Threaded holes on back of PM-1022V Bed casting

[Pfeffa]

What is the purpose of the pair of threaded holes on the back of the PM-1022V bed casting?

They are near the middle of the bed ~125 mm apart (horizontally) and appear to be threaded M10-1.5, and there is a square patch around each which is not painted like the rest of the casting.
My guess is that there once was a milling attachment for some model of lathe that uses this casting, like in the Grizzly Combination Lathe-Mills (but they don't have a 10x22 version of these).

Has anyone made use of them?

[Apologies if this has been covered, my due diligence search yielded nothing.]

 

[markba633csi]

Probably right- an optional milling head

 

[B2]

Some portion of a Taper cutting attachment point?

 

[ivel03]

Most likely a milling attachment. Here is the PM 1022's cousin:

WEISS WBP250F 10"x22" Variable-Speed Combo Lathe and Milling machine

WEISS WBP250F 10"x22" Variable-Speed Combo Lathe and Milling machine

weissmachineryusa.com

 

[B2]

Most likely a milling attachment. Here is the PM 1022's cousin:

Is the mill not attached to the cross feed saddle so that it can be moved along the lathe's z axis (along the bed). I think that @Pfeffa said the holes were in the back of the lathe bed... so a fixed position? Or maybe I do not understand how the mill is attached and moves.

 

[ivel03]

Mill is fixed. X and y table are the lathe cross slide. I purchased a Weiss 11x27 with mill and sold off the mill portion as I have a standalone mill.

 

[markba633csi]

Mill fixed. Workpieces mounted on carriage, and it helps if cross slide is flat with two or more T-slots, but it's not nearly as capable as a real
milling machine
Emco-Maier did some of the best ones with the Super 11 and 13 series, and I think even the Compact 8 and 10 had the feature

 

[Pfeffa]

Correction: there are four holes in the Bed casting - the upper two were concealed by the carriage scale for the DRO - vertical spacing ~33 mm C-C.

 

[ivel03]

See attached pic:

 

[Pfeffa]

I presume the block appearing near the top of your photo spaces the column a few inches back from the mounting surface on the Bed casting.
That head and column appear similar to those on the Weiss VM18L 5-1/2″ x 20″ Benchtop Milling Machine Variable Speed R8 Spindle.
I suspect mounting a milling head to your lathe ways would have significant adverse effects on their alignment, but as long as you raise the head to a consistent height while using the lathe function, it should at least be repeatable.
However, as I said earlier, two of the mounting holes are obstructed by my saddle DRO scale, so it wouldn't be a practical option for me anyway.

Thanks everyone, especially ivel03, for satisfying my curiosity.