Re: [CAD_CAM_EDM_DRO] Re: what will i damage?..running 220 1ph into220 3phase transformer?

Hi David,

So far I have had no problems with my Geckos at full current and 75V.
They do need reasonable heatsinking though. I used a 300mm x 200mm piece
of 3mm ali plate with all 3 drives on it. There is another thin ali
plate mounted about 20mm away from this plate and a 80mm fan blows air
between the two. It runs slightly warm to the touch.

I easily get 96IPM rapids without losing steps. I have also never
noticed any lost steps while taking heavy cuts.

How have you got your steppers wired up? I noticed a significant
improvement when running the motors with just 2 windings as opposed to
series or parallel.

If servos weren't so expensive I would scrap the steppers as well. I
much prefer servos.

Les

ibewgypsie wrote:

> I did not have success with gecko drives on my bridgeport. IF YOU do run
> them make sure to heat sink them with a fan. I lost 4 total... Larken Cobra
> drives are much more suited to the Nema 42 motors and I run mine at 8 amps
> and get 110 ipm out of it. NEVER could I get that speed from a gecko on the
> system without losing steps. DON'T get me wrong, geckos are fine drives
> just a nema 42 stepper is on the upper thresh hold of the drive... USE
> maximum precautions with heat and current voltages.. That heavy slide will
> generate enough decell-inertia related voltage to kill them drives also. If you
> limit the current to 6.5 amps and keep them drives cool you might be able to
> run 30-40 ipm... IF anyone is running faster then this with this setup I want to
> see it. Look to lose steps under heavy cuts with this setup.
>
> Someone on another board equated this to running a YUGO motor in a
> corvette. Made fun of me for even trying out geckos on my mill..
>
> I rewired the taps on the 3 banks of stepper transformers about ten or more
> times trying to find something that would work with single phase, I didn't.
> They need to be seperated cause the 3rd coil on the common armature will
> affect it.. YOU could try using two of the coils on the bank and ignore the
> third, not sure what that'd do.. I kept ending up with a odd voltage on the 3rd
> coil.. I have heard of people cutting the armature in between the coils and
> they work fine..
>
> I replaced the transformer bank with a 2kva 220/24+24=48vac transformer.
> Still running fine with Larken drives and that setup.. I have lost a bridge
> rectifier. Seems not all of them are as good as some of them. Current model
> is a 35 amp IOR 600 volt. I have 4 100amp stud mount diodes mounted and
> ready if I have another bridge go out..
>
> Lots of good parts inside that boss setup to reuse. Them capacitors are
> great. Terminal strips, 220/120 transformer, 24 volt system switches and
> other goodies..
>
> I had pictures posted on the net of my machine, but I deleted them to make
> room for some ebay items. I can repost them next week probably if you'd like
> to see how I skinned a cat. There is more than one way you know..
>
> I think if I had it to do over, I'd run 5:1 servo motors on my mill/ Rutex drives
> and the rest the same.. GUT it all and sell the steppers on ebay.. *I did throw
> about six hundred pounds of old boss junk into a box and ship it to a happy
> ebayer who runs original hardware..
>
> David
>
>
>
> --- In CAD_CAM_EDM_DRO@yahoogroups.com, "Mike Mueller"
> <mueller914@y...> wrote:
>
>>Bridgeport Series 1 w/Boss 3 controller:
>>
>>looking at the main electrical box, I wired up power going to only 2 of the 3
>
> main fuses as follows:
>
>>(left to right)
>>
>>left= hot
>>middle= hot
>>right= no connection or power
>>(yes, machine is grounded)
>>
>>The three transformers for the steppers read 53vdc, i can feel that the
>
> stepper motors get energized. The controller does not work, which is fine
> since it's being removed as the Bridgeport will be operated via my PC and
> G201's.
>
>>
>>Am I asking for trouble running it this way?
>>VFD is going to run the spindle motor.
>>
>>Thanks,
>>
>>Mike
>
>
>
>
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