Rotary Table Question

[Al_The_Man]

Originally Posted by NC Cams I need/hope to find + & - drive voltage wires (105 or do vdc would be optimum) to the DC motor, 2 Tach feedback wires, home and brake engaged signals, and finally A+, A-, B=, B-, I+ and I- from the encoder and a case ground. Anywayt, these are what I need for my adaptation but any other signals might be useable/adaptable. Anyone else done any 4th axis adaptations of this genre???? .

The biggest obstacle in fully integrating a rotary table or 4th axis is whether or not the control already has the capability, if you can configure the 4th axis, and the control out is ±10v analogue, and the feedback is by quadrature encoder, then the possibilities are almost endless, select any motor/drive combination that will operate the 4th axis together with a suitable encoder, you should not need the tach feature if you configure the drive for Torque mode.
Obviously you need the ability to scale the encoder feedback for the correct resolution.
If you require the brake feature, the motor control command MUST be turned off while braked.
Al.

[NC Cams]

In my case, the system is the BMDC based DX32 that is used in a Bridgeport V2XT 'mini' VMC. The cabinet is prewired for 4th axis - you simply plug in the connector and it recognizes its presence and away you go.

The amps are Motion Science and require tach F/B - they are not very well suited fo "customization" as they have some of the "fits all" features hardwired into Bridgeport only compatability - attempts to get schematics to "see" what's going on so as to get around tach F/B have not been successful.

The addition of a tach to the motor is not something that I cherish. Although encoders are fairly adaptable, the Bridgeport servos seem to be chock full of custom goodies which makes DIY changes a real PITA. Besides, the last time I sent servo's to a factory authorized service center, the bill made me wince and all they did was rebuild the motors (new brushes, new bearings, and 1 new armature - apparently it was shorted/shorting).

One might have more luck in re-arranging the tach feedback thing BUT since the BMDC card is already programmed and access to the code is quite limited, I don't know about the possibilities of patching around the tach F/B issue.

They did this no tach deal with the TC22's but they used "custom" digital amps and special heretofore undocumented PWMINT cards piggybacked onto the BMDC card and special software to make it work - I don't anticipate EMI providing much help as to what PWMINT does nor how it does it software wise for a DIY'er.

Besides, getting the guys at Haas to even respond to a non-Haas adaptation proved to be a HUGE PITA after several tries, I did get the pinout info for the DC motor system (BTW, DC motors will be obsolete shortly as they're going brushless). But I digress.

After some searching, I found some take off servos and take out amps from a V2XT that are the same as what I have - thus true bolt ins. They were not free but very reasonably priced providing I gave them a good home.

I also found out that Troyke build BPT's 4th axis' for BPT so I gave them a call. Seems that if I supply the motor, they'll build a table not unlike what they did for BPT when they built them way back when.

Ultimately, I'll be able to hook up to the factory prewired MIL plug and have a turn key 4th axis, ala factory style. For once, I'll hopefully have a system that isn't a kluged up deal that will just run. I'm simply tired of having to fix and reverse engineer stuff just to make parts....