You are very welcome! Glad it was helpful. The cap on mine is just hand tight, so if you need any more photos, just let me know and I'll be happy to take them. Pretty simple design.
Thanks Dan, but I have already started on the design and drawings for such a cap to fit on the Clausing mills. It's pretty straight forward. I just never ever sat down to give any thought to how a person could set this up before.
Can I ask what the value of such a mill is? I really like the size of that one and will try to keep an eye open for one, but what do they bring dollar wise?
Prices for Clausing 8520 mills vary quite a bit. A good one will usually run somewhere around $1000 or more, depending on condition. These machines do have some things to watch out for, and there were four different models:
8520: Most common model, has a #2 Morse Taper in the spindle
8525: Same as the 8520 except that the spindle has a B&S #7 taper in the spindle.
8530: New and improved version of the 8520 but with a heavier knee and a two speed crank drive for the X feed on the table, as well as end caps on the table that would catch coolant running out of the T-slots. It also has a slightly taller column. Uses MT2 taper. Not nearly as common as the 8520, but a great prize if you can find one.
The 8520 was originally sold by Johannson, and those machines are found for sale from time to time. They are every bit as good as the ones with the Clausing badges on them. Clausing bought out Johannson at some point.
These mills do have a weak spot: The gears for the fine quill feed. They are made of brass and are often damaged with a number of teeth missing. Some parts are still available for these machines, but I do not know about the fine feed gears. If I recall correctly they are not available any longer.
The Clausing mills also perform much better with a 1HP motor on them in place of the smaller 1/2 or 3/4 HP motors.
You can find more photos and details about them here:
http://www.lathes.co.uk/clausing vertical/index.html
A similar mill was offered by Rockwell, though I forget the model number. From what I understand they were just as good as the Clausing, but I think the Rockwells are a little harder to find. There are differences between the two brands of machine, so don't assume that they are the same under the skin. More info on the Rockwell is available here:
http://www.lathes.co.uk/rockwellmillers/
ON EDIT: I found a good listing of small milling machines and who sells them here:
http://bridgeport.askmisterscience.com/smallmills.htm Definitely worth a good look!