THE CNC PROJECT

Part 2

DUST AND MORE DUST

All milling machines make dust – or swarf, or shavings or whatever you want to call it, but the faster they work and the better they cut, the more dust they make and you better have a way to clear that away for your milling head or it will clog up, overheat and maybe even break a tip.

So you need a dust collection system.

Yes, you could just get a shopvac but that won’t cut it: once the vac bag gets about half full its suction drops off and you are forever going to be buying new dust bags, and this thing is going to be sucking a lot of dust over long periods.

What works so much better is a cyclone filter. This is a specially shaped chamber that causes a “cyclone” in the air that gets the particles in the air to drop out. This goes in front of the vac so that the air being sucked into the vac is almost clean while all of the dust is easily collected out the bottom of the cyclone.

At first I thought of putting the whole thing under the CNC but this is a very useful thing to have: almost every workshop power tool makes dust and they have a collection port that you can hook up the vac to, so why not have it on a mobile trolley for general use?

The cyclone cost $32. The Shop Vac was $100. Other than that there were some bits of 50mm PVC plumbing and a metal 20L drum I found for free at my work. I had a trolley that I got for some other use that just happened to be exactly big enough to fit the shop vac on the bottom shelf. I estimate the total cost at $180.

Just have a look at how much the fancy shop vacs go for and note that these do not usually have cyclones on them: you will be buying a lot of dust bags if you want to use them for a CNC mill.

The big pipe has a threaded joiner in the middle that acts as a swivel so that the top can be removed from the cyclone (the black bit) and the drum has a clamp on it that can be undone to get the dust emptied. The fitting on the bottom that locks onto the vac has a swivel that is airtight and has slots that lock on the pins on the vac body so you can remove the bits above it easily to empty the vac itself (although this won’t be often).

There are other neat details but the main thing is that it all works well. See the picture below.

As a project this worked out really well. It made me think and it was good practice putting various parts together to make something that works properly.

It also kept me going while I waited for parts of the CNC to arrive.  There was a lot of waiting involved.