Simpson
Air over oil can probably get round the expense issue but suppose that depends on whether you have access to cheap air and hyd cylinders, working repairing boats hydraulics are fairly easy for me to obtain, air not so easy but eBay is wonderful
I was fortunate that this is standard equipment on the mill so no thought at all had to go into it from me thankfully
Quill versus knee and ballscrew versus rack will always be debated, personally my thoughts are quill with ballscrew for fast work and knee for tool offsets is the best way, well bedmill is the best way but I dont have one and probably never will due to headroom, so thats not an option. The Beaver has an induction motor on the knee so fitting a servo would not be a problem, maybe an alteration to the mount and thats it. It does however just have a leadscrew on it but I am hoping the backlash is linear so comp should work well and the weight will negate any problems with tool trying to lift it I think
Rack would be, I think, hard to get any kind of backlash free accuracy from so never considered it, the comp could be used I suppose but then the tool could push and pull it so some form of damping/lock would be needed, again not impossible but would it be worth the hassle?
Hood