baffle vs top hat?

[Rick T]

I built my 'top hat'- style separator several years ago... when they first appeared on this forum. I consider it very good when it comes to separating the dust, which is important because I have a Wynn pleated filter that isn't equipped with a shaker paddle to dislodge dust that becomes embedded in the pleats.
I'm now questioning the overall effectiveness of my DC doing it's basic job which is to intercept and collect dust from my woodworking equipment. I've read somewhere in the myriad of threads and info that the top hat separator introduces @ 30% loss in air flow. Does that reduce the air flow to an unacceptable volume? I'm pretty much on the fence at tis point.
For the last while most concentration has been on 'top hat' design. Any thoughts on it's performance vs a straight baffle design in terms of a) ability to separate dust and b) impact on air flow? Does the simple baffle design flow more?

I'm working with a Delta 50-760 equipped with Wynn poly pleated filter and 10' length of clear 5" dia flex hose. My table saw has 1- 5" port. I move the DC from machine to machine as necessary.

[retired2]

I built my 'top hat'- style separator several years ago... when they first appeared on this forum. I consider it very good when it comes to separating the dust, which is important because I have a Wynn pleated filter that isn't equipped with a shaker paddle to dislodge dust that becomes embedded in the pleats.
I'm now questioning the overall effectiveness of my DC doing it's basic job which is to intercept and collect dust from my woodworking equipment. I've read somewhere in the myriad of threads and info that the top hat separator introduces @ 30% loss in air flow. Does that reduce the air flow to an unacceptable volume? I'm pretty much on the fence at tis point.
For the last while most concentration has been on 'top hat' design. Any thoughts on it's performance vs a straight baffle design in terms of a) ability to separate dust and b) impact on air flow? Does the simple baffle design flow more?

I'm working with a Delta 50-760 equipped with Wynn poly pleated filter and 10' length of clear 5" dia flex hose. My table saw has 1- 5" port. I move the DC from machine to machine as necessary.

I am using the same Delta DC as you, but in a stationary setup.  My top hat build introduces a CFM loss closer to 40% than 30%, and that figure comes from measurements taken with an anemometer.   This loss results in machine beds that are not quite as clean as when the separator is removed. 

However, in your setup, i.e. moving the Delta from tool to tool, you should not see much difference with or without the separator.

[Rick T]

Have you seen any comparisons of loss, top hat vs baffle using a 50-760?
I sure like the separation and less cleaning of filter, but it isn't of much benefit if the flow is insufficient. That's why I'm curious about the possibility that the baffle may institute less loss and perhaps not do quite as good a job at separation.
I remember years ago when consumer versions of the pleated filters appeared, like my Wynn, some people made shop conversions to add a paddle that dislodged the dust which fell into the collection bag. Now most of the filter perhaps come with paddles for this purpose.
On the flow issue, my table saw is the biggest offender. I notice dust congregating in the large cavity under the blade and a fair amount being flung off the blade above the zero clearance insert rather than being sucked off the blade on rotation. I really need to get an overarm guard connected to the DC.
Either way lower flow challenges the 50-760.

[retired2]

Have you seen any comparisons of loss, top hat vs baffle using a 50-760?
I sure like the separation and less cleaning of filter, but it isn't of much benefit if the flow is insufficient. That's why I'm curious about the possibility that the baffle may institute less loss and perhaps not do quite as good a job at separation.
I remember years ago when consumer versions of the pleated filters appeared, like my Wynn, some people made shop conversions to add a paddle that dislodged the dust which fell into the collection bag. Now most of the filter perhaps come with paddles for this purpose.
On the flow issue, my table saw is the biggest offender. I notice dust congregating in the large cavity under the blade and a fair amount being flung off the blade above the zero clearance insert rather than being sucked off the blade on rotation. I really need to get an overarm guard connected to the DC.
Either way lower flow challenges the 50-760.

How would you use a baffle with a 50-760? 

