[widgitmaster]

My old surface grinder came with a tank and a pump for wet grinding, however the vacuume blower motor was missing from this external unit.
Because my shop is small and abrasive dust can damage or rapidly age my machines, I would like to get the flood unit on my grinder working!

There is little available in used complete units for wet grinding, so I have decided to rebuild the unit I have.
So the question is simple, what CFM (cubic feet per minute) blower motor is needed for this application?

I have found an industrial centrifical blower unit with 167 CFM, and is capable of moving moist or wet substance. This unit sells new for $135.00 USD, so I would like to get a little input prior to hooking it up and blasting it with wet spray & steel particles!

Fantech FR110 Inline Centrifugal Fan - 4" Duct 167 cfm
www.rewci.com/fafrincefan41.html

Anyone have a mist collector on their ssurface grinder, if so what are the specs on your unit?

Widgit

[widgitmaster]

Also, the inlet diameter is around 2", and the exhaust will be 4"
Does this change the CFM?

Widgit

[widgitmaster]

Am I the only one with a wet grinder?

[Glacern]

I grind wet but I don't use the vacuum dust collection port.

[skippy]

Go on Widgit, confess! You swept and vacuum cleaned that floor prior to taking those photos right in order to have us believe that that's how the floor is every day of the week?

[joecnc1234]

I don't think you know what a wet grinder is. The vacuum unit is to remove dust. The coolant tank is for wet grinding it is low pressure like a swamp cooler pump or submersible pump it puts coolant on the part and drains off back to the tank.
Joe

[widgitmaster]

I don't think you know what a wet grinder is. The vacuum unit is to remove dust. The coolant tank is for wet grinding it is low pressure like a swamp cooler pump or submersible pump it puts coolant on the part and drains off back to the tank.
Joe

I Could say the same thing to you Joe! On my grinder both the coolant pump and the vacuum blower can be run at the same time!

The tank unit that came with my grinder has a pump, a 3/4" fluid return port and a 2" dia vacuum return port. Both ports empty into an extra fine stainless steel screen basket inside a sealed tank. The back of the tank had a centrifugal blower unit that created a negative pressure in the tank. There is a fluid discharge line which mounts on the spindle guard, and a 2" dia suction hose that also connects to the top of the spindle guard. The spray mist and particles are returned into the tank through vacuum line as well as the fluid drain near the bottom of the magnet! The tank holds about 8 gallons of fluid!

I bought this unit because of its ability to grind wet, and because it has ball roller tracks for the table! The grinder is made of heavy cast iron and weighs around 1100 Lbs. The pump motor is 3-phase 220 VAC, not a problem as it has been wired through a static phase converter. The Grinder has been dismantled, cleaned, scraped, and I have replaced all the central oil lines & fittings. The spindle on the grinder is in excellent condition too!

All that's left for me to do is find the replacement centrifugal blower to create the vacuum in the main tank!

The pictures were taken when the shop was initially setup, and the yellow lines on the floor indicated the machines new home!

Regular dust collectors will not work with a heavy flood spray, as they have paper filters! And using the grinder wet without collecting the nasty coolant spray is a bio-hazard to say the least!

My initial question regarding the CFM of the centrifugal blower still remains unanswered.

Widgit

[joecnc1234]

how much grinding are you doing? you could probably use a small shop vac if your'e that worried about it. If seen alot of wet grinders and I don't recall too many people using the dust collection. Mainly stainless, coolant took all the dust away.
Joe

[handlewanker]

Hi Eric, looking at the photo's in post #7, could you "reinvent" the vacuum part and just build the vacuum suction part from a shopvac less the bottom drum collection, onto the top of your tank?

It would probably only require a steel plate and gasket to cover the top, with the wet vac motor top grafted into it, and at least 1/8" thick to allow for the vacuum which will put at most 15lb PSI (atmospheric) on the plate surface.
You might have to put a few creases in the steel top to make it resistant to buckelling.
The exhaust is bigger than the suction to prevent back pressure and motor over speeding.

Most vacuum cleaners pass some of the sucked air, after the filter bag, through the motor to cool it as they're running at top HP and would burn up without this forced cooling, but the wet vac ones appear to have the motor isolated from the exhaust stream, which allows them to pick up wet material.

I've got an old Black & Decker shopvac with the motor gone bad, so if you want a photo of the guts taken apart you might get an idea of the layout on how to cobble up to your needs.

I'll probably be in the same position as you soon, as I've got a Macson hand surface grinder, (for polishing my nails lol), and as soon as the stone needs dressing I'll be wearing the dust, and the wet spray will go where it pleases.
They're selling wet vac units, 5 gallon drum size, at our local big harware store for $99 and $125, so I might go down the path of big spender.

On the other hand the bl##dy noise of the vacuum close at hand will be enought to cancel all future engagements for HiFi listening.
This will definately be a park outside unit through a hole in the wall.

The vacuum unit has always been the problem with these S/G's as the proper units cost a bomb, whereas the pump can be a pond type as long as it can supply enough and resist the coolant.
At my last employ they were using a pale green clear synthetic coolant, not the soluble oil type, and this was beut as it left the machine and parts clean and oil free.
Ian.

[widgitmaster]

Actually, I have thought of that! The only problem other than the noise which you have mentioned, is that all the wet / dry shop vac's are made from pre-molded plastics. None of them will adapt easily to the rectangular opening!

When I found the inline blower, it looked way easier to adapt to the plate! Plus, I can run the exhaust line out the window!

Now, I have looked at all the different shop vac's, and they have a CFM lower than the inline blower, which tells me that it should work fine! All I have to do now is shop around to find the lowest price, buy one, and adapt it to my grinder's tank unit!


Thanks Ian,

Widgit

[handlewanker]

Hi Eric, come to think of it, the shopvac idea probably wouldn't be practical anyway.
Although it would produce a vacuum at the pipe's end it probably wouldn't shift the CFM at the entry end by the surface grinder.
The suction pipe is about 2" diam at the business end, and if you go to 4" square at the intake to get all the dust as it come off the stone when you dress it, or the spray when you run it, then the suction at the intake would probably be down anyway.

The larger snail cam type centrifugal blower with a decent size motor runs quieter but shifts a lot more air, and doesn't need to produce anything near a vacuum cleaners suction, just capacity.

I think my analogy is out on this one as CFM is CFM no matter what the suction level.
The difference would be that a larger slower moving air mover would require ducting at the same size, but progressively bigger the longer you go, to deliver the CFM without loss due to skin friction in the pipe, whereas the higher vacuum type starts off with a small bore pipe and shoves it along at a higher compressed rate, something like high voltage electricity with power line sizes and low voltage power with heavy cables etc.

Usually the shopvac type vaccies fail when the bearings go, so that's what you pay the extra for in the industrial model.
Ian.