Bridgeport Series I CNC / Gecko Driving Superior Stepper - Specs?
Hello, My first post to the group after months of lurking and absorbing the knowledge base.
I bought a Bridgeport series I CNC mill in great shape and want to use the existing superior motors (with the black fins). (Photos in my gallery)
My question is does anyone have the specs for this motor?
current rating, voltage, inductance?
Kevin
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Background:
Based on information I found here in these fourms I've already configured my machine as follows:
54Vdc power supply with 20,000uf worth of caps wired in star arrangement to three 203V's Gecko's set to 7Amps (no resistor). The motors are wired parrallel per a post I found here on cnczone.
I had the machine working great for 20 minutes but lost operation in the Z drive out of the blue. No load on machine. I was getting Z speeds of 70 ipm and x and y of 120 ipm as the limits before the motor started to miss steps. Accelerations where 17 as I recall. Mach 3 s/w and cnc4pc BOB.
The Z axis motor has holding torque but does not step. I confirmed proper logic voltages out of brake out board (0 and 5V) 5us pulse time and 16ma into opto isolator of Gecko step and direction but no movement. The motor does not appeared shorted(.5 ohms across motor leads). The drive shows a green light. Drive was sent back to Gecko for checkout.
So the question is, am I asking to much of the Gecko drive to power this motor or do I need to upgrade to a better motor? I have heard some posts that the existing motors don't like microstepping.
As for those out there that want to build a low cost power supply my solution was to modify the existing 240 to 120v transformer (T2? the big 1kva transformer on lower right of the power box). It has three layers (19 turns each) of around 10 ga secondary. Originally with 120V on the primary the secondary gave 82Vdc after ran thru a 35A full wave bridge rectifier and caps. This was too high so I cut into the outside layer of the secondary effectivly removing 19Turns. The result was a rectified and filtered voltage of 54Vdc.
I have a Tri-Onics cnc (Copy of your machine) that I converted using 203v's and a CNC4PC C11G breakout board. I used the original MAE nema 34 steppers also at 7 amps per phase. I originally ran without a current limiting resistor but I would occasionally get a red led (overload) on my Z axis. I added a 270 ohm resistor and I never had the problem again, so I presume I was overloading the 203v. I realize you mentioned never getting any faults on your drives, but if memory serves me correctly, Your steppers are larger than mine and would typically draw more current especially if you are running them at a lower voltage than they were originally.
My motors are 200 steps per rev with a 2:1 timing pulley turning a 5 tpi ballscrew which gives me .0005 resolution- no need to microstep....
Hello hybidder,
Thanks for the response. I considered the lower current setting on the motors. I've been further testing the X and Y axis motors and have yet to have any problems with them with full current setting (7A). So maybe the Z axis driver (gecko 203) just had a problem. I'll let you know what they find on the drive.
In the meantime I added more capacitance to the power supply and since my leads between the filter caps and Geckos is around 18" I may add a 470uf cap at the gecko.
The Gecko driver was found to have a component with an intermitant. This drive was on the z axis. The folks at Gecko diagnosed and shipped the repaired unit with a one day turnaround. Good folks to work with!
The good news was finding the intermitant on the Gecko rather than a more concerning issue of not being able use the gecko with the existing superior steppers. Once the repaired unit comes in I hope to get all axis' working.
Well the Z axis Gecko was recieved and installed. She lives and cuts well with existing superior motors. I cut a 1 inch diameter hole thru 1/2" aluminum using a mach 3 wizard and the result was easily with .001" of what I asked for. No backlash compensation needed.
As for the Gecko settings I ended up with: 6A 270K resistor, 470uf cap on power and ground at gecko. Motors wired in parrallel per a post I found here on CNCzone.
Bridgeport Series I CNC / Gecko Driving Superior Stepper - Specs?
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