Machsupport Forum
Mach Discussion => General Mach Discussion => Topic started by: TT350 on August 13, 2010, 11:39:29 AM
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From time to time I run across a VMC like a Haas,Fadal, Mazak at actions.
They are sold as is where is and I don't want to fall prey to some ones
proprietary controls.
Has anyone retrofitted a commercial VMC with a tool changer with Mach?
I hope I've posted this in the right place.
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I have done a large lathe which has a 6 position rear turret and a 4 position front toolpost.
The main thing that will be an issue is the VMC/Lathe or whatever will almost certainly have analogue amplifiers/drives so you will need some way of converting the Step/Dir signals that Mach puts out into an analogue voltage. The lathe I did came without the amplifiers as it was a dual buy by me and a friend and he was wanting the old HIAK drives, I put AC Servos and drives on and the drives could accept Step/Dir so I never had that problem.
If however the amps/drives are in working order on your machine then you could use one of the motion controllers that can utilise analogue drives, the ones I know of are
Galil
DSPMC
K-Flop
Hood
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i have a question about analog servo driver.
there are a pair wire for analog input(+-10V) ,when i connect this two wire (i mean 0V for analog input),i see motor rotate a little ,While must motor Remain motionless. i use yaskawa driver.
why?
Amir
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i have a question about analog servo driver.
there are a pair wire for analog input(+-10V) ,when i connect this two wire (i mean 0V for analog input),i see motor rotate a little ,While must motor Remain motionless. i use yaskawa driver.
why?
Amir
I am not sure how you are connecting the wires but it is likely there will be noise getting picked up so there are mV present thus the motor rotates.
Hood
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i connect pin 14 to 15 .
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I am no electronics expert but by doing that you will get a small voltage, likely due to the internal circuitry of the drive or possibly the wire itself picking up noise. It only takes a few mV to move the motor.
Why are you doing that anyway?
Normally in these drives you can offset the voltage to overcome this creep, in modern drives its done in software, in older drives it was done via a pot.
I fitted a servo to the spindle of my manual lathe (gearbox was noisy) and I use a =-10v via a pot to control speed but use auxiliary position input to stop and hold the motor stationary. Without using the position mode the motor would creep like you are seeing, I could offset that in the software but it would obviously affect the reverse direction rotation as the voltage in reverse would need to be higher than the offset before it would turn.
When connected to a CNC control this is likely not an issue as the control itself would see the motor moving so would command an opposite voltage to hold it stationary.
Hood
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i think i have Ground issue.
yes , i also connect range 0 ~ +-10V and motor rotate .all thing is ok but i have noise in system.i think
in addition my driver dont have position mode.
Amir
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WHile is is simple to get basic functions working xyza axis control it can be a BEAST to get all the other functions working as they should. It will require knowledge in using a PLC and ladder logic for the tool changer AND a plugin to get the tool changer function working as it SHOULD.
Mach is very usefull but it does have its limits. There IS a reason that proprietery controls seem very complicated. They have to be for a reason.
For applications that need a GOOD analog solution Keep a watch on what SteveM is doing with the MESA line of motion controls(PCI and USB). These controls have been used in the emc world for a while now and are very good quailty and a fair price to boot. MANY COOL options available as well. Things like rigid tapping and electronic gearing are possible. Steve has been working HARD to get the plugin up to speed.
Just a thought
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i test with digital driver. In this way ,when i connect S-ON pin to GND, motor lock( dont can rotate with hand ) and motor stationary.
now with analog drive ,when connect S-ON to GND motor stationary BUT i can rotate shaft with hand To both sides.
What difference there?
Amir
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AND a plugin to get the tool changer function working as it SHOULD.
Terry, why would a plugin be required to get a toolchanger working, all the ones I have seen are basically I/O and/or timers and can easily be done in a ladder and M6 macro.
Amir, not really sure what you are saying but really you should start your own thread as you have kind of hijacked this one with questions that dont really relate to the original posters questions.
Hood
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Some times the machines are cheap enough that I would be willing in gut entire
system motors, PLC's etc and start from scratch.
Just a 4th axis for one of these machines can cost $2000-$3000 used and if the controls
hasn't be configured for a 4th axis it can cost big bucks just to up grade.
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Hood when you are working with a 24 T changer that needs look ahead or hot swap then it gets very complicated for VB to handle in a fast action function. as the tool changer needs to run WHILE mach is running Gcode. If you notice I said WORK AS IT SHOULD (;-) I just assumed the OP wanted it to work close to what the original machine was like. So far I have never seen a MACH tool changer(mill) work well with just mach I/O and VB. I have seen a plugin tool changer function work just a well as the commercial machines
Now if you can handle a "very" slow tool changer function it can be done
But that is just my opinion, others may vary
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Yes they can be cheap BUT if you are starting from scratch(no motors drives etc) it will be VERY expensive to get it back up to runnning condition. Commercial drives and motors of the "size" needed to run them are NOT cheap.
Just the drives here for a Mazak (rebuilt drives) run $1800 each plus your old drive. AND a set of old 34 steppers and geckos won't get the job done(;-)
Now if you have the drives and motors you will need to get an analog conversion to run them from mach as mach only does step and direction in native mode. So what seems like a cheap retrofit can really ADD UP in a hurry
Not saying it is not a good idea it IS A GOOD IDEA, but double check your cost BEFORE you jump into the fire. Been there done that as well.
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Hood when you are working with a 24 T changer that needs look ahead or hot swap then it gets very complicated for VB to handle in a fast action function. as the tool changer needs to run WHILE mach is running Gcode. If you notice I said WORK AS IT SHOULD (;-) I just assumed the OP wanted it to work close to what the original machine was like. So far I have never seen a MACH tool changer(mill) work well with just mach I/O and VB. I have seen a plugin tool changer function work just a well as the commercial machines
Now if you can handle a "very" slow tool changer function it can be done
But that is just my opinion, others may vary
Terry the toolchanging I would do in the PLC, that is what they excel at in my opinion, VB would only be used to tell it to start and get told when its done.Similarly hot swap just started by a m code and the PLC would do its stuff while Mach is going on its merry way, when the time comes for the next toolchange it would all be done and the only thing Mach would do is look to make sure its correct.
As for very slow toolchangers, I think the reason the ones you have seen are that way are because the hardware is the original and was that slow on the original control. My lathes turret and post are hydraulically operated and are no faster or slower than they were on the original control.
The turret I will be replacing the front post with, one of these days, however will be much faster. The reason it will be faster is I have a servo on it and it can go forwards or backward and doesnt have to clamp at every tool like the one on the rear of the lathe does.
One day I my even get round to making a changer for my mill that I have promised myself ::)
Hood