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Dust collection question

Denny Nebgen

Denny Nebgen

Joined
Dec 19, 2021
Messages
62
Likes
23
Location
Irvona, PA
Website
originalrevolutions.com
I am moving from a Nova galaxy DVR lathe to a Robust American Beauty and the way I had my dust collector port next to the Nova will be less than ideal for the Robust AB. I will need a bit more flexibility to move the port along the bed with the AB than with the Nova.
Currently I have a computer monitor stand bolted to the wall and it works well with the Nova but the AB the swing just isn't going top allow for enough movement.

Do any of you have some ideas (perhaps with Photos) of how you handle your dust collector at the lathe.

I'm looking for ideas.

Thank you
 
I have a stand from woodcraft that came with a dust hood. Thought it would do the job, but I didn't like the thing as-purchased. So I attached a length of 3" PVC pipe w/coupler to the stand (it has a short section of pipe attached to the top of the stand). I also turned a bell mouth for it, which works so much better than the hood (or the bare end of the pipe, which I also liked better than the hood). The PVC keeps the stand at a respectable distance and lets me get the bell mouth where I need it.
The outside diameter of a 3" PVC coupler is the right size for 4" dust hose.
I glued a couple magnets to the back of the DC's remote and glued a strip of metal to the top of the PVC (both harvested from an old name tag), so the remote is usually right there when I move the pipe.

Of course, this exact setup won't work if you have wall rather than floor behind your lathe - but maybe there's an idea or two in here for you.
IMG_8547.JPG
(Older photo from my previous garage temporary-shop setup)
 
Dave Landers said:
I have a stand from woodcraft that came with a dust hood. Thought it would do the job, but I didn't like the thing as-purchased. So I attached a length of 3" PVC pipe w/coupler to the stand (it has a short section of pipe attached to the top of the stand). I also turned a bell mouth for it, which works so much better than the hood (or the bare end of the pipe, which I also liked better than the hood). The PVC keeps the stand at a respectable distance and lets me get the bell mouth where I need it.
The outside diameter of a 3" PVC coupler is the right size for 4" dust hose.
I glued a couple magnets to the back of the DC's remote and glued a strip of metal to the top of the PVC (both harvested from an old name tag), so the remote is usually right there when I move the pipe.

Of course, this exact setup won't work if you have wall rather than floor behind your lathe - but maybe there's an idea or two in here for you.
View attachment 58150
(Older photo from my previous garage temporary-shop setup)
Click to expand...
Dave, you’ve reduced your 4” hose to 3”? How has this upgraded the collection aspect? More suction velocity? I am not a “hood” fan and just use the 4” hose for collection. I use Ken Rizza’s mounting system on my AB. I find it stiff (a necessity) and sometimes in the way of my banjo…..it works well otherwise. I look at your floor mounted version and get a case of “it’s always greener on the other side of the hill” syndrome, lol!! Yours does look intriguing!
 
Dave Landers said:
I also turned a bell mouth for it, which works so much better than the hood (or the bare end of the pipe, which I also liked better than the hood).
Click to expand...
Dave, I have the Big Gulp (is that what it’s called?) from CSUSA and have always been frustrated to note that while it catches a lot of the dust when I sand, I notice that some goes right past it. I’m intrigued by the idea of a bell end instead and will turn one and see how it works. I wonder if anyone can explain the physics/aerodynamics of this and why it seems a better solution even with a smaller opening area?
 
Mine is pretty simple - a piece of the semi-rigid hose held up with an assortment of scrap wood held together with carriage bolts and spare knobs all held up by an old IV stand someone left in my studio a couple of decades ago.
I changed out the rectangular hood for a bell mouth intake found online cheap. I don’t know the physics involved, but it works much better and has a wider area around it that it pulls from.
A0051DD9-F1C4-4313-9A53-16E64ABEF7D8.jpegF269CA6C-D36F-40CD-9DAB-C8A0BBBD95A0.jpeg
 
