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nc5a
04-29-2019, 11:02 PM
Except for the doors and the vacuum hose/nozzle that reaches each grinding station the table is done. But the vacuum hose/nozzle is causing me problems.

I'm looking for a flexible 1 1/2" to 2" OD smooth bore hose that stays put where ever I bend it to. My plan is to use one flexible vacuum hose and bend it where necessary to reach each of the 6 grinding stations. So when I adjust it to suck up the grinding dust I want it to stay where I put it.

What kind of hose would that be and what search words would one use to find it? Vacuum hose would work although it's not smooth on the inside but it would work. But the problem is making it stay where I put it. I really don't want a bunch of clamps or brackets hanging all over the place to hold the hose. Probably 20-24 inches of hose will get me to all the stations. The 2" diameter hole in the center of the table is the vacuum source port.

Any Ideas?

Ron

https://i.imgur.com/QRw44FJ.jpg

https://i.imgur.com/BuUP7BY.jpg

https://i.imgur.com/75emrtB.jpg

https://i.imgur.com/VWJRXPc.jpg

Tundra Twin Track
04-29-2019, 11:33 PM
Flexible steel exhaust tubing should work, but mount tubing so grit does not plug up spiral joints.

alanganes
04-30-2019, 07:24 AM
Maybe attach the hose to a section of goose neck like the sort used to hold lamps and microphones. If you anchor it in the center of the table by your vacuum inlet, it could reach around to any of you grinders.

Nicely done setup, by the way.

JoeLee
04-30-2019, 07:41 AM
Flexible steel exhaust tubing should work, but mount tubing so grit does not plug up spiral joints. How would you do that??
Grit is going to collect on the inside walls of the piping no matter how you mount it.

JL...............

JoeLee
04-30-2019, 07:45 AM
This is what I rigged for my SG and my T&C grinder if it's any help.

If I have to do any heavy grinding with my bench grinder I take it out side.

https://i.postimg.cc/PCm3vRBv/IMG-20190425-191235.jpg (https://postimg.cc/PCm3vRBv)

https://i.postimg.cc/wtq6s93w/IMG-20180427-112812.jpg (https://postimg.cc/wtq6s93w)

JL...........

Mcgyver
04-30-2019, 07:51 AM
As we do exhaust and dust collectors occasionally, the starting point is what sort of CFM each pick up point needs. I believe there are tables of suggested values for small machines, 500 CFM comes to mind for a grinder. Maybe its less, can't remember but its likely a lot more than a vacuum can deliver. It would be worth looking at, you might need a more powerful blower to get the results you want.

Tundra Twin Track
04-30-2019, 11:50 AM
How would you do that??
Grit is going to collect on the inside walls of the piping no matter how you mount it.

JL...............

The way the flex pipe is crimped when manufactured the flow of product should only travel one direction so not forcing product into the seams.On a grain vac if you have it the wrong way the Vac really jerks as the flow of product cavitates.

BCRider
04-30-2019, 12:15 PM
What about individual collection funnels for each wheel that you plug the regular hose onto? Each of the grinders you show will have it's own unique pattern of where the majority of the swarf flies. And that pretty much means a different shape of collection funnel to catch and work with the energy of the swarf so it works for you. And that pretty well means different funnel designs for each wheel. And if that's the case you simply connect the regular plastic hose that comes with the vacuums to each collector funnel which is mounted to each grinder.

I'm getting some deja vu here.... Was it a thread of yours about this same topic where I mentioned the same idea of separate collection funnels?

ahidley
04-30-2019, 12:22 PM
How about a four way valve? Plumb them all through a 4 way manifold and have a valve to only allow one to suck at a time and have it set up like the above post..

Paul Alciatore
04-30-2019, 05:50 PM
The swami SEES all.

The swami SEES a vertical pipe (3" PVC?) in the center The swami sees a smaller vertical pipe (2.5"?) that slides in that pipe, held by a thumb screw and with some packing to hold the vacuum.

The swami SEES an elbow on the smaller vertical pipe bringing it horizontal.

The swami SEES an even smaller horizontal pipe in that pipe, again with thumb screw and packing.

The swami SEES a second elbow to bring the third pipe down toward the grinding stations.

The swami SEES another, even smaller pipe in the downward pipe. This, final pipe is once again held with with thumb screw and packing. It can extend to each grinding area. It has an elbow that can face the wheel to catch the dust.

