Nebula Limits Switch Challenges... Again.

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4DThinker
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Nebula Limits Switch Challenges... Again.

Postby 4DThinker » Mon May 09, 2016 4:29 pm

End of the semester. Using a 1/4" spiral up end mill to cut slots on a thick red oak panel. Lots of audible vibration from the long bit. Our Nebula had been working generally reliable since I last swapped out a Z-limit switch, and tightened up the connections on the other limit switches with X axis being the most persnickety.

It started throwing limit 2 errors while in the middle of cutting. I blew out and manually tapped the Z switch several times but no matter what I did the same error would pop up within a second ( as soon as the bit met wood) after restarting this job.

I took the router, clamp, and back plate off to get to the switch. Replaced it with a new one. Put it pack together. Job started fine until the next x move where a limit 0 error popped up to stop everything. I blew out, re-crimped connections, but finally had to put a jumper between the X wires to get the machine to continue.

This student was able to finish this job. I came back the next day to check out the Nebula. Powered it on. Took the jumper off and re-connected the X switches. I tried to HOME it only to watch the Z axis move DOWN rather than up to look for a limit switch. Had to E-stop it. Nothing I did (restart software/restart PC, power off/on the controller) would get me past this. The Nebula acts as if somehow the Z axis wiring was reversed.

Summer classes start in a week. This Nebula is out of service for now.

4D

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ProbotixLance
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Re: Nebula Limits Switch Challenges... Again.

Postby ProbotixLance » Tue May 10, 2016 7:12 am

After discussing it with the boss man we think it's a communication error with the DB25(parallel Port) connection. Unplug that and ensure it is clean and possibly blow out the pc if can. Ensure that it is plugged in correctly and restart the whole system. Please keep me informed as I would really like to hear what the issue is here
“Give me but a firm spot on which to stand, and I shall move the earth.”
― Archimedes

4DThinker
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Re: Nebula Limits Switch Challenges... Again.

Postby 4DThinker » Tue May 10, 2016 8:06 am

Thanks Lance. I'll be up at the shop later today and do a thorough unplug/blowout/replug of the PC and controller. We put filter material over the air inputs on both the PC and controller, but it is only partially effective. Our nebula and meteor are definitely in a dusty environment.

Will report back when I can.
Thanks again.

4D

4DThinker
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Re: Nebula Limits Switch Challenges... Again.

Postby 4DThinker » Thu May 12, 2016 2:14 pm

I went into the shop yesterday and a student was using the nebula and reported it was working OK. I had a meeting to attend, so left it as it was.

Today the same student emailed me to report Limit 2 errors on our Meteor. First sign of limit errors on the Meteor, but I'm loosing faith on the quality of limit switches used. The normally closed strategy leaves them open to generating errors if vibration bounces the contacts apart. I suspect the contact plate (always under load) fatigues over time and becomes easier to flex. We do run our Z axis through most of its 5 inch range, and the farther down it goes the more flex there is in the router mount. Love to find a better made switch replacement.

4D

4DThinker
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Re: Nebula Limits Switch Challenges... Again.

Postby 4DThinker » Thu May 12, 2016 3:37 pm

Latest report is that both the nebula and meteor are now down and out. Student finally gave up. I plan to have a look at them in the morning.

4D

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Re: Nebula Limits Switch Challenges... Again.

Postby probotix » Thu May 12, 2016 5:09 pm

There is an option in the new configurator to run the machine with soft-limits only. They still work as home switches during homing, but then are disabled until you have to home the machine again.

4DThinker
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Re: Nebula Limits Switch Challenges... Again.

Postby 4DThinker » Wed Aug 02, 2017 9:21 pm

I wanted to bump this topic again as mention of the new configurator and soft limits option is (IMO) genius! Worth every owner of a Probotix CNC seeing. Our fall semester starts up soon, and I anticipate having to deal with a bad Z-axis limit switch on our nebula again. It failed on the last day of classes last semester, and will not HOME properly until we deal with that switch. This Nebula is chronically nagged by false limit switch errors, and the new Soft Limits feature will (hopefully) solve that completely.

4D

tkton
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Re: Nebula Limits Switch Challenges... Again.

Postby tkton » Sat Jan 06, 2018 2:05 am

Is There Any Way you could tell me where do i select soft-limits only!! have had limit switch issues that had ruined some jobs..

Thanks in Advance...

4DThinker
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Re: Nebula Limits Switch Challenges... Again.

Postby 4DThinker » Sat Jan 06, 2018 11:08 am

You'll have to use their configurator app that you can find on their wiki page. It is an option you can select as you run through it.

4D


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