Re: [CAD_CAM_EDM_DRO] Step & Direction for Bridgeport Boss 3/4/5/6

Sorry to have to contradict you Jon, but the BOSS stepper drivers are very
solid and reliable.
I have several hundred machines retrofitted using the original drivers and
they do not have problems. Further, if one did have a problem, they are very
easy to fix.
The bad press that the drivers have gotten is the fault of the control
system that needs to be replaced.
What happens is when the old BOSS controller makes any move over three
inches a minute, it starts by jumping from dead stop to about three IPM and
then ramps up to the programmed rate. At the end of the move it ramps down
to about three IPM and then slams to a stop. The table or quill will try to
keep going (inertia) which turns the stepper into a generator which puts a
reverse voltage across the transistor. Transistors do not do well with
reverse voltages.
My control ramps all the way up and all the way down and I have many
machines that have been running on the same set of transistors for over five
years.
Oh, another reason that some people have trouble with their transistors is
they got tired of paying a service tech and started buying from Radio Shack
and doing their own repairs.
The BOSS drivers are rock solid and trouble free if you quit hitting them
with a hammer.
Darrell

----- Original Message -----
From: "Jon Elson" <jmelson@...>
To: <CAD_CAM_EDM_DRO@egroups.com>
Sent: Wednesday, August 02, 2000 9:37 PM
Subject: Re: [CAD_CAM_EDM_DRO] Step & Direction for Bridgeport Boss 3/4/5/6

> The reason everyone does this is that the least reliable part of the
> BOSS machines was the stepper drivers. There are other reliability
> problems with them, but the stepper cards are supposed to blow
> a transistor a week (one one of the three axes) in production
> service!
>
> Jon
>
>
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