That should give you complete adjustablity in all three dimensions and the ability to aim the suction port directly at any of the wheels, at any height, and at any angle.

At that final position, you could use an elbow that adopts to a larger pipe size to increase the area of the suction port. You will need to drill and tap the PVC pipe for the thumb screws: If you use thinner gauge pipe you could add half of a splice fitting on the ends to increase the thickness to allow more threads there. That half splice could also be made to hold the packing/gasket that seals against leaks.

http://bbs.homeshopmachinist.net/attachment.php?attachmentid=5127&d=1556660524

With this design, the walls are smooth and the transitions are always from smaller to larger so the accumulation of grit inside the pipe should be minimal. Another idea just hit me: add a long, vertical spring on that first vertical adjustment to hold most of the weight of the assembly. That would make adjustment easier. That would work better for me than you as you need a full 360 degree rotation there.

PVC pipe fittings will have a friction fit. That means that you could have different collecting funnels for each station. They would fit into the final elbow.

I like this idea - yea, I know it's mine so I should. But I am planning a multiple grinder station, probably on a rotating table and I had some other ideas in mind. They involved multiple air gates and would be somewhat involved and perhaps more expensive. But this looks better so I may very well use it myself. One advantage for my grinder station would be that my table could rotate around the largest, vertical pipe so the vacuum stays still under it. But that will not be today or even this month or next. I have too many unfinished projects as it is.

Paul Alciatore
04-30-2019, 06:00 PM
Another idea just hit me: Using my idea above, attach one or two of those small, LED, goose-neck lights to the horizontal arm, near the second elbow. They should provide excellent illumination for your/my work.

It just gets better and better. "I love it when a plan comes together."

nc5a
04-30-2019, 06:17 PM
What about individual collection funnels for each wheel that you plug the regular hose onto? Each of the grinders you show will have it's own unique pattern of where the majority of the swarf flies. And that pretty much means a different shape of collection funnel to catch and work with the energy of the swarf so it works for you. And that pretty well means different funnel designs for each wheel. And if that's the case you simply connect the regular plastic hose that comes with the vacuums to each collector funnel which is mounted to each grinder.

I'm getting some deja vu here.... Was it a thread of yours about this same topic where I mentioned the same idea of separate collection funnels?

BCrider.....I think I remember you posting a comment about vacuum/dust collection arrangements but I don't remember if it was directed toward me. But I get the drift about different shaped collection chutes. I'm trying to make this simple so I use it every time I grind. Recognizing of course that it probably won't be very efficient. Designing and building collection chutes for the 6 grinding stations isn't something I have time for right now.

When I get my surface grinder up and running it will require more careful consideration for a collection chute.

nc5a
04-30-2019, 06:39 PM
The swami SEES all.

The swami SEES a vertical pipe (3" PVC?) in the center The swami sees a smaller vertical pipe (2.5"?) that slides in that pipe, held by a thumb screw and with some packing to hold the vacuum.

The swami SEES an elbow on the smaller vertical pipe bringing it horizontal.

The swami SEES an even smaller horizontal pipe in that pipe, again with thumb screw and packing.

The swami SEES a second elbow to bring the third pipe down toward the grinding stations.

The swami SEES another, even smaller pipe in the downward pipe. This, final pipe is once again held with with thumb screw and packing. It can extend to each grinding area. It has an elbow that can face the wheel to catch the dust.

That should give you complete adjustablity in all three dimensions and the ability to aim the suction port directly at any of the wheels, at any height, and at any angle.

At that final position, you could use an elbow that adopts to a larger pipe size to increase the area of the suction port. You will need to drill and tap the PVC pipe for the thumb screws: If you use thinner gauge pipe you could add half of a splice fitting on the ends to increase the thickness to allow more threads there. That half splice could also be made to hold the packing/gasket that seals against leaks.

http://bbs.homeshopmachinist.net/attachment.php?attachmentid=5127&d=1556660524

With this design, the walls are smooth and the transitions are always from smaller to larger so the accumulation of grit inside the pipe should be minimal. Another idea just hit me: add a long, vertical spring on that first vertical adjustment to hold most of the weight of the assembly. That would make adjustment easier. That would work better for me than you as you need a full 360 degree rotation there.

PVC pipe fittings will have a friction fit. That means that you could have different collecting funnels for each station. They would fit into the final elbow.

