9a thread dial retaining screw size

[mds30br]

I picked up an aftermarket thread dial for my 9a and would like to get a screw to hold it in place. There appears to be a tapped hole in the apron for just this purpose and was wondering if anyone knew the size/pitch of screw needed. I don't have any way of measuring inside thread pitch and don't have a set of taps (yet) to be able to do my own modification.
The machine was made in 1945 if it helps.
Thanks in advance,
Mike

 

[Bob Itnyre]

thread dial retaining screw

I checked mine and it's a 1/4 x 20 set screw. cheers Bob

 

[mds30br]

Thanks for the info and the quick reply.
Mike