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Sunday 30 June 2019

CNC controller enclosure - Shapecut part 3

I realised this afternoon that I have completed the wiring for the CNC machine. At least to the point, ready to test. The component parts are all mounted in an enclosure and the connections necessary to control the X, Y and Z axes, are all in place.
This is the next step for the proof of concept to convert an ancient Shapecut Oxy Gas cutter to CNC control.

When looking for boxes to put the parts in to, I was surprised that I could get a good quality metal case at a very reasonable price. I was even able to download the CAD drawing of the Schneider enclosure to use in Fusion 360.

I offered everything up in Fusion 360 before starting anything in the workshop.

I was going to cut a sheet of steel as a mounting plate but I happened to have the exact right size, already cut! That does not happen very often.

I'm using Rivnuts to secure everything. I'm not normally a fan of them because if they slip it is very difficult to remove the bolt. In this case, it would not be too difficult to repair and they make mounting the equipment much easier.

It's all fitted very nicely with only one flaw. I had not allowed for the bolts to mount the lower outer panel of the case. I've had to cut some holes to make space for the nuts to protrude through.

I've deliberately designed it to have air from side to side, over the driver heat sinks and through the power supplies. I think the result looks very tidy, plus I've added some branding.

I've used wire ferrules for better connections and a tidier job. The interconnects between the enclosure and the CNC machine are provided using GX series aviation style connections. In this case GX16's. They are a common choice of connection for hobby machines but I am not impressed. The sockets are circular with a nut fixing. Unless you have a specially shaped punch tool, they are always going to twist in their mounting holes. They are also time consuming to solder. Their only advantage is that they are readily available at a low price and have a suitable power rating.

I did briefly investigate proper industrial power connectors but the cost, for something with a locking hood, came to well over £100 each end!

Joan having a cat nap

I tested every cable end to end to make sure there are no shorts or breaks.

I made a last minute design change to mount the emergency stop within the main case. I was going to have it on a fly lead but for my requirements, that was an unnecessary complication. It did require re-arranging the internals in the case and re-making a couple of the wire harness links.

I'm pleased with the result, so far. The next job is to sort out the software and test it all.


Shapecut Series:
Part 1 - Magic Eye to CNC
Part 2 - CNC proof of concept design
Part 3 - CNC controller enclosure


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