Re: [CAD_CAM_EDM_DRO] Bridgeport Trivia, Question further down

info.host@... wrote:

> (There is a question about bridgeports further down):
>
> It's absolutely insane what people throw away. And it's worse that you can't
> get to it and use it again without being forced to do community service for
> the rest of the year. Our tip has a huge furnace they where going to use for
> ultra high heat melting of plastics (Nasty), but so many people objected
> it's just a land fill now. I've never seen much more than old cookers down
> there but the guys there are really evil about people taking things. If they
> see you touch something they might want they come running over and try to
> scare you off telling you it's illegal, then they drive off with it at the
> end of the day.
>
> Back to where this post started. 3000lbs! Dammit that's heavy. We have found
> there is an auction taking place close by with a series one bridgeport cnc
> up for grabs which is predicted to go for under £1000 (A rare sight in the
> UK so far for me). We are probably going to go down to have a look to see
> how much interest there is in it and possibly.... buy it. The problem... no
> forklift. We own a Volvo estate which I suppose MIGHT just take a thousand
> pounds which would be the head and other bits but what can I do with the
> rest? Would a transit van be able to take it?

I'm not sure what a transit van translates to in 'American', but if it is used
to
move household goods, it should do fine. A Series I is really not that
intimidating.
It is easy to tip over, however, so lowering the center of gravity is a good
idea.
Take the head off in 3 pieces (motor comes off with 2 bolts, then three nuts
near the top of the main head casting are removed and the belt housing
slides straight up the spindle). then take the main casting off. Note - it is

REAL heavy, nearly 100 Kg.

> Can I slide the knee and base
> itself into the garage like the Egyptians with the logs of wood? I will be
> able to get another friend to help.

Absolutely. be careful that it doesn't run off the end of a roller, use the
smallest
diameter rollers you can find, and be VERY careful on slopes - it can get away
from you very easily. On a flat, smooth concrete floor, it moves almost too
easily.

> I don't own a mill so if I get down there what sort of things should I be
> ready to take? What I mean is how much damage. First of all, rust. If it's
> on the way's does that not mean they'll need rescraping?

I doubt you'll see rust on a CNC. these machines almost certainly have chromed

ways. If the chrome is worn off in one part of the way, that is a sign of VERY

heavy use, or very poor maintenance. I would beware of a machine in that
condition.

> The mill will still
> have it's servos, should I expect them to still work smoothly and quietly?

Well, depends. Most of the older Bridgeport-branded CNCs were stepper
driven, not servo. Bridgeport did make special units with high-end servo
drive, but the lower-cost BOSS models (BOSS 3 through 6) were stepper
driven. The BOSS 7 and 8 were servo driven, using the same motors they
still use in the EZ-Trak machines (SEM). Many of the non-bridgeport
CNC machines built on the Bridgeport iron were made with servos of
various sorts.

>
> Should I expect the drivers for the servos to still be working since those
> look to be the most expensive parts of a servo system? I'm not too bothered
> about cosmetic damage, that's what they make Hammerite for, but should I
> look out for chips and deep scratches on the bed?

Deep mars in the ways are going to be hard to fix, even WITH scraping.
I'd avoid that!

> How much would a power supply for this mill cost?

Power supply? For what? Stepper drivers or servo amps? What make, size,
etc.? Some servo amps have integrated power supplies, some use one big
supply for them all. If you have the servo amps, the power supply will be in
the same box. If you're missing one, you'll be missing both.

> If the pendant isn't with the machine how do you
> connect the existing drives to the parallel of a computer, is it the same
> termination?

Again, it all depends on what is there. the pendant is NOT the CNC control
on the older systems. The CNC control was in a huge box on the back of
the main casting. The pendant might only have LED displays and buttons,
or it might have a CRT in later models. Only the very latest CNCs have
all the works INSIDE the pendant. In general, you can't connect servo amps
to a PC parallel port. You can connect stepper drivers, with or without
some intermediate conversion to a parallel port. but, for servos, you
need an encoder counter and a DAC to make the analog signals.
Find out what is (and isn't) there, and I'll be glad to offer more advice.

Jon