Re: [CAD_CAM_EDM_DRO] Re: Cost estimate for machining of acme screws

Brian wrote:

>Hi, well i found that a tool post grinder just amplified any looseness and
>by the time i got it squared away i could have had it done by hand, wrapped
>and shipped to the customer. Yea a tool post grinder is ok when you need to
>fix a taper but for production work -useless in my book, a good lathe with a
>keen ground and honed edge tool (how many hone the edge these day?)
>and a familiar operator should be able to hold finnish and size! Not on a
>used 9 inch South bend but maybe a Good 10ee Monark, Hardinge made to do the
>job.
>

Well, there are certain steels that cut beautifully with a sharp HSS
tool, and you can get
excellent surface finishes, fine tolerances, etc. with them. I have to
say that the couple of
ground, precision ballscrews that I have cut were NOT of this sort of
material. HSS was
useless, even if you annealed the screw. One one particular job, I was
only left with
6" of thread on a screw that needed 5" of travel, so I really could not
anneal the ends without
ruining it. You definitely don't want to do the whole job with a TP
grinder, it would take a
year. But, you can take off half a tenth easily and then mike the part
of try the fit of the
bearing on it until you get the right interference. I had only this one
screw, paid $100 plus
shipping for it, and there were no more to be had.

Jon