Bad Probe? Losing Z orientation....

[Chris Costello]

Hello all,
I'm Brand new to CNC.
I own a Larken 2424 Camtool.
I purchased Aspire 3.5 at the end of last year, and just got the 4.0 Upgrade. I'm trying hard to learn as much as I can about Aspire before going to Jim McGrew's camp in a couple weeks. Can't wait for that.....

Now for my question.... My Father and I are wood and wax carvers by trade,

and I want to digitize some of our work. I bought a touch probe on ebay. You can see it here:

ebay item number: 150931049789

I tried using it to scan a 2 inch starfish sculpture (it.s about .4 inches tall). It seems to work fine in the x and y orientation, but when it comes up over the model it doesn't come all the way back down to it's original Z zero level. The control software tells me it's at zero, but by the time I've gotten halfway through the scan the probe is moving back and forth above the model scanning nothing. I would guess that after each pass it has risen 0.05 inches.
I thought maybe I was scanning too fast so I dialed al the settings back to the slowest speeds and increments but I still get the same result.

I've cut a job that I created in Aspire, and didn't see any problem with the machine holding its Z orientation so I'm suspecting the probe but I'm brand new at this so I don't even know if I'm asking the right questions.

Has anyone had a similar experience with a touch probe? If you think this probe is junk can you recommend a good one?
Thanks in advance.....
Chris

[Gene Crain]

if your planning on doing a lot scanning you should look at a digital scanner not a touch probe, faster and more accurate.

[Chris Costello]

Thanks for your reply Gene. Do you own a digital scanner? Can you recommend one?

[Chris Costello]

After watching the probe in action a little more closely I've found that the machine is losing its place in the upward travel of the scan. If I jog the probe around manually and measure the height of my model I come up with exactly 0.35 inches. If i run the probe so it climbs to max height on the first pass, when it gets to the top of model it's telling me that it has only risen 0.298. Thus it only goes back down 0.298 and not the actual 0.35 that it climbed.

After figuring this out I spent some time manully jogging the machine up and down in slow mode trying replicate the action of a scan. I couldn't detect any loss of steps by doing this. The machine zeroed out to the same place after each attempt. I haven't used the router alot, but I only see error when I'm using the probe.
Still, I don't know if this is a software problem, a stepper slipping, or a bad probe.

Are the touch probes antiquated? Were they ever any good? I thought that a touch probe would be sufficient for digitzing small relief type models, but I can't find hardly any posts about them here on the creek. I looked at the nextengine scanner website last night. They look awesome, but between the router and Aspire I've maxxed out my budget for a while. Are there any other viable options out there for good digitizing?

Thanks in advance for any insight.......