April 2002
Jarkman and I have made a bunch of dust-collector cyclones. Their complex gas dynamics hold no fear for us, not with our multiple physics degrees and Oxbridge education.
On the other hand, our first cyclone was just made from an old bucket and a load of glue-gun glue. They've all worked pretty well, so clearly they're not that fussy about design.
Jarkman's current (2000) dust collector, mainly for routing.
The Cursing Chemist had a load of spare aircon ducting, so we scrounged it. MIG welded a base onto it, a few plumbing parts and an old Hoover, and away you go.
Works fine, but the narrow corrugated hose is prone to blocking with shavings. Doesn't like being squashed or trodden on either.
My dust cyclone (2002). I wanted something a bit bigger, to cope with the sawbench.
A reprise of Linda, with a different lid. Yes, if you're an old VAX hack, you'll recognise the disk pack (an RK05 ?) case we used as a lid. They have a nice airtight rubber seal at the base, that saved us some work. Linda used the same seal rubber, shortened to fit the narrower duct. Debbie just Gripfilled the whole lid on the top.
Inside is pretty simple. Another length of (smaller) aircon duct, Gripfilled to the lid.
The hose fittings to the vacuum cleaner are just 40mm plumbing parts. The lid fitting is a kitchen sink drainer. Use the type with an internal "spider", not a ring of holes. The spider stops the occasional shaving going to the vacuum cleaner, but the holes would limit the airflow too much.
My vacuum cleaner is a cheap plastic industrial (sic) model, Jarkman's is an old domestic one. Mine works much better, enough to make it worth buying one.
Inside is pretty dull. There's a 2" steel tube MIG-welded in through the side for the 60mm inlet hose. The inlet hose is bigger than the outlet (about twice the area). This improves clog-resistance for the input, but isn't enough to upset the airflow.
For better airflow I've since made a smooth radius around the tube end with body filler. Years ago I used to gas-flow race car heads. It never mattered what you did to the passages, so long as you avoided sharp edges on the ends of the inlet trumpets.
Down at the other workshop, there's a 4" dust collector. it was easy to make up another lid, with an appropriate-sized hose spigot. Now I can swap them around, if I ever feel like cycling three miles with a dust cyclone tied to the back of my bike.
The dust collector (a ½HP Elektra Beckum) is a little underpowered for running a cyclone. It's a high-volume low-pressure device and doesn't cope too well with having a cyclone added to it. The cheap vacuum cleaner actually works better.
