Cushman 4-jaw hole spacing question

I finally scored a decent 4-jaw to replace the ancient worn out light weight Skinner that came with my machine.
It is a 6" cushman and compared to theskinner is it mighty weighty.
But... as I was working out how to make a backplate for it I realized that the mounting holes seem to be very close to the center.
I did not bother to measure accurately (yet) but they are about 3" apart.
Is this normal?
Could this chuck be intended for some other application other then a lathe?



Thanks for any insight you can offer!

Josh

I have a 10" Skinner on my 14.5" lathe right now, and its mounting bolts are ~5.25" apart so it looks very similar, not something I would worry about.

Thanks for the replies.
It is going on my 9" South Bend, so the top speed and max load are pretty limited.
I guess I am not so much worried as curious...

It might be for a grinder, but the K.O Lee 4-jaw I have is an open back cast iron chuck that is way lighter duty then this.
The small mounting bolt circle and register lip do look like that though.
Hitting it with a file leads me to believe it is steel (or semi-steel whatever that means) not cast iron.

I am visually comparing it to other Cushman chucks on ebay, so for instance here is a 6" that is currently for sale (not mine).
The bolts on that one are way out near the edge compared to mine.

Does anyone know how to decode the (serial number?) marking?
Mine is 10 003 06 000D

Thanks,
Josh

jkopel said:

Does anyone know how to decode the (serial number?) marking?
Mine is 10 003 06 000D

Thanks,
Josh

Click to expand...

TOLL FREE 888 ...Bob

TOLL FREE 888

Click to expand...

Ha
Already tried that.
I called this afternoon, and the guy I spoke with said "well I can tell you that it is a 4-jaw".
At this point I am just going to use the thing and stop thinking about it.