need some comments on baffle performance

[DonJ]

Last week I made a baffle for my Delta 50-760 collector and just started using it. It seems to collect well as there was very little dust making it into the collector bag but it is not zero like some reports I see on this site. I just took everything apart today and cleaned the baffle, collection bag, and filter bag to get a better idea going forward.

I have attached some pictures of the baffle showing how I built it and some deposits on the baffle surfaces. I question if this is okay or should it be squeaky clean.

I have a self-built air filtration system from a hvac blower with 3 filters in it. I have all my tools connected to the collector except bandsaw, jointer, and RAS. I am in process of making more connections to eventually have them all included. My problem is that I  still have a fine dust covering everything in the shop. This is the main reason I made the baffle to improve collection or filter performance. I am considering exhausting the collector outdoors if you think it would help.

Please comment on the baffle coatings of dust and any suggestions for improving my shop environment.

[galerdude]

Hi DonJ, Nice photos.They really compliment your explanation of your situation. I'll try to share my observations and opinions.



• Looks as though the remaining dust is real fine as if from sanding. I have read where sanding dust is a common challenge for most of us.
• Have also read that the exhaust outlet is supposed to enter into the separation chamber at half the height of the chamber. Yours appears to be about a third  of the height.
• Also, whenever I empty my collection container, there is a bit of residue inside the separator but appears to wind up in the container  eventually and not in the bag.
• On my system; the residue comes from router, table saw and planer. For every 30 gallons of collection I get less than 1/2 cup in the bag.

Hope these observations help.

Regards,
Gale

EDIT: Was talking out my hind end on info in point #2. I apologize for any confusion. I thank DonJ for confirming the correct info which is entry distance = 1/2 the diameter of that pipe.

[Bulldog8]

I would look at air flow. Is the filter bag caked with fines? You could also partially open a second gate and see if yoy get the same result.

Steve

[DonJ]

Thanks for the input.
The dust is from a drum sander which is real fine.
The outlet is down about 2" from top. I think I saw a comment from Phil that said it should be approximately one half of the diameter which would be right for a 4" outlet pipe.

I will try to see if it clears up when more chips pass through.

[RCOX]

I am still having some problems of my own, so I may be the wrong one to speculate on this.

The one thing that I noticed is the thickness of your baffle. I remember Phil being adamant that "thin is in". He has stated that the best separation comes from a very thin baffle. I seem to recall him saying that about 1/8" thick baffle is best, no more than 1/4". I hope my memory serves me correctly in this.

Hope this may be of help.

Raymond

[DonJ]

I know I have seen others that are 3/4" thick but maybe if that is so Phil would comment?

[RCOX]

Let's wait on more feedback. I don't know if others have started with one and changed to the other or not. If so, they should be able to give a hands on answer.

Raymond

[DonJ]

Raymond
Checkout this post where comments on this distance.
http://www.jpthien.com/smf/index.php?topic=610.0

[galerdude]

Raymond
Checkout this post where comments on this distance.
http://www.jpthien.com/smf/index.php?topic=610.0

Thank you DonJ for pursuing and posting the correct info on distance. I apologize for my hasty and mis-informed post; i.e. point #2. I edited my original post, thanks to you.

Wish I could be of more help.

Thanks,
Gale

[RCOX]

DonJ: I didn't copy the link, but check out Phil's answer to Kooshball's post "Ideal material and cross sectional shape for HF Thien separator" on page 4 dated Sept. 11, 2011.

This is the responce that I was talking about. Knew I had read it somewhere.

Raymond

[phil (admin)]

Thinner baffles are better.

But separating fine sanding dust is a challenge that even large cyclones struggle with.

You guys have to keep in mind that those that are honest about their cyclones indicate that their filters still get plenty of fine material.

Take Steve Knight, for example.  He runs a CV cyclone and got tired of having to clean his cart. filters so he build his own baghouse.

Now, I run a drum sander and I do pretty well on separation.  But I'm using a Ryobi drum sander with a 2-1/4 (gasp!) port and my entire system is shop-vac based.  So why does mine work well?  Probably because of the lower CFM (and velocity) in my separator.

For the sake of science, you could always try to choke-down the blast gate from the sander a bit and see if it makes a difference.

OH, and one other point.  On units with elbows for inlets (like yours, and mine), it is critical that the elbow is positioned so the opening is a tangent with the side of the bucket.  I've seen some builds where it is "aimed" too much at the side, or too much toward the middle.