FAQ

Frequently Asked Questions

 

Q1: Should I use Mach4 or Mach3?

A: Mach4 without hesitation.  If you value your time whatsoever, and you want to avoid frustration, use Mach4 and don't use Mach3.

  1. If something is going wrong Mach4 will report what is going wrong, Mach3 won't.
  2. Mach4 had all of the Height Control written from the ground up inside of the SmoothStepper and its plugin. For Mach3 is partiality inside the SmoothStepper and partially inside of Mach3 where things can go wrong.
  3. SheetCam has a post processor written for it, that takes advantage of all of the Anti Dive features provided by the TMC3in1. This will eliminate may many crashes and save you lots of frustration and material. These features are not available in Mach3.
  4. Other than this documentation, we won't support Mach3 with the TMC3in1. It is not worth our time or your time. Please just believe us and use Mach4 and SheetCam.

 

Q2: How does the TMC3in1 and ESS perform Height Control?

A:The TMC3in1 measures the current (actual) tip voltage over 187,000 times every second and filters that data down to about 2500 data points per second. If Height Control is allowed ( by the H.C. On/Off button, Arc Okay, and all the other Anti Dive modes) then the TMC3in1 will compare the current tip voltage to the target tip voltage 2500 times per second and command a Z axis velocity up or down to get the two voltages to match. The ESS responds to the commanded velocity and makes the Z axis move and then reports the Z positions back to Mach4. This process loop the repeats continuously.

 

Q3: Are OOB (Out of Band or non coordinated) motors required with the TMC3in1 and ESS?

A: Out of band motors are only required for the way Mach4 handles Height Control, without the ESS. We wrote everything from the ground up (for Height Control in Mach4) and Mach4 has nothing to do with Height Control when the ESS is used with a TMC3in1 or an Up / Down H.C. module. The ESS does not need OOB motors to perform Height Control. However if you are using an ESS, you could choose not to use the ESS's Firmware based Height Control and instead use the slower and less responsive Mach4 Height Control.

 

Q4: Do I have to use SheetCam with the TMC3in1?  Could I just write a post processor for Fusion 360 (Vetric or another CAD package)?

A: You certainly could write a post processor to make another CAD package control the torch, by using one set of M62/M63 GCode commands to turn the torch on and off. It would be easy to modify an existing post processor to do that (by changing the M3 and M5 commands). Assuming that the torch is on Output #3 you would use "M62P3" to turn the torch on and "M63P3" to turn the torch off.

However, Anti Dive Choice (Mode) 2 (lead ins, lead outs and small circle / arc radii) would be a different output, say Output #5. SheetCam will look at the GCode it is generating and intelligently decide where to place "M62P5" to allow THC Z axis motion and "M63P5" to prevent THC Z axis motion. This took about 2 weeks to get everything working nicely, and how to make it work correctly in Fusion 360 is a huge question that I don't have time to work on and perfect. (If someone else did want to do that, I would gladly post their post processor on our site.)

Having Anti Dive 2 automatically enable and disable Height Control is a significant advantage for the TMC3in1 and this is why we recommend SheetCam. It adds a little bit of cost, but it makes everything run so much smoother once it is set up for your machine.

 

Q5: I am just looking at the setting is SheetCam and it seems like there are multiple places to set up the delays. It looks like there is one is the cutting tool and the one in the post processor. In the cutting tool there is a “pierce delay” and an "ESS delay after Arc Okay in seconds”. Which one should I use?

A: The SheetCam delay would just be a plain G04 delay.

The ESS precision delay was requested by some people who work with VERY thin metals, and and wanted a very short and precise delay (like 25 ms). This would not show up in the GCode, but it would happen just before a G04 and the two would some together. Both of these delay motion.

The Anti Dive 1 Delay after Arc Okay does not delay X, Y or Z motion. This only delays the activation of HC (torch Height Control).

 

Q6: What is Probing?

A:Probing is a generic term, but refers to the fact that you are moving an axis, typically the Z, (but it could be multiple axes at once) until the probe makes contact. The probe could be a fancy high end one that has springs and electronics built into it or the probe could be a mill / router bit or the tip of your torch nozzle simply completing an electrical circuit (an ohmic probe).

