Lathe Dust Collector - a free design

[Evanism]

Hi all,

Not much happening today. Terribly bored. Rockler sent an email today which had a fairly cool dust collection system and a video showing it working.

I HATE DUST!!!! Especially lathe sanding dust!!!!!!!

So, this naturally reduced my ennui for a short time... whipped this up so I have a plan to follow.

Here is the Rockler device: Dust Right® Lathe Dust Collection System | Rockler Woodworking and Hardware (http://www.rockler.com/dust-right-lathe-dust-collection-system) for ~$70 + ~$30 postage... and the Video: https://www.youtube.com/watch?v=jLXKm1-u6HE

So I designed one using nothing but 20mm dowel, a few lengths of 50x20 pine and a few twist knobs. The main catchment is 150mm PVC and the back is 100mm pvc simply glue-welded onto the back at an appropriately cool angle.

-- There is nothing entirely novel about the solution other than it offers a slightly bigger catchment of 6" and a bigger 4" suction. BobL no doubt can improve this with the curvy-trumpet-thingy.... but the Sketchup doesn't handle compound curves intersecting with any grace.... so elaborate away!

-- I like the way my design offers two sliding grip points for the pipe rather than Rocklers one on the end. I seriously doubt you'll need as much adjustment/movement as I put into each rod, they are 500mm each and simply that long as I stretched them until it looked "cool".

-- The two attachment points are shown in detail... the tricky 90°-90° joiner could use a tweak depending on load. The pipe clamper is simply curved on a bobbin sander (or such) to match the curve of the 6" pipe and secured with a couple of screws from the pipe side.

-- The main support rod looks very long. I intend to attach the 4" pipe to the back using the pipe grippies from Carrols CWS Store - 2Pc Double Loop Squeeze 4" Hose Clamp | Carroll's Woodcraft Supplies (http://www.cwsonline.com.au/shop/item/2pc-double-loop-squeeze-4-hose-clamp) and an Occy strap over the long base bit to keep the pipe tame.

-- Use some knobs like the T-Tracks here: CWS Store - T Track Knobs | Carroll's Woodcraft Supplies (http://www.cwsonline.com.au/shop/item/t-track-knobs) or make your own:

-- The front bit that attaches to the lathe is the design I use for my other accessories on the Cougar EVS300. One bit follows the gap in the bed, the lower bit clamps upwards and exerts force to clamp it closed. I do this for the disk sander module and tool rack sitting on the end. It slides off easily and doesn't get in the way of the underside webbing. Modify to suit your lathe, of course...
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Use as you will. I'm not even sure if it'll work! No copyright. Sketchup attached. 367172

[BobL]

Sorry to disappoint but the 4" ducting and design of the opening (i.e. not a bell mouth) will not collect much more dust than a naked opening and will in fact restrict flow.

This is the sort of thing you should be looking at.
http://www.woodworkforums.com/attachment.php?attachmentid=362025&stc=1

[Evanism]

I was far more interested in the armature assembly. The DC I expected would be as you say. I've constantly struggled with good placement due to restricted room.

One thing I was thinking of, that may matter, for me at least, is I have only 100mm pipe at the moment. It was interesting to see what the spindle did in front of the sliced-pipe in that video. It seemed the obstruction of the spindle caused a fairly wide area to be collected. Perhaps it matters not if you simply move the sucker around as you work.

BobL, how is that hunk of pipe held in place/move?

[BobL]

I was far more interested in the armature assembly. The DC I expected would be as you say. I've constantly struggled with good placement due to restricted room.
A widespread problem for turners, especially if you want to use 6" ducting.


One thing I was thinking of, that may matter, for me at least, is I have only 100mm pipe at the moment. It was interesting to see what the spindle did in front of the sliced-pipe in that video. It seemed the obstruction of the spindle caused a fairly wide area to be collected. Perhaps it matters not if you simply move the sucker around as you work.

A naked duct opening will draw around 30% of its air from BEHIND the duct opening. This air has to turn angles of greater than 90º to enter the opening. In doing so it crashes into the air coming in from the front. The net effect is to generate turbulence and slow down both air streams. This is not what you want when dealing with dust capture.