I like this idea - yea, I know it's mine so I should. But I am planning a multiple grinder station, probably on a rotating table and I had some other ideas in mind. They involved multiple air gates and would be somewhat involved and perhaps more expensive. But this looks better so I may very well use it myself. One advantage for my grinder station would be that my table could rotate around the largest, vertical pipe so the vacuum stays still under it. But that will not be today or even this month or next. I have too many unfinished projects as it is.

Paul.....I had a brother that was given away at birth, could you be him? We have exactly the same idea except mine is constructed with 1 1/2" plumbing fittings like used under a kitchen sink. The flexible joints would be possible with the nuts and cone seals lightly snugged up and the nut locked in place with a tab. This was my plan until I discovered this, https://flexpvc.com/cart/agora.cgi?product=Loc-Line-025-2-1/2inch. I think it's made to order and self supporting to 36". A bit bigger than I need but it's already anti static and built for vacuum systems. Nice drawing by the way.

Ron

Tom S
04-30-2019, 09:59 PM
I'd be worried about the suction loss you would see with all the bends and reductions in that design. The reduction in pipe size as you move away from the might be sufficient to keep a higher level of vacuum, but at the cost of a reduction in the volume of air being pulled in by the vacuum. Think of it as the reverse of a pressurized tube, reducing your diameter over distance will keep the pressure up, but will also result in a reduction of cfm. And like Mcgyver mention, you need a certain amount of cfm to have a sufficient dust removal system.

I'd go with BCRider's recommendation of a variety of different collection funnels permanently mounted to the machines, with a smooth-bore vacuum rated tube that can be switched from funnel to funnel. Keep the bend radius of the tub large when accounting for the different funnels to help keep the suction level where it needs to be.

Paul Alciatore
04-30-2019, 11:17 PM
That stuff looks neat but the price seems a bit steep. 24"= $60 and 36" = $90. I haven't priced it yet, but the PVC or drain pipe ideas may be a lot less expensive. Re: PVC vs. drain pipe, I think the PVC with thumb screws would be easier to adjust but the drain pipe would probably have better seals.

I don't think going to a larger pipe/tube size and then back down to a size close to the original vacuum hose would have a large effect on the suction. And the larger size would make the effect of the elbows somewhat less. After all, PVC pipe is used for central vacuum systems; the 2" size I think.

On that brother thing, I don't know. But my mother says they found me floating around in the flood when the levee broke after a hurricane. Thank goodness that basket was waterproof.




Paul.....I had a brother that was given away at birth, could you be him? We have exactly the same idea except mine is constructed with 1 1/2" plumbing fittings like used under a kitchen sink. The flexible joints would be possible with the nuts and cone seals lightly snugged up and the nut locked in place with a tab. This was my plan until I discovered this, https://flexpvc.com/cart/agora.cgi?product=Loc-Line-025-2-1/2inch. I think it's made to order and self supporting to 36". A bit bigger than I need but it's already anti static and built for vacuum systems. Nice drawing by the way.

Ron

BCRider
05-01-2019, 11:43 AM
Losing the suction through small diameters is certainly a factor that needs to be closely examined. I've got a couple of shop vacs which came with the small 1 7/8 hose but with an inlet fitting that would take the 2 1/2" hose too. When fitted with the larger hose the difference in both volume and velocity was like night and day. The increase in air loaded the motor down but it moved so much air and would suck things in from a lot further from the end of the hose. Just what we'd want for a vacuum system on the grinders like this.

Now if the vacuum had a lower power motor going to large on the hose would not maintain the FPM in the hose. And I saw this in writeups on dust collection systems when I was trying to pick the size of ducting for my wood shop collection system. Basically these instructions all said the same thing. Keep the duct or hose as large as you can while still allowing for a fast enough FPM in the duct/hose to stop the particles from settling. And it actually warned against using reduced size diameters at the collection funnels as this would act as a restriction and reduce the FPM in the duct/hose. But at the same time it also stressed the need for smooth inner surfaces.

Bottom line is that for a good shop vac I'm thinking that between 2.5 and 3" is likely the optimum size to get the most volume and still have a good flow rate in the hose. And if using the commonly available stuff I'd certainly go with the 2.5" hose and ensure it stays at 2.5 through the whole collection system from connector funnels to the vac.

