Shapecut 3200 Magic Eye to CNC - Part 1

I've been interested in making my own CNC router for some time however a friend mentioned an ancient oxygen gas profile cutting machine that could do with bringing up to date.

Nothing like jumping in at the deep end. The Shapecut 3000 series machines are large industrial machines that can cut up to about 2" thick steel plate!

The machine originally used a 'Magic Eye' to follow a black line on a paper drawing.

I managed to find a video of one in operation.
https://www.youtube.com/watch?v=Vlz6i_wB_8E

These machines date from the late 1970's and apart from that video, I have found nothing else of use on the internet about this specific machine.

There is information about oxy-gas or oxy-fuel cutting.
Such as this article:
https://www.parkindustries.com/metal/processes/oxy-fuel/oxy-fuel-cutting-101/

The implication from this information is that there is little point in trying to automate too much. Even today's, oxy-gas cutting machines have manual control of the cutting flame, gas flow rate and the speed of the cut for a given thickness of steel. The CNC element controls the direction of the cut.

It is fairly common to convert old machines to more modern electronics. The mechanical structure is sound. There are several companies that provide this service but the trouble is, it costs thousands, often tens of thousands, for the conversion. This machine may not generate enough revenue to justify that cost. However it would make a challenging project.

I have no idea if I will be able to complete this, so I am going to put my progress in this blog to help anyone else who may attempt something similar.

Firstly I copied the ancient paper manual to a PDF, for easier reading.
The circuit diagram is, unfortunately, faded, so it is only of partial use. If anyone reading this has a more usable diagram, please send me a good quality photo of it.

So far:

• The machine is marked as a Shapecut 3000 but I think it has been updated to a 3200, some time after 1979.
• The motors are 400V servo motors with a gearbox. The diag says they run at 10 rpm.
• The cost of modern servo motor drivers is expensive at over £500 each.
• Matching modern drivers to the old servo motors would be difficult.
• It would be lower cost to replace the motors with modern stepper motors and possibly new gearboxes.
• Matching the new stepper with a modern driver and power supply should be easier.
• Deciding on the required torque for the stepper might be a bit of trial and error or simply over spec the stepper and gearbox.
• It is only necessary to control the X and Y axes.
• It would be beneficial to have the ability to manually vary the speed of the cut mid process. At the very least, the speed has to be set based on the thickness of metal.

The CNC control part of it should be fairly straightforward. Most of the software includes the options necessary for use with a plasma or gas torch .

I like the idea of a self contained headless solution but as the gas torch has to be manually aligned on the work piece, having a large display of the tool path would be beneficial. Therefore, at the moment, I'm thinking of using Mach 4 or UCCNC running on a used PC. Either of those need some sort of motion controller card.

So few PC's have parallel (LPT) ports now that I would prefer to use an ethernet controller. These are common.

That's about as far as I have got at the moment. I'll write more when I have made some progress.

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Downloads:
Shapecut SCM 11 3200 manual (PDF)
Shapecut SCM 11 3200 circuit diagram (PNG, original A1 size)
Shapecut SCM 11 3200 frame diagram (JPeg, original A3 size)

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

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