Auto tool zero

[wildcat]

What does the "Auto Tool Zero" button do in Mach3? I don't seem to be able to find any thing about it in the Mach3 manual.

[Barker806]

It is a button that you can add VB code too...
You can enter in code like this:
Zmove = 1.5 'amount the tool will move down to hit the probe
Zpos = GetDRO(2)
Tool = GetDRO (24)
ZOffset = .5 'enter height of probe here

OldZpos = Zpos
ZPos = Zpos - ZMove
Code "G31 Z" & ZPos & " F20.0"
While IsMoving()
Wend
Zpos = GetVar (2002)
If Zpos = OldZpos - ZMove Then
responce = MsgBox ("ERROR! The tool did not hit the probe and DRO was not set" , 4 , "Probe ERROR!" )
Else
SetDRO (2,ZOffset)
End If

Code "G00 G53 Z-.1"



This will set the Z to the right height over the part

Thanks
Brian

[Normsthename]

This will set the Z to the right height over the part

I am really interested in getting this working on my CNC setup
Quick question.....
When the Z axis comes down and the bit touches the plate (3mm Thick for instance), the Z axis then backs up a set distance, say 10mm
You can then remove the plate and wire clip and press cycle start??
Does the VB code then add some sort of tool compensation so it knows that the Z axis is 13mm above the actual material???

TIA

Andy

[ger21]

Originally Posted by Normsthename Does the VB code then add some sort of tool compensation so it knows that the Z axis is 13mm above the actual material??? TIA Andy

It resets the DRO to the correct Z height when it hit's the plate ( SetDRO (2,ZOffset)). Then when it moves up 10mm, it's just a normal 10mm Z move.

[Normsthename]

Then when it moves up 10mm, it's just a normal 10mm Z move.

I understand that it resets the DRO, but do I need to change 'Z' origins in my CAD package to tell it that the tool is actually 13mm above the material??

Thanks

Andy

[ger21]

No, the origin (Z=0) is still the top of the workpiece. When Mach3 moves up 10mm, it knows it's 10mm above the work.

[wildcat]

Is the 13mm you refer to the height of your touch probe? If so, it would appear that you would alter the previously posted VB code and update the touch probe height.

Could someone post a reference to one of these electronic height probes? I have seen mechanical ones but not electrical ones that could be interfaced to a computer. I assume they have some mechanism for handling overshooting. The VB code looks like it probes at 20ipm and I know my setup would overshoot at that speed.

[Normsthename]

s the 13mm you refer to the height of your touch probe?

The 13mm was just a 'test' figure which equated to a 3mm thick touch plate, and then the Z axis moves up 10mm to equal 13mm in total
Hope this helps.

Could someone post a reference to one of these electronic height probes?

All it consists of is an output wire from your breakout board, which you attach one end to a steel plate, and the other end you fit a crocodile clip or similar. You then put the touch plate under the bit, and attach the clip on to bit.
When the Z axis lowers and makes electrical contact, the VB code then does the rest.
You need to assign the output to the digitiser probe....I think.........

I will have a go at getting this working tomorrow.

No, the origin (Z=0) is still the top of the workpiece. When Mach3 moves up 10mm, it knows it's 10mm above the work.

Thanks GER21 for all your input

Andy


Andy

[wildcat]

A potential problem with this approach may occur if the Mach debounce and G31 feed rate high enough that before Mach reports the contact as real the tool has over shot. The mechanical ones that I have seem allow for overshooting (basically they are a fancy dial indicator). The steel plate would not be as forgiving. When I use an electronic edge finder I change the debounce to a low value and feed very slowly (1ipm). It would be really slick to be able to feed down fast and measure the overshoot. Perhaps with an electronic dial indicator?

Here is a DIY version of the mechanical height gauge.

http://www.industrialhobbies.com/how..._gauge_pt1.htm

[Normsthename]

A potential problem with this approach may occur if the Mach debounce and G31 feed rate high enough that before Mach reports the contact as real the tool has over shot.

Other Mach users are using with no problems, I will try it and see!

Andy

[ger21]

Originally Posted by wildcat A potential problem with this approach may occur if the Mach debounce and G31 feed rate high enough that before Mach reports the contact as real the tool has over shot.

As you mentioned, you can set the feedrate in the VB script. It doesn't have to be 20. Set it low, and just jog down close before you run the Script.

[Normsthename]

Today I made up the touch plate, and wired this into Pin 15 on my breakout board, and the other wire to a earth on the breakout board.
Finally I assigned the probe to this signal.
Everything works fine when I touch the crocodile clip to the plate, I get a probe signal showing on the diagnostics screen in Mach3
Problem is when I actually clip the crodile clip onto the router bit, I get an intermittent signal flashing on the probe signal display
I would guess the intermittent signal is flashing approx. twice every second. It is very random flashing signal.
The router is powered off at the electrical socket. As soon as I unclip the wire from the router bit, the flashing signal stops???
I thought that it could be picking up noise from the Stepper motors, so I positioned the plate very near to the stepper motors with the clip off the router bit, and no flashing??
I tried altering the debounce setting, and it made it better, but I have to have a large value (2000+) before it is usuable.
Its very odd, Anyone know why I am getting this.
I have temporally altered the VB script so I now lower the router bit manually while watching the diagnostics screen, and when the probe signal is solid, I press the auto tool zero button.
It then records the thickness of the touch plate, and then moves the Z axis back upto 15mm
This works fine, but I would like to know why I get the flashing signal.

TIA

Andy