Re: cnc conversion of jet 9 x 42 knee mill

--- In CAD_CAM_EDM_DRO@yahoogroups.com, Ron Ginger <ronginger@...>
wrote:

>
> >
> > HELLO TO THE GROUP, I,VE JUST JOINED THIS GROUP. I OWN A JET

JTM-2

> > KNEE MILL THAT I AM GOING TO CONVERT TO CNC AND WOULD LIKE TO GET

A

> > GENERAL OPINION FROM THIS GROUP BEFOR I ACTUALLY PUT OUT THE

MONEY FOR

> > THE PARTS. FOR STEPPER MOTORS 1290 OZ/IN FOR X AND Y AND 600

OZ/IN

> > FOR THE Z AXIS "I WILL DRIVE THE QUILL ". X AND Y WILL HAVE 2 TO

1 BELT

> > DRIVE, NOT SURE ABOUT THE RATIO FOR THE Z AXIS YET. THE MOTORS

ALONG

> > WITH GECKO 203V DRIVES WILL COME FROM HOMESHOPCNC, NOT SURE

ABOUT

> > WHICH BREAKOUT BOARD YET. I WOULD APPRECIATE ANY AND ALL
> >

OPINIONS

> > THANKS
>
> I did a Jet knee mill just a bit smaller than yours, 8x36 table.
>
> I think you might be to big on the X and Y motors- excess torque

but may

> limit the speed. Id use about 700 oz-in
>
> My strong advice is to move the knee not the quill. Once you have

used a

> powered knee you will wonder why anyone would ever do a quill.

Having

> the quill free to do tool changes, or to re-set tool height is very

handy.

>
> I used a 1200 oz-in motor with belt drive to the screw. I initially

put

> the motor on the crank handle, but later removed that shaft and put

the

> motor under the table- it fits very well with a nice short belt.
>
> I used Geckos, and PMDX breakout boards.
>
> I did have some trouble with lost steps on the knee, but that was

solved

> by switching to the Smoothstepper instead of par port. I have now

runs

> several jobs that took hours- one a 3" taper pipe thread, that all

came

> out perfect.
>
> There are some photos of my conversion on my web site,

plsntcov.8m.com

> although I have not updated it with the knee motor move.
>
> ron ginger
>THANKS FOR THE REPLY. I HAVE BEEN THINKING ABOUT THE 740 OZ/IN

MOTORS FROM HOMESHOPCNC, SAVES A LITTLE MONEY. DOES ANYONE WITH THIS
GROUP HAVE AN OPINION ABOUT SUPPLIERS FOR THE STEPPER MOTORS OR A
PATICULAR BRAND OF STEPPER MOTOR