Re: [CAD_CAM_EDM_DRO] Bridgeport Stepper Voltage/Current?

Hi Kevin,

The original stepper drives run at above 100V. However, Gecko G201s at
about 70V and full current will run them quite well. You can make a
cheap power supply by reusing the big 110V transformer. If you wire the
transformer for twice your mains voltage you end up with 55V out. In my
case the mains is 230V (measured) so I wired my transformer for 460V. As
some of the auxiliary systems on my machine need 110V I wired them to
the 230V input of the transformer. As the transformer is running on half
it's designed voltage this terminal is now at 115V. As long as you don't
draw too much power (say less than 200W) this is perfectly safe.

There are some suitable smoothing capacitors and bridge rectifiers in
the control cabinet (use at least two of the 200V capacitors). The end
result is a very solid power supply that works really well.

You can fit all the control electronics and the computer into the power
cabinet but you do need to find a compact computer case as it is a tight
fit. In my case I moved the power cabinet to the side and scrapped the
control cabinet. As you cut the stepper wires this may be a good idea
for you to do. If you cut the wires close to the cabinet they should
still be long enough.

Les

Kevin R. Walsh wrote:

> All-
>
> I removed the control cabinets from my rigid ram Bridgeport Series I
> CNC when the riggers moved the machine into my shop. I fully
> intended to to a complete update, so I was less than detail oriented
> when I disconnected everything. OK, I admit it, I "disconnected"
> most of the cables with a hacksaw. The riggers were standing there
> to the tune of $125/hour, so I had to work quickly.
>
> Anyway, what voltage do the stepper motors on the Brideports run? I
> intend to remove all of the drives and supplies and replacing them
> with Gecko 201s for now. I was planning on building a new DC supply
> out of what is left in the box, but wasn't sure what to build it to.
> Obviously something less than the 80V the Geckos want to see. The
> electrical cabinet now only has test points for +/-5V and +/-12V,
> which I assume are logic leveland not the actual drive voltage.
>
> I have the latest Home Shop Machinist magazine witht the 3rd article
> in the series on retrofitting the exact machine I have. He has the
> motor connection diagrams, but not the power requirements. I'm
> trying to get a hold of the other two back issues right now.
>
> Thanks
> Kevin
>
>
>
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