[sansbury]

I have one of the passive probes. The problem that I am having is that it is not switching on and off properly. Specifically, if I probe an edge using G38.2 and then jog back to clear the edge, sometimes the probe stays tripped. If I jiggle the end around by hand, I can get the switch to close, but it makes it unusable for automated probing.

I will confess that I had a bad crash involving a Z axis rapid plunge (don't ask, stupid mistake) with it recently that required a new tip. I'm not sure that eyeballing it would tell me whether there's any damage or not, but it looks OK. I took the probe apart and all the internals appeared ok and nothing was obviously bent. Prior to the crash, the probe was more reliable, though I was getting transient issues very similar to this. I blamed these on software misunderstanding, but wondering if it was actually the same issue just less extreme.

Other than calling Tormach (which I fear will result in them telling me I have to buy a new probe) is there anything else I can or should check first? This is getting a bit frustrating as I had a job which I really wanted the probe for and I just got the replacement stylus today only to have the thing basically not work at all....

[Hirudin]

Does anything physical apparently happen when you jiggle the probe by hand? Like, can you hear it click back into place or anything?

Is there a "Diagnostics" tab in the Tormach version of Mach3? If so, does an "LED" go off when you trip the probe? Maybe you can use this indicator to figure out why it's not working right by activating it a bunch of times by hand.

Just in case you didn't know: After you change tips you have to recalibrate the probe. As I understand it the Tormach Mach3 has a built in calibration utility. The calibration makes sure the probe tip is concentric with the spindle. I found calibrating the probe tip to be a hassle until I put small pieces of hard rubber around the screws. I used a cut up o-ring but small rubber washers would probably work better. This allowed me to get predictable results when turning the calibration screws.

[gjvander]

Open it up and clean it. It is a simple device. Then re-calibrate.

Geo

[sansbury]

I use linuxcnc which has a signal monitor so I can see the probe state. There's no obvious click or anything like that. If it doesn't settle back to a closed state properly, a downward tug on the stylus does it. It's not consistent though. It's almost like there isn't enough spring pressure.

Here's a dumb question: when I opened the probe the three small pins that rest on the bearings were covered in a translucent green grease. Should this be cleaned off or is it there purposefully? The directions didn't say anything so I haven't touched it yet.

[gjvander]

Clean it off. That is where the contact is made and would explain the problems you are having.

Geo

[TurboStep]

google for "contact lubricants"
Step

[sansbury]

So in other words the grease belongs there?

[bjones]

what, do you think they put grease in there just for the hell of it?

[sansbury]

Tell that to the guy above who told me to wipe it off. I'm not a probe engineer so I don't know. That's why I asked here.

[gjvander]

Not a probe engineer either. But I do own a Tormach passive probe, and have opened it up. I am pretty sure there was no grease on the contacts.

Tormach sent me Service Bulletin 37 with the probe, which has instructions on cleaning when you have contact problems. Perhaps it mentions if it needs to be re-greased. I will scan it and upload so it is available for reference.

Regards,

Geo

[Dylwad]

If your having problems after a z axis crash with the probe, I would stretch the spring out a bit to give it more tension, or replace it.

The grease is good, deoxit cleaner/lube is good too, but having the grease on there as well should help in the long run, your sliding hardened pins on hardened balls, some type of lube is needed.

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[sansbury]

I sent an email to Tormach earlier today and Scott Johnson sent me a copy of SB37. Nothing special, just use scotch-brite to clean the contacts and then wipe with a light oil. I'm going to take it apart again and see if I can take some measurements to see if anything is significantly twisted and then try stretching the spring a bit. It seems to me that if the probe can trip properly ever, then it should be usable as long as there's enough spring pressure to push it back into place.

[SCzEngrgGroup]

Why would the repair kit for the prove includes dielectric grease, if not to prevent corrosion on those contacts:

32798 - Rebuild/Repair Kit for Digitizing Probe

SB0037, which is supposed to be instructions for repairing the probe, does not seem to be posted on the website. At least a search returns no hits....

Regards,
Ray L.

[Hirudin]

It's a trick!

[sansbury]

Last night i took the probe apart and wiped off some of the grease as there were fairly large globs of it on the contacts. I measured everything I could think of on a surface plate with a height gauge. The disc that holds the ball bearings was flat as the proverbial pancake and the pins were also all straight and level. One of the bearings appeared to be significantly (~.02") higher than the others but this appears to be how it was made and might not be significant to its function. I also pulled on the spring a bit to stretch it, then re-assembled the probe and tested. So far it is not working flawlessly, but is failing perhaps one out of ten times rather than one out of two, which at the very least suggests that it's not scrap. I'm going to see if I can stretch the spring a teensy bit more as I think that might do it.

[Scott_M]

Sansbury

I built my own kinematic type tool setter and when "tuning" it for spring tension I found that something was not quite symmetrical. It did measure out fine but it turns out that it prefers to be in a specific location. As in this arm between these balls. I numbered a pin and a set of balls and tried all 3 positions and sure enough it worked with less spring pressure in one position and acted like you described in the others. Just something else to try.

Also I use "Superlube" as a lubricant, it helps and has very good dielectric properties. available most anywhere



Scott

[BAMCNC.COM]

Before tearing into anything the 1st step is to ohm out the probe. If you get a high reading you have found the issue(depends on probe setup)

Next would be tear apart and find out why, to much grease, maybe coolant, dirt, or spring screwed up?

You can get di-electric grease at any auto parts store, but its quite thick and if the spring can't push through it then its a bad idea, I personally use "EML" for all electrical contacts. It's a light di-electric oil, not grease. Grease is not the correct application for a probe, especially a "cheap" probe, you would be better off with WD-40....

[Dylwad]

Before tearing into anything the 1st step is to ohm out the probe. If you get a high reading you have found the issue(depends on probe setup)

Next would be tear apart and find out why, to much grease, maybe coolant, dirt, or spring screwed up?

You can get di-electric grease at any auto parts store, but its quite thick and if the spring can't push through it then its a bad idea, I personally use "EML" for all electrical contacts. It's a light di-electric oil, not grease. Grease is not the correct application for a probe, especially a "cheap" probe, you would be better off with WD-40....

Super lube grease is more like a super thick oil ( much lower viscosity than automotive silicone dielectric grease, slick inbetween your fingers, not sticky) good stuff actually, I use it for a lot of things, won't find any in my probe though, deoxit ( red stuff for cell phone batteries) works good so far.

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[BAMCNC.COM]

Very cool, I'll have to pick some up today, I've been looking for an alternative to grease.