Is your lathe against a wall or in the open? If you are in the open, then you need a stand like the post above. If you are against a wall, then there are many options. I need to 'new and improve' my drum that I use for sanding, literally a 55 gallon food grade drum with some plexiglass on the end so the bowl is about 75% enclosed. I think I would opt for a French cleat system, 45 degree bevel on board screwed to the wall, and the hood mounted on a mating 45 degree bevel that you could slide back and forth depending on where you want it. The more enclosed the piece is, the more dust you collect. Maybe check out my video I did. The bad thing about that hood is that I have to take it off to turn, but it does get ALL of the sanding dust. Sheet stock of the white plastic is available in sheets up to 5 by 10, so possibly a club project. The 1/4 inch thick is kind of difficult to bend, but they have many thicknesses. Even a cardboard box can be made to work.


robo hippy
 
Lou Jacobs said:
Dave, I have the Big Gulp (is that what it’s called?) from CSUSA and have always been frustrated to note that while it catches a lot of the dust when I sand, I notice that some goes right past it. I’m intrigued by the idea of a bell end instead and will turn one and see how it works. I wonder if anyone can explain the physics/aerodynamics of this and why it seems a better solution even with a smaller opening area?
Click to expand...
This isn't a physics-based answer, and certainly not based on any knowledge of aerodynamics... but to my view, those big gulp things aren't really larger openings, but more a sort of box around the end of the pipe. I think the idea is that if you can get the dust to fall in the 'box' then it ought to eventually end up in the pipe. But they don't really do anything about air flow that I've experienced. The bell mouth (wikipedia link) does let air flow in more efficiently - I think since it's a gradual curve into the pipe rather than an abrupt pipe-end. So the air can curve into the pipe rather than taking a hard left turn (or something like that).

I saw a few others making bell mouths, thought I'd try it cause it's round, and I do round. Also figured if it's good enough for F1 engine intakes, it might be ok to try.

Before I had the bell mouth, I just used the bare end of the pipe - and even that worked better than the big gulpy thing for me. Mainly because I could get the suction (end of the pipe) closer to the actual sanding. The bell mouth just improves on that - I watch most of the dust flowing into the DC pipe, even when I'm sanding on one side of a bowl and the pipe is on the other.

I think @robo hippy 's thing works because it's a much bigger 'box' that actually does surround the workpiece and there's basically no place else for the dust to go. So a different solution that works for him and probably others.
 
We're kinda getting away from Denny's question about mounting his dust collector, however... I just sanded this piece (from the bottom tenon up to that pencil line) from 120 up to 400. You can see the dust on the banjo that the DC didn't catch. The rest went in the tube.

IMG_8587.JPG
 
Thanks for the thoughts on the bell mouth collector. I am also in search of the best way to handle dust and therefore what type of intake and mounting for dust collector hose. Most intrigued by Richard Raffins solution. But will. keep up the search f or a few days.
 
Several years ago Fine Woodworking did a tool test on dust collectors - and they researched the effect of different collector ends or intake shapes. The results were significantly better (higher air flow) using the bell shaped intakes. It also expanded the area of the intake to three or four times the diameter of the hose.
I've done a search for that issue a few times in the past when this question arises on the forum, but can
t seem to call up that article. If someone has access to one of their archives you might be able to search it up...
 
Got tired of trying to hang/position my dust hood using bungies so also rig'd up an articulating arm (flat screen mount) mounted on
T-tracks for horizontal movement also ... not much room avail behind the lathe. Very happy with it now since don't have to fuss much with adjustments.

One thing I don't like about the hood is the rear intake port being inline since doesn't leave much room for the hose (since I'm so close to a wall) ... would rather have a sweep down for hose attachment.

Here's some more pics.
 

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JeffSmith said:
Several years ago Fine Woodworking did a tool test on dust collectors - and they researched the effect of different collector ends or intake shapes. The results were significantly better (higher air flow) using the bell shaped intakes. It also expanded the area of the intake to three or four times the diameter of the hose.
I've done a search for that issue a few times in the past when this question arises on the forum, but can
t seem to call up that article. If someone has access to one of their archives you might be able to search it up...
Click to expand...
Helpfull information for sure. Sometime I try to imagine what is going on with these bell shaped intakes. In my mind I'm wondering if it allows the air flow to get organized and kind of act like.a whirlpool. On the same note, do we turn one, or just go buy the giant wooden salad bowl at the thrift store for $8. It would be kind of fun to turn one complete with a 4 inch intake.
 