[alan m]

from what iv been reading lately. it doesnt matter whether you put the same resistance before or after the blower.

my thining is that if the material is going through the impeller then the moter has more work to do because of the extra mass of the material.
also it is easier to build a pre seperater to minimise the losses. be they from too small a diameter or the height of the seperater etc


my preference is for pre seperaters because nothing goes throught the impeller

[Rick T]

Have you seen any comparisons of loss, top hat vs baffle using a 50-760?
I sure like the separation and less cleaning of filter, but it isn't of much benefit if the flow is insufficient. That's why I'm curious about the possibility that the baffle may institute less loss and perhaps not do quite as good a job at separation.
I remember years ago when consumer versions of the pleated filters appeared, like my Wynn, some people made shop conversions to add a paddle that dislodged the dust which fell into the collection bag. Now most of the filter perhaps come with paddles for this purpose.
On the flow issue, my table saw is the biggest offender. I notice dust congregating in the large cavity under the blade and a fair amount being flung off the blade above the zero clearance insert rather than being sucked off the blade on rotation. I really need to get an overarm guard connected to the DC.
Either way lower flow challenges the 50-760.

How would you use a baffle with a 50-760?

Could it not be made just as for other conventional DCs and installed in the lower area (just below the entry port and  above where the collection bag installs with the expanding clamp in the lower portion of the steel ring. Use either thin metal or hardboard, cut drop slot similar to top hat and baffle design ie 240 deg).
I'm just thinking out load here as I don't recall seeing anyone do this but that's not to say they haven't.
When I was emptying the collection bag I notice there is a small semi-circular metal ring @ 1/4" dia that is installed into the deck of the steel ring. It doesn't go completely around the opening to the collection bag.. only partially. Wonder what purpose that serves? 

[Rick T]

from what iv been reading lately. it doesnt matter whether you put the same resistance before or after the blower.

my thining is that if the material is going through the impeller then the moter has more work to do because of the extra mass of the material.
also it is easier to build a pre seperater to minimise the losses. be they from too small a diameter or the height of the seperater etc


my preference is for pre seperaters because nothing goes throught the impeller

Alan, again just thinking out load here again, if virtually the entire loss of the pre-separator is eliminated and replaced by that of the baffle which doesn't hinder most air flow (to the filter), is that not a substantial gain?
I'm not sure how much actual loss relates to the dust and crap sent through the DC. Suppose it may be an issue but without testing in some way, I don't have any idea.
If the baffle design works on a Harbor Freight conventionally designed DC, can't it work in the same way on a 50-760?

I know this is a very odd time to be considering this since so much work has been done on the 'top hat' but we need to be confirming progress compared to some datum, and I suppose it's a naked DC sans filter.

[alan m]

im not familier with your dc machines. im assuming its like most others out there. one ring for the ipeller going ito the second ring with the bag and filter
i dont see why you cant do the same as most have done on their post seperaters


to do a post impeller seperater you will have to put a top on the ring and put a pipe down into it in the samw way as you would with a top hat
im assuming that the resistances incurred are the same. if they are the same diameter and height etc they should be.


if you put the resistance before or after the result should be the same.  maybe the dust going throught the impeller could make a post seperater less efficient. i dont know either

the only real way to know is to try it and see what happens
but to get any real hard data the resistance of the pre seperater would have to be the same as the post seperater. that would be hard to do given that it is built already

[retired2]

from what iv been reading lately. it doesnt matter whether you put the same resistance before or after the blower.

my thining is that if the material is going through the impeller then the moter has more work to do because of the extra mass of the material.
also it is easier to build a pre seperater to minimise the losses. be they from too small a diameter or the height of the seperater etc


my preference is for pre seperaters because nothing goes throught the impeller

Alan, again just thinking out load here again, if virtually the entire loss of the pre-separator is eliminated and replaced by that of the baffle which doesn't hinder most air flow (to the filter), is that not a substantial gain?
I'm not sure how much actual loss relates to the dust and crap sent through the DC. Suppose it may be an issue but without testing in some way, I don't have any idea.
If the baffle design works on a Harbor Freight conventionally designed DC, can't it work in the same way on a 50-760?