Mcgyver
05-01-2019, 11:52 AM
Losing the suction through small diameters is certainly a factor that needs to be closely examined. I've got a couple of shop vacs which came with the small 1 7/8 hose but with an inlet fitting that would take the 2 1/2" hose too. When fitted with the larger hose the difference in both volume and velocity was like night and day. The increase in air loaded the motor down but it moved so much air and would suck things in from a lot further from the end of the hose. Just what we'd want for a vacuum system on the grinders like this.

Now if the vacuum had a lower power motor going to large on the hose would not maintain the FPM in the hose. And I saw this in writeups on dust collection systems when I was trying to pick the size of ducting for my wood shop collection system. Basically these instructions all said the same thing. Keep the duct or hose as large as you can while still allowing for a fast enough FPM in the duct/hose to stop the particles from settling. And it actually warned against using reduced size diameters at the collection funnels as this would act as a restriction and reduce the FPM in the duct/hose. But at the same time it also stressed the need for smooth inner surfaces.

I'm not the engineer who sizes up this stuff, but I can tell you it doesn't work out by accident. The CFM needs to be adequate, then you workout the static pressure necessary for the ducting run which has to do with length, curves, dia etc. You often see them get larger as they move away from the pick up, but that's so that many pickups can work at the same time. If you're only using one (with no others or others shut), you don't increase the diameter. Often when the diameter is increasing (to accommodate several pick ups), you need to have a way to introduce air so that the velocity doesn't fall too much going from small to large

BCRider
05-01-2019, 01:36 PM
... you need to have a way to introduce air so that the velocity doesn't fall too much going from small to large

In my reading that was a big point that was made too. For the air to move we have to let it get in is so it can move.

In the case of my table saw I stuffed the openings between the top and the sheet metal sides and also made up overlapping panels to close off the big opening in the back and still allow the motor to swing for angled cuts. And on the bottom it has a sloping side box to catch the sawdust with the 6" duct outlet on one side. But at the same time I included a 4" gate on the opposite side of the "V" to let in air to make up for the small openings. This also created a strong cross wind that keeps the dust from piling up in the sloping sided box.

There's online calculators for figuring this out that I found at the time. I took the CFM and static pressure ratings of the dust collector I bought and the calculator suggested 6 point something to 7" ID's for the short runs I was able to use. So I opted for 6" since there's more stuff available for that size. Also it was the size of the inlet at the blower fan housing.

Oddly enough I use it between my table saw, the sliding compound saw sitting in a big shroud to focus the dust collecting and also on the jointer in the same way that you want to use with your grinders. The machines are all grouped right around the dust collector and I've got an 8' piece of 6" flex hose that I shift from duct to duct to pick up the chips from each machine as needed. Not as convenient as a multi path system but it sure provides excellent dust grabbing. And since the wood working shop is in the basement and I don't want the dust flying around the house I find that this works well.

Paul Alciatore
05-01-2019, 05:50 PM
I did not put any actual pipe diameters on my sketch above. This was deliberate. I did mention starting with a 3" diameter in my text, but that is not an absolute. You could easily go larger.

You should start with the diameter (internal) of the vacuum that you are going to use and work from there. But work BACKWARDS from the intake at the grinder wheel. So if you have a 2" vacuum intake, go with a 2" intake at the grinder wheel end. And work up from there as you proceed towards that vacuum itself. At no point should the opening be smaller than that two inches or whatever your vacuum has.

With PVC you can use thin wall pipe to allow the telescoping without getting ridiculous with the final diameter. Or even alternate thin and thick wall pipe so the thumb screws will rest on thick wall while the sections that they fit into are thinner. A few minutes at the local hardware or home supply store would be a good place to pick the pipe diameters. Some of the stores in my area sell short lengths of PVC that make testing easier.

This may not produce the "ideal" system in terms of suction, but it will probably be as good as it can be, given the restraints of the grinder work station.

J Tiers
05-01-2019, 06:43 PM
To McGyver's point, you really DO need to "design" it to do the job.

You can make it easier by enclosing the wheel as much as possible, and not letting the sparks/dust get outside the enclosure. If they did, you would need enough air velocity to capture them, which is difficult.

A funnel behind the wheel is not doing the job, even though you may think it is. You just do not have "wind tunnel" type volume and velocity, some of the dust, perhaps most of it, is escaping. You DO have some advantage because much of the dust is directed at the funnel by how it comes off the wheel. But not all.

With limited volume and velocity, enclose, then exhaust. That way, the limited volume of air is all passing the dust generator (wheel) and picking up dust. The enclosure is responsible for capturing the dust into the airflow.