Todd Bowen said:
Helpfull information for sure. Sometime I try to imagine what is going on with these bell shaped intakes. In my mind I'm wondering if it allows the air flow to get organized and kind of act like.a whirlpool. On the same note, do we turn one, or just go buy the giant wooden salad bowl at the thrift store for $8. It would be kind of fun to turn one complete with a 4 inch intake.
Click to expand...
google something like ‘air intake bellmouth’ lots of premade intake horns for automotive use. I think you’re on the right track with the better organized air flow. Ultimately it doesn’t matter if you turn one or buy something that’s the right shape.
 
Bernoulli's Principal is at play here. For those that aren’t familiar with it, in simple terms when a larger diameter is reduced to a smaller diameter, the larger size has higher pressure and lower flow. When transitioning to a smaller diameter the pressure decreases but the velocity increases. You can see it in homes when the HVAC ducting decreases in cross sectional area as the ducting gets further away from the plenum. It’s used in aerospace and a good example are the Venturi tubes to create suction for instruments and inlets to improve the amount of air entering the opening. The cowl on a piston plane has inlets that are curved to improve the volume of air that enters for cooling. If the inlets are sharp edges, disruption in the airflow an act as a damn blocking some of the air. Bottom line is the same volume of air is going through the different size hoses. Another great example is a pressure washer. Big line into a small opening and high velocity water shoots out.

Now down to dust collection.

The bell shape end on a vacuum hose increases the air entering the hose more than just an opening with the same diameter. Again Bernoulli comes into play.

The big gulp looks like a good idea for sucking away the dust but it really isn’t a good design. The opening is much larger than the hose opening and there isn’t much velocity in the big gulp till you get to the hose opening. This means dust can drift in the lower air movement area.

A small hose into a larger hose is better than a large hose into a smaller hose.

The bell shape is much better than a salad bowl. The bell mouth has less turbulence than a funnel shape unless the edge of the salad bowl has a rounded over rim. Again a big bowl is like a big gulp and dust can drift more due to lower air velocity.

Also, efficiency is reduced as the hose gets longer and sharp turns such as 90 degrees can add the equivalent of 10 feet of hose.

Inefficient designs still work to some extent. They do so due to bigger and more powerful vacuums rather than by efficient design.

Soooo, if you want to want your dust collector to suck more, understanding how Bernouilli's Principal works will help your design.
 
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Denny Nebgen said:
I am moving from a Nova galaxy DVR lathe to a Robust American Beauty and the way I had my dust collector port next to the Nova will be less than ideal for the Robust AB. I will need a bit more flexibility to move the port along the bed with the AB than with the Nova.
Currently I have a computer monitor stand bolted to the wall and it works well with the Nova but the AB the swing just isn't going top allow for enough movement.

Do any of you have some ideas (perhaps with Photos) of how you handle your dust collector at the lathe.

I'm looking for ideas.
Denny Nebgen said:
I am moving from a Nova galaxy DVR lathe to a Robust American Beauty and the way I had my dust collector port next to the Nova will be less than ideal for the Robust AB. I will need a bit more flexibility to move the port along the bed with the AB than with the Nova.
Currently I have a computer monitor stand bolted to the wall and it works well with the Nova but the AB the swing just isn't going top allow for enough movement.

Do any of you have some ideas (perhaps with Photos) of how you handle your dust collector at the lathe.

I'm looking for ideas.

Thank you
Click to expand...
Click to expand...
My dust collection system ends with a section of 6-inch flexible hose. I affixed a band clamp to the hose with an overhang long enough to reach from the side of the lathe bed up to the spindle height. I then epoxied a large super-magnet to the clamp. This allows me move the suction end of the hose as needed by placing the magnet appropriately along the lathe bed.
 
I also use Ken Rizza's track system on my AB. I like the flexibility to move the rig along the bed and it stays where I put it. His beam clamps lack rigidity, so I had some made by a machinist friend that do a much better job of clamping the track to the lathe..
 
Webb Willmott said:
Bernoulli's Principal is at play here. For those that aren’t familiar with it, in simple terms when a larger diameter is reduced to a smaller diameter, the larger size has higher pressure and lower flow. When transitioning to a smaller diameter the pressure decreases but the velocity increases. You can see it in homes when the HVAC ducting decreases in cross sectional area as the ducting gets further away from the plenum. It’s used in aerospace and a good example are the Venturi tubes to create suction for instruments and inlets to improve the amount of air entering the opening. The cowl on a piston plane has inlets that are curved to improve the volume of air that enters for cooling. If the inlets are sharp edges, disruption in the airflow an act as a damn blocking some of the air. Bottom line is the same volume of air is going through the different size hoses. Another great example is a pressure washer. Big line into a small opening and high velocity water shoots out.

