan, cut a hole in the side and created a side entry Thien cyclone. I set the trashcan on the roller plate that the original HF dust collector came with, wall mounted the blower, connected the blower to the cyclone with a slip fit connector, and connected the blower exhaust to the filter with 10' of insulated duct (poor man's muffler).

I setup a box fan with a furnace filter to help contol fugitive dust.

[dbhost]

That looks like an interesting setup. Any problems with having your exhaust hose that long and bendy?

[pitbull]

I would think most likely not. Its a lot easier to push than suck and the restrictions coming from the inlet side would more than outweigh the outlet pressure.

[JakesDad1]

I think DB brings up a good question, have you thought about going this route ? I guess that another thing to concider is that eventually your going to want to clean the filter.                                     

Interesting picture!!!!!! LOL

The reasons for the long exhaust:
  1) provide sound deadening,
  2) only place I could figure to put the filter out of the way
  3) The HF blower has a 4-5" outlet, the insulated duct is 6"
  4) The filter sits on a rack. I climb up on a stepladder to take it down. I've cleaned it once in 2 years use.
  5) I don't know, but it works and is way quiet.

Merry Christmas

[pitbull]

You are right on JakesDad. The pressure on the flow side of the motor is a lot less than originally spec'd, with 6" ducting and especially with a big canister filter on it. There is no way that your ducting even if it was in wound in loops is going to reduce performance.

Just like us humans its easier to blow with more pressure than we can suck. Its the same with these impeller driven dust collectors.

As a benefit, good job on the muffler.

[pitbull]

Chuck you are right that a 90 degree bench or any crimping on the exhaust side would impede the inlet sides ability to suck. But in his design this is not happening. It is very free flowing. Also as long as his exhaust ducting has the ability to push more air than the original machine specified there will be no decrease in performance....regardless of velocity of outlet air. Velocity would come into play on the inlet side side ducting.

If he is using 6" ducting no the inlet than he should be well with in the claims of what the machine can do CFM wise. 6" Duct has max theoretical airflow of 800CFM.

Also of note. Your vertical drop that was superimposed on the inlet ducting would acutally cause a decrease in sucking performance vs the benefit of a shorter exhaust line.

(Source: Rick Peters -Controlling Dust In The Workshop)


BTW, nice work on your table saw dust control.

[Negative_Zero]

Having watched this forum for a while, I would not dismiss Chuck's thoughts too quickly.  I really like the revision of moving the blower up to shorten and straighten the total travel.  I am not convinced that longer travel before the impeller is different than longer travel after the impeller.  Perhaps the technology of an impeller is different than how I use a straw...

I am very interested is the question of what are the negative consequences of using 6" smooth ducting with an impeller that is designed and speced for 5" flex ducting, since I am going to be doing the same on mine.  If it is going to kill the motor sooner, I am okay with that, but if it will reduce the total suction that does not sound like an improvement.  I am ready to learn more.

-Will

[pitbull]

Chuck no need to mind you own business, this is a forum. I am not discounting his comments...only adding my own. I am making my point, you are making yours. This is how people learn.

Again I will clarify. If he is exhausting through a 6" duct. He has a theoretical max CFM rate of about 800-850 CFM or so. I don't know what teh HF dust collector is truly rated at, but it is handicapped by what ever static pressure loss that occurs through the length of the diameter of the piping used on the inlet. Plain and simple.

If he has run his whole shop with what looks to be 4" line (400CFM max) not including the static losses from all the footage run through the shop multiple connections, fittings (blaste gates) and angled wyes....not the mention the loss at the separator.....there is no way that his CFM is anywhere near the capacity of his outlet ducting. I agreed that crimping this outlet ducting would cause a loss in performance but as it sits now, changing to your configuration would add more loss, (small as it might be) to his suction due to an increase in footage of inlet pipe before the motor housing.

Also you suggest in an earlier post here that he possibly should use a 5" exhaust line in lieu of a 6" line because of decreased velocity. This contradicts your point on exhaust efficiency as shown by relocating piping as per your picture. If velocity is your concern, than why not use a 4" pipe or smaller. Velocity is much more a concern on the inlet side. The separator is where we want all the chips/ dust to go....so if your point is that the chips and dust will not make it to his filter because of a decrease in velocity...then it actually is better to have a decreased velocity on the outlet side in this case because all but the lightest dust will end up in the separator while still providing more than enough CFM to more the air through the filter without obstruction.

This is evident in you basic dust collector design....such as the HF model in question. In its stock trim it pulls in air through the inlet and then discharges it through a duct (to maintain a quick velocity).... then pushes it into a cyclonic whirlwind where instantly the chamber opens up to a considerable diameter before entering the filter. Why is this done? To make heavy particles fall while maintaining CFM. You want the velocity scrubbed before the filter as much as reasonably possible to keep it from caking up.

