J. Phil Thien's Projects

Steamngn - you made a comment in an earlier post in this thread that I think has been unduly ignored -

"Efficiency comes into play big time on the outlet side of things. Blowers (including exhaust fans for ventilation, which is what I am schooled in) are far better "pullers" than "pushers". much is being done to increase the efficiency on the "pulling" side while the "pushing" outlet side not so much.
4" pipe to a separator followed by 6" pipe separator to a blower with an 8" or 10" outlet with no bends... better to put an elbow at the top of the riser from the separator into the blower and have the blower exhaust in a straight line into the filter instead of the elbow on the outlet side.... of course space considerations come into play but you get the idea... I hope!  ;D"

This would actually be an easier set-up for me to build for my shop, and without having done a ton of thinking about it, it might solve some other problems as well.  I'm assuming that the bend from the top of the separator into the blower would be a large radius sweep that would follow the radius recommendations found elsewhere. Would you think that we would still benefit from including a straightening vane between the bellmouth and the blower? If so, would you have a recommendation as to where it would be best located - close to the bellmouth or close to the blower? And would you have any predictions about the amount of efficiency to be gained by having the outlet of the blower going straight into the filter?

Thanks in advance for all of your help.

Follow - up -

I was vacuuming the other night and noticed a sharp drop off in suction, so I checked the filter, and it was caked with fine dust. I would say that I had twice as much stuff in the bottom container of the shop vac as would have previously caused me to empty it and clean the filter. I'm not a math genius but I'd say I have reduced my filter cleaning by one half. And, cleaning the filter was easier than it used to be, because it was only fine dust, that easily shook out of the filter into a trash can.

So, there - not a miraculous improvement, but an improvement none the less. But the experience of building and using it, as well as the information on this forum that indicates that the double height top hat works better on fines has me considering building a double height unit when I build the big one for my dust collection system in a few months.

Hey, Randy - your build looks good, I wish I had seen it before I started mine!

I have just about filled up the lower canister of my vac, and it is still performing very well. I probably would have emptied it once by now, and be due to empty it again, with the filter still down in that area. I'm planning to  see how many times I can fill and empty the bottom section before I have to clean the top filter.

Also, a lot of the Ridgid filters are washable with water, which might save you having to replace them as often.

BW68, I haven't used mine enough to really say, at this point. After about 20 minutes of vacuuming up everything from planer shavings to very fine dust that has been sitting on top of ducts in my basement, I definitely had some fine dust in the filter and top section, but it was no where near enough to clog the filter, and the vacuum was sucking just as hard as when I started. I'll be doing some work next week, and will report back then.

By the way, though, on the Shop Vac model, is the filter any shorter, or is it pretty much the same configuration as the Ridgid? I miss being able to stash my vac under my workbench.

Thanks, R2 -
I ended up buying a "muffler" that Ridgid sells, from which I got the part that my hose attaches to. The other, working part of it fits the output of the vac, and makes a tiny difference in the sound - mostly in the high frequencies. IMHO, not really worth it, but as I said, I bought it for the connector.

I did about 20 minutes of vacuuming last night - the first time I ever rushed to the shop so I could vacuum - and opened the thing up to check it out. There is definitely fine dust getting into the top chamber, but the filter still has plenty of capacity. I vacuumed up some  dropped screws and nails, and a few chunks of hardwood, and the foil tape still looks fine. Of course, that will need to last a lot longer to really have proven itself, in my book. the dust in the bottom chamber is piling up around the sides, which I would expect. It isn't deep enough yet to really risk "scrubbing."    I'll report further in a few weeks, when I've had the chance to use it more.

Finally, I used a piece of rubber weatherstripping to make the seal around the bottom of the separator and the lower part of the shop vac. I sealed up the original inlet of the vac with some tape. Now that I know that it works, I'll buy one of those expandable rubber plugs to put in there.
I used a couple of bungee cords to hold it all together, and tested it out.

I found that the outlet wind speed stayed the same, at 46 MPH. This makes me think I have not added a significant amount of turbulence or flow restriction. Amazingly, the inlet air speed actually went up by about 1 MPH, but it is probably within the margin of error for my testing methods. I think that what may have happened is that I have achieved much better sealing between the various parts than the vac had off the shelf, and that made up for any loss due to the added vortex. In terms of static pressure, I again stuck my hand over the inlet, and would still rate the suction as "Pretty hard."

So, I vacuumed up a pile of dust, and it seemed to perform as well as I remember the thing working before. It didn't make any additional noises, and was able to suck up some fairly big pieces of wood. As soon as I can, I'll try sucking up some jointer shavings.

One think I like about it, is that if I ever need to vacuum up something wet, I can just take my new midsection off, stick the hose back in the old inlet, and do the job. I do wish that I could have made the whole thing shorter, but I didn't want to change the filter arrangement. If you wanted, you could probably find a way to lower the profile of that chamber by making your own filter.

I think I'll give the whole thing a coat of paint, and use it for a while. If any major flaws show up, I'll be sure to post about it, but for now, I'm pretty pleased, and think this is something that other folks might want to try.

