When using the Shop-Vac the other day I noticed all the dust I was sucking up was being blown out the back of the vacuum… all over me. Intrigued and filthy, I decided to investigate…
I emptied the vacuum and took the filter outside to knock as much dust and crud off of it as I could. I employed the standard method of smacking it on the building and quickly twisting it back and forth in the breeze being careful to stay upwind so as not to breathe the fine and disgusting particles liberated.
When replacing the filter I immediately found the problem, or more accurately I didn’t find a key part of the vacuum cleaner. The filter retainer was missing. Without it, whatever the vacuum sucks up can shoot through the open bottom of the filter through the impeller and get blown all over me. Fabricating a quick replacement from parts on hand took no time at all. Sure, I could have bought the replacement part for $9 and had it next day from Amazon, but where is the fun in that?
I found a suitable scrap of 1/4″ acrylic onto which I traced the inner and outer diameters of the filter.
Using a jigsaw with a coarse blade I cut just outside the outer diameter. Cutting acrylic or polycarbonate with a jigsaw (or CNC) can be tricky, friction heats the blade and the chips can weld the opening closed behind the cut as pictured here. This piece was easily broken away with my hand, but I’ve had polycarbonate heal itself apparently stronger than the uncut material when cutting too fast without any coolant or compressed air to clear the chips.
Using a ruler and pen I measured and marked the center of the diameter along several angles. Using the hammer and punch, I punched the mark for drilling (the dimple allows the drill to center more accurately). This level of precision was not necessary but I find striking things with a hammer fun and habits like punching before drilling are good to reinforce.
I clamped the burgeoning new cover in the vise and drilled the center hole. The bolt hardware is the ubiquitous 1/4″-20 (1/4 inch diameter, 20 threads per inch, super common stuff), so I’m going to drill the hole a little larger, 3/8″ to make it easy to slide on and off. I don’t want to drill a hole that large to start with in the acrylic because it will catch a lot and cause chipping or cracking, so I started with a smaller 1/8″ drill and worked up through a couple sizes.
Now I need to install a mounting rod in the bottom of the vacuum cleaner. Marking the center of the bottom of the vacuum cleaner filter holder was even easier. I just connected the lines between the edges of retaining tabs on the outer edge. This plastic is thin and soft enough to drill directly with the 1/4″ bit.
Then I installed the filter holder pin by putting a 4″ 1/4″-20 bolt through a lock washer, then a fender washer then fed it through the hole from behind (from the vacuum cleaner side) to stick out the bottom. I followed that with another fender washer, a lock washer and a nut. The fender washers sandwich the plastic to spread out any load and prevent cracking around the hole. The lock washers keep the nuts tight even under the vibration of the running Shop-Vac.
The filter slides over the outside, and the cover slides over the bolt to seal it in place. Another fender washer, lock washer, and convenient wingnut secure the assembly with a good tight seal.
At this point the filter replacement was functional but by no means done. Workshop88 is a makerspace, and that means nothing is done unless you’ve used the laser or a 3D printer, so Christine engraved the lid.
I could have easily ordered the appropriate replacement and had the fresh new part the next morning, but by creating one myself I get the satisfaction of a job well done, and I was able to vacuum up the acrylic chips from the jigsaw and drill right away.
D. Scott Williamson