Re: [CAD_CAM_EDM_DRO] Bridgeport Questions

info.host@... wrote:

> Thanks to Jon and Mr. Vicars (I didn't see your first name),
>
> I am not any CNC genius, you probably guessed from my questions, so I
> just assumed the mill would run under servos. It must be steppers as I've
> been told by others that the mill will almost certainly not bring more than
> £1000 (~$1500). I have spoken to the guy selling it who says it's in good
> condition but grubby, seeing some of the used things described as 'grubby'
> though makes me want to speak to him a bit more (Grubby read bust). I'll
> call him soon.
>
> I am 16 which means I don't work right now so the summer holidays was my
> oppertunity to get some money for a mill. No matter how many places I called
> no where seemed to want a 16 year old for some reason, I wonder. I really
> want the mill for making turbine discs, compressor blades, parts for a
> lathe, machines guns... I'm only kidding! The biggest problem I can see is
> moving the mill home again. A transit van is one of those things you'll see
> would-be do-it-all'ers with, the ones with sliding doors on the back.

Sure, this will do it. If you can get one with a 'lift gate' (a hydraulic
plate
that raises and lowers loads from/to ground level) you will be totally
set. Don't even think about using a ramp and a dolly. The only safe
way is a lift gate or a forklift truck. (A crane will also work, but that is
really expensive.)

>
> The mill is 45 minutes driving away in Manchester and I can go up to
> have a look the day before I've been told. I wish my sister had left her
> camera here and I could have taken a few pictures. If the mill is using
> steppers are they going to be microstepped or just put through a high belt
> ratio for accuracy?

They WON'T be microstepped, but you could put that in if you retrofit
with a new control.

> I need it to be atleast as accurate as a Sherline
> because the discs will be spinning real quickly and inaccuracies any bigger
> will just vibrate them to a 100,000rpm violent death.

As long as the inaccuracies repeat on each blade, then it won't cause
imbalance.

> How much is a rorary
> table for a mill like this from Bridgeport?

Sounds like you might want an indexing head more than a rotary table.

> I've never seen them second hand
> so I'd probably have to buy it new. I've seen other brands ranging between
> $250 and $800 minus the stepper.

Yes, but used ones ARE around, you just have to look a little harder.

> My real concern my lack of everyday
> expirience with running a mill so I don't know how much say, a patch of
> rust, will do to accuracy. I know from reading books on scraping lathe beds
> that small inconsistancies aren't much of a problem if the slide moving over
> them is much larger.

Yes, but you are not likely to find rust on a CNC machine, anyway.

> I knew the Bridgeport S1 cnc had the control inside the box but I was a
> little confused about it at first. If the mill is stepper driven, has it's
> drivers and supply, then I just 'remove' the old, I forget it's name,
> controller and add my own surplus 200mhz MMX in it's place. It has 32mb ram
> and 2gb hard drive (Old is the word, it has a 16x cd drive and cost £2500
> new!).

Well, there's a little more to it than that, but essentially, yes.

> The old control will have plugged into the drivers of coarse, do I
> then do the same and terminate one end with a parrellel plug for the
> computer in it's place? I am working on the idea there is some source of
> information on which pins go to which bits. I have Corel Linux but I'm
> hopeless at it right now, I'll have to stick RedHat on for EMC won't I? Or
> will it run under Corel? I mean Corel as in, the idiot GUI level with
> colourful backgrounds.

There are others that have done this upgrade, but not much sense talking about
it until you actually at least see the machine, and know what exact model it
is.

Corel will be fine, but it has to match the exact kernel version to be
compatible with
a particular EMC version. The most common ones are 2.0.36 and 2.2.14

Jon