Materials for building an impeller

[DennisCA]

I am building my own impeller using Matthias Wandels dust collector plans, reason being it's much more efficient per HP than material handling impellers and I wanna get as much useful work out of this DC I am building. But I am wondering if I should build it from plywood and hardwood, I also had some ideas of buildilng the vanes from softwood and epoxying thin sheet metal on the surfaces to make a really durable vane.

Now I am wondering, could I forego wood entirely and maybe use plastic, I got this idea in my head now of a completely transparent dust collector with a viewing window in the housing. I'm not sure if it would be a good or bad idea. I dunno if the materials I got access to could work, I could use either polycarbonate or SAN (styrene acrylonitrile) for this.

Anyone here a engineer or something with the relevant qualifications to take a stab at this? I kinda thing it would be as durabe as wood at least. And it would be much more uniform weight wise than plywood. And it would look really cool  :D

[Zamfir]

Ohh man!  This sounds right up my alley!  I currently have a material handling impeller old delta and I am converting the dust collection system (currently a bag for a vent and its rolling canister over to a Thien separator with a Wynn filter for the output rather than the bag.  So now the impeller would not be handling the heavy materials any more.  Would making my own impeller help out my system in this case?   If so, which plans are you following?  I am googling it now but there seem to be a lot of variations. 

[DennisCA]

I'm using matthias wandels plans from woodgears.ca

[R.True]

I just finished upgrading my impeller and I used 1/2" MDF for the plates and an off cut from a 4x4 cedar post for the fins.  It works awesome.  Sandwiching the fins between a top and bottom plate of some sort is essential I think.  I also made a new housing from 1/2" MDF for the top and bottom plates and 2x4 cut on the band saw (as per Matthias videos).

An all clear system would be really cool but that would probably distract me from the tasks at hand...  8)

[DennisCA]

Got any pictures? I was under the impression MDF wouldn't stand up to the stress.

[R.True]

I don't have any pictures of it.  Next time I take it apart I'll shoot some pictures.

I don't think there's any issue with MDF for the main plates.  I think MDF is more stable or at least as stable as melamine and people use that all the time for making their own disk sanders spinning at 3450 RPM.

[DennisCA]

This ones only gonna do 2800-2900 RPM though because of the 50hz electricity grid we got in europe. Still in the plans I got it cautioned strongly against using anything but high quality (preferably baltic birch) plywood. I did however see that youtube user Marius Hornberger also used MDF in a homemade impeller.

Another youtube user who made his own impeller used plywood but it came apart at 3450rpm. He then rebuilt it and used fiberglass to reinforce the vanes.

[R.True]

If you can find some 12"-16" dia PVC pipe you could make the fins from that (they are already curved too ;)  ).

If you look at Matthias' builds he pretty much uses what ever plywood he has on had.  I noticed in one of his previous builds he was using wall panel boards which are just about 3/16" thick and not the best grade......

Will see if my MDF plates fall apart or not.....if when they do I'll just rebuild the unit using plywood and PVC pipe for the fins.

[DennisCA]

It seems a laminate would be stronger than a solid piece, so I think I am going to try and make my own bent laminations from spruce and see if that will work. Cutting a groove in the impeller base for the vanes also seems like a good idea to make them hold better.

[DennisCA]

Started building the impeller over the last few days, went with a 51.5cm diameter impeller, cut the bottom from 12mm birch plywood and a top from 7mm plywood.

I have had a real hard time finding suitable poycarbonate sheets, and it's quite expensive what I did find (only 3mm thick) so plywood it is.

I then cut 6mm grooves into the bases for the vanes to slot into using my router table, it required me to drill a hole at the proper distance in my router table top and put a screw into it from below. But I can reuse it now if I need to mill more of the same cutouts and lowering the screw was easy.

I suppose I will be making wooden vanes now, thinking about cutting thin strips and steaming and laminating with glue.

[R.True]

That's a big impeller!! (20-1/4" Dia for us who don't know metric)  What you going to be powering it with?  2hp I would think minimum.

Pictures?