I used some heavy-duty foil tape to make the inside of the baffle chamber slicker, and also used that to smooth the transition out of the inlet. We will see if the stray nail, screw, or chunk of wood I suck up will tear that up or not. You could easily use some of the aluminum flashing you can buy in rolls for the same thing, and it would be a lot tougher.

For the baffle between the filter section and the separator, I used a piece of 1/4" plywood scrap. I cut a hole in it, made two other rings for support, and used a $4.00 , 4" bell-mouth that I bought from a supplier of speaker building parts that I found online. I set it so that the bottom of the bell-mouth was right in the middle of the chamber, vertically. The chamber ended up being just over 3" tall inside. I didn't do a whole lot of thinking about the size of that inlet, or the height of the chamber, to be honest.

I did get a nice smooth fit on the tube from the bell-mouth into the filter chamber, and used a round-over bit to make the "output" of that whole thing more like a bell-mouth. I also didn't bother with any kind of air straightener, because I think there is enough separation between the vortex chamber and the blower, and who knows what kind of flow patterns are happening inside that chamber, anyway.

Nothing really radical about the 120 degree baffle, although I did include a bolt for support.

More pictures of the inlet

You will notice that the thing is pretty tall. This shop vac, like many, has the filter that hangs down below the motor, and I had to have room for that. So there is basically a tall upper volume that the filter sits in, separated from the lower cyclone part by a 1/4" plywood baffle with a hole in it. More on this later.

I bought some shop vac fittings to use to make a round to rectangular transition, as well as to hook the vacuum tube up to. I made a wood piece that ended up with the size and shape I wanted the inlet to be, and started heating up the parts hoping to push them on the form, and voila! perfect transition. It took me a few tries, and produced a kind of lumpy final product, but in the end, good enough.

I measured the inside rim of the lower part, and found it to be 16". I had the idea of using concrete form tube to make the body of the unit, and had noticed in previous projects that the Despot sells their form tubes nested one inside of the other, so I knew I would have a range of tubes to choose from. I ended up finding one that was a good match for the rim of the vac. In retrospect, I should have sized it to the top part, which had a groove that the cardboard fit into nicely. In the end, I cut some rings off of the tubes to use to help fit the vac to the tube, as well as to reinforce the main tube itself. The lower part of the vac was easy to get a good seal to.

I cut the tube pretty easily using the crosscut sled on my table saw, and rotating the tube around. It produced an OK edge, and it remained fairly square. I glued the pieces up using the vac to size it. I had also already cut two discs, one 1/4" plywood and one 1/8" masonite, to be the top and bottom of the Thien chamber, and I had them inside the tube to help keep it nice and round and stiff.

Hi, everyone - I hope this is of interest. I decided to try to modify my Ridgid Shop Vac, bought a few years ago from the local Home Despot, to include a Thien separator. I didn't want to go with a separate trash can model, because floor space is at a premium in my shop, and I move the vac around a lot. So, in the posts below, I'll show you what I have done. But first, a few things -

I tried my best to do this project "quick and dirty-" since I wasn't eve sure if it would work. And that rarely works for me, because halfway through I start liking the project, and wanting to do it "right." But I managed to keep this one pretty quick. And, of course, I now know how I would do it, if I decided to do it again.

In terms of quantifying my results, I did two things. First, I used a wind speed meter to measure the baseline performance of the vac. I found that it was drawing air in at a speed of 31 MPH, and blowing it out at a speed of 46 MPH. I attribute the difference to the lack of a really good seal between the top lid, and bottom bucket of the vac. Secondly, in terms of static pressure, I used the very scientific method of sticking my hand over the opening, and feeling how hard it sucked. I'd quantify it as "pretty hard."

Below, see pictures of the very common vac I started with.

Thanks, Athomas, glad yours is working well for you!

Ok, thanks for that.

I mentioned that I was in contact wit the people at vortab about their flow conditioners. For a six inch diameter flat disc one, I was quoted a price of just over $600, which is more than I want to spend. So, I think I'll make a fin type one.

OK, so I am now in the design phase for my top hat separator. because of height restrictions, I am planning on a single height unit. I plan on following retired2's design pretty closely, but from what I have found from testing my collector, I can use 6" pipe for the main run. I plan to transition that round into a rectangle for the top hat inlet, and I'm wondering about proportions of that rectangle.

The six inch pipe has an area of 28.27 square inches, so I could pretty much match that if I transitioned to a 7 inch tall by 4 inch wide inlet. Obviously, I could make the rectangular end of the inlet in any variety of proportions to equal the cross sectional area of the round duct, and I am wondering what people's thoughts are on what the ideal proportion would be.

It would seem to me that the closer to square the proportions get, the more it is like a round inlet, so I would lose some of the benefits. On the other hand, I know that there are ideal proportions for duct work, and tall and skinny isn't among them. So, do we say, as in life, all things in moderation? What do you all think?

Oh - by the way - in regards to the air straightener question - I have been in contact with the people who make the Vortab flow conditioner mentioned in another thread. http://www.fluidcomponents.com/products/flow-conditioners/vortab-products/vip-flow-conditioner
They think their product will work for our use, when I hear back from them in regard to cost and distance from the impeller, I'll let you all know.

BTW, retired 2, I am jealous of all of your nice old green Powermatic equipment. I bought mine after they switched to the current mustardy gold.