Re: Newbie bridgeport cnc conversion quetions

--- In CAD_CAM_EDM_DRO@yahoogroups.com, "toorigid" <iszrblack@m...> wrote:

> I have been a member of the group for a while and read the posts in
> the digests sent to my email. I have a old bridgeport series 1 with
> a 1J head. The table and the ways are not the greatest and I cleaned
> and painted it to make it a respectable machine. I just bought
> another machine much nicer and I am considering selling this old
> one. But then I began thinking about keeping it (if I can afford to)
> and converting it to a cnc. I run a Hurco at work so I have CNC
> experience. I am wondering what is the best (most bang for the buck)
> way to convert machine? I am capable of making all the brackets to
> mount the motors. What are the in's and out's of servo vs stepper?My
> other concern is the machine itself. The ways are slick(no
> scrapings) and not chromed. There is some slop with the table locks
> loose. Can you run with the gibs snug to get the slop out and still
> make good parts? I mean you can indicate the part in if the t slots
> are not square to the head, but table and saddle move square to each
> other. Do I make sense or am I missing something? Or do I sell this
> machine and wait for another one that's in better shape and when I
> can actually afford it. I just hate to get rid of the machine if it
> usable as a cnc. Thanks alot for your time consideration.
>
> Ian Black

Over the years the one theme from guys that have "been there, done
that" are to put your time into adding the controls to an existing CNC
mill rather than take a non-CNC unit and have to add ballscrews,
Motors, Controller, motor drives, software, etc. Ususally older CNC
machines depreciate faster than manual machines for the simple reason
it costs a fortune to keep them running. A "broken" CNC Bridgeport
with tight ways and no slop will fetch about half what a similar
manual version brings. Of course I didn't listen to that logic when I
was offered a sorry looking Gorton 10. I have spent countless hours
cleaning and painting then pulling everything apart and fitting
ballscrews (A must for precision work) and building the motor mounts
and getting it generally ready for CNC conversion. Two years into the
project i still need to add the actual control cabinet and get it
running with a PC controller. Along the way I have used it manually
to build 3 other CNC machines.

Shop around for a mill with a broken controller. For the non-hobbiest
that is not aware of the existence of the low cost CNC options, a
busted CNC looks like 3000 lbs of heartache. Most shops when quoted
the 10 grand to fix a broken unit, will just opt to buy a new one. If
the basic mechanical parts are sound then you are 75% of the way to
having a good CNC machine instead of the 25% you will be at with an
old manual machine.

Do as I say, not as I do!!(:-)