NEQ5 Pro security screw

[blindman]

Hi all,

I have missing end Shaft security screw (8.55mm measured hole).
If someone having NEQ6 Pro mount, can measure that screw and send me a photo, I will appreciate. Or if you have that not in use as a part I would like to buy that.
Many thanks Neven

[LewisM]

I seem to recall it’s actually an M6 hole, so all you need is an M6 bolt and a large washer

[Saturnine]

I just measured the safety screw out of my HEQ5 and it is M12 X 1.75P , The standard 12 millimetre metric course thread.
Also checked my EQ6 Pro and it is the same, though I do recall that the older EQ6 Safety Screw was only 6mm X 1.0 P.
That was measured with Vernier calipers and thread gauges so about as accurate as you need to be.

[blindman]

Thank you guys. Still confusing, I measured with calipers hole in shaft and it is 8.55mm.

[Saturnine]

So if you are measuring the inside of the hole, the inside diameter of the thread, it seems too small for the ID of a 12mm thread. Have measured mine and the ID is approx 10.2 mm, my handbook gives a tapping drill size of 10.2 for a 12 mm thread.
The 8.55 mm that you measured is close to the tapping drill ( inside diameter ) of a 10 mm thread. How old is your mount, maybe Skywatcher have changed the thread size recently. Would be handy if some other recent owners of the mount could chime in with some info to enlighten us.

[Saturnine]

One way to find out is go to a hardware store or fastener supplier and buy a short 12 mm and 10 mm set screw and find out which one fits. Will only cost a dollar or two for them , so no great outlay involved and at worst you will have a spare screw of the size that doesn't fit.