Hi,
using a torque limit to detect the presence of the plate is to drive the tip of the plasma into the plate...if you think that is good for your $500USD watercooled Hypertherm plasma tip ....
go for your life. I'm saying that NO servo should be used in this manner. Lets ay you set a torque limit of 1Nm being a suitable value to get worthwhile acceleration
of the axis. Then that same 1Nm would be applied via the ballscrew to the plasma torch before any over-torque detection could occur. It does not matter how
fast the servo can react it will and must apply its torque BEFORE it can detect that the torch has impacted the plate. The force will likely destroy the tip.
That is what a G31 probing move is for. There will be a certain amount of after-run AFTER the plasma tip has contacted the plate, depending on the speed of the probing move
and the deceleration of the axis. At 50mm/min probing speed and 0.15g acceleration the after-run of my mill is 1.15um. The force between the tip and the plate at 1.15um
interference is minimal. This is the strategy used by nearly all manufacturers to set torch height and is supported by all controllers.
Fact: Clearpath has one, and only one digital output, and by PWM of that output one, and only one, analog variable.
Clearpath servos use an encoder of 12800 count per rev
Clerapath want $517 for a 400W servo
Compare to these facts: Delta (B2 series) has six digital programmable digital outputs, two analog outputs, a full suite (A,B,Z) auxillary output encoder
and an analog input for velocity and torque modes.
Delta (B2) has a 160,000 count per rev encoder, vastly better.
Delta (B2) 750W kit (servo, drive and cables) costs $438.
With Delta I get twice the power of a Clearpath servo for less money.
My opinion is that Clearpath have poor IO capability, modest (at best) encoder resolution, and are expensive for what you get. This is assessment of FACT. It is not misinformation
or disinformation, but a personal assessment of FACT. I can well understand that you don't like it....but tough, I have an opinion and am entitled to it.
I understand also, and certainly approve that you should wish to correct any factual misinformation about your products but I do not have to agree with your conclusions or opinions,
facts yes, opinions no.
Now lets talk about OP's actual situation.
He needs a signal to indicate when the plasma tip touches the plate. Lets say you devise a strategy to use the HLFB to indicate that condition, then how would you indicate
a Following Error or overload condition? You only have one output, and by definition if you use it to signal one condition you cannot use it to signal a fault as well, its one or the other.
the Mach controller can still easily stop the other axes from moving and crashing when any motor shuts down. I’m not sure why you think this is not possible;
Of course its possible, that is after all the primary purpose of the HLFB.....but you can only use it once.
What you said about the ClearPath being designed specifically to appeal to “first time servo buyers” is incorrect. You’ve mentioned this on other forums before, but I wanted to address this here because others reading your post may not realize it, so I will quote/paraphrase what a colleague of mine recently wrote to you:
Design decisions made for the ClearPath motors were done with our typical OEM user base in mind (generally experienced controls engineers in a wide variety of machine automation industries). In addition to high-performance and value, these companies tend to value overall system reliability very highly. By incorporating many features into the motor’s firmware, we were able to remove the need for many additional inputs and outputs, thus increasing the overall system reliability.
Our experience over more than thirty years of technical support has proven that the biggest cause of malfunction in machines using servos is electrical corruption of the input and output signals, or intermittent or bad connection of one or more signal wires. We, and our customers, have found that overall system reliability is greatly enhanced by reduced wiring.
Despite the fact that Teknic products are designed for the OEM market (see the About Us page on our website), a side effect of the reduced wiring problems and the ease with which a ClearPath servo system can be implemented, is that many corporate end-users and hobbyists have been attracted to ClearPath. And even though we didn’t set out originally to sell to end-users and hobbyists, we are happy that ClearPath has been well-received, and we enjoy supporting such a wide range of people and applications. Supporting first-time users has been an interesting experience for us over the years since ClearPath was introduced, and it has led us to create even better website features, documentation, and support videos among other things. And that is a win for everyone.
All opinion only, and not all of which I agree with.
For instance your name for your servos 'Stepper Killers', is that or is that not designed to entice first time buyers?
I would agree that Tecknics do a a masterly job at supporting customers, and I have never claimed otherwise. I would also commend that Tecknics follow on-line forums for any issues related
to your products, to whit, you and your colleagues have taken me to task about my opinions on forums other than this one. As I have stated I base my opinions on the facts of Clearpath servos
and and willing to change my opinion in light of
new facts, but refuse to be badgered out of my opinion
without new facts. That you don't like it is immaterial to me.
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