Bridgeport Manual to CNC conversion...

[Davek0974]

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I hooked the rebuilt head up to my VFD today, sounds a hell of a lot better, for some unknown reason it runs a bit warm around the top bearing plate though.

Its not quite right though yet as the vari-speed system seems to do nothing in the higher end when in back-gear, but is ok in normal gear??

[Davek0974]

Nearly got the x-axis motor fitted, once that's on I can lash-up the drive and controller and do motion testing :)

[Davek0974]

We have motion In 2 axes at least. Done some basic servo tuning, cut the top speed to 5000mm/min as 7500 was just too scary. Got homing and soft limits working nicely. Homing is silly-accurate with index-homing turned on - about +/1 0.01mm or better as far as i can measure.

Next I fitted up the Spindle VFD, expecting serious issues with my complex manual/auto speed control idea. I was totally amazed that I have perfect control of speed from 40rpm to 3000rpm within about 25rpm tolerance! It tells me to choose back-gear or high-gear and high or low speed-pulley setting depending on speed chosen by code.

The only issue it does have is that if it is set for say 100rpm in back-gear low range, and the code calls for 2000rpm in high-gear high range, it will spin up the spindle and then tell me to change gear - this cannot be done without smashing the drive.

I have all the code in SpindleSpeed.m1s - can it also be made to stop the spindle and restart it after pressing enter without wrecking the code-flow etc ??

My bench-top lash-up, well it's not a bench but the plasma-cutter but here you go ...



Going to need a pretty big cabinet.

[JAZZCNC]

I have all the code in SpindleSpeed.m1s - can it also be made to stop the spindle and restart it after pressing enter without wrecking the code-flow etc ?

Can't see any reason why not. Post the file your using and I'll take look.

[Davek0974]

I had a second thought last night - it's not as simple as i thought as not only does it need to stop the spindle and restart it, it has to restart it in the same direction as it was running previously because when in low range/back-gear the motor has to run in reverse.

Not so sure its possible now??

I'll get the code up though soon.

Thanks

[JAZZCNC]

Not so sure its possible now??

Anythings possible just changes how hard it is to achieve.!

Explain a little about how it's working now.? How do you run motor direction now directly via VFD or M3/M4.

[Davek0974]

At present, it runs via VFD and 0-10v signal from CSMIO, the motor has back-gear for speeds below 400rpm and also has a variable speed mechanical control that i am using in conjunction with the VFD to enable maximum torque to be obtained at all speeds. The VFD runs from 25Hz to 75Hz so keeps the motor in the power band.

In SpindleSpeed.m1s macro i have some code that examines the requested speed and compares the current pulley range - if it is out of range it warns me to set high/low speed on the mechanical dial and possibly set the back-gear or release it if needed.

Mach is set up with 4 pulleys.

I will go get the macro and pulley data.....

[Davek0974]

Here we go...

Spindlespeed macro
spindlespeed.m1s.zip

Pulleys are set in Mach as follows...
1 - 40 to 126rpm & motor reversed
2 - 127 to 366rpm & motor reversed
3 - 367 to 1031rpm
4 - 1032 to 3000rpm


So 1&2 are back-gear and 3&4 are high-gear.

I was amazed at how closely the speed was set via Mach, works really well.

[Davek0974]

VFD control ?

I currently have my fwd and rev signals wired through two relays using the built-in VFD control supply to control itself.

Is this worth it or should I bin the relays and connect the VFD ground to the CSMIO control ground and go direct from CSMIO output to VFD input?

Its a little layer of isolation but also mechanical complexity if not needed.


Safety relays....
The CSMIO manual shows a PILZ safety unit being used, I gather others are just as good? PILZ are damn expensive but other like Telemechanique items are better priced.

I gather they are used because they monitor the main control contactor/relay and also offer forced contact seperation etc internally, any other reasons? Any types to look out for?

[Davek0974]

Z-axis is coming along nicely - got all the parts machined on the mini-mill ;)

Last step is to make the link from the nut to quill.

My first idea is to plasma-cut a part from 10 or 12mm steel plate, then fit it up and weld it to original bridgeport part. This would make assembly easy as i can fit the parts up on the mill then clamp together and remove to make the weld.

Sound like a plan?