----------------------------------------

To answer Negative ZERO's question without getting to technical,

There is no way you are going to hurt the motor on the DC by running 6" smooth ducting vs 5" flex. The difference is going to be found in efficiency and velocity of air. "Bernoulli's principle" If you are planning on running ducting with angle and multiple drops than you better run as large a pipe, with minimal obstruction (smooth pipe) as possible to maintain the CFM rating the motor is capable of for you main line. Drops can be made smaller diameter. A smaller pipe increases air speed, but restricts the volume of air capable of flowing through it.

[JakesDad1]

Hey guys, I appreciate your comments. My next/another project is to figure out how to make an effective fugitive dust filter that works and doesn't cost a fortune.

[WayTooLate]

Adding to the discussion...  

IN REGARDS TO EXHAUST DUCTING...
Since the 'exhaust' duct is larger, there will be a decrease in air velocity.  However, since it is AFTER the Separator, the larger chips have been removed and only 'fines' will remain in the airstream.  Since these will float along more easily, a slower air flow is acceptable.  

One thing that is being overlooked with the CFM & FPM Calculations is Static Pressure.  This is perceived as the amount of 'suction' you can feel.  The amount of static pressure your blower can work against is the truest measure of its efficiency.  Many systems can move a lot of air when they are unrestricted, but as soon as filters or bags begin collecting debris, they quit in a hurry...  

This is why Phil's separator is so beneficial, it removes the vast majority of the debris from the airstream so the filter/bag can work for a much longer time before getting 'clogged'.  

Blowers require 'some' amount of static pressure.  Particularly, those on high efficiency cyclones.  Without ANY back pressure, the blower is overloaded with incoming air.  The motor is working too hard and is likely to burn out in a shortened life.  If your motor does NOT draw too much current when the exhaust ducting/filter is removed, your blower is inefficient.  Some systems were 'designed' that way - to be so inefficient, they cannot overload the motor with too much air.  Unfortunately, most of the DC systems we get from HF and others are under-performers - so they can't create problems...

In a well designed system, you would fine tune the size of the exhaust ducting so that it provides just enough back pressure that the motor runs at its 'full load' amp rating.  Then, the bag/filters are sized so they are large enough to accept a reasonable amount of 'debris' without reducing the performance of the system.  The more material that is removed 'upstream' by the separator, the longer the cycle time before you have to clean/change the filter/bags.  

However, in the 'real world', we buy the biggest DC unit we can afford and accept its performance as our realistic standard.  

REGARDING THE 'FUGITIVE' DUST:  
My assumption is that this is dust that has escaped your dust hoods on your machine and has never entered your DC system.  As opposed to having gone through your system and passed through your filters as 'fines' that are too small for your filters...  

If they are the latter, I consider it a very serious problem.  Your "Dust Collector" is now a 'Dust Circulator'!  It is taking the most dangerous fines and pumping them into your air.  

If it is the most likely cause of not getting into the system, what is the source?  Chips from a jointer are generally larger and heavier - they are a nuisance, but less of a health hazard.  If they are coming from a sander, then it requires more serious attention because of the health risk.  

Better hood designs are always being developed and everyone has their customized tricks to suit their equipment and needs.  However, nothing beats having plenty of CFM to draw those fines into the system.  Being able to improve hood designs is critical because 40mph airflow cannot compete with the chips from the teeth of a 150mph saw blade.  

On table saws, most of the better hoods I have seen and used have restricted the openings around the base that permit 'clean' air to enter the saw and get sucked into the system.  This permits 'dusty' air to float away without being drawn into to the system.  However, you can't seal everything, you have to allow at least as much area for inlet as you have in your ducting.  If you don't allow enough air into the saw, you won't have enough CFM for the higher speed velocities to carry the chips to the separator.  

For health reasons, I would get a simple box fan and place a square HEPA filter over its 'intake' side.  Tape off the sides or open space so it has to draw through the filter.  Hang it overhead and have it blow towards you at your machines.  This will provide a supply of 'clean' air for you to breathe.  It will also keep those 'floating fines'  stirred up until the get caught in your HEPA filter.  It is a poor man's way to keep breathing clean air...

Hope these ideas help you think of more ways to make your system work better!

[RIP_Ray]

question: what hapen when you"forget" to empty the trask can & the ship stert to climb to the filtre?

Ray

[WayTooLate]

A great advantage of Phil's Separator is that it maintains a very uniform performance until it overflows.  (That isn't Phil's fault - it is our own procrastination and neglect!) 

Once filled, then ALL debris gets passed on to the filter/bags.  They will clog just as quickly as they used to (before using Phil's separator).  Then with the DC clogged, no air passes and the dust piles in your machines and you can't figure out why you are ankle-deep in sawdust.   

Then... you remember that you once dumped your trash can and maybe it would be a good idea to check it again... 

[JakesDad1]

Sure glad I have a "sight glass" on the side of my cyclone! :)



I guess its time to empty!  :o