07403, 12 x 18 Mystery Holes?

[TinkerToy]

At the rear of the ways on my crosslide base (carriage?) there are two holes, 3/8 tapped I think. I cannot get to the back to see them very well.
It is a machined surface, I was just wondering what they were for and what size they are. I'm thinking about using them for a mount of a bracket.
Thanks,
JD

 

[hermetic]

Taper turning attacment?

 

[Round in circles]

i found similar on my old ancient lathe Tink,
I suspect they can be used to mount all manner of things that are required to move with & machine things but are not able to fit in the slide the taper attachment is but one of them .
You could have a perspex chip shield , a coolant feed pipe , a moving light or magnifying glass with light source etc etc .

 

[TinkerToy]

OK, thanks. That makes sense. Probably a taper attachment is most prevalent.
I tried a 3/8-24UNF bolt in one of the holes and it doesn't go. Is that the correct thread? I don't want to force it.
JD

 

[wa5cab]

JD,

They are 3/8"-16 UNC by 3/4" deep. The were originally for attaching the Atlas No. 700 Taper Attachment. I don't know what the Craftsman Model Number was. The center to center distance between the holes is 2". And the holes are each 3/8" down from the lower flats on the carriage dovetail.

Robert D.