I have an Industrial Hobbies mill I inherited which has seen next to no use. So after mulling over the the addition of ball screws and doing something bout the spindle bearings (felt rather gritty when turning the spindle by hand - that can't be good) I think I'll replace the lower bearings with angular contacts, and the upper with pair of deep groove bearings. So for replacing the lower bearings I'm looking at sending the spindle assembly out to a machinery repair place and have them do it. Then I'll look into getting the ball screws. I've been looking at HIWIN 2005 C7 ballscrews.
I figure that I will go the route (hopefully) of:
DMM Dyn4 750W servos for X, Y, and Z; and a 1.8 kW Dyn4 servo for the spindle. But I'm beginning to think that lesser may be entirely adequate for X and Y, like 400W servos
I've decided on the Centroid Acorn board. I wanted the Oak but that will absolutely kill the budgeted amount available for the build. So that uses up the available spaces for the axes as far as the Acorn is concerned. I really wanted, down the road, an axis for a vert mounted rotab which could come in pretty damn handy but 4 is all I'm gonna get out of the Acorn. Ah, so be it.
I have to work out a gas strut doohickey counterbalance for the head. I've taken out all the gears and stuff,l so at least there will be a little weight taken off the head.. That was the noisiest sonuvabetchin mill I ever heard when I turned it on! I can't hardly stand it! My wife asked "What is wrong with that thing??" Lol!
So I have the one-shot oiler about half way done. Still need to install the fittings. Have milled all the oil grooves in the ways and on the non-gib angled surfaces as well. Putting in HJA-1 metering units for the X, Y, & Z axes with 5/32" tube. And size 0 for each of the ball nuts. I'm thinking about putting an oil passage hole through each gib that will allow oil to pass through to a groove in the gib to lubricate the mating angled face.
Ridiculously, the chinese only provided one little tiny oil port on each way! You know da kine, has a little ball in the tiny fitting (meager to say the least). And obviously nary an oil groove.
And incidentally I noticed they never provide a lead-in for tapped holes nor do they deburr or chamfer anything. Well it's all I've got. And getting a Bridgeport into my basement (let alone with 7 ft. basement ceiling!) assuming I could afford one would be a serious problem. The stairs are very steep and make a 90*° turn at the next to last step!