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View Full Version : Problems with Emergency Stop/Stop function.



MrEmo
07-23-2017, 02:37 AM
Yesterday I tried calibrating my machine and I tried cutting some parts. However I had some issues with the THC and the Z axis went down on the material and triggered the limit switch.

The machine stopped moving but the Torch stayed on and continued cutting even if the rest of the machine stopped. The torch did not turn of until I manually pressed the M03/M05 button. This also happened with the emergency stop.

Anyone have any idea to why this happens? I will try again today and see if I can reproduce the issue.

Al_The_Man
07-23-2017, 09:54 AM
Do you have the schematics for the M/C?
If you want the over travels to stop the whole machine then you need to wire them into the E-Stop relay circuit or there is something amiss in the E-stop wiring.
Al.

MrEmo
07-23-2017, 01:18 PM
The emergency stop was activated within the program, I have not yet connected my Emergency Stop button. That will be done within the next few weeks.

Al_The_Man
07-23-2017, 04:49 PM
You need a typical Hard wired E-stop circuit and relay, all conditions NAND'ed together.
NAND = Not-And in Boolean
Al.

MrEmo
07-24-2017, 09:44 AM
Not to be rude, but this doesn't really have anything with my issue to do.

My problem is that if I activate Emergency Stop in the software the machine stops but M03 is still active and the plasma cutter keeps on cutting!

Al_The_Man
07-24-2017, 09:52 AM
Then it would sound as though you have a fault in the software itself, I am not familiar with the PlanetCNC but it sounds as though the CNC software receives an E-stop input and acts on the S/W. but this is not relayed to an output to also engage the hardware E-stop as it should and is done in a proper integrated system.
Edit: I would contact PlanetCNC and request an answer as if the CNC has is issued an E-Stop then it should not only have a suitable stop output but also turn off M code triggered outputs.
Al.

rodw
07-25-2017, 04:35 AM
Having spent the last 12 months building a plasma machine that was fired up for the first time on the weekend, I can say they are very complex devices which may not always be triggered by an M3. You have reminded me to review my wiring and possibly loop my torch on signal is looped through a relay triggered by an estop. Personally, I think you need to accept some responsibility becasue you have been running a torch on an incomplete machine. Under these conditions, anything can happen. An estop switch was the first thing I wired up.

Al_The_Man
07-25-2017, 10:19 AM
Under these conditions, anything can happen. An estop switch was the first thing I wired up.

Congratulations on ensuring a proper E-stop.
But I think, especially in a DIY situation where a system is put together with components from different manufacturers or sources, many of these sources are only concerned with their particular product and do not go into the idea that is actually part of a larger system as far as the safety/E-stop integration of the whole system is concerned, so it lies with the builder to ensure that this is covered, but many are not aware of the Industry customs in this area and just rely on the parts supplier to cover it.
At least, that is my take so far from many previous posts here.
Al..
.

PlanetCNC
07-25-2017, 10:53 AM
Make sure "Settings/Options/Stop/Outputs Off" is enabled.

Proper emergency handling is complex and most people do not understand how to handle it properly. There are several requirements that we need to consider.
Most important is to protect people from getting injured. Then we need to protect machine from breaking. Last but no least we need to protect tools and materials. Relying that controller e-stop signal will always work is not smart. Runaway servo motor or spindle will not stop when commanded so e-stop on controller has little effect. Only cutting off power will make them stop. But then again, if spindle motor is working properly then controlled stop with braking will slow it down much faster.
It is a task of machine builder to ensure that required safety is achieved. When I build machine for local school I used industrial grade PLC that was monitoring all CNC components and acted when something went wrong. It also controlled red/green light above machine and safety switches of machine enclosure.

Al_The_Man
07-25-2017, 11:08 AM
But then again, if spindle motor is working properly then controlled stop with braking will slow it down much faster.
.

This is why the use of a Safety Relay is mandatory in some jurisdictions, it is optional still in N.A. but many parts of the EU have it I believe.
These have a an option of a Controlled Stop where it is safer to allow a function to complete before removal of power if it is deemed safer that a abrupt loss of power.
Al.

MrEmo
07-30-2017, 03:03 AM
Yes I understand. The machine isn't quite done yet and I understand that things might not work as they should. But in how I see things work is that if you are running a machine for instance a cnc plasma, when the emergency stop signal is activated within the program or physical with an emergency stop button. The machine should stop sending outputs to the various components. Everything should stop.

I didn't realize that there were an option for this, but I will activate this feature and try again. Other than that the machine has been working very well. But as you guys clearly state there is a lot to keep in mind with building machines. The emergency stop is ordered and will be assembled as soon as it arrives.

Do you guys have any other suggestions to good ideas to make the machine safer?

rodw
07-30-2017, 04:23 AM
Hmm, I had exactly the same problem today with LinuxCNC on my evolving table. An error in my hand coded test file left the torch on at the end and it careered off toward home blazing away. The closest estop was the torch breakaway so I grabbed it and was left holding a flaming torch in my hand. I have a relay that is triggered by an estop to disable the stepper motors. I think it has a spare set of contacts so I think I'll route my torch on signal through it as well.