# Ambiguous technical drawing sizes

I'm having trouble reading several dimensions on this technical drawing.

First, I don't know how big is the diameter of the marked cylinder. M24 is a threaded hole in my opinion and that cannot say anything about the cylinder.

And what is the diameter of the rotor ? Is it 40 ? if yes then why they didn't put any diamater mark next to the number 40 ? And I cannot find out the angle of the central key relative to slots?

Figure 1. The cylinder is 24 mm diameter with an outer thread of M24 x 2 (pitch) extending to 16 mm from the end.

And what is the diameter of the rotor? Is it 40? if yes then why they didn't put any diamater mark next to the number 40?

Yes, 40 mm. It should be marked with a Ø symbol or "DIA".

And I cannot find out the angle of the central key relative to slots?

It's not there in the extract you have given. I would assume 45° - but that could be an expensive assumption.

• regarding 45 degree assumption. I don't think the OP image qualifies as proper technical drawing. I think the image probably comes from some sort of homework exercise that students are expected to draw a proper technical drawing.
– NMech
Commented Mar 6, 2021 at 12:03
• @NMech your assumption is correct Commented Mar 6, 2021 at 12:50