Messages

2231

General Mach Discussion / Re: Stop CV issues...

« on: September 13, 2015, 06:41:06 AM »

Its a confusing thing plasma, the bottom of an internal corner is always rounded because the bottom of the flame or arc lags the top by about 15degrees or so, so as the top has passed the corner the bottom has no option but to round it leaving a bevel..

I think the main crux of my question was is there way to stop the jerks when transitioning from a straight to an arc when using stop-cv???

2232

General Mach Discussion / Re: Stop CV issues...

« on: September 13, 2015, 03:26:22 AM »

Pretty much, yes, its a plasma PITA

With CV on i get a bit of a radius on the top of the cut, (the bottom is always rounded due the the flame lag) and with CV off the tops are much improved but there is this jerk when going from straight to curve every time, not much, just a judder in motion.

I'm just tuning up my new table so looking at ways to get the best, I have tried pushing acceleration into the shudder zone but the stop-CV is still the best for a sharp corner. Acceleration is currently around 0.3G and speeds are around 4000-5000mm/min on my test parts.

As i say, I'm just looking for improvements really, Mach is doing what it does best as usual

2233

General Mach Discussion / Stop CV issues...

« on: September 12, 2015, 02:51:28 PM »

Been trying to improve my plasma cut quality on internal corners, using the "Stop CV on angles >89" appears to help but I seem to get a visible jerk in the cut upon each transition from a straight line to an arc or radius, is that normal??

Is there any improvement to be had or is it just the way it is?

2234

General Mach Discussion / Re: Odd setup issue, new machine...

« on: September 11, 2015, 11:25:44 AM »

Yeah, in an ideal world i would, but I think the fact it's running and seemingly happy is all that matters now I think.

More important to get it making money now.

Thanks for the help though.

2235

General Mach Discussion / Re: Odd setup issue, new machine...

« on: September 11, 2015, 09:36:56 AM »

1 - Yes, the original scheme worked, that was with different drive boards and the faster pc.

2 - This scheme worked with the new drives and a slower pc and cheaper BOB.

3 - This scheme failed with the new drives, a faster pc and the same BOB as 1.




Thanks for the help though, much appreciated as always.

2236

General Mach Discussion / Re: Odd setup issue, new machine...

« on: September 11, 2015, 08:17:50 AM »

Interesting point there, its a well known setup though, might have a chat with them.

It does seem to have fixed the issue though which is the important part.

I have also asked them about why they set the speed to 45k when i upgraded my THC to their system.

2237

General Mach Discussion / Re: Odd setup issue, new machine...

« on: September 11, 2015, 06:14:18 AM »

thanks Stirling,

i have sorted it now i think, CandCNC advised me to flip the settings back and up the pulse width to 5us this seems to have done it.

I will ask them about the clock rate as it was their THC upgrade that switched it, i originally had it on 25 but after the upgrade it was running 45 no idea why, will ask.

Dave

2238

General Mach Discussion / Re: Odd setup issue, new machine...

« on: September 10, 2015, 02:14:37 PM »

Can't edit now but..

One difference is that the test PC was underpowered and only ran at 25khz, the work PC runs at 45khz, step and dir pulse length is 2us on both PC's

2239

General Mach Discussion / Odd setup issue, new machine...

« on: September 10, 2015, 12:31:02 PM »

Finally got to move my working PC setup from the old table to the new-build one today, seems ok apart from one odd issue.

The settings were copied from the test pc i was using to debug the table build, not transferred, i just manually copied each setup screen from one to the other.

The Drives are digital DSP drives from CNC4You.UK and are new, the BOB is part of an MP3000-DTHC2 setup from CandCNC, this was taken from the old table.

The oddity is this - when testing the jogging I find Z and X axis work perfectly but the slaved Y&A axis sounds and runs very notchy and rough. My concern is that all drives are the same, all motors are the same and therefore i set all "Step Active Low" settings the same.

However, upon changing the step active low settings for Y&A seems to fix the issue.

But, I cannot see why these two axes need opposite step signal levels???

Any ideas here?

2240

General Mach Discussion / Re: One physical switch as end switch and ref

« on: August 30, 2015, 05:09:05 AM »

Maybe try adding some input debounce, 30-40 works on mine???