Bridgeport Manual to CNC conversion...

[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?

[komatias]

Hi Dave,

I have taken photos as part of my advert so thought I would share just to give you ideas.

Started off with a plate that I flattened and cut out holes to allow access to the tramming bolts and the quill front. Used the two steps on the front of the head as a means of alignment but found they were about 0.5mm off plain. So I have shimmed the one of the flats.

Behind the ballnut you will make out a socket cap screw that engages with the actual casting where I drilled and tapped an M8. The box above I made using some scrap piece of 6mm plate and practiced my aluminium welding.




The ball nut mount is made up of two parts that sort of dove tail into each other. This part is made of mild steel and I was well chuffed to get the clearances between the parts to 0.05mm. The two parts are held together by the M8 socket cap just behind the ballnut. I could thus home the Z, undo the screw and use the quill manually.






The mounting plate is secured on the bottom through the old feed hole in the front using a top hat boss which allows me to not lose too much quill travel.




On the side, since the quill powerfeed is not used any more, I have used the holes to mount a side brace. If you notice there is a small M4 screw just under the elbow of the pressure regulator, this is to tension the belt of the motor. I have built this kind of tensioner in all the axes of my machine.



Yours is bound to look prettier of course, hope you got some ideas though.