J. Phil Thien's Projects

I have not heard of that, but in the woodgears dust collector, there's a filter manifold before the blower.

Not much has happened, real life interferes a lot. But I've decided to return the air back into the shop after all. So I will put in a filter bank after the separator and before the impeller. I am thinking a manifold that uses 3 or 4 smaller HEPA filters for shop vacs, or however many is needed for the the filters to not restrict air flow too much.

I read it's better to separate before, the impeller dislikes back pressure behind it more than an obstruction in front.

Ditto here. Well at least I made a table...

Thanks! Just got my new router (a bosch GMF 1600 CE, finally something to replace my €40 lidl-special) so I'll be working on a spiral cutting jig to get the walls just right. I figured out I don't wanna glue them together like Matthias Wandel did. I tried that and it quickly got annoying as heck, esp. since I don't have a miter saw or a miter gauge.

Also doing some other projects now so time, always so little time...

Well finally got the bearings. So I used my circle jig and made it round:


Then I balanced it on an M12 rod with bearings:


And it's back


Standing with the switch 10 meters away outside the shop I started it, probably a dozen times. Longest and last time was 5 seconds. Here it's in action, spinning down:


Seems to be holding up, and while it it's round and turns true in that way, though there is back and forth wobbling, especially on the front face, more so than the back face, which means it's not flat. I am not sure how big a deal it is, if I should set up a tool rest and correct it.

It's a really scary monster, the sound it makes makes me feel like a small bird getting sucked into a jet engine... And all the air it stirs up, jeezus good thing I am putting this in another room. I'd like it in the attic even, far away.

Still waiting for the parts, checking my mailbox every day for the bearings, getting disappointed nearly every day too. Shoulda bought locally.

No point in doing that until I trim it I think, I'll have to rebalance it again then. I've ordered a bunch of ball bearings of the same bore diameter as the motor shaft  (28mm) so I can have the impeller turn on those in the circle cutting jig, otherwise I won't get a perfectly centered cut. So gotta wait for those to arrive. Then I can balance it. Building the enclosure instead meanwhile.

Picture of the Mark II


Sides will be trimmed yet, should be 18" when done.

I've seen that you could run a screwdriver or similar along the hose with some pressure, to change the material shape a bit, that should make it less perfectly repeating and thus remove the annoying sounds. I dunno if it was Jay Bates who did that...

Been on a break, but I've glued and assembled the impeller vanes & hub now, top plate still needed, and then balancing. I will try static balancing this time using bearings on a threaded rod, but I need to wait for the bearings I've ordered. So much waiting.

Spun up the impeller plate only though to test it and thought, damn, this is scary, this is really ****** scary. Definitely don't want to be in the same room.

Going slow, laminating the vanes still, here's a picture:


It actually worked better to just stand the jig up and use clamps.

Also yardworking, prepping & sowing a lawn, casting concrete slabs, stuff like that.

Well it's going to be a little while now I think. I've had to order new router bits so I can route grooves that will fit my vanes, and bending and laminating those will take a while as well. I've also ordered a 28mm brad point bit because the drill bit I used to make the holes earler was less than optimal.

As I understand it, the taller the better the separation, same goes for diameter (or was that less resistance). So for simplicitys sake a  transparent or semi transparent separator is useful, then you can see where the stream of dust goes and place your baffle accordingly.

A soft starting unit was cheaper than i had expected, I could get a new one from germany for 140-150 euros shipped. That might be worth it considering the long run.

I cut out a new impeller disc last night at 45cm, I am scaling it down a bit. Partly because I also have plans printed for this impeller to 1:1 so it'll make things easier to visualize. There will be changes though to the vanes I think, slightly curvature and I will make them longer so they go all the way into the hub and cut the vanes at an angle so they don't protrude from the top lid. Much like a commercial impeller.

Quote from: phil (admin) on June 03, 2015, 07:14:28 AM

Quote from: retired2 on June 03, 2015, 06:09:44 AM

Quote from: DennisCA on June 02, 2015, 09:45:51 PM
No pics but I can see that the epoxy had let go, the bond wasn't very strong after all. So only the screws held it in place and they had been pulled straight through the the plywood bottom when things let go, one vane shot off into the ceiling and broke a fluorescent tube. These vanes are heavy and dangerous, I was lucky I put the circuit breaker on an extension cord and moved to the other side of the shop and stood crouched behind the jointer.

I'm remaking this but using plywood or MDF vanes like Marius hornberger used in his build- I think the lighter weight means there's less momentum to overcome as it starts up so less stress in that initial jolt, at least the vanes shold be light I now feel, the backing disc could probably be made heavier from 18mm plywood for deeper grooves.

Also I think the wood glue bond with wooden components will be a lot stronger than this failed epoxy joint, and safer if it blows up. Next time I'll be testing it with the top on too. I think I will follow Matthias wandels design closer in terms of vane layout for this new design, perhaps make it a little shorter, I had aimed for 10cm but perhaps 8cm will make for a stronger impeller.

Even with a successful build, I would always be worrying about when it was going to explode at full speed.  Home built blowers, especially large ones, should be isolated from the rest of the shop with a "blast barrier" - a very strong one to keep it from adding to the amount of shrapnel in an explosion.

I imagine a sufficiently strong wood housing would absorb most of the damage, no?

I think one important factor demonstrated here is to never spin-up a partial blower, one that doesn't have both the top and bottom glued on.  Having the top in place would have made the entire wheel exponentially stronger.

I think it as as well that I tested it without, the epoxy bonding had clear flaws I would not have been privy to knowing about without this test.

I think if I had used screws with large flat heads or washers, those could have held the impeller together, perhaps. And perhaps some other glue, like polyurethane construction adhesive.

Still now I think making the vanes as light as possible is the best way to go, that way the explosion when/if it happens won't be as catastrophic. I think the plastic vanes would work if you used large bolts all the way through, and a steel disc backer instead of wood, that might be strong enough to handle material.

I also remember reading on Bill Pentz site something a bout how a wooden cage stood up to abuse better than a sheet metal one did.