The bell mouth collects more air from the front of the opening in a non turbulent manner. More importantly, compared to most other openings it doubles the air speed at any distance from the direct front of the opening so the ability to grab dust id further increased.


BobL, how is that hunk of pipe held in place/move?
This was before the bell mouth was attached.
http://www.woodworkforums.com/attachment.php?attachmentid=218563&stc=1&d=1344257928
See http://www.woodworkforums.com/f245/bobls-shed-fit-134670/21#post1531937 for details

[Ron Rutter]

A widespread problem for turners, especially if you want to use 6" ducting.



A naked duct opening will draw around 30% of its air from BEHIND the duct opening. This air has to turn angles of greater than 90º to enter the opening. In doing so it crashes into the air coming in from the front. The net effect is to generate turbulence and slow down both air streams. This is not what you want when dealing with dust capture.

The bell mouth collects more air from the front of the opening in a non turbulent manner. More importantly, compared to most other openings it doubles the air speed at any distance from the direct front of the opening so the ability to grab dust id further increased.


This was before the bell mouth was attached.
http://www.woodworkforums.com/attachment.php?attachmentid=218563&stc=1&d=1344257928
See http://www.woodworkforums.com/f245/bobls-shed-fit-134670/21#post1531937 for details
Bob. I'm not sure about this " More importantly, compared to most other openings it doubles the air speed at any distance from the direct front of the opening so the ability to grab dust id further increased." The secret to collecting fines is a slow moving higher volume of air. Too small of an opening & the air tunnels - higher velocity- & doesn't pick up the fines.

[BobL]

The secret to collecting fines is a slow moving higher volume of air. Too small of an opening & the air tunnels - higher velocity- & doesn't pick up the fines.
Thats fine for dust being carried in slow speed air but if the air containing the dust is moving faster than the air being carried away by the DC then the dust will not be grabbed to begin with. My measurements of air speeds being spun off objects being turned is that the air moves too fast to be efficiently grabbed by a naked port. Naked ports also grab air from the back and sides whereas when turning the dust is usually being generated at the front of the hood. A Bellmouth hood grabs about 10% more air to begin with and it grabs it direct from immediately out the front which is where the dust is being made and moving radially outwards and then upwards (it's warmer )at speed, albeit slowing down. The Bellmouth collects the air at higher speed that is fast enough to overcome the spinning off speed of the air containing the dust.

[NCPaladin]

My design is similar to the first, you can make a wood banjo (shown) or use your tool rest banjo. Pickup is a mounting box for a floor register wich comes with the 4" connector built in. The box is rectangular but if you snip off the outside edge it will go oval.
Can be set to any height and articulates in all three planes. I used Velcro to attach the choaker or for attaching extensions. If sanding a platter you will probably want it centered vertically, if left open it will draw from both sides; with the choaker it only draws from the side you are sanding on. For spindles you may want an extension so dust is thrown down onto the extension and pulled in.
If you use a sanding disc at the lathe you can insert the collector from the bottom of the banjo to have it directly under the disc.
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[Ron Rutter]

Bob. In a sense you are agreeing with me. With a large bell or similar opening you have slowed down the velocity of the air & it will pull in fines from a broader area more efficiently.

[BobL]

Bob. In a sense you are agreeing with me. With a large bell or similar opening you have slowed down the velocity of the air & it will pull in fines from a broader area more efficiently.
there's a bit more to it than that. When I get back from my camping trip and have access to more than this iPad I'll draw some sketches that show things better than I can write.

[Nifty Nev]

Hi Bob,

Would either https://www.machineryhouse.com.au/W338A or https://www.machineryhouse.com.au/W338B be on par with your bellmouth setup.

