C7 Ball Screw Quality, Bent Screws

I'm thinking these will be OK after some more work, I'm using the Millrite as my press and some v-blocks. This particular kit puts the Y axis motor out the back of the column, it will stick out straight unless I make a plate to mount it on the side and use belt drive. I like the idea of no motor sticking out the front. This kit also reuses most of the bearings for the screw supports, I have read that back lash can still be an issue so I will see how that goes once I get it assembled.
I haven't decided on software to run it yet, probably should stick with Mach to start. I went with this machine because there is so much info out there I figured I wouldn't have to reinvent the wheel, lol
I'm not the most computer savy so I will have questions around that. I'll take pictures as I go, if anything its a great reference to look back on if something just doesn't seem right!
I appreciate all the helpful comments.
Mark
 
Are these ground or rolled ball screws. Most sold in this price region are rolled. Rolled screws you can not measure in the manner you are describing. Some ground screws are rough rolled to boot The crest (which is not really a crest on a ball screw) is not used at all on a ball screw and in the rolling process excess metal is moved to this point. So this area is uneven. You need to place in a good accurate lathe, engage thread cutting box for the grooves per inch on the screw and place the indicator at the bottom of the groove. Now are you rotate the chuck you can see runout in the root. Remember to you can not change direction of rotation while measuring or the back lash in the threading screw/box will cause false readings as the indicator will move in relation to the ball groove. It can be quite a pain to machine the support and drive ends and keep the groove concentric with a chuck. Hopefully the screw was center drilled and one can turn between centers the cut/face to length
 
Well you get what you pay for, if you want a precision machine, get a ground screw, if you are willing to accept a .001~.002 backlash, a rolled screw will do. Most problems start with thrust bearing anyways. I found a Bridgeport casting that I would like to make into a CNC, but I don't know if I can justify 10K to convert it with top quality parts. A Fanuc control would be awesome but in reality I am probably stuck with a Gecko system. I will probably look at real ground screws and a good lube system though. Tim
 
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