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Author Topic: Machine Limits without limit switches? to stop me crashing  (Read 2992 times)

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Machine Limits without limit switches? to stop me crashing
« on: December 27, 2011, 04:28:50 PM »
Hi Guys
I am new to this, I have watched the video on homing and limits but its talking about the use of limit switches and i dont have limit switches, i am sorry if this question has been asked a thousand times, i have been searching for a while and playing round in Mach 3, i just want to understand how to set up limits without limit swithces so it doesnt crash into the ends?
Thanks
Chris

Offline Hood

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Re: Machine Limits without limit switches? to stop me crashing
« Reply #1 on: December 27, 2011, 04:43:13 PM »
Jog each axis to its extent (X and Y fully negative, Z fully positive). Then press Ref All button. That should zero the machine coordinates. You can then go to Config menu and then Homing and limits and set up soft limits. The values you enter there will be 0 for X and Y min and Z Max and whatever your travel is for X, Y and Z, Z being a negative value. Then make sure Soft Limits are enabled on the main screen of Mach and you should not be able t jog to the end of the axis. You may have to adjust the Slow Zone distance if it does not slow down fast enough when jogging at full rapid.
Hood
Re: Machine Limits without limit switches? to stop me crashing
« Reply #2 on: December 27, 2011, 05:05:26 PM »
Thanks hood, I will go try it out  ;D

Offline RICH

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Re: Machine Limits without limit switches? to stop me crashing
« Reply #4 on: December 28, 2011, 12:50:38 PM »
To be fully candid, you can't really count on Mach's software based limits to keep you from hitting your physical end limits, there's just too many ways for those limits to get mis-set or ignored.

Its not that hard to put physical limit switches on your machine, take the time to do that, it will definetly pay in the long run.

Get lever switches that are normally closed and wire then in a loop from switch to switch. This way if any of your wiring or connections fail you know right away and failure doesn't disable your limit switch system. This is also the easiest limit system to setup and its simplicity has advantages.

Lever switches are cheap and easy to mount and get set up, just machine some small blocks that mount on the other surface that actuate the levers.

Paul T.
Re: Machine Limits without limit switches? to stop me crashing
« Reply #5 on: December 28, 2011, 08:31:47 PM »
Thanks guys, i will look into limit switches.

Another silly question i have is,

I have everything set and homed, now if i move the gantry up to the material and zero it out and run the gcode, when its finished and i hit return to zero it returns to where i zero'd it out not to the home back in its corner, the only way i can get it to do it is to close the program and open it again and the hit return to zero and it goes back to its corner?

i am sure its something simple i am missing
Thanks
Chris

Offline Hood

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Re: Machine Limits without limit switches? to stop me crashing
« Reply #6 on: December 29, 2011, 01:53:09 AM »
That is normal, the Go To Zero is for offset Zero and that is what you have set up by zeroing out the axis. If you want to move to machine zero then you would either have to call it in code, MDI or make a button to do it.
Hood