Thursday 31 October 2013

Adventures in CNC - Part 4

A Leg To Stand On

Check out PART 1

So you have finally purchased your CNC machine and are anxious to slap it together, power it up, and start cutting. But before you touch the first bolt you have a very important decision to make...where are you going to put it, and what are you going to put it on?

This may seem like a trivial question considering the number of expensive decisions you have been forced to make to get to this point, but it is crucial to the overall stability and function of the machine.

CNC machines are heavy beasts with a lot of kinetic energy and love nothing more than trying to throw themselves around your shop. You need to provide a rock solid base not only for safety, but also accuracy. A wobbly base can actually effect the precision of your cuts.

Location also matters. It's a good idea to think about things like access to power outlets, dust collection, noise reduction, and accessibility for maintenance.

I considered many options when planning for my new CNC. I looked at plans for everything from wooden workbenches to welded steel tables. All I knew was that I wanted to do it right the first time.

While researching the XZero CNC machine I ultimately ended up buying, I noticed that they also sold some pre-fab corner brackets specifically designed to help make your own CNC stand. You just supply the steel in the size you require. The price of the brackets came to $120.

XZero Brackets

I bought some 2" x .100" HSS Square Tube Steel from a metal supplier and had them cut it to length. I needed the following pieces:
4 x 52" pieces for the length of the table
4 x 34" for the width
4 x 28" for the legs

The total came to just over $100 for the steel.

I clamped the brackets to each steel leg and drilled through it with my drill press and a 3/8" Milwaukee Cobalt Drill Bit (do not try to drill steel with a regular wood bit). This way I was able to correctly align the holes. I took it slow and used plenty of lubrication to keep the bit from dulling and in the end, I managed to complete the job with one bit.

Cobalt Drill Bit - Strong enough for steel

Use cutting oil

After the drilling, I primed the steel with Tremclad Grey Primer then gave it a coat of Tremclad Safety Blue - Professional Rust Paint. My neighbours must have thought I was getting into modern art.

The next step was to bolt the table together using 3/8" x 16 bolts, washers, and lock nuts.

Finally, I cut two pieces of 3/4" thick plywood for the tops and secured them with 3/8" carriage bolts.

This table is rock solid and does not move an inch when pushed so I am confident it will stand up to anything the CNC can throw at it.

Total cost for this little adventure:

XZero brackets - $120
Steel tube - $100
Bolts and hardware - $100
Plywood - $50
Cobalt Drill Bit - $12
Paint - $15

Check out Part 5 - Building the Beast

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