OK, I'm the kind of guy that walks in to a Dodgers Beer Garden and cusses the Dodgers, just so I can get my azz kicked. So, feel free to get it out of your system. I've done enough reading to fully understand everyone's emotional attraction to this subject. Yes I searched for this.
Bought a J head for nearly nothing. I tore down it down. Everything was dirty, so I pulled off the table and acme screws, and Y axis slide (whatever you call it), and yoke. Cleaned it all up, not too shiny, but a lot better than the last 4 years of non-use had left for me.
So, putting it back together I put the Y axis slide back together without a drive screw, and pushed it back and forth by hand. Tightened the gib (?), until it didn't move right or left and moved smoothly, cool. But, when I push the slide all the way towards the turret, it binds pretty bad, and when I pull it towards the front it binds. Obviously, it has dished out in the center, fairly bad but not too bad. (BTW, if I loosen the gib to where it will move throughout the entire Y axis, it flops around a little in the center, didn't measure it, the difference is obvious.
So, It's a nearly free machine. I'm not going to dump a lot of money into it, and have it professional done. One of the reasons for buying it, was to learn how to fix it, I'm crazy that way.
My idea was by a granite straight edge on Ebay, there's one that claims +/-50 millionths, (over what I don't know)
http://cgi.ebay.com/BLACK-GRANITE-ST...item3ef2ecdb74
Buy a scraper, and a book, and try to get the ways flat towards the ends. How crazy does this sound? Should I replace the gib key first? Or, is that a waste of time? Something like this http://www.machinerepair.com/Orders.html
Then, I was going to see if that helps the Y axis move, and then figure out what to do about the dovetails, if anything. I understand the blue ink transfer, but have no clue how you blue a dovetail.
I'm not shooting for tenths accuracy here, I want the axis to not bind. I'm even willing to over scrape the ends a few thousand, to keep from having to touch the dove tails. I do plan on putting servos on it soon. and, I'm sure the X axis will have some problems too. If I totally screw it up, I'll part out the machine and buy another one, so I'm not scared too try this.
OK, unleash the dogs.