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stevep
04-05-2015, 01:43 PM
Hi All, I am building a gantry style router, and was wondering if anyone has come up with a fail safe system should the gantry begin to crab... if for example one of the motors or stepper units failed
Thanks for any input......stevep

Boyan Silyavski
04-05-2015, 02:16 PM
If the gantry starts to rack, Leadshine modern stepper drives/AM822, etc../ sense it, stop and emit alarm signal to breakout board so all stops.

Other solution is to clock the 2 ball screws using belt and only one motor.

In reality if you make a precise and sturdy machine with not very wide gantry, one side motor could stop and all continue to move without any problem cause instead of racking the other screw turns by itself. See my first build link below in signature.


So what is your exact problem that needs solving?

stevep
04-05-2015, 04:08 PM
Hi Silyavski (http://www.mycncuk.com/members/10304-silyavski), I have already built my machine, and have been wondering how to safe guard the failure of one side of the gantry to move, on my machine they are lead screws with stepper motor and drivers on each side of the gantry axis,
so the problem is how to save damaging the machine if one of the stepper motors, stepper units or even a slipping feed nut coupling etc failed
Stevep

Clive S
04-05-2015, 04:39 PM
Hi Silyavski (http://www.mycncuk.com/members/10304-silyavski), I have already built my machine, and have been wondering how to safe guard the failure of one side of the gantry to move, on my machine they are lead screws with stepper motor and drivers on each side of the gantry axis,
so the problem is how to save damaging the machine if one of the stepper motors, stepper units or even a slipping feed nut coupling etc failed
StevepAs have been stated modern digital drives have an alarm output which is then connected to the BOB or motion controller etc and that will then disable all drives and thus the motors. ..Clive

Boyan Silyavski
04-05-2015, 05:35 PM
i would rather change the 2 drives to Leadshine AM882.

Otherwise you will have to stay and watch the machine at all times:joker:. Ok, sorry, i am joking.

the only other method that i am aware of is using steel cord and some pulleys


https://www.youtube.com/watch?v=JkqfoA5LXR4

Boyan Silyavski
04-05-2015, 05:37 PM
here is the original solution https://cockrum.net/cnc.html

stevep
04-05-2015, 08:11 PM
Thanks for the info.....the cross linked cable is interesting
Stevep

JAZZCNC
04-05-2015, 10:01 PM
Thanks for the info.....the cross linked cable is interesting
Stevep

It also doesn't work very well so don't waste your time and effort.!!

This can be done without changing drives using an arduino and tacho's or encoders on each screw then compare readings and if large difference then send a signal to the input on controller to e-stop.

But for the cost and complexity you may has well just buy AM882 drives that have stall detect and will most likely be much better than the drives you have already.