I know this is a very odd time to be considering this since so much work has been done on the 'top hat' but we need to be confirming progress compared to some datum, and I suppose it's a naked DC sans filter.

Well, it shouldn't be too difficult to cut a baffle from tempered hardboard and come up with some temporary attachment method for the sake of testing.

The immediate downside I see is you are still left with emptying the plastic bag, which on this DC I find to be a real PIA.

Without actually trying it, I don't know if this would do much to improve separation versus no baffle.  It seems fines have a way of getting to the filter no matter what, so you will still be stuck with cleaning your Wynn filter eventually.  I haven't added one to my system, so I don't know how much of a chore that is.  The Wynn's recommend using compressed air on the outside. 

My feelings are that placing a baffle in the location you are discussing would create little or no additional cfm losses as opposed to no baffle since the plastic bag is already ventless and all air must exhaust through the filter.

Give it a try.  You should be able to do a "non-destructive" test and it shouldn't cost very much in material.

[Rick T]

from what iv been reading lately. it doesnt matter whether you put the same resistance before or after the blower.

my thining is that if the material is going through the impeller then the moter has more work to do because of the extra mass of the material.
also it is easier to build a pre seperater to minimise the losses. be they from too small a diameter or the height of the seperater etc


my preference is for pre seperaters because nothing goes throught the impeller

Alan, again just thinking out load here again, if virtually the entire loss of the pre-separator is eliminated and replaced by that of the baffle which doesn't hinder most air flow (to the filter), is that not a substantial gain?
I'm not sure how much actual loss relates to the dust and crap sent through the DC. Suppose it may be an issue but without testing in some way, I don't have any idea.
If the baffle design works on a Harbor Freight conventionally designed DC, can't it work in the same way on a 50-760?

I know this is a very odd time to be considering this since so much work has been done on the 'top hat' but we need to be confirming progress compared to some datum, and I suppose it's a naked DC sans filter.

Well, it shouldn't be too difficult to cut a baffle from tempered hardboard and come up with some temporary attachment method for the sake of testing.

The immediate downside I see is you are still left with emptying the plastic bag, which on this DC I find to be a real PIA.

Without actually trying it, I don't know if this would do much to improve separation versus no baffle.  It seems fines have a way of getting to the filter no matter what, so you will still be stuck with cleaning your Wynn filter eventually.  I haven't added one to my system, so I don't know how much of a chore that is.  The Wynn's recommend using compressed air on the outside. 

My feelings are that placing a baffle in the location you are discussing would create little or no additional cfm losses as opposed to no baffle since the plastic bag is already ventless and all air must exhaust through the filter.

Give it a try.  You should be able to do a "non-destructive" test and it shouldn't cost very much in material.

I certainly agree,  the bag routine is challenging. I hear people recommend bag on the outside of the ring, temporarily use magnets to hold bag in place and use large hose clamp.
I visualize much of the loss in the 'top hat' system being the energy expended spinning the air around the pre-separator. It also expends some energy spinning it again in the normal collar, but perhaps to a lesser degree.
When I get a bit of time maybe I'll give it a go.
Thx for the input.

[retired2]

from what iv been reading lately. it doesnt matter whether you put the same resistance before or after the blower.

my thining is that if the material is going through the impeller then the moter has more work to do because of the extra mass of the material.
also it is easier to build a pre seperater to minimise the losses. be they from too small a diameter or the height of the seperater etc


my preference is for pre seperaters because nothing goes throught the impeller

Alan, again just thinking out load here again, if virtually the entire loss of the pre-separator is eliminated and replaced by that of the baffle which doesn't hinder most air flow (to the filter), is that not a substantial gain?
I'm not sure how much actual loss relates to the dust and crap sent through the DC. Suppose it may be an issue but without testing in some way, I don't have any idea.
If the baffle design works on a Harbor Freight conventionally designed DC, can't it work in the same way on a 50-760?

