Here’s another approach you might try. You’ll end up with about
the same thing as the Rainbow, but it will be lots cheaper.
I use an old (20+ yr.) Craftsman wet/dry shop vac. The entry
hole the hose attaches to goes directly into the tub. If you’re
going to dedicate the vac to the bench grinder/polisher, most
shop vacs can be modified to work with a water bath very easily &
The small end of the wand is usually the same size as the end of
the hose that connects to the vac. This small wand end usually
will fit the inlet hole of the vac. Most inlet holes are in the
top cover of the vac & go straight through into the tub. To check
hole size, remove the top cover. Empty the contents of the tub
into the trash. Try to insert the small end of the wand in the
inlet hole from the inside. If it fits you’re in luck, if not,
back to the drawing boards.
1. Assuming it fits, draw a line around the wand where it
meets the bottom of the top cover.
2. Remove the wand.
3. Replace the top cover on the vac.
4. Insert a tape measure/yard stick through the inlet hole
until it touches the bottom of the tub. Note the measurement
at the bottom of the entry hole.
5. Transfer this measurement minus 1 inch (for starters),
(e.g.. noted measurement 14 3/4 -1 = 13 3/4 in) to the wand
with the mark. Measure down from the mark. Cut the wand off
at this point.
6. Remove the top cover from the vac.
7. Insert the cut off portion of the wand securely into the
inlet hole from the bottom of the cover.
8. Fill the tube with water to a depth of 2- 3 inches.
9. Replace the top cover with the cut off portion of the
wand extending down into the water from the inlet hole.
10. Turn on the vac before connecting the external hose.
11. A bubbling/guggling sound should be heard & the exhaust
vent should be exhibiting approximately the same volume of
air as before the modification. The exhaust air should not
contain any water mist/droplets.
12. If the previous test was successful, connect the hose
between the vac inlet & the machine that's the source of the
Check the tub after several times in the 1st hour of operation.
The water level may need to be increased/decreased for
satisfactory operation with your model of shop vac. Until you
become familiar with it’s operation, check the water level daily.
The reduced pressure in the vac tub cause the water to evaporate
faster than water left at atmospheric pressure.
The water should trap the majority if particulate matter. If
everything appears to be operating ok, you may want to replace
any filter your vac uses. The sludge & dirty filter can be
returned to your refiner if you want to recover any precious
If the wand from you model does not fit the inlet hole on the
inside, measure the hole dimensions, both inside & outside
diameters. Check your local hardware or plumbing store for
plastic plumbing fittings &/or pipe that may fit or be modified
Check your hardware, home supply store or any store that sells
shop vacs. They usually sell hoses & hose ends of different sizes
and shapes that may make collecting dust from your ‘dust
generator’ a little easier.
If everything is a disaster for you, the worst that can happen
is you’ll have to vacuum while crawling on your knees (bg) or
spend about $5.00 for a new wand.
I’ve never tried these instructions; but if the need were
present, I’d not be afraid to. The only cautions I can think of
are: only use a large shop vac (over 2 hp with a large tub
(aprox. 16" high x 16" dia), if your vac uses a 3 wire power cord
(grounded cord), be sure to use a grounded outlet ( if the ground
prong is broken off, replace the plug or cord before proceeding)
& if you hear, see or smell anything unusual investigate the
source & correct the problem before continuing.
Here’s to cleaner air!