# Mach3 XHC Motion control odd tool path.



## Imfree (Aug 7, 2021)

Hi guys. I have rebuilt a Syil X4 with a 3.5kw spindle and XHC motion control. I went into this with every confidence but quickly realized that this CNC caper was in fact a great deal more involved than first thought. I have managed to fossick around and found the answers to my many issues and learnt a great deal in the process but this time I am stumped.
I create G Code in Fusion. In simulation on fusion the tool does exactly what I want it to do.
I use the mach3mill post processor unchanged to generate G code
First operation 2D Adaptive radial stock to leave 1mm Axial .5mm runs prefect no problem
Second operation 2D adaptive also Radial stock to leave 1mm Axial 0.0mm it runs off the tool path cutting a corner and then at the end carves a 5mm slot down the wall. It's not random. If I run the same g code I get exactly the same result. 
So I think ok I lost steps and thats the problem. No it did not loose steps it returns to zero perfectly. Ok the problem is in the G Code so I find the offending line and send the mill to the position. I jog the Z down to find it is exactly where it should be. I get a little excited and think that I somehow fixed it so run it again and it errors exactly the same as before. Now I'm scratching my head and grasping at straws for answers and thats were I have been for the last few days. 

I can cheat and run all of the clearing in the first operation and set it for multiple step downs but I learn nothing from that. This is an operation cleaning up a 3d Printed part so yes scrapping 2 parts is not good as they take 8 hours to print but no real cost involved but if I just spent the day on a part and it did this random thing at the end it would alter my demeanor somewhat.

My current position is I do not trust the mill setup at all. It has been a fight the whole way to this point and given my lack of confidence I'm about ready to get rid of Mach3 and install a Masso. This is about my last ditch effort to solve these on going challenges. The Mill it's self with the 18,000rpm spindle is awesome! Super happy with it but I regret running with Mach3.


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## Reddinr (Aug 7, 2021)

So are you North or South Island?

My guess is that the unmodified post-processor has some error in it.   Likely the post is assuming something about how Mach 3 interprets things that are not true.  Since you are not losing steps, the machine is doing exactly what it is told.  I've run Mach 3 for years and have run into an occasional operation where I had to fix up code (generated by a post-processor in Bobcad).  I don't have experience with Masso but I assume if the g-code tells it to run it will say "how far" and you have the same problem.

I almost always "cut air" for any new g-code.  I generally end up tweaking the code a bit, then go back to the original file, change things as needed and regenerate the code.  That way I don't lose track of things like changing feeds or speeds by hand and forgetting it a few months later if I rerun parts.


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## JimDawson (Aug 7, 2021)

Maybe try turning the lead out off and see what happens.


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## Imfree (Aug 8, 2021)

Reddinr said:


> So are you North or South Island?
> 
> My guess is that the unmodified post-processor has some error in it.   Likely the post is assuming something about how Mach 3 interprets things that are not true.  Since you are not losing steps, the machine is doing exactly what it is told.  I've run Mach 3 for years and have run into an occasional operation where I had to fix up code (generated by a post-processor in Bobcad).  I don't have experience with Masso but I assume if the g-code tells it to run it will say "how far" and you have the same problem.
> 
> I almost always "cut air" for any new g-code.  I generally end up tweaking the code a bit, then go back to the original file, change things as needed and regenerate the code.  That way I don't lose track of things like changing feeds or speeds by hand and forgetting it a few months later if I rerun parts.


Thanks for the response guys.

Taranaki North Island.

Up till now I have been able to work my way through each problem and ultimately it was a lack of understanding that lead to the problem. This I have almost no doubt will end the same way. But it sure makes no sense from my current vantage point. I have turned of both lead in and out. I have rebooted as this has resolved odd issues in the past, After watching an excellent video about setting up the CV function I spent sometime on that this morning and the mill now runs much smoother and faster. To the limit of my understanding I have examined the G Code looking for all the G1,G2,G3 triggers and that all looks good. When it goes rouge it correctly shows the tell tale green dots on the screen so it knows its out of bounds but like a 4 year old does it anyway. Its approximately 50% of the dia of the 12mm endmill. So its very rapidly removes a lot of material that I'd quite like to leave in place. In this case had I run the whole program air cutting I would have found the error but it sure as hell is not indicated in the purple lines on the screen. Keep in mind this is not random. It will repeat this error with meticulous precision.
I maybe expecting too much but my intention was to get to a point where I head out to the shed with my USB key, plug it in set my WCS and press go. Sadly my personality type requires that I screw things up a few times first and I readily accept those moments. I don't need assistance from Mach3/XHC creating more of those moments. So far I have only had 2 end mill casualties but with time I'm sure to improve on that number.


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