I had some suitable material on hand in the form of a nice bit of 1 mm sheet steel. It was sawn to measure and folded. Then got some holes to suit the ones in the motor casing as shown below.
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The 10 mm wide edge on front, back and to the right were folded in 45 degree angle . The fold to the left is 90 degrees to fit closely to the drive belt plate at the headstock. All for a good fit.
Following a trial fitting the swarf tray was sanded, cleaned and the corners were filled with epoxy glue to becomer more stable and enable smoothing without sharp corners. Then a couple of coats of paint, this time red to fit the machine.
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The trial fitting showed that it was necessary to enlarge the fixing holes between the drive belt plate and the headstock about 1 mm upwards to compensate for the tray thickness. The holes are the two to the right of the large vertical opening.
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With that done, the tray was fitted between the machine feet and the motor casing. The screws were secured, and heureka, the machine has now got a swarf tray that looks as it had been there all the time.
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IT is really quite odd that there were no swarf tray from the beginning, but this little project solved the det6ail and gave me a better machine as a result. Now smallish parts does not fall of and hide anymore, and the swarf stays in the tray.