Bridgeport VMC760 retrofit

tommylight wrote:

spincycle wrote:

I assume the procedure is similar for newer drives if running analog?
Yes.

spincycle wrote:

I would tune the velocity/torque in the drive software, then tune position through Linuxcnc.

Yes.

spincycle wrote:

It looks like a few of the modern servo drives I've looked at have encoder outputs. Those will just run back into a Mesa card like the 7I97?
Yes.
3 for 3, nice!
New drives can also be controlled by step/dir and also have encoder outputs, and those can again be used in LinuxCNC.
And there are several boards from Mesa that can be used, not just 7i97, a lot of combos there so when you are ready to order stuff, ask here first as we have the Mesa Master with us here, always, in the form of PCW.

Ace! Thanks Tommylight.

I have a 7i96 kicking around from a machine that never got off the ground, but I assume the lack of encoder inputs means I should use a different card.

This machine originally had rapids of 32,000mm/min with 16mm pitch ballscrews - 2000rpm on the axis. Would there be any benefit of analog over step/dir or even ethercat, to maintain such rates of speed and precision?

I just got off a 10hr flight. I took the original Bridgeport machine schematics with me to asses the control side of things. It looks like the Heidenhain output a 24v (sourcing?) signal to a bank of relays to control the solenoids, enables, mag motors, contractors etc. I assume a Mesa card, like the 7i84U could take this role?

It'd be bloody awesome if I could just retain these original distribution/control boards and halve the amount of wiring required!

langdons wrote:

Whoa, hold up.

Households in Austrailia use 415VAC?!

(little kid): "Hey daddy, what's this? ...kzapp! [kid gets electrocuted]"


 

Haha, I wish.

Some have 415 3ph, but normally we just have 240v single in houses. Most single phase outlets here limited to 15amp, even in industrial settings (high amp ones do exist, but aren't as common as high amp 415 3ph). Hence, I'll need 400v 3ph drives as that's the high amp I have available in the shop.

Alright.
Based on my research from the last couple of weeks, I've come up with the following plan and list of hardware for the retrofit.

Servos
Replace the dead 611 Simodrive system and associated axis motors. (I would like to reuse the Siemens motors, but refitting the encoders looks like a headache at this stage)
I'm looking at the Leadshine EL7 drives and associated motors. These come in 380v 3ph. Documentation seems good and the prices aren't bad direct from Leadshine.
Run these in via analog +-10v signal. Position feedback via Linuxcnc. Ideally run battery box encoder cables to keep position even when powered off.

Spindle
Retain the original 9/11kw spindle motor. I'll test the poles on it when I'm back, but I see no reason to not reuse it.
I've already got a good deal on a used Delta VFD110E43A. Paid less than 20% of a new one.
I'll have to get a braking resistor for this.
Run the original spindle encoder (or replace it) back to Linuxcnc for rigid tapping and spindle orientation.

Control
Looking at the following Mesa boards:
7i97T to handle analog control of servo drives, spindle VFD and all encoder feedback. Some I/O.
7i84 to handle additional I/O. Tap into the original Bridgeport relay boards to control tool mag, air solenoids etc.
7i73 to handle control panel keys, rotary encoders, MPG etc.
Coofun CK41 Celeron J4125 mini PC 
27" ELO touchscreen (got a lead on a cheap one here, might be a little big though)
A few panel buttons, MPG and rotary encoders for the interface.
GMOCCAPY looks like a great choice and reminds me of the Heidenhain control, which I've really learnt to love. I wish my Fanuc machine was more like it!

Other than the drives, vfd and front interface, the plan is to retain as much of the original control and wiring as possible. As previously mentioned, it doesn't look too hard to tap into the original I/O feeds from the Heidenhain. I also spent some time earlier in the year replacing all the capacitive snubbers on these control boards (with ones that don't light themselves on fire!) Fresh contractors in some spots as well.

Retain all the original breakers and transformers. There is a large contactor, breaker and transformer (415 to 380v) for the servo drives which I'd very much like to reuse (and not rewire!)

Let me now if any of this sounds entirely wrong or you have better ideas on how to execute. While I've played with cnc machines for a while now, this will be a my first experience with Linuxcnc feedback loop on servos/spindle and controlling a tool changer. 

Many thanks,

J 

I've just heard back from the team at Leadshine.

It looks like the EL7 drives have a 0.0625ms delay on the encoder outputs.

Know people have had an issue with the 5ms delay on the DMM drives. Anyone think this might be an issue?

I've just enquired regarding any delay from analog velocity signal to drive reaction, which I assume would effect tuning as well.

Thanks,

J

The 7i97T has one SS configured on a connector, but with two S devices (7i73 and 7i84) you will probably need to flash a firmware with an additional SS port on the DIL connector.

RotarySMP wrote:

The 7i97T has one SS configured on a connector, but with two S devices (7i73 and 7i84) you will probably need to flash a firmware with an additional SS port on the DIL connector.

Thanks for your input Mark.

Excuse my ignorance, but I assume the SS refers to the RS-422 serial connection?

Love your channel by the way. Digging the engine build. The John Britton diy way must run deep, and rightly so.

Be aware that switches due wear out, especially from DC, capacitive, and inductive loads.

If you notice sparking sometimes, replace the switch.

Remember that worn-out switches will only spark sporadially b/c AC power cycles and the swith will only spark near the peak of the cycle.

I recommend you keep all original brusheless motors, but perhaps you don't care about preserving old motors enough to spend the time.

Try to sell them, they may be worth more than their scrap value.

(Not sure what scrap metal prices are like where you are)

I'm assuming the closer you are to China (and Vietnam, Thailand, etc.), the higher the value of E-waste because the shipping to the recycling center in Asia is cheaper.

langdons wrote:

I recommend you keep all original brusheless motors, but perhaps you don't care about preserving old motors enough to spend the time.

Try to sell them, they may be worth more than their scrap value.

(Not sure what scarp metal prices are like where you are)

I'm assuming the closer you are to China (and Vietnam, Thailand, etc.), the higher the value of E-waste because the shipping to the reccling center in Asia is cheaper.

Hi Langdons,

I'd like to reuse them, but I haven't been able to find any successful examples of this online so far.

I can find Delta drives in the right voltage and they sell all their encoders as spare parts. I guess it's a matter of deciphering the spare part codes to match the right drives and figuring out how to adapt them. There is space to mount on the back of the motors where the Heidenhain encoders are.

Anyone done this?

Do you need all new drives?

I thought only one broke.