[BobL]

Hi Bob,

Would either https://www.machineryhouse.com.au/W338A or https://www.machineryhouse.com.au/W338B be on par with your bellmouth setup.
Aside from the fact that they are only 4", both will be slightly better than a naked port in that they will take less air from the back. Both still generate some turbulence at the point where the surrounding flat surfaces turn immediately into 4" different ducting. The rectangular funnel shaped collector is the better of the two but suffers from the problem of a asking up too much room but it's ok if you have the room behind a lathe. There are also issues of air speeds but that is a bit hard to explain without a diagram , when I get back from camping I will draw up a picture to explain this.

[DaveTTC]

Thanks to all the input here. .as yet i have nothing but working on it.

Does height and anfle of the mouth make much difference. If it was lower, say level with the bed but angled up to centre would this be as good?

Dave TTC
Turning Wood Into Art

[BobL]

Thanks to all the input here. .as yet i have nothing but working on it.

Does height and anfle of the mouth make much difference. If it was lower, say level with the bed but angled up to centre would this be as goo
In general it's better to collect fine dust from above because warm air rises which the fine dust rides around on. To collect chip it's better to collect from below because they fall. Angling the duct towards the dust source is a good idea.

[Evanism]

Ive the big mouthed version as per the second link above: https://www.machineryhouse.com.au/W338B

Its a cumbersome beast that seems to have weird centres of gravity and never wants to stay where its put. This is sort of what interested me with the arm design. The actual mouth wasn't that interesting as thats a well worn topic, but what isn't, is trying to get that damned mouth in the right place in a manner that doesn't burn up a heap of time.

The big mouth catches virtually no chips, but does a very good job for dust when the bottom lip rests on the lathe bed, but angled upwards at about 45°... the hassle is the hose hangs backwards and wants to twist it backwards. If it could be mounted well, then it does a good job at catching the dust - especially for spindle work. As I sand bowls and plates, its not so good, but then again I'm only using 4" on a 2hp machine and positioning the thing is part of the problem.

A little while ago, I tested the big mouth with an incense stick and was amazed at how far out is attracted the air in from... it was a great black hole. This year I'm definitely moving to 6" pipe.

[smiife]

inQUOTE=Evanism;1920359]Ive the big mouthed version as per the second link above: https://www.machineryhouse.com.au/W338B

Its a cumbersome beast that seems to have weird centres of gravity and never wants to stay where its put. This is sort of what interested me with the arm design. The actual mouth wasn't that interesting as thats a well worn topic, but what isn't, is trying to get that damned mouth in the right place in a manner that doesn't burn up a heap of time.

The big mouth catches virtually no chips, but does a very good job for dust when the bottom lip rests on the lathe bed, but angled upwards at about 45°... the hassle is the hose hangs backwards and wants to twist it backwards. If it could be mounted well, then it does a good job at catching the dust - especially for spindle work. As I sand bowls and plates, its not so good, but then again I'm only using 4" on a 2hp machine and positioning the thing is part of the problem.

A little while ago, I tested the big mouth with an incense stick and was amazed at how far out is attracted the air in from... it was a great black hole. This year I'm definitely moving to 6" pipe.[/QUOTE]

Hi evanism,
I have the same set up (big gulp ), with some blast gates
set up I can change from sanding , shavings or cleaning up!
my big gulp is screwed to a piece of timber on brackets on the
back of my lathe , a floor sweeper fitted nicely between the
lathe bed underneath the lathe to catch shavings/chips etc
also have a collector on the floor to sweep any other stuff
In to! a few photos to explain better maybe !:2tsup:
Also a vacumn cleaner pipe to clean up anything that
has been missed:U
Hope some of this info is of help !

[Flindersia]

I like the relative simplicity of your design Bob. I've no experience with 150mm fittings though so any chance you could post some details of the components that make up the construction? Eg What is the bell mouth made from? What is the diameter of the flexible hose and what is the fitting (collar) that it is attached into?

[BobL]

Some details and more photos here.
http://www.woodworkforums.com/f200/air-speeds-duct-openings-blades-nb-invisible-dust-discussed-157526/6#post1542011
the rest of that thread has some technical details about Bell mouth hood.
It was designed and built as a test port on which I did a fair bit of testing but it worked so well I ended up painting it and using it as is.