THE CNC PROJECT

Part 1

Overview

What I really want is to make nice clean things that work because the parts all fit together neatly. I want to make some spinning motors and such in future and that needs high quality accurate machining. It will take time to develop, yes, but the results will be usable as opposed to rough-as-guts hand manufacture. I know that only too well.

The best way to do this is with a CNC Mill. That’s Computer Numerical Control. When I worked in a machine shop as a teenager the CNCs were big and expensive. We cut stainless steel like it was cheese.

Nowadays there are small, cheap and low power models that you can run from your garage. This is defined as subtractive machining – you take a lump of material and subtract the bits you don’t want from it. The opposite is additive machining, or 3D printing. I have one of those too – they are good but the parts it makes cannot equal the strength of a machined aluminium part. Having both in your workshop is the best option.

I looked around the net and after careful thought I decided on the OneFinity Woodworker X-50 32 x 32 inch. It cost about $5K AUD including delivery from Canada.

Why did I choose the OneFinity?

1. Ball screws. It has Ball screws which are solid unlike a lot of other machines which have belts. Belts are fine for machinery that does not take a lot of force such as 3D printers, but for milling they are just too weak imo.

2. Solid construction with linear bearings. This is the only home CNC that has decent rails and lead screws.

3. Flexibility with the choice of machine head and software.

The maker does not recommend using it for cutting steel and that is fine. They also don’t supply a milling head or drag chains and that’s fine, I will get my own. They supply the three motion axes, the controller box for them and the control panel. There are a few extras that are worth getting from OneFinity such as the touch probe but everything else you get for yourself and assemble yourself.

So now there is a whole lot of work to get all of the parts together and assemble them into a working machine - metalwork, woodwork, electronics, plastic work, painting, design . . . . there’s all of them needed and a few other things too. Then once it is all working I need to work out the software to make it all go.

I actually started the whole thing in august last year. There has been a lot of time spent waiting for parts to arrive and a lot of frustrations when things did not go according to plan, but now it's looking pretty good.

The Bench

The machine needs a solid bench and I bought one, twice.

The frame of the bench needs to be solid and it looks like the best one is made by a company called Kreg. It comes in parts that bolt together and it is thick steel – but for some reason they are very hard to get here in Oz. The first time I ordered it they refunded me a week or two later because they could not get one.

I ended up having to buy a smaller one just for the vertical legs and a set of long horizontal bars direct from the US. It was worth it though, I did not see any other item that was as solid.

I tried out other options -  (getting cheap chinese metal benches and widening them) - but they were so flimsy and wonky that the bench would never have been stiff enough to use. They are okay for what they are – I have three in the garage, but no good for mounting the CNC on.

Then there was the bench top.

I could not get plywood thick or wide enough for my initial plans so I ended up getting thinner 12mm sheets, redesigning things so the bench was only 1220 deep (max plywood width) and then gluing two sheets of the ply together to make one solid plate 24mm thick to mount the CNC on.

I don’t recommend this to anyone: with no proper tools or even a bench 1220 x 1300 to sit them on it while gluing it’s surprising that they turned out okay. Even then the whole thing is not quite flat: it has a slight bulge in the centre.

I had hoped that gluing them together would flatten it but nope.

Now that the machine is bolted to it I will use the machine itself to mill the middle of the bench flat before I put the spoil board on.

Other bits

I added a lower level shelf from some bits of a cheap metal bench and another piece of the same plywood to stabilise the bench a bit and give me somewhere to put other parts of the machinery out of the way – the electronics, the water cooling system for the milling head and the suction hoses and so on.

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The plan

I didn’t just throw all of this together, I made plans from the start – and I designed, re-designed and re-re-designed things in 3D using Blender, my preferred design tool.

This is version twentyfour of the Blender model, and for reference below is a photo of the real thing : Not too far off. The cover frame is only a test fit here.

I am missing out a lot of the details here, trying to give a short report on a very long and drawn out project. This is where I spend my weekends.

More soon in Part Two. Thanks for reading.