Prox sensors not soing there job

[twelchPTM]

This came up as a result of another discussion but I figured it would be more helpful to me and others if I brought it to its own thread.

If I tell my machine to move beyond the physical limits of the table whether through a partfile, command line input, or the keypad, it will hit the hard stops and continue to try and move until it thinks it is where it was going. I am told this should not happen and the prox sensors should shut down the movement.

At first I thought I could use this to my advantage and set up multiple production zones but that is just beyond our needs and usage. I am beginning to also see the hazard in this situation.

Any iput or advice on rectifying this situation would be greatly appreciated

[jerry_stanek]

When you move a piece of metal in front of the sensor does it trigger a light on your screen. Do you have the I have prox switches turned on and do you have the correct type switch chosen in your setup under VN

[Brady Watson]

If C3 is working and you are hitting the hard stops when you use the K, Move or Jog commands, then that tells you the limit switches are turned off. The 1st setting in the VN lets you turn them on or off.

Bear in mind that many users prefer to leave them turned off because they are experienced enough to know not to run the machine into the hard stops (I'm not implying you are not experienced enough) - but the main reason being that static charges can trigger the limits to come on in the middle of the table, 'for no apparent reason' - which can be mind boggling and frustrating. So...if you want to turn those limits back on, be aware of this possibility. The long proxy wires act as antennae to higher than 24v potentials, such as those typical in a static discharge.

-B

[twelchPTM]

the reason this came up is because I have been having a lot of issues with the SB3 software since I updated it and the machine made a completely ridiculous move trying to go to some extreme negative location. fortunately I was close to the stop button when it happened. Considering the amount of plastic and foam I cut the issue with static could definetly be an issue.
Thanks for the help, I like knowing why things work the way they do....

[tomwillis]

So I would like to jump in on this too. My machine has a tendency not to come off the prox switches correctly and exactly each time....maybe as much as .125 in. I have most of my prox cable wrapped in alum foil to act as shielding for the wires. Does this even make sense? Or should I be looking at replacing these original SB prox switches with ones that have shielded cables?

[Bob Eustace]

If C3 is working and you are hitting the hard stops when you use the K, Move or Jog commands, then that tells you the limit switches are turned off. The 1st setting in the VN lets you turn them on or off.

Bear in mind that many users prefer to leave them turned off because they are experienced enough to know not to run the machine into the hard stops (I'm not implying you are not experienced enough) - but the main reason being that static charges can trigger the limits to come on in the middle of the table, 'for no apparent reason' - which can be mind boggling and frustrating. So...if you want to turn those limits back on, be aware of this possibility. The long proxy wires act as antennae to higher than 24v potentials, such as those typical in a static discharge.

-B

Another dumb question from Australia! Our C3 works perfectly but does gently hit the bump stops and has done so for two years. Is this OK. We rarely have crashes into the frame only when one forgets to zero oooo.

[bleeth]

Bob:
You should either move your prox switches or move your stop blocks. Stop blocks should be at or near the true physical limits of the table. Prox switches should be inside these although they can be close. You want to make sure that the C3 is only picking up the prox switch limit as once your gantry hits the stop blocks you will lose steps and get an inaccurate location reading.

[Brady Watson]

Tom,
Grind the head of the bolt head target flat. Then set gap to somewhere in the .025-.035" range. This should improve repeatability.

Bob,
Are you running a BT or DT tool? The switches are different between them. If running a BT, I would recommend moving the mechanical stops closest to X0 and Y0 outboard as far as you can. This may mean removing one bolt that holds the stop on the gantry beam to slide the block against the blue end plate. You can easily get a couple more inches of travel by moving stops...My BT48 would go 52.5 x 25.5" if I recall. Keep in mind that on BTs or PRSs that targets are in no precise location...YOU have to move them where they need to be (but the ones underneath on the powerstick should be close).

-B