J. Phil Thien's Projects

Heh, heh.  You said "huge fan" in a forum about dust collection.  Heh, heh.

You're right about the baffle.  It really is no big deal to remove the screws once in a while.  Just seems that putting a weight on the baffle would make it that much easier.

-- Russ

Got it.  Thanks!  The light tent explains everything.

-- Russ

Hi John,

Thanks for the reply.  I thought about the sawdust issue, too, and thought it wouldn't be a problem for a two reasons: 1) If the separator is working right, there shouldn't be any sawdust in the upper chamber where the valve would be, and 2) when the valve opened, the clean air rushing in should blow out any debris that might disturb the seal.  That's the theory, anyway.

I think I'll go ahead and try my idea and see what happens.  Then I can report on exactly why it didn't work!

-- Russ

PS: What kind of lighting did you use when you took the pictures of your valve?  Those pictures really are nice.

Another nice description, and beautiful photography of a great idea!

Like you, I just put together a shop vac/Thien separator setup with a 20-gallon garbage can that collapses when the inlet hose gets blocked.  And, like you, I started thinking about a vacuum relief valve.  Unlike you, however, I haven't got as far as actually trying to build the valve.

I was considering something like what I've shown in the picture.  There would be a bolt extending through an oversized hole in the lid with the head of the bolt on the inside of the can.  Under the head of the bolt would be a big washer-like plate, perhaps with an O-ring or something similar to help it seal against the inside surface of the lid.

On the outside of the lid, a spring would live between the lid and a nut and washer threaded onto the bolt.  This spring would be in compression and would act to keep the plate under the head of the bolt sealed against the inside of the lid.

When a blockage occurred, the increase in differential pressure across the valve would compress the spring so that the inner seal would leak and thus allow air to flow around the bolt and into the can.  The compression in the spring--and therefore the pressure at which the valve opened--could be adjusted by moving the nut up and down on the bolt.

After seeing your valve, which would be quite a bit more complicated and difficult to build, I'm wondering if you might have started with something simpler like I'm talking about and discovered some reason that it wouldn't work.

Any insight?

Thanks,

-- Russ

Nice writeup.  Nice pictures.  Nice job!

-- Russ

Got it.  Thanks.

Try this:

http://www.jpthien.com/jpthien/demo.wmv

Phil,

Newbie poster here.  I saw that you edited my very first post, presumably to change how the pictures were handled.  For future reference, is there someplace on the forum that explains how you'd like to have it done?

-- Russ

Quote from: rhossackI think I understand what you meant when you said, "I started by cutting the tube to roughly match the curved surface of the can.  Then I used that piece to trace the location and shape of the hole in the can".

Did you eyeball the shape or a template and what tool did you use to cut the wand?

To get an idea of the shape of the curved cut needed on the wand, I held the wand in the desired position, but above the rim of the can.  Then I could sight down from the top and draw a line on the wand that sort of matched the curve of the can.  This wasn't very precise, but it came out close enough that I could then use the cut off wand as a template for tracing the location and shape of the hole in the can.  If you try this, be sure to leave yourself some extra material so you can make adjustments or just try again if it doesn't come out right the first time.

I made the initial, rough cut in the wand with a bandsaw, and then cleaned it up after everything was all assembled using a little sanding drum in a Dremel.

Quote from: rhossackLooking at that hunk of wood for the plumbing in the lid must have been fun to cut with a hole saw.

I bored that hole out on a lathe.  That way I could sneak up on the hole size so the shop vac hose fit correctly.

Quote from: rhossackWhat did you use for a gasket?

That's a piece of cheapo sticky-backed foam weather stripping that you can get at the BORG.  It's stuck into a groove that's not quite as deep as the thickness of the foam.  I made the groove with a router and a circle cutting jig like the one in the pictures below.

Quote from: rhossack"I just have the baffle sitting on three little blocks of wood that are mounted to the can with screws run in from the outside."

Another neat idea.  Is it necessary to screw the baffle to the 3 blocks of wood?  Could you just set the baffle on top of the 3 blocks and then you could remove the baffle to empty the can?

That's how I tried it at first, partly because it seemed easy, and partly because I would then be able to experiment easily with the position of the drop slot relative to the inlet port.  However, the suction from the vac was strong enough to lift the baffle off the supports and up against the outlet port.  Oops!  My knee-jerk reaction was to screw the baffle to the support blocks.  That solved the problem, of course, but as you note, it is now a hassle to remove the baffle in order to empty the can.

I started thinking about all kinds of fancy latches and such to replace the screws, but that seemed silly.  I also think the less stuff you have in there to disturb the airflow, the better it's going to work.  I'm now thinking that the best idea is to simply make the baffle heavier, either by making it from thicker material (mine's 1/4" MDF--not much weight there) or else by attaching a hefty chunk of platinum on the bottom in the middle to weigh it down.  Iron might work, too.

-- Russ

Quote from: dbhost on June 19, 2009, 01:54:03 PMAll I would add is seal the joint between the tube and the can with RTV Silicone Sealant and lose the duct tape. RTV will hold especially with that bolt there...

I'll probably do that.  The duct tape started to come unstuck from the inside of the black plastic tube right away.  I replaced it with some of that really sticky Gorilla tape, but the RTV idea is probably better yet.

Quote from: dbhost on June 19, 2009, 01:54:03 PMVERY interesting idea about the baffle in the can... Easier to orient it right that way to the tube in the can...

Yes.  And it also made the whole thing a tiny bit easier to build.  As I mentioned, it might be a hassle when emptying the can.  I also wonder if that little tab in the middle of the drop slot will affect the separation.  So far, though, it has worked so well that I'm afraid to change anything for fear that I'll mess it up!

-- Russ

Yesterday I got a Thien separator far enough along to do a tiny bit of testing.  The results were amazing!  I picked up maybe two or three gallons of sawdust and other shop debris and essentially none of it made it into the vac.  I can't wait to see how it performs over a period of extended use.

I decided to introduce the air into the can through a tangentially mounted tube instead of through the elbow in the top.  I made the tube from an official shop vac extension wand so that I could easily connect a shop vac hose directly to the tube.  I started by cutting the tube to roughly match the curved surface of the can.  Then I used that piece to trace the location and shape of the hole in the can.  After I cut the hole, I stuck the tube in, put a single bolt in the end to hold it in place, then sealed everything up with duct tape.  Hopefully the pictures will make this all clear.  I used a piece from the other end of the cut-up wand for the short tube that sticks down from the exit hole in the center of the lid.

I also decided it might be easier to attach the baffle to the can instead of to the lid.  It doesn't show up very well in the pictures, but I just have the baffle sitting on three little blocks of wood that are mounted to the can with screws run in from the outside.  The jury's still out on this idea.  It works fine for separation, but I'm not sure how awful it's going to be to empty the can.  In theory, anything that enters via the drop slot should come out through the drop slot.  We'll see about that.