Thread: Fan follies

Looks like an interesting project Ian.

One comment, the fan looks like it is specifically designed to work with the four heads (4 openings, 4 blades - My dusties both have many more blades than that). It may not work efficiently with the single opening. Something tells me the performance could be greatly enhanced by modifying/making a fan more suitable to the single opening configuration. As it is, it would probably work ok just as a result of the brute force factor, but when you have it together if the performance is less than you expect or need, that would be where I would be looking.

I wish you well with the project and wish I had enough power to the shed to run a beast like that.

Doug

It's a pity how much work you have put into it already. because I agree with doug about the fan,
It's THE serious limiting step in your setup.
Those types of flat bladed radial fans are more suited to high pressure low volume flow and for air containing stuff that sticks to the blades which is usually not a problem for wood dust.
Even with a 5HP motor (unless a VSD is used) the fan can still only turn at 2850 rpm and given that the fan has only 4 blades it will be lucky to move much air.
A 5HP motor should be able to move a much bigger impeller than 13" and hence move a lot more air.

Hi Doug and Bob

Thanks for you comments.

You can't see it from the crappy photo but the fan has 6 blades. Like these things always do it feels like it is moving a lot of air but it is really impossible to tell at this stage.

Something bigger and with a better shape would be good but at present I can't find it. It is really a question of starting somewhere. If something better turns up I would be perfectly prepared to walk away from the one I have.

I have vaguely thought of a VFD. The motor has the bearings to go faster and the fan has been properly balanced. I will get the whole thing mounted and get the first duct run in and see what I think.

Regards

Ian

Pity you are not a bit closer as I would offer to bring my air flow test gear over and do some testing. ANyway, good luck with the project.

Ian,

With the smaller impellers and 2850 RPM it is a good idea to build a larger cyclone body as you did. When I make cyclones for friends I do as you did and spot weld all together then seal. I do recommend soldering the cone to the upper cylinder just for additional strength then either solder or use polyurethane for sealing.

Your undersized blower is not going to move the full 1000 CFM we need for good fine dust collection, so I would optimize what airflow you can by stepping up to an 8" diameter main and 7" diameter down drops that split when needed into ducts with a total area of equal to or slightly greater than the area of a 7" duct. This extra area will greatly reduce your total resistance and help with the airflow considerably.

Still, the bottom line is with insufficient airflow you do not end up building a low pressure bubble around the working areas of your machine ample to pull in the fine dust before normal room air currents disperse the fine dust. That means you should put on your mask and turn on a strong fan before you start making dust. Our particle counters show you need to keep on that mask and fan blowing out the back of your shop with a main door open 4 or 5 inches for about a half hour after you stop making fine dust. This will avoid a buildup of the fine residual fugitive dust in your shop that otherwise would escape collection. This invisible fugitive dust in most shops that use indoor dust collectors and cyclones ends up so bad that just walking around will stir up enough dust to fail the EPA air quality standard of 0.1 mg per cubic meter.

With your Robland, you probably should remake the lower blade guard to upgrde to a full 5" port and hose. I had to make mine oval to fit and still maintain full blade tilt. You also need to redo that big 4" hood port to make it at least a 5" and preferably a 6". Those two changes will make your unit far cleaner both in terms of chips and fine dust.

Regardless, well done on your build.

bill

Originally Posted by TheNutter

Hi all

Its hot ...

Again like many others I started to look around for a fan to drive the whole thing, 14" 3 hp seems to be the gold standard. Just before Christmas I scored a 13" 5hp 3ph fan built into a four head industrial dust collector. I paid $50 for this. The good side is a simple strong paddle fan, quality CMG motor and switch gear. The downside was the fan body. It was a square with some rounded parts and an outlet in each corner. Some surgery was required.

After a lot of thought I made up a template using the ideas from Bill Pentz's site and cut the fan body to shape. The scribed line can be seen in the picture. I cut the two sides using a (nice new!) jig saw, the result can be seen in the picture. I then cleaned up one of the old bag mounts and wrapped it around the cut down fan snail and welded it into place. The somewhat blurry photo shows it being held by a ratchet tie. I did learn that welding sparks readily ignite those bands.

I then remade the outlet with another piece cut from the original fan body and added a mounting for the eventual outlet. This can be seen in the picture. Finally some polyurethane sealer between the welds and paint.

Concurrently with this I have made up a 20" cyclone from Bill's plans. I did this the easy way by first cutting the parts, then getting them rolled, folded and spot welded together. Rather that soldering it (I hate soldering) I sealed it with polyurethane.

This will all be installed in an outside structure which I have still to work out the details for. In any event it can't be done until after the break of season. Digging the hard ground and cutting the steel outside with an angle grinder is not a job for summer!

Regards

Ian

Blower Cyclone 008.jpgBlower Cyclone 001.jpgBlower Cyclone 011.jpgBlower Cyclone 006.jpgBlower Cyclone 013.jpgBlower Cyclone 015.jpgBlower Cyclone 007.jpg

Thanks Bob, some actual data would be wonderful, pity about the Nullaboredom!

Thanks Bill, I must say your plans went together like a dream. When the sheet metal worker assembled it he rolled a 15mm flange horizontal to the bottom of the body and to the top of the cone with a jenny. The two joins were offset and the two flanges spotwelded together. This seems to have made the whole thing very rigid. If I had done it I would have had to do segmented cuts and soldered it got the rigidity back.

When I bought the Robland (very second-hand) it was missing the riving knife and the blade guard and so I followed your reccomendation and bought a Shark Guard. I took a little grinding to fit to my older machine but now looks good, I obviously haven't really tested it yet. Below the blade there is 4" duct but no containment so I will have to make that up from scratch. I am aiming for 3" above the blade and 5" below but this subject to evolution. There is no provision at all on the jointer/thicknesser so I will have to make that from scratch. The shaper is missing some parts so I will think about that if I actually use it.

Regards

Ian