Bridgeport Conversion to CNC, questions

[rsicard]

Another common option is to use a remote hand pendant. With one of these you can set any axis to move continiously when the wheel is turned, or step one increment/step at a time (i.e. 1 ten thousandth, 1 hundredth etc). You can set any constant feed speed no matter how fast you turn the wheel/dial or set it to go faster/slower if the wheel speed changes. Bottom line it it's like a very flexible and precise power feed on every axis. I use the mill this way often for small, simple or other "manual cuts". Your CNC screen is in essence your DROs. Much more precise and error free than turning wheels by hand and once you get used to your pendant, it becomes second nature, just like the hand wheels.

Coherent:
Really like your suggestion about a remote hand pendant. Which Bridgeport CNC conversions you know of have provisions for hand pendant? Also, do some CNC conversions use DRO scales as inputs for axis positioning? From what can be seen, CNC conversion use encoders within the drive mechanism which DOES NOT account for lead screw backlash. Your thoughts please.

Regards,

Rolly, Tucson Arizona

 

[JimDawson]

Also, do some CNC conversions use DRO scales as inputs for axis positioning? From what can be seen, CNC conversion use encoders within the drive mechanism which DOES NOT account for lead screw backlash.

Yes they do, which automatically compensates for backlash, within reason. But there is no substitute for a mechanically good machine.

I'm a fan of magnetic scales, I have those on my machines. These are 1 micron (0.000039'') resolution. Been working fine for the last 5 years.

 

[Cooter Brown]

I am converting a 1960 J-Head Bridgeport to CNC with Clearpath servos and a Masso controller......

Mine will be CNC only but Its not impossible to make the hand wheels still work.... I have been running mine with the keyboard and using the cnc display as a dro.... I got that Manual CNC Mill DRO.....lol


Check out the thread.....

Bridgeport CNC with Masso Controller/Clearpath

This is going to be my first CNC build and my First build log. I've decided that a build log on this forum might be a good idea for this project so the next guy to take on this project doesn't have to deal with the stupid stuff I'm already running into. This is my Masso Controller I will be...

www.hobby-machinist.com

 

[rsicard]

Yes they do, which automatically compensates for backlash, within reason. But there is no substitute for a mechanically good machine.

I'm a fan of magnetic scales, I have those on my machines. These are 1 micron (0.000039'') resolution. Been working fine for the last 5 years.
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Jim:
Thanks for your response and the photos of the magnetic sensor and scale. Still looking for sufficient quality ball screws for X and Y axis of Bridgeport Mill. It is really difficult to find them at reasonable quality and price. Need to get details on zero backlash ball screws. Still working thru rolled versus ground ball screws. The latter require a lot more machining than the former. Just wondering about the hardening and durability of the shaft for the two different types.