Re: [CAD_CAM_EDM_DRO] Re: Newbie bridgeport cnc conversion quetions

The ballscrews are 650 from Rockford and brand new i.e. haven't been crashed and traversed a million times, zero backlash. With good ways and a new set of ballscrews we are practically back to a new machine. Thats what makes old manual mills so attractive to retrofit, low traverse distance over time, driving the knee for Z for instance, it sees very little movement in manual use. The swap out with the old acme's is two hours and thats working at a liesurely pace. The stock bearings in the endplates are used, no additional thrust bearings are used in this type of changeout.

Buying an old CNC machine can conceal many pitfalls. If it's an old stepper system the control upgrade is an ongoing experiment and alot of finger crossing. Many of it's features have to be discarded because present PC based control software will not support them. If it's an old servo system, make sure they are DC brush type motors within the acceptable voltage and amps range of the drives you intend to use. Anything else they are basically useless.

The servo mounts for a J-series can be simple or as complex as one wants to make them. Some are just a plate of aluminum with exposed belts. Wouldn't take over an afternoon to produce. The big plus to retrofitting a standard bridgeport is: If you ever decide to upgrade machines, everything will bolt right up to a brand new one. An old CNC machine on the other hand, you'll always have an old CNC machine.

Just a different opinion about retrofit candidates,

Ron



Les Newell <lesnewell@...> wrote:
Hi George,

Price up some ballscrews, thrust bearings and motors. Now add in a lot
of time to make them fit. Even if you are doing this for fun your time
is worth something. It will more than likely come to considerably more
than a CNC with blown control.

IMHO it is only worth converting if the machine is absolutely mint and
you want the challenge of converting a machine.

Les

George Taylor, IV wrote:

>Why can't I find those deals :(
>
>Seriously, following the posts in this group, I was about to begin
>buying ballscrews, servos and drivers to upgrade my J-head to CNC but
>now I guess I will have to re-think that idea. My mill is in great
>shape but if it's too expensive to CNC it rather than look for a cheap
>CNC-ready mill, maybe I shouldn't bother. Comments?
>
>George
>
>
>

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