Begging for help on Probe

[rob_jones]

I believe I have tried everything now. Here's the problem: Randomly when I am probing something, the Z axis location changes, I know this because after a while when the probe comes down in a blank area to the max depth it now sits 1/4" or so off the table. If I leave it running it will keep doing it and eventually not even be touching the part anymore. I have been doing 3D machining flawlessly with the machine, but can't get it to probe.
What I've tried:
Old and new control software, twice each.
Changed my surface tolerance to everything in the book.
Changed my pattern size.
Changed my stepover values.
Changed my XY and Z move speeds.
Taped the probe to the router so it won't turn.
Tightened the probe tip.
Verified ground on the whole machine to the control box.
Changed the resistor on the underside of the probe to many different positions.
Cleaned the probe.
Changed probe tips.
Re-verified all my wiring over and over.
Deleted everything from my computer and reinstalled all shopbot applications and drivers.
The Hokey Pokey.
(and turned myself around)
It almost looked like it was going to work when I changed the sensitivity under the probe... it scanned for 3 hours and 30 minutes before messing up. The only thing that kept me from scaling it out into the deep Maine woods was the probe does not belong to me.
Does anybody have ANYTHING I can try to get this to work? Please? (and thank you!)

[Brady Watson]

Robert,
It has been about a year since I have used my probe, since I now do laser scanning. Prior to this, I have done many 2D & 3D (mostly) scans using the 1st generation SB probe with mechanical contacts. Your probe is a much better design and less prone to problems than the earlier ones. I have scanned many parts ranging from a few hours to a week & a half.

There are a few fundamental things that you must get right if you want to be successful. First, make sure that the sensitivity is not too sensitive, or you will get false triggers in mid-air. Definately tape your probe to the spindle. Do not use the CopyMachine routine if you are having problems. Early on, a few of us discovered that some probe routines work better than others. For whatever reason, the old DOS version routines work best. I am attaching the old DOS routine for 3D scanning using the SB probe, that I have used successfully in SB3 without any problems.

You run this file just like any other SBP. You MUST zero your probe just above the max Z of your part & then using the keypad, determine the max distance that the probe must go in the negative, WITHOUT touching the table/spoilboard. Make sure you have a little bit of a gap between your stylus and the spoilboard at all times or you will waste a substantial amount of time probing the table. If need be, prop up your part. Carpet tape works well for holding parts while probing. When you run this file, fill in each field when prompted. Don't select 'Use Default Settings' unless you FE & change them. The routine runs a little differently than the CopyMachine utility, but I have found it to be the most reliable routine yet. When you have completed scanning, take the SBP and run it thru the probe to surface converter to get a 3D DXF that you can setup for toolpathing.

Let me know how this works for you. Try something small to start, maybe 2" square or something to make sure it will do what you want to do. No need to look for a model 2" square...just set the probe to scan a 2" square area on your existing part.

-B

S_prb3d2.zip (http://www.talkshopbot.com/forum/messages/312/S_prb3d2-25827.zip) (2.2 k)

[rob_jones]

Thank you very much for getting back to me so quick. I will give it a shot on Sunday. I have a craft show Saturday. I really appreciate the help.
Rob

[rob_jones]

I tried this file and it did the same thing so now I'm going to try the impossible... I'm creating my own probing program. I modified the one you gave me so that when it contacts something going sideways, it will not write to the file, but instead, pull up 1/4" and come back down, writing to file when it contacts moving vertically, then pull up 1/4", move over and drop down again.
I also noticed with your file that there was no provision for setting a max Z depth so I added that Input screen as well.
We'll see how this one goes, probably a bit slower, but hopefully more dependable.

[Brady Watson]

Robert,
What seems to be the problem? Is it that it will not complete a scan or you feel that the probe routine is not doing what you think it should? As I've said before, make sure your probe is not set to be too sensitive. Also, the routine I've posted has run unattended for days and weeks at a time with no screw-ups on an inferior probe design than the one you have. While I commend you for writing your own routine, keep in mind that it might be a good idea to successfully probe something using a known good routine before writing your own...The routine seems to have funky moves to it when you are not familiar with it. It works well as is. The data you get at the end is the most important part. Don't worry about the side-triggers writing a data point. It will all be resolved when you run it thru the SBP to DXF converter. It essentially takes the point data and wraps it into a mesh.

