Newbie- 4th axis - Bridgeport 412 + Heidenhain TNC155

[Fudge]

Hi all.

We have a TNC155 on a Bridgeport 412 3-axis mill, and for a student project are looking to design, build and mount a 4th axis for it. The software supports XYZA interpolation, I gather, but there I can see no hardware in the cabinet for a 4th (A) axis.

For axis hardware I'm planning to use an old (but still good) dividing head with manual operation locked out and an electric drive fitted, running through a timing belt and pulleys.

Actuator options are large stepper or servo, but how would I go about hardwiring an interface to the Bridgeport's controller, and making sure that the axis calibration was set right, for example to convert degrees to encoder pulses or to steps? I know how to get to the Heidenhain's parameter page and change settings, but am unsure how to activate its 4th axis.

Anyone here with that experience?

Tim Ward
University of Bolton
UK.

Oh - and I'll also be looking to update our EdgeCAM postprocessor to 4-axis when that's done

[machintek]

Under the MOD key there is a page to turn the 4th axis on and off.

George

[Fudge]

Thanks George.

I actually knew that, but I think the problem is ore fundamental than a software switch.

We have no servo, encoder or stepper driving the dividing head, and I'm looking for ways to move forward on a design strategy that will produce a powered 4th axis that actually interfaces to the TNC155 via the power amps.

Alternatively, I might do a complete upgrade to Mach3, EMC2 or openCNC - any ideas?

Tim

[gus]

There are a bunch of parameters relating to encoders and feeds and everything

I mean no offense, but if you are looking in the cabinet for hardware that quite obviously would not be there, you have a ways to go in understanding the issue.

I think the tech manual is available for download on the heidenhain website, start there.

One of the easiest ways to start would be finding a servo amp that is the same as the other existing amps, since you would be able to assume some parameters transfer over. Ditto a servo motor

[Fudge]

Thanks gus.

I mean no offence either, but if I truly understood the issue I would not need to ask here. It's one thing to design a system from scratch, quite another to go modifying or adapting to existing hardware. The stupid questions are not the ones you ask - they're the ones you don't.

Anyway, it might be quite obvious to you that the hardware would not be in the cabinet, but unless I look, I have no way of knowing whether the 4th axis amp/decoder might have been there to start with even though only 3 axes are active. Unfortunately, my former colleague who bought the machine all those years ago has passed away and I can't ask him.

I agree that the manuals may well be on the Heidenhain site - haven't found them yet, but I'm still looking.

Regards, Tim.

[ichudov]

Originally Posted by Fudge Thanks George. I actually knew that, but I think the problem is ore fundamental than a software switch. We have no servo, encoder or stepper driving the dividing head, and I'm looking for ways to move forward on a design strategy that will produce a powered 4th axis that actually interfaces to the TNC155 via the power amps. Alternatively, I might do a complete upgrade to Mach3, EMC2 or openCNC - any ideas? Tim

I have a Bridgeport Interact 2 running under EMC2. Adding a 4th axis was rather simple, though trivialities like what wire terminals to use, resolver to encoder converter, etc made it take a while.

[gus]

OMA Controls section

I 'think' the 151 AND 155 start with similar parameter sets, meaning a 151 tech manual can be a start

[awemawson]

I agree with Gus - go find the 151 manual under oma controllers on the Heidenhain site. The 155 is just a 151 with graphics capabilities on the monitor.

I have a back burner project to add a 4th axis to a TNC355 on a Beaver Partsmaster - I got bits together a few years ago for my TNC151 / Interact 1 machine but then it got smashed in transit. Fortunately the TNC151/155 and the TNC355 are rather similar.

You will need a servo board - (its a Bosch item on the Interact 1), a servo motor (possibly a SEM 340) and an encoder compatible with the TNC155 ie probably sinewave signals not digital. If you also use the Bosch servo drive you will need a centre tapped choke. After getting the bits together and making the mechanics sound, it's just a case of setting appropriate parameters and tuning the servo.

Keep us posted - where are you in the UK?