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Speed Tolerance and Smooth Moviment

PostPosted: 19 Mar 2013, 20:20
by viniciusronaldo
Hello!

I am using Mk1 for a CO2 laser cutting machine, and it is working very well.

I am having two problems:
1 - I set speed 1800mm/min but when cutting a circle it varies from 900 to 2200 depending the part of the circle it is. I tried speed tolerance parameter and initial speed but did not work out.
2 - To cut a square, the movement at the corners are very rigid, how to make a smooth movement to cut a square with 1800mm/min.

My best regards,

Vinicius

Re: Speed Tolerance and Smooth Moviment

PostPosted: 20 Mar 2013, 08:40
by Andrej
1. It might help if you check "Disable Helix Interpolation"
2. You need to set acceleration and look ahead. Post your settings and I'll examine them.

Re: Speed Tolerance and Smooth Moviment

PostPosted: 22 Mar 2013, 21:13
by viniciusronaldo
Attached the setting file.

Re: Speed Tolerance and Smooth Moviment

PostPosted: 23 Mar 2013, 14:54
by Andrej
Your "Lookahead angle" is set to 180 which means that it is disabled.
Your "Initial speed" is at 2500 which means no acceleration for speeds under 2500.

Set "Lookahead angle" to 150 and "Initil Speed" to 0.

Re: Speed Tolerance and Smooth Moviment

PostPosted: 25 Mar 2013, 20:37
by viniciusronaldo
Thanks a lot, it improved so much the machine movement.
To cut a 110mm diameter circle with speed 1800mm/min, the speed varies from 1700 to 2000mm/min. Is it normal? Is it possible to have less speed tolerance, like from 1750 to 1850? Is there any other parameter to change?

Now I have three more questions, can I use this topic?
1 - I am thinking to upgrade the laser power for 400w to cut stainless steel. Can I still using MK1? Because there is some cutting details like attack the laser outside the draw, wait a second and than enter the draw and start to cut. Is there someone cutting metal by laser using planet CNC?
2 - Is there any way to cut the inside parts first? Like at letter "A" cuts first the nucleus and after the outline?
3 - What is the advantages of MK2 an Mk2/4 for my 3 axis machine?
4 - I set the machine size and checked the soft limits but it doesn't works. The machine only stops at the limit switch and is is not soft stop. How to soft stop at machine limits?

Thanks

Re: Speed Tolerance and Smooth Moviment

PostPosted: 27 Mar 2013, 07:13
by Andrej
1. You can use Mk1 but Mk2 and Mk2/4 are faster, smoother, better speed profile, better acceleration ramps,...
2. You'll need to generate g-code with correct order yourself. Perhaps you could use SheetCam? I don't have experiance with it but I know it has some handy features for laser cutting.
3. Mk2 and Mk2/4 are faster, smoother, better speed profile, better acceleration ramps,...
4. Soft limits only work with Mk2 and Mk2/4

Re: Speed Tolerance and Smooth Moviment

PostPosted: 27 Mar 2013, 15:05
by viniciusronaldo
Ok, I will buy new hardware.
1 - The Mk2/4 are faster, smoother, better speed profile, better acceleration ramps... as the Mk2? Or Mk2 is a little better then Mk2/4 in this points?
2 - About the accelaration ramps, does Mk2/4 has S-curve? (example link http://www.ni.com/white-paper/4824/en)
3 - While with my Mk1,with the parameter you told, to cut a 110mm diameter circle with speed 1800mm/min, the speed varies from 1700 to 2000mm/min. Is it normal? Is it possible to have a short speed tolerance, like from 1750 to 1850? Is there any other parameter to change?
4 - Is it possible to turn outputs off on pause?

Thanks a lot!

Re: Speed Tolerance and Smooth Moviment

PostPosted: 27 Mar 2013, 19:37
by skillalot
You should use cam software for making the g-code. Sheetcam is probably good for you.

What laser powersource do you want to use for cutting? The CO2 lasers are not suitable for cutting metal, they work at the wrong wavelength, it's not only about power.
Lasers that can cut metal are expensive...

Do you have some pictures of your machine?

Re: Speed Tolerance and Smooth Moviment

PostPosted: 27 Mar 2013, 21:00
by viniciusronaldo
I downloaded Sheetcam, sounds to be very nice, thanks.

Sheetcam has a lot of post processor options, do you now which one is better for Planet CNC?

Actually my CO2 laser power is 150w, but I thinking about to upgrade for a 400w CO2, Coherent or Synrad. In the Synrad website there is a Laser Power Calculator for material x thickness x cutting speed. It says that cuts metal sheets also, something around 2mm of thickness. What kind of laser you can sugest me that is suitable for metal cutting? This lasers cost around U$ 55,000.00.

Attached some machine pictures. If you need more of any detail, please let me know.

Re: Speed Tolerance and Smooth Moviment

PostPosted: 28 Mar 2013, 11:08
by Andrej
Nice machine. I would definitely use Mk2 or Mk2/4 for it.

1. Mk2 and Mk2/4 are same except Mk2/4 has less inputs/outputs.
2. Article on this link is wrong. Take a marble. Put it on slope and release it. Marble will start to accelerate. This acceleration is trapezoidal and there are no jerks. Marble will move smoothly.
3. Mk2 and Mk2/4 do this better. And to get more accurate speed on display you need to check "Measure Speed" setting. You can also check "Disable helix interpolation" and force controller to interpolate whole path.
4. No, not possible.

Try one of EMC posprocessors.

I can not help with laser selection.

Re: Speed Tolerance and Smooth Moviment

PostPosted: 28 Mar 2013, 14:31
by viniciusronaldo
Thanks Andrej, I will buy MK2/4, it is the best solution.

The question of laser selection is for the forum user named skillalot, he knows about laser types and wavelenght for metal cutting.

About the S-curve: My delta servo-driver has a configuration software that you install in a computer and it comunicates to the driver by a special cable. This software adjust the servo, autogain tunning and a lot of other parameters. It also has a jogging option. When I jog the machine I set the paremeters acceleration, deceleration, S-CURVE and speed. Attached a screenshot. When a jog the machine by the delta software after this settings, it moves very very smoothly. So I thinked that S-curve makes this difference, but maybe not. I hope Mk2/4 moves smoothly like delta software.

Re: Speed Tolerance and Smooth Moviment

PostPosted: 01 Jan 2018, 18:29
by danilo.lettieri
Andrej wrote:Your "Lookahead angle" is set to 180 which means that it is disabled.
Your "Initial speed" is at 2500 which means no acceleration for speeds under 2500.

Set "Lookahead angle" to 150 and "Initil Speed" to 0.


Hi Andrej,
with these suggestions I solved most of the problems of not fluid movements.
However, under certain circumstances, the speed drops to 100 mm/mim and then returns to the speed set by F.
Can you help me?
(I attach the configuration)

Re: Speed Tolerance and Smooth Moviment

PostPosted: 10 Jan 2018, 13:17
by Support
Have you considered our TNG software?


We released our new motion software PlanetCNC TNG. It is supported only with MK3 series of controller.
It is far more superior and advanced than CNC USB sw:
https://planet-cnc.com/list-essential-p ... tutorials/