Plasma users commonly use ohmic probes to touch off of the metal (to determine the height before a pierce). The ohmic probe would do something similar to applying (an isolated) 12V or 24V to the exterior of the torch body / nozzle and then connect the return circuit terminal to the metal work piece. If the torch is not touching the work piece no current will flow and the probe is not active. If the nozzle touches the work piece, current will flowing through the nozzle / work piece / return circuit path, which will cause the probe to activate. However, please remember that these ohmic probes NEED to be able to withstand 200+ V signals being applied across them (your torch's Arc Voltage will be applied across the circuit). Ohmic boards will be designed to withstand that and they will then produce an output signal that is safe for other break out boards to read as the probe signal.

If you try to connect a 12 V or 24 V probe circuit up directly to the torch head and the metal being cut, directly into one of the TMC3in1's Isolated General Purpose Inputs on J6, it will destroy your input.

 

Q7: What is distance between probing references in SheetCam? What is a typical value?

A: The distance between probing references is how often SheetCam will insert a G31 probing command so it can find the surface of the metal. If you are using 2" thick steel plate that is perfectly flat, you could get by with only a single probe at the beginning of a job, or maybe every 500 mm or 1000 mm just in case your table is not level. If using 18 gauge stock that warps easily and could very well be bent from handing, you may want to probe before each and every pierce to make sure you don't crash while piecing do to metal that is up in the air, by setting that distance to 1 mm. It does take time to pierce, and if you have a job with 100 pierces, you would probably like to speed things up as much as possible by probing as little as possible, but avoiding crashes by probing enough. Most users I know, set it to about 1 mm so they never crash.

 

Q8: What is pierce drop to fire torch? What is a typical value?

A: In order to fire the torch with the M62P# command, we need to have just a little bit of movement in the Z just after the M63P# command. This setting will issue the GCode to fire the torch and move the Z down a few percent, and then sit and wait there for the Arc Okay to turn on. Once the Arc Okay is turned on, we will then run the next GCode command which will be the remainder of the Z move from pierce height down to cut height.  The smaller the better would usually be the case for the pierce drop value, but you need to make sure that the value will always be at least one or two real steps of Z motion.  If it is not, then Mach4 will ignore the M62P# command that turns on the torch. A value of (your typical pierce height - your typical cut height) * .03 would be a good default value.

 

Q9: How can I tell if my Z axis is moving via Height Control?

A: You will see motion in the HC Z Delta field, which will tell you that the ESS is commanding the Z axis. Alternatively, you can put a Zip Tie on your Z axis coupling (between the axis shaft and the motor shaft) , and you will be able to see the zip tie rotate.

 

Q10: My Z axis isn't responding to Height Control, but I see the commanded velocities changing on the screen, what should I do?

A: Please try the following:

  1. Make sure that your Z axis is assigned to motor 2 in the ESS Outputs tab and in the Mach4 Axis Mapping tab.
  2. In the Mach motor tuning tab, try smaller values for the Z acceleration and Max Velocity fields (10% of what you currently have for both) to see if it responds.
  3. For the TMC3in1 Linear Response Band, try using LARGER values for the "Above Target Band" and "Below Target Band" fields. I have seen this help with very fast motors a few times. A value of 50 or 100 for each will let you see if this is the problem. You may need to change these values in your GCode and / or your TMC3in1 configuration window.

 

Q11: Do I need or can I use another BOB (Break Out Board)?

A: You don't need to use another BOB, other than for the EStop input. With the TMC3in1 you are limited to only being able to use Port 1 and / or Port 2 of the ESS for additional BOBs. Please read the first section of the Requirements page for more details regarding BOBs.

 

Q12: What is Dry Run?

A: In TMC3in1 v019 Mach4 release, we added Dry Run support. This will allow the probing and all normal motion to occur when running your GCode, but the torch will not be fired. When the Dry Run button is pressed, the TMC3in1 will NOT turn the torch relay on, but instead just turn the Arc Okay signal on, so that the GCode will run. You may want to turn OFF Height Control with the on screen button first as well as power off your plasma unit.

 

 

 

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