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UCCNC - THC Response - Field Request

Posted: 28 Jul 2017, 01:55
by robertspark
Andrew,

Would it be possible to have the THC response as a UCCNC field please (with a defined field number)

That way it could be added to a screenset (toolpath, in replacement of the spindle parameters?) and adjusted via a slider or buttonpress to allow for fine tuning whist the cut is in operation please.

Thanks

Rob

Re: UCCNC - THC Response - Field Request

Posted: 30 Jul 2017, 05:50
by admin.neuron
No problem Rob.
I will add this on the next week.
Also notice there is a "AVC Acceleration" value that affects to the THC response. This acceleration value controller use during automatic voltage control.

Re: UCCNC - THC Response - Field Request

Posted: 30 Jul 2017, 17:06
by robertspark
Thanks Andrew,

There is no rush, you can add it to your next development cycle release whenever that will be.

AVC Acceleration >> This is the acceleration parameter used during THC, but would think that it was a static number that you tune (as high as possible) and then there is no need to adjust it.

An interesting point about cnc acceleration is that most cnc controllers use trapezodal acceleration / deceleration profile.

However hypertherm with their Pheonix controllers use an "S-curve" profile which will give a smoother acceleration than trapezodal, and allow for a higher peak acceleration.
PDF page: 82
https://www.google.co.uk/url?sa=t&rct=j&q=&esrc=s&source=web&cd=1&ved=0ahUKEwjLvu_5vbHVAhVLDcAKHT9kDTEQFggoMAA&url=https%3A%2F%2Fwww.hypertherm.com%2FDownload%3FfileId%3DHYP104318%26zip%3DFalse&usg=AFQjCNEp7X5mPtVou0-PSFfGRj2QTUrdAA
breif explanation here:
http://www.ni.com/product-documentation/4824/en/

Another bit more detailed post here:
https://github.com/synthetos/TinyG/wiki/Jerk-Controlled-Motion-Explained

Re: UCCNC - THC Response - Field Request

Posted: 01 Aug 2017, 18:23
by admin.neuron
Yes, AVC acceleration value is static number. Recommend value is 300-400 mm/sec2.
Higher value make control unstable, lower value - down the control speed.

Yes, you right about S-curve acceleration. It's more smooth.
As I know UCCNC use trapezoid acceleration, Neuron too.

Now I'm very worried about how UCCNC motion planner works.
I mean constant acceleration / deceleration on each section of the trajectory. Even if there is a very small angle between them.
I have two customers who return back to the Mach3 from UCCNC for this reason.
Balazs says it's physics and so it should work like this. But I am try to play with planner settings and increase acceleration. All start work ~fine on 7000 mm/sec2 acceleration!!! It's is not possible in the real life.
I am look on the old Mach3 and Mach4 - this path they go very smoothly. Physics is physics, but it's plasma and we need the maximum constant velocity.
In this reason antidive future work not correct too.
For example if dxf file was generated in the CorelDraw we have a lot short line segments. UCCNC on each segment acc/dec - antidive always ON. THC always off.
It is sad. :(

Re: UCCNC - THC Response - Field Request

Posted: 01 Aug 2017, 22:09
by robertspark
Andrew, with regards to the UCCNC motion planner, there are a few things to consider.

Mach3 is a worse motion planner (and is also no longer being developed). It is worse because you cannot tune the motion planner.

UCCNC you can tune the motion planner via the Configuration >> General Settings tab.

You have:
Linear error max
Linear length addition max
Linear unify length max
Corner error max

All of these items are not available within Mach3 and I'll bet that very few people understand them and very people adjust them from the default values.

As far as acceleration, deceleration and corners are concerned, Corner Error Max is the one to watch, along with your maxiumum acceleration and feedrate (you also need to consider your steps per unit too setting as plasma is normally very course).

Can you give me some settings from your machine?

What is it's steps / unit?

What is it's acceleration setting (units / sec/sec)

Presume the units you use are mm?



I suspect that people are not adjusting the Corner Error Max setting and it's affecting their feedrate that the machine is trying to cut at as the error the machine is allowed is unrealistically small (at the default of 0.03units [mm]!!)

See my post here http://www.forum.cncdrive.com/viewtopic.php?f=2&t=685

Re: UCCNC - THC Response - Field Request

Posted: 03 Aug 2017, 07:06
by robertspark
Andrew, looks like I got a few replies that my be of use with tuning and setting up UCCNC with regards to plasma.

So, the Corner Error Max setting will be important to keep the feedrate near constant and trying to avoid over-burn within internal corners (or changes in direction generally), because setting it lower than the minimum step resolution on your machine (or even ~1/2 the kerf width) will affect the feedrate and reduce it un-nesseserily.

The reduction may only be for a very very short time (mSec) but it is unessesary, and it will also allow for reducing the amount of unnessesery data buffered / computed by the motion controller for unnessesery steps (that the machine either cannot make / are pointless given the kerf of the plasma arc)

Maybe those turning back to Mach3 may reconsider now or at least be given an insight into other settings that need considering before turning back to old and no longer developed software (I too wish it had continued to be developed, instead of a ground up redesign of Mach4 which still does not "fully" incorperate plasma THC ...... although with a neuron you can now run M62/M63 for syncronous control of the THC, problem is I am now better at c# than lua and don't really want to flip to Mach4 because uccnc development and progress is done every few weeks and following disussion with users by cncdrive and thier needs) .... I await G41/G42 for wizards similar to Hypertherm Pheonix.... (your Rip-Cut gave me the idea of working on wizards / plugin specifically for plasma X,Y & A axis).

Rob

Re: UCCNC - THC Response - Field Request

Posted: 02 Oct 2017, 19:50
by admin.neuron
THC Response was added. Textfield #2751
Please install new plugin and update screenset with BMP files from DropBox: Dropbox\Neuron Files\UCCNC_Testing

Re: UCCNC - THC Response - Field Request

Posted: 02 Oct 2017, 21:05
by robertspark
Thanks Andrew, much appreciated :)