Programs cant runin the negative Z range????

Programs cant runin the negative Z range????

Postby Boxersix » Wed Sep 25, 2013 5:01 am

Hello again. So its been some time sincei first asked about the torchmate post processors and finally had the time to sit down and tinker again with the demo software. It seems that the available PP will work but i came across a different issue.

I noticed in the material setup section of each program that you can easily select and designate the Z axis zero and datum point. However it appears that this can only be set as a positive number? Is this this same for the full version of the software( vcarve, cut 2 and 3 d)???

My machine is a torchmate routermate that i custom built to my specifications with full flood coolant, dust collection, auto tool length sensing, etc. Sized at 12x6 feet with a Z axis travel of 14". When homing, the Z axis moves up and zeros off a prox switch in the head, and then debounces .050" off that point. That is Z 0.0 and any z axis movement from there is downward and calculated as a negative number when setup in the CAM software. Its a nice feature as it gives ample room for all tooling setup and prevents initial tool crashing from incorrect data as you have more than enough time to watch the z axis clearance to it rapid position and stop it in the event of a problem.

So what i'm trying to figure outis if either the software can be setupto work in the negative z travel and datum area, or do i have modify the machine with secondary homing proxswitches for positive z axis movement, and setup a completely different file system for the controller to make it all sing and dance correctly?

Im very eagerto make this software work. My current CAM program is the biggest piece of garbage this side of the Mississippi and the sooneri can be rid of it the happier ill be

Thanks folks!!!
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Re: Programs cant runin the negative Z range????

Postby martin54 » Wed Sep 25, 2013 1:24 pm

Im not sure I understand you set up, sorry maybe it's just me but if you are homing your machine & then using this as z zero then how does the machine know where to start cutting or how deep it has cut in any material?
I've not actually got the z axis homed on my machine just the x & y axis.
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Re: Programs cant runin the negative Z range????

Postby usLEDsupply » Wed Sep 25, 2013 2:06 pm

Plasma machines are normally a bit different as they home to the bottom of the Z so the g code would be all positive numbers
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Re: Programs cant runin the negative Z range????

Postby Boxersix » Thu Sep 26, 2013 6:39 am

martin54 wrote:Im not sure I understand you set up, sorry maybe it's just me but if you are homing your machine & then using this as z zero then how does the machine know where to start cutting or how deep it has cut in any material?
I've not actually got the z axis homed on my machine just the x & y axis.



My machine has three separate proximity switches for homing, one for each axis. The one that is on the Z axis is located at the top of the head assembly. When I home the Z axis from any given point, it moves upward until it moves into proximity of the switch, and then retracts off the switch a set amount( debounce, set at .050"). The controller then sets the location of the machine Z axis as Z 0.0 Any vertical movement up on the Z axis from this point would be in the positive range and any movement downwards on the machine(towards the bed) is in the negative numerical range. Being that the home location of the Z acis is at the top of its travel at this point, the only permissable movement possible is downwards(negative)

The bed of my machine is located exactly 12" below this home location, measured off a machined point on the spindle housing. When i am setting up a 3D CAD model in my CAM software to program the toolpaths, I have to locate this model in the CAM software as it is mounted in my machine.

For example......lets just say im taking a 1.5" thick piece of aluminum plate and machining a mold pocket into it. This plate material is going to be clamped down directly to the machine bed table. In my CAM software, due to the nature of my machine, I need to setup the program exactly as such. So the top surface of the plate is actually located at a Z position of -10.50" in relation to the spindle home poisition(-12" + 1.5" plate = -10.5"). Im basically just programming the machine in the CAM software to always have to move down to the workpiece, never up and over it to clear a tool before plunging in to make the cuts.

This is where I run into problems because in these programs that im demo-ing here I cannot set the top surface of my material as -10.50".

Does that help describe my situation better?


Now i know i can set up a homing switch at the bottom of the z axis travel and the program a completely different setup file that makes the machine work inthe opposite fashion i have set now but its a huge undertaking on this machine as ill haveto completely disassemble the gantry head to get a switch in place and then reassemble/align/set parallelism/etc.

Hence my question in regardsto whether the full version of these softwares can be setup to run in a negative Z number function, or am I sol nd have some machining to do on my machine :(

Thanks!!
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Re: Programs cant runin the negative Z range????

Postby martin54 » Sun Sep 29, 2013 9:25 pm

Yes I understood how it worked but missed the bit about auto tool length which I know nothing about anyway, without that because tools will be of different length I couldn't understand how the machine knew where the tip of the tool was lol.

Far as I am aware the demo versions of the software are exactly the same as the retail versions with the obvious limitations on what you can cut. Maybe worth sending an email to vectric support just to confirm this though.
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Re: Programs cant runin the negative Z range????

Postby Boxersix » Mon Sep 30, 2013 3:48 am

Yeah my controller software has auto tool length sensing built into it. Very handy just having to select the tool from a dropdown menu and click ok for it to do thevrest and calculate the appropriate offsets. Still no full blown aito tool change but beats the old z block every day. I know mach3 and other software have similar programming thats easy to setup. I machine my own tool setter switch block with overtravel instead of using the common copper touch plate(can chip small carbides) or super expensive tool setters out there. Still accurate and repeatable to half a thousandth.

Yeah i send them a message definitely. Thanks!!
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Re: Programs cant runin the negative Z range????

Postby TReischl » Wed Oct 09, 2013 1:23 pm

When your machine "homes" to the top of the Z axis, it is actually setting "machine zero". Same thing is true for x and y axis.

Once that is set, the machine is either jogged off the machine zero and the operator sets Z zero point for the work. Just like is done with the X,Y axis of the machine.

The control does the math of calculating the difference between machine home and workpiece homes, or zeroes.

Not sure what control software you are using, but sounds like Mach?

All of us router guys run our machines in the Z negative range when we set up our Z zero on the top surface of the workpiece.

My machine is like yours, with the homing switch at the top of the Z axis. When I select machine home, the axis moves up and trips the switch. I then use an autozero routine to touch off on the top surface of the material using a metal plate. I can also do it manually with a gage block.

I don't think you want to move your Z zero to the bottom of the axis, you could easily run your head into material on the machine when you press the buttons for machine homing.
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