-B

[bill.young]

Rob,

Usually if there's a problem with the probing routines you will get either bad points from false triggers...spikes on the output files...or the probe will get "stuck" and probe the same spot over and over again. What you're describing sounds like a loss of Z-axis position, especially your earlier picture of a output scan.

I'd double-check the things that might cause a Z to lose location. Could the probe be sliding in the collet? Does the Z-axis hit the top stop when it lifts up at a high point on the pattern? Is there any binding anywhere in it's travel range?

If you don't find any mechanical issues, then maybe modify the probing routine to take the X and Y moves out, so that the probe just goes up and down and makes contact at the same spot. Then set a Z-zero location, let the routine run for a long time, and then check the Z-axis location against your original one and see if it has moved at all.

Bill

p.s. Oh yeah, the current Copy Machine routines do probing the way you want them to. When there's a sideways contact they don't write the points to the file, but instead lift up to clear and then move straight down to record the contact point.

[rob_jones]

You guys are early risers!
I am probing a sea shell, I set the maximum z depth to be just above the surface, maybe .010 or so. The problem is, after a while, sometimes 20 minutes, sometimes 3 and a half hours, I will come out to the shop to see the probe acting like it is at the max Z depth, and the red display box says it is at that depth, but the bit is now .25" up to 1" up off of the table.
I substituted my XP machine to try probing and it did the same thing, in fact, after 3 hours, and tantalizingly close to completing a good file, it messed up. So I tried to restart it and it messed up on the first move. ie, it started at 0,0,0 and moved down to the max Z just up off the table, then pulled up a couple inches, went back down to .5 off the table and started moving sideways. Someone suggested setting it up to contact the table, and I still get this fault. Not predictable in any way.
I have been doing some quite complex 3D carving without any problems at all, so I thought my mechanical things are spot on.
I have actually had it (sort of) work a couple of times. But the output DXF file has issues, the path the probe took was, say 10 points .050 apart along the surface, then started up the face of the part, but the output file just has a long sloping knife edge from the edge to the top of the part, and occasional spikes.
This last file that I probed was a 5" x 5" area that came out to be a .SBP file 280K. When I tried to convert it, it told me it was going to make a... are you ready for this one? 17.8GIG dxf file. My friend who has scanned this same thing successfully on his Alpha ended up with a 2M file. I opened it in Shopbot editor and can't see any difference in the two files.
This is really kicking my butt, occasionally I just do some cutting, since everything comes out successful, but I have got to get these things scanned in soon.
I was wondering if maybe the USB translating device could be working wrong so I was going to try to uninstall the IOGEAR program and re-install it but I can't find it on my machine. I unplugged the USB cable, and just re-installed the program, hooked up the cable again to every different port on my machine and I get all the same results.
Sorry this is so long... About the sensitivity of the probe. I tried turning the resistor on the bottom side. It was all the way clockwise when viewed from the bottom which worked for my friend but not for me. I noticed that as I turned it CC, the light changed from red to green and it seemed like the probe then works in the reverse (normally open) I have tried a few different locations in the Normally Closed position, (red light on and input 1 lit) and had the same results.
Does it matter at all which way the probe is turned relative to the axis of movement? I noticed the probe has 3 sensors inside, does it matter how these are oriented relative to X and Y?
I wish I knew someone else close to me I could borrow a probe and determine once and for all whether it is probe, probe-er, or probe-ee. :-)

[Brady Watson]

Robert,
It does not matter which way the probe contators are oriented. Just be sure to tape it to the spindle to prevent turning.

A .05" stepover on the probe is very coarse for 3D. If you want good results, try using a 1/16" stylus and a .02" stepover value for X & Y. I think that you mean 17.8MB, which sounds about right for the size of the file that you mentioned. I often work with raw digitized files (only points - before converting to 3D mesh) approaching 2 GB.

