Shop Vac sandwich

[Tacuabe]

In my small shop, dust collection is dealt with a shop vacuum which I hook to outlet ports in different machines (Since most are shop-built I normally include a suitable dust port in them). Full fledged DC are not very common here (Uruguay) and shop-sized ones are virtually non-existent.

Lately, I had been considering some kind of cyclone to improve my shop vac but found them too bulky. So I gave the Thien Separator a try. I cobbled a quick (and crude) arrangement and was both quite surprised and pleased with the results.

However, I wanted to have something compact so I settled to more or less copy Jeth arrangement (see his post: Shopvac Sandwich Made). The attached photos tell the story much better than I do. As you see, after the baffle was constructed I carried out a second test. The results were even more amazing. The amount of fines getting through appears to be negligible. Suction is not affected and remains constant, as if the vac had just been cleaned.

My shop vac uses 1 1/2" hose, so I dimensioned the separator accordingly. The original inlet was plugged with a rubber gasket and a new inlet constructed at the bottom. The hose coupler was modified and mounted on the separator inlet. The separator itself has a 1/8" hardboard baffle, a 1/4" hardboard top and a scrap hardwood built-up ring. I sanded it smooth and applied  a couple of coats of sealer plus some well buffed wax.

The final product uses a heavy cardboard drum which I shortened to have the whole contraption fit in its assigned space. The wheels let me drag the ShopVac around. Initially I used just the two big wheels and a piece of scrap at the front to keep the whole level. This was not very comfortable so a couple of casters were added. That was a big improvement but left the unit with a tilt. No big deal, I didn't want to modify what I had and found I could live with it. It even helps to tilt the unit even more and drag it on the big wheels to a new location.

Now my filter stays clean and I don't lose suction when the dust bucket starts filling up. Cleaning is also easier. I hinged the orignal Vac in order to ease bucket removal. Now I only have to empty its contents in a bag, reassemble and go back to work. From time to time I remove the filter cover and give it a good wash with warm water and soap. And, yes, maybe next year I'll even change that filter.

[alan m]

hi there. welcome to the forum

nice seperater . i like the cart.,
what kind of efficiency are you getting

[Tacuabe]

Hi alan m!

I don't know of any scientific procedure to evaluate the separator efficiency. If pressed to venture an estimate, I would say it's near 99% good. Just noticing the ridiculous amount of fines that get by and appreciating the constant suction available I get that impression. I'm very happy with the results.

[alan m]

to measure the efficiency. weigh  a board  etc  thensand plane route etc into it, then weigh it again. take the difference . then weigh the contents of the drum. then put this over the difference form the first weights. then express that as a percentage. .

you could also weigh the filter before and after doing the work (new filter preferably)  then put that difference over the difference in the board weight . that will give you your level of inefficiency.


you could also put the differential weight from the filter over the total weight (diferential weight from filter plus weight of dust in the drum). this will give you your seperation efficiency

if you add your differencial weight of the dust in the drum adn the filter together and put that over the diference in the board weight then you will have your collection efficiency.


the problem with the first few methods is that the presume that 100 persent of the board difference is being sucked up. you could have a very high seperation effieciency but low colection efficiency.

which method is best im not sure  but it should be an interesting read

[Tacuabe]

Here's an update on my Shop Vac arrangement.

After reading some of the latest posts, I decided to increase the height of my separator. The original height was 35 mm (slightly more than the 32 mm inlet pipe). I added a new ring on the underside of the chamber. This second tier is 20 mm high, therefore total chamber height is now 55 mm.

The inlet was left unchanged and thus is as high as possible inside the chamber. Following this mod, there was a noticeable improvement in fines separation.

Finally, a much delayed paint job was carried out! Photo enclosed.

[phil (admin)]

That is a nice paint job!

Glad it is working well for you.

[Tacuabe]

Hi Phil!

Thanks for the compliments!

Here are a few photos of the inside. You can clearly see the new 20 mm thick ring I added. The baffle is now removable for eventual cleaning or in case of clogging. Please note that the outlet protrusion (16 mm) into the chamber was NOT modified. I failed to point that out in my previous post. Therefore, the outlet is now 39 mm up from the baffle.

The top of the chamber and the upper side of the baffle clearly show how the dust swirls during operation.