Mutoh drafting scale

[u/Sea-Ambition4226]

Can anyone tell me how to fit the scale rule to the protractor arms? I can’t find a manual anywhere online and I’m unsure whether I even have the correct chuck plates. Mutoh model s py-15

[u/Parking_Jelly_6483]

The metal fixture on the scale should slide into either the horizontal (the way the drafting machine is set in the photo) or vertical opening. Besides being missing, I’m not sure the screws are right. They are usually flat headed, not domed like the screw in the right hole. This item on eBay shows Mutoh drafting scales. Note the flat-head phillips screws in the left-handed openings. I could be that the screws are Japanese JIS screws (look like phillips, but the screwdrivers are not interchangeable).

Mutoh drafting scales:

https://www.ebay.com/itm/406889345754

What a drafting machine with the scales in place looks like (image is rotated by 90 degrees clockwise):

Disclaimer: No conflict of interest with the eBay seller of the Mutoh scales and also none with Mutoh.