I know this is a very odd time to be considering this since so much work has been done on the 'top hat' but we need to be confirming progress compared to some datum, and I suppose it's a naked DC sans filter.

Well, it shouldn't be too difficult to cut a baffle from tempered hardboard and come up with some temporary attachment method for the sake of testing.

The immediate downside I see is you are still left with emptying the plastic bag, which on this DC I find to be a real PIA.

Without actually trying it, I don't know if this would do much to improve separation versus no baffle.  It seems fines have a way of getting to the filter no matter what, so you will still be stuck with cleaning your Wynn filter eventually.  I haven't added one to my system, so I don't know how much of a chore that is.  The Wynn's recommend using compressed air on the outside. 

My feelings are that placing a baffle in the location you are discussing would create little or no additional cfm losses as opposed to no baffle since the plastic bag is already ventless and all air must exhaust through the filter.

Give it a try.  You should be able to do a "non-destructive" test and it shouldn't cost very much in material.

I certainly agree,  the bag routine is challenging. I hear people recommend bag on the outside of the ring, temporarily use magnets to hold bag in place and use large hose clamp.
I visualize much of the loss in the 'top hat' system being the energy expended spinning the air around the pre-separator. It also expends some energy spinning it again in the normal collar, but perhaps to a lesser degree.
When I get a bit of time maybe I'll give it a go.
Thx for the input.

When I said a "post-separator" baffle might not impose much if any additional losses, it was without giving thought to the need for some kind of necked down port into the filter area.  I assume that would be needed and that would surely impose some losses.

Probably the Harbor Freight guys are better qualified than me to recommend the best way to try this, and they are probably better able to guess the results.

I'd like to see someone give it a try just to see if it is better than a pre-separator.  It would have to be pretty darn good for me to make the change for two reasons, 1) the frequency of dumping the plastic bag, and 2) the filter will still have to be cleaned periodically, and my guess is that interval will be very close to the same for a pre or post separator.

[alan m]

i think without putting a top and center pipes into the second ring, you will get very little fines seperation and posibly reduce the speed of the air spinning .
we wantthat air spinning as fast as poible.
without that top and pipe then there probably wouldnt be much loss of cfm but with it i feel (only my un educated in such things felling, i could be wrong) that the losses having the seperater after the impeller would be the same as if you had the same scaled and same constructed preseperater.

i was reading (probably in the links retired2 posted about the air straightener)  that blocking the outlet of the impeller has the same effect as doing the same to the inlet
thats why im thinking that either side should be the same.

obviously thats all theory .

[alan m]

the problem i think is that any air has to go throught the preseperater and then go through th esecond ring before it gets to the filter
if you had one of the DCs with a pipe between the impeller and 2nd ring you could go straight outside or into the filter without that extra loss

[Rick T]

What Wilburpan is proposing s what I had in mind basically for my Delta 50-760. http://www.jpthien.com/smf/index.php?topic=845.msg0#new
It has a 5" dia inlet so I should be in the 6-8" dia hole or chimney to filter.

[retired2]

What Wilburpan is proposing s what I had in mind basically for my Delta 50-760. http://www.jpthien.com/smf/index.php?topic=845.msg0#new
It has a 5" dia inlet so I should be in the 6-8" dia hole or chimney to filter.

It's been a while since I looked inside my 50-760, but as I recall the outlet from the fan doesn't enter the separation area in the fashion you might expect.  It might need some internal baffles to direct the incoming air in a more conventional manner.  This is probably the reason you don't seem many, if any, implementation of a Thien baffle in the 50-760.

The most unique setup I've seen just recently are people installing a Super Dust Deputy cyclone under the 50-760 so that the outlet of the SDD ports directly to the inlet of the 50-760.  But the $64K questions are 1) does it separate any better than the Thien separator, and 2) does it result in more or less CFM losses.