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Programming safety switches

novotny731

Plastic
Joined
Mar 14, 2019
So I am programming a MultiCam 3000 series. This for a production. My program has a stop half way thru so you can tilt the fixture down and cut out a hole. Well my boss wants me to put a switch on the fixture and program it so second part of the program will not run unless the switch is activated. If anyone has any ideas on how to do that would be awesome


Thanks,
Jake Novotny
 
A quick and dirty idea?

Wire in a normally open* switch in series with the cycle start button. If there isn't anything touching the switch on the table, the cycle start button won't do anything.

*(assuming the cycle start switch is also normally open)
 
A quick and dirty idea?

Wire in a normally open* switch in series with the cycle start button. If there isn't anything touching the switch on the table, the cycle start button won't do anything.

*(assuming the cycle start switch is also normally open)

And he'll be able to start the first part of the program how? He would need some feed back from the switch to the program so that the first part of the program could only start without the tilt and the second part only with the tilt.

Regards,

Bill
 
And he'll be able to start the first part of the program how? He would need some feed back from the switch to the program so that the first part of the program could only start without the tilt and the second part only with the tilt.

Regards,

Bill

Another switch, wired parallel with the 1st. Doesn't have to be on the table, could be a switch next to the cycle start button that requires the operator to push start with both hands (2nd op will only require 1 hand).

I do get what you are saying, you are right. And what I just wrote is NOT foolproof, but a step in the right direction...

At least it SHOULD get the operator to think about what is going on.


Edit: although I realize that the operator could just NOT tilt the thing, and just hit the 2-handed cycle start routine in the middle of the program.

Oh well, back to the drawing board.

I like the M-code with a finish signal idea, if the machine has such a thing.
 
If you can add some logic to the control then a pretty clean solution can be made.

I don't know the control on your machine and the following is based on the assumption that the Cycle Start signal is a 24VDC momentary input to the control. This is typical of all CNC controls that I have worked on, but again, I don't know yours.

If you can't do the logic change, then dandrummerman's suggestion is a start, but needs another switch added.

Fixture safety switch.jpg

The switch mounted to fixture needs NO and NC contacts. When the fixture is in the OP1 orientation, the switch should not be actuated. When the fixture is oriented for OP2 the switch should be actuated.

An additional switch with both NO and NC contacts needs to be mounted at some position where the machine can actuate it, but not its "normal" starting point.

When the first operation is ready to be run, the fixture will be in position 1 and the machine will be in its normal starting position. At this point, power will flow through the NC contacts of both the machine switch and the fixture switch and the machine Cycle Start switch can function to start the program. If the fixture is not in the OP1 position, power is interrupted and the cycle will not start.

Just before you temporarily pause the program, position the machine to actuate the machine mounted switch. The fixture is then moved to the OP2 orientation. Now power can flow through the NO contacts of both the fixture and machine position switches and the machine Cycle Start can function to start the continuation of the program. If the fixture did not get positioned to the OP2 orientation, then power is interrupted and the the cycle will not continue.

Hope that made sense. Sorry for the schematic being folded. I thought it might end up too wide to view as an attachment so I drew it folded. Turns out I did not need to. If it is confusing, let me know and I'll re-draw it unfolded and post again.

As with most things it is not foolproof as fools get smarter all the time. Nor is it failure proof. It will catch a lapse in operator memory though.
 
If you can have the machine actuate a contact it is straigt forward i think
Machine actuates a NC contact in series with the NO of the start button (If that is a momentary NO contact at least Probably)
The contact on the ficture is a NO parrallel over the NC contact

The nice idea (thanks Vancbiker) is to have the machine actuate a contact With that idea you can make it work

Peter
 
Very clever, Vancbiker! I suppose the machine switch would then be flipped back after Op 2 is done, but that would likely be done almost without any effort or just ending Op 2 in a different position as Op 1 or whatever.

Jake - do you know, or can you find out, if your machine has digital inputs who’s “state” (i.e. 1 or 0) can be referenced in a program? Many controls allow you to say, “IF this switch is flipped go to the next line in the program. If not, throw up an alarm that says, ‘fixture not tilted, bro!’”
 
.....I suppose the machine switch would then be flipped back after Op 2 is done, but that would likely be done almost without any effort or just ending Op 2 in a different position as Op 1 or whatever......

The switch on the machine would just be a momentary type and would revert back to it's "normal" state as soon as the machine moved away from it. That's OK because the Cycle Start signal is a momentary input to the CNC.
 
Thank you guys for all the ideas. I have been busy with other stuff. I have contacted multicam should be back with a response tomorrow. Also Vancbiker I'm going to look into. Again thanks everyone for your ideas. I'll let you know what I come up with.
 








 
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