I think that your problems stem from having the sensitivity too high on the probe. Experiment by chucking the probe in the router and leave it sit. Then bang on the Y car, Z axis, router etc with your hand and see if the vibrations cause the probe to trigger. Watch the light on input 1 in SB3, not on the probe itself. Some movements when using the probe can cause vibrations or sudden jolts, causing the probe to misfire as a result of vibration. These false triggers can screw up where the probing routine thinks the machine is and possibly cause your Z to drift up. I discovered early on that a probe adjusted too sensitively is unreliable and shows a much noisier data set than a probe that is adjusted to trigger like a limp flounder-like stylus. On your probe, shoot for about a 1/8 to 1/4" stylus movement side-to-side. Start there and if need be tighten up. You won't know if it is good or not until you get all the way thru a scan.

Loosen up the settings on the probe, tighten up your stepover and try again...It's really a simple device to use, and I wish I was closer to you to show you how to get it setup in about 10 min.

-B

[rob_jones]

I'll head out to the shop now to try... the file size said 17,822,849,504 bytes. Another thing I'm going to look at is if the probe threads are loosening. I also saw a post just now from Stephan Voekle that he had Z problems when the file was being written across a network. I'm not doing that, but I thought I would atleast try shortening the writing path to a file directly on the C: drive.
I found a nice magic trick on creating a smoother file... I translate it to DXF surface, open it in Rhino and under transform, apply the smooth tool with a factor of 1. That end up looking really smooth. Anyways, heading to the shop... who needs sleep anyway?

[rob_jones]

I hit everything with a rubber mallet and got nothing. I set the probe down near the table and touched a board to the edge then jogged the Y axis in .010 increments to see when it would trigger. It was .040. I set the resistor on the underside to the most extreme clockwise and I got .060 deflection when it triggered.
When I turn the sensitivity CC until the red light goes out, I turn it back clockwise until it comes back on and moving the stylus does not make the red light go out. I slowly turn the sensitivity clockwise while pushing the stylus sideways and at just the point that it will trigger the red light out I checked the deflection... .040" So it appears that on this probe I can only adjust it between .040 and .060 side deflection before it triggers. Does this sound right?

[bill.young]

Rob,

"So I tried to restart it and it messed up on the first move. ie, it started at 0,0,0 and moved down to the max Z just up off the table, then pulled up a couple inches, went back down to .5 off the table and started moving sideways."

If I understand this part correctly, the Z-axis moved down to MaxZ which was just a little bit above the table surface, then moved up and back down to MaxZ which was then .5" off the table surface? So the Z-axis zero location was off by 1/2" after one move?

It's hard to imagine a problem with the probe or the probing routines that would cause something like that, since if I understand correctly the probe didn't actually make contact. And even when triggered the probing routines don't ever reset the location of any of the axis, but just write that contact location to the output file.

Have you tried contacting Tech support?

Bill

[rob_jones]

So Angry!!!!!!!!! Nothing I try works!!! I disconnected the zero plate and clip from the plug in case that was making stray triggers, un-wired everything and re-wired it per the book, ran speed check and got 73.8% I called support before I tried this post and it all boiled down to them telling me to send the probe back for a refund but the probe is not mine, and the probe works fine for the owner. How can this thing possibly cut everything perfectly and NOT probe something? I went to Radio Shack and bought a different USB to serial converter to try. I am so frustrated and just out of things to try and patience to try them. When or if I do get this thing working I am going to make sure I post whatever the solution was here so hopefully someone else doesn't have to go through this.

[rob_jones]

Does the following information help in determining the problem?... I set it all up to probe as normal and had the little tool ready to remove wires from the probe plug. As the probe was moving across the surface, I removed and re-inserted each of the wires to see what would happen. The z axis lifted up and plunged down deeper than before and the axis value changed! Now, when I have been probing (fortunately) it changed in the upwards direction. But I did get the axis value to change. So, the next step is to find out where I might be losing connection intermittently. I'm going to try straight wires from the probe connector to the control board to rule out the cable. I know the connections at the board and probe are good.

[myxpykalix]

When i had my probe, after breaking it 3 times we finally determined that the connector was wired incorrectly. Maybe you could check that as a possibility. Call Scott, he fixed me right up.

[rob_jones]

Well, after trying everything, I'm sending my control board back to Shopbot for them to test. I gave the probe back to the owner, he hooked it up and did a perfect 12 hour scan of the part I was trying to do on the first try. Grrr. Oh well, I have the scan I need.
I will still put whatever the final result was in here so it is documented.