Now down to dust collection.

The bell shape end on a vacuum hose increases the air entering the hose more than just an opening with the same diameter. Again Bernoulli comes into play.

The big gulp looks like a good idea for sucking away the dust but it really isn’t a good design. The opening is much larger than the hose opening and there isn’t much velocity in the big gulp till you get to the hose opening. This means dust can drift in the lower air movement area.

A small hose into a larger hose is better than a large hose into a smaller hose.

The bell shape is much better than a salad bowl. The bell mouth has less turbulence than a funnel shape unless the edge of the salad bowl has a rounded over rim. Again a big bowl is like a big gulp and dust can drift more due to lower air velocity.

Also, efficiency is reduced as the hose gets longer and sharp turns such as 90 degrees can add the equivalent of 10 feet of hose.

Inefficient designs still work to some extent. They do so due to bigger and more powerful vacuums rather than by efficient design.

Soooo, if you want to want your dust collector to suck more, understanding how Bernouilli's Principal works will help your design.
Click to expand...
Thanks for your detailed explanation. I'm still working out my intake. I did find 14 inch, truly bell shaped wood salad bowl at the thrift store yesterday which will lead to a 4 inch, 1200cfm intake. The bowl is perhaps 9 inches deep. With the precision of dead reckoning, do you think I should just turn a small bell mouth similar to what you see in the automotive industry. Or just go ahead and try what I already have? The use will be multifocal, Pens, wine bottle stoppers, Salad bowls, hollow forms. Of these, it seems the salad bowls generate the most dust.
 
Regardless of the shape of the hose inlet, or its adjustability in positioning, I still insist that having a box, adjustable or fixed, is the best way to control the dust from getting into the atmosphere of the shop. Without a box, once the dust is only an inch or three from the spinning wood, it wants to go everywhere. With the box, air is drawn into it only from the immediate area of the turning, where the dust is initially being thrown into the direction of the box and the vac tubing. It makes the most sense to draw and contain the dust from the direct path from which it is being thrown. See robohippy's version, or Raffan's, Tomasic's, or <cough> mine (based on Raffan and Tomasic).

A bell shaped inlet, sitting by itself out in the open air, is not going to catch all the dust possible compared to having it inside the box where it only draws the air surrounding the turning, that airstream that actually contains the dust. We want to capture and contain the concentrated dirty air, not the open clean air from all other directions while allowing dust to escape the grasp of the suction airstream.

As an comparitive example, auto body shops paint cars inside of a giant box, with the suction system at the opposite end of the box from the door and the air intakes. It's not just about suction, it's also about capture and containment.
 
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Todd Bowen said:
Thanks for your detailed explanation. I'm still working out my intake. I did find 14 inch, truly bell shaped wood salad bowl at the thrift store yesterday which will lead to a 4 inch, 1200cfm intake. The bowl is perhaps 9 inches deep. With the precision of dead reckoning, do you think I should just turn a small bell mouth similar to what you see in the automotive industry. Or just go ahead and try what I already have? The use will be multifocal, Pens, wine bottle stoppers, Salad bowls, hollow forms. Of these, it seems the salad bowls generate the most dust.
Click to expand...
1200 cfm thru a 4" line will be loud and you will need your shorts on tight if you get close to it. will definitely draw dust.
 
I like the idea of a big box. I use a small box ~8”. Hopefully my explanation was informative so one can get the most volume movement with what they use.

With a big box, how the hose attaches does have some impact on efficiency. The transition from flat to tube should be curved and not sharp.

Just for show and tell, here are 2 pictures of the cowl inlet on a plane I just finished building. Once with sharp edges around the opening, and the other after I finished the fiberglass work. Note the curve doesn’t have to be dramatic to eliminate the turbulence of the air entering the inlet.
 

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Just about any cone/bowl shape will work, including a bowl that you have gone through the bottom of. I have heard of 5 gallon buckets and even cardboard boxes.

robo hippy
 
I have tried several horn like end pieces and finally decided to try Richard Raffan's model and I like it a lot. It may not be perfect but much better than a hose out in the open. I probably need a bigger vacuum than my Jet 1100.
 

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