Pressure When Probing

[iwik]

Hi, First I would like to thank you for a wonderful piece of Software. My table hasn't been the best for pcb work, not to level and when I saw this my eyes lit up.
I am still fairly new to it but ran it for the first time and noticed when it first probed the pcb it appeared to put a fair
amount of pressure. This was observed by the Dremel im using being pushed up slightly in the holder. The dremel was pretty tight before I started although it could have been tightened more. I also noticed that when It had done a few points and was over the board which had slight bow I could see the board being pressed flat against table top. It continued on but I stopped it soon after. Thinking that if that going to move like that then ill be losing accuracy.
I thought it would just touch the surface until it read contact. Am I missing something, please excuse me if ive screwed
up somewhere but any comments would be appreciated. I had zeroed above the pcb by 8mm.
Or is this the pressure that would normally be exerted when etching. Im pretty green to this form of pcb etching.
Thanks
Kindest Regards
Les

[daedelus]

Hi Les,

You are right to stop the process as it doesnt sound like you would get very good results like that. You are also correct in assuming that each probe should barely touch the surface and no real pressure should be applied during probing. Have a look at my video on the front page as this shows the probing process at the start. The point where an electrical contact is detected should be fairly instant give or take and you should certainly not see any pressure being applied by the probe. During milling, there may be be a small amount of pressure and you really should ensure that the board is very secure to avoid differences between probing and milling.

Anyway, with probing, the first thing I would test is whether the problem is mechanical or electrical. I suspect it is mechanical, i.e., the surface is detected as it should be by the probe but the Z-axis takes a lot longer to come to a stop than it should. Try another probe run but this time keep the digtise/ probe-in panel open and see if theres a difference between the detection point and the Z-axis stopping point. This might be too quick to tell so you might need another method. Have a play around.

I better get back to work for now or I will get in trouble

[Country_Bubba]

To add to what James said, verify that your electrical connections are making properly. Are you putting a clip on the tool itself or are you relying on contact through the bearings etc. I have found that relying on bearing contact can be a bit "iffy" at times.
Just for the record, when I first started out, I put a loose piece of aluminum foil on the table that was slightly wrinkled. I probed the surface and the foil did NOT move from any pressure by the probe.

[daedelus]

Much better idea Art Try some slightly wrinkled foil. As Art said, the foil shouldnt crumple much when probing

[Country_Bubba]

Much better idea Art Try some slightly wrinkled foil. As Art said, the foil shouldn't crumple much when probing

As previously stated, the foil didn't crumple ANY. There was one exception and that is when the probe hit a spot on the foil that had a dab of epoxy on it and of course this is an insulator!

[iwik]

Thanks Guys,
Problem solved ,realized that it was just going to -1 then reversing. Funny thing was I could short the probe out before
it got close to zero and it would stop. The problem was that I had not enabled the probe pin, but only configured it.
Why it responded the way it did I don't know. So I was going along thinking it was enabled because it seemed to work outside of the Probing Program.
Les