Help find lost Zzero plate routine

[MDCochrane]

I had a crash in the shop yesterday. A large bit pulled out of the collet (PC 3hp) and the Z car jumped off the rails. I had to drop the motors out of gear and realign and re-set the car. No apparent damage, except… since then, the Zzero routine with the Z plate will not work. I cannot find a setting on the input switches (is it switch 3?) that will give me continuity when I attach the grounded alligator clip to the bit and touch the Z plate to the bit. No green light on the console.

Other than the probability that some internal wire has broken, is there some software re-set that I’m missing?

In experimenting with the input switches, I’ve forgotten where they initially were set? What is the standard setup for input switches that operate the Zzero.sbp function?

How would you recommend I troubleshoot this issue?

Oddly, in one attempt among many to fix this, I did see the #1 input light come on to indicate continuity when I touched the Zplate to the bit — but I didn’t have the alligator clip on the bit! I ran the Zzero routine successfully and made a cut. I put the next piece of wood on the machine and the Zzero routine failed - no green light. (No changes to the setup.) It’s got me confused.

Thanks for the help. I’m not doing a very good job of setting the Z zero level by eye!!

Mike

(table is a 10 or 12 year old PSR-4896 with upgrades)

[Brady Watson]

Hey Mike,
You only need 2 wires for the Zzero plate. The black one goes to input 1 & the other wire (could be white or green) goes to the ground terminal next to Input 1 in the control box. Chances are one of those wires got yanked and either broke or only has a 'whisker' holding on. Take a real good look on the back of the X car and see if you can spot any stretch or strain marks on the wire.

-B

[myxpykalix]

Right at my carriage i have a terminal block(?) where my zero plate is plugged in (because i also had a probe that plugged in there. If you have anything like that you might want to check to see if any wires have pulled out from there or are loose.
Possibly you could check with a meter to check your continuity on your wires?

[MDCochrane]

Thanks to Brady and Jack. You are two of the most vigilant help-givers on the planet (planet ShopBot). I'll be in the shop tomorrow and look into your suggestions. I've also read a library of your advice to other guys with a similar problem. Got some good ideas there, too.

In the mean time, and just to make sure, how should the input switches, #1 through #3, be set in the [VN] fill-in dialog box? The options are "0 - Standard Switch", "1 - Nrm Open Limit", "2 - Nrm Closed Limit", "3 - Nrm Open Stop", "4 Nrm Closed Stop". (And what's "Nrm" mean?)

The machine is an old PRT. The wire on the Z plate is green and disappears into the black jacketed cable that heads back to the control box. There is an alligator clip that is grounded to a bolt on the mast of the Z gantry. I don't have any nice connector boxes. I bought the machine used, so I don't have a good understanding of it like I would if I was the one who wired it.

Thanks!

Mike

[myxpykalix]

I usually take my alligator clip and clip it to a bolt however the proper procedure when zeroing your Z is to take the alligator clip and clip it to your bit in your router/spindle and it is possible that your problem is that you don't have a good connection at your router grounding it to the machine and therefore you are not completing your circuit.
By clipping it to your bit you are making a very short distance for the circuit to have to travel. But make sure to remember to unclip it before starting!:eek:
Try that and tell us if that works.

As far as some of your input switches questions...Brady is the technical geek and knows all that stuff:D

[frank]

Hi Mike,

Input one should be set for a standard switch. If you have a PRT then input 2 is also a standard switch and input 3 a normally open limit.

[gundog]

I cut the alligator clip off mine years ago when I changed from a router to a spindle. There was a post years ago that said the alligator clip was put on because the Porter Cable Router mount had a nonconductive plastic sleeve that isolated it from the machine and the clip was necessary.

In fact recently I cut the wire connecting the plate and installed an alligator clip to the wire. Now when I zero I put the plate down clip the alligator clip I installed that used to hook directly to the plate and zero that way. I added an electric drill to my Z and no longer had a good place to store the plate.

Mike

[Brady Watson]

Mike,
You should run the UR command to 'reset' your machine configuration & it will update all the proper settings for your PRT. You should find your tool listed under the 'Older ShopBots' folder.

Nrm = Normally - as in Normally Open (NO) or Normally Closed (NC). Normally Open means that when no power is applied or the switch is in the OFF position, that there is a break in connection - or an Open gap. This is like untwisting a pair of wires and holding the ends apart - Open. Normally Closed means that the switch is bridged - meaning that it will allow current to flow through it in it's Normal state.

The only issue you may have when you run UR is that Input#4 may flash telling you the e-stop is on. If you press the e-stop and Input4 goes off, you'll have to change the e-stop state to Normally Open. PRS and newer tools all have an NC stop in case the wire gets run over or something & the connection gets broken - it will stop the tool.

Wiring the inputs is REAL EASY - don't get confused.

Your E-stop will go to Gnd (green wire) & Input 4 (black)

Zzero plate - Black to Input 1 & white or green to Gnd (ground...ANY Gnd on blue terminal)

X Prox - Black to Input 2, Green to Gnd, Red to 5v+
Y Prox - Black to Input 3, Green to Gnd, Red to 5v+

That's pretty much all there is to it.

Now...if you don't like shooting yourself in the foot, being frustrated and disappointed - Take your time and wire the tool up properly. Nice clean, pretty bundles of wires with proper strain relief where they could get snagged. If this is an 8-10' long tool, find center on the machine back lower C_channel (or AL table side) and make a nice loop that gets tied to the center. Drop the motors and run the X car back & forth - adjust the loop so no wires get snagged etc from max X to min X and back. When you are happy with that - tie it up & test it again.

I've been to countless shops where they have 'problems' with their CNC only to find that they have some Rube Goldberg contraption for wire management or a sub-par wiring job that resulted in broken wires in the bundle.

-B

[MDCochrane]

Apologies! I see that I've forgotten to close out this thread.

The source of the Z plate error turned out to be a broken wire, which, thankfully, was not buried deep within the wiring harness, but relatively easy to access. Looks like the grounding wire was gradually wearing with movement over time (9 or 10 years) and the shock of the broken collet was enough to separate the final strands.

Thanks for all the help, once again. Knowing the probabilities of the causes, as you guys described them, reduced the time I might have wasted on less likely solutions.

Mike