This is likely a syntax error... The M91 is in the wrong place. Did you add this line in the post? or did you create it at the control? The M91 is generally the last item in the line. J

If you want to see different positions on your heidenhain, do this; When you are in "program run" mode (auto...) press the MOD hard key on the control. You will see "Position Display 1" and "Position Display 2"...You can cursor over them and press the GOTO key and a list will show up. Choose the REF selection and this will show you the Machine absolute encoder position. Use that value in your M91 line! J

I know what is going on here. Your operator is showing you the very, very safe way to use a heidenhain. The "Block Scan" feature is scanning the entire program, executing the blocks in the PLC, then restoring the machine to the exact position it was in prior to the block you selected. This is why the machine picks up the previous tool... because that is the exact state the machine would be in if you got there naturally. If you want to avoid this behaviour, you need to select a block after the tool you are using. You can safely block scan to any line on a heidenhain. Pick your first XY line after the TOOLCALL. Alternately, if you know what you are doing, you can simply use the GOTO button instead of the "Block scan" function. This method will NOT scan the file. It will simply start where ever you ask it to. J

Now I've REALLY upset them!

Looks like I've upset the fanbois... Sorry I ever mentioned that Mastercam may in some way be flawed! Long live Mast3rcam! My most humble apologies.

I know. I can do it too, but it's all time. I just never expected that a CAM software in the year 2018 wouldn't have this ultra-basic feature. It's tough to update a post at the same time you're training the staff how to run the new machine! I'll get it all done, I just expected it to be much easier than this! J

I will be doing this. For sure. But, it all comes down to time. I'll get my posts updated for the "next job"... But I need this absolutely right now. You know how it is in this industry!

That's not easy... It's disastrous if you forget. It's a total catastrophe waiting to happen. The software needs a radio button to specify that a particular tool is "Manual only", then whenever you select it, the post processor will complete the tool change safely, based on that value. Anything else is a hack job. It's clear. The answer is that I need to develop a post to do this safely. Thanks, J

Not really.... You need to empty the spindle of the current tool, Call the "manual tool/empty pocket" into the spindle, go to a fixed tool change location and then M00, Do the work.... Return to fixed position and M00, Then carry on. Mastercam doesn't even have the facilities to add a M00 AFTER an operation(BUT before the toolchange!!!!)... I just can't believe it. J

Seriously.... Does mastercam not support a manual tool change out of the box? Do I have to do all the coding by hand to get this to work? Do I need to use a precious misc. value, and develop a post to support this? I know mastercam is bad, but is it really this bad??!?? J

UPDATE: After some more testing, it would seem that "step-up" helps a lot. It looks to me, that optirough uses a very strict "constant Z level" approach to slicing the model, and if a flat doesn't just magically land on one of these slices, it completely ignores it. Not very "opti" if you ask me... Allowing "step up" lets the system go "up" and re-cut those faces. Problem solved(-ish). J

This is what I ended up doing, but it's a band-aid at best. Set stock to zero and use limits to stop where I want. You end up with 10 operations instead of 1 because you need a "cut depth limit" for each critical depth; then another OP to continue deeper. Terribly messy. Oh... also 1 stock model per OP or you cut miles of air too...! I've solved the problem with workarounds, but I'm so sick of working around; I just want the software to work. Colin, I cannot share files. You just need to cut any flat surface on any model and it will ignore the flats. My testing file leaves .080" on all the flats. The catch is....It only behaves this way if you choose to leave stock on your model. If you put the stock to zero, it cuts everything just fine. if you add .001" it will completely ignore flats, and leave ALL the stock on the part. J

So... Why does Opti rough always seem to mess up flat surfaces? Whenever I use it, it leaves 1 stepdown worth of stock on flat faces, totally ignoring the stock defined for floors and walls? What gives? There is no option like "critical depths" or "machine flats". nothing. Other than "get better software", are there any options to solve this basic, basic, function? J

Heidenhain datums are conceptually the same as fanuc. Except where you would say "G54", you simply say "Datum 1". Using the preset table, you can have hundreds of datums defined, datum 1, 2, 3,.....99. you simple call the datum (using cycle 247) and that's it. The preset table allows you to name them with plain English text as well so you can easily identify. Alternately, in manual mode, you can just enter the datum management screen, choose a value from the table, and press activate. The tables are all just text files and can be saved to you network quite easily. They live in the TNC root directory. J

Use "M140 MB MAX" to send the tool home. It moves the tool home in the tool axis, to the limit. You can also use M140 with a distance, but in this case "MAX" tells it to go as far as it can. And as previously mentioned, M91 is the "machine reference" code. J