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Tangential Knife Setup
« on: November 09, 2009, 11:31:39 AM »
Hi, I was able to configure the 4th axis to control a stepper with a Knife on the end. The Tangential move is ok with this parameters:

A axis: steps per units: 0.5555555555555 -  Velocity:25000  -  in settings (alt+6) tangential control enable

but the z lift is no done at angles. I try with a very simple square or triangle.

I changed the default value of 45 degrees (in profile file) by other values and have not obtained results.

Any thoughts on this?



Re: Tangential Knife Setup
« Reply #1 on: December 05, 2009, 12:12:41 PM »
Can you email me a copy of your XML for the tangential knife? I read over the mach3 manual and it really doesn't address how the tangential cutting is initiated.
Do you simply set up the A axis like a rotary table where the steps per unit is set for 1 degree? Also to implement tangential control on a tool path file do you simply click on the tangential button in Alt 6 setting screen  before pressing cycle start? Last is the g code for the A axis simply left blank and mach3 figures the values to orientate the knife in the direction the axes are moving? dmauch@seanet.com
Re: Tangential Knife Setup
« Reply #2 on: December 08, 2009, 09:27:35 AM »
yes, is very simple. The step/units is steps/degree for example if the stepper is 200steps/revolution the value is 200/360=0.55555 and the velocity value approx. 25000/30000.

Is not necessary to have the 4th motor to simulate this, simply configure the A axis and Tangential control enable in (alt+6) and is wonderful to see how it moves along the tangent.

But my z axis is not lift in all the angles >45degree, only random in some points.

Any idea

Re: Tangential Knife Setup
« Reply #3 on: December 09, 2009, 06:36:03 AM »

Iam using Mach on a tangential knife table.

My Z axis is pneumatic so in the config I have selected 2.5D. As there is a time delay for the ouput to activate a relay then to work a actuator what I have done iin my gcode set my z+ to 200 and retract to -200. The way 2.5 D works is that any Z value in the minius ie -1 the output is activated. The +200 down to -200 up when using feedrates of 5000-10000mm/min is time enough to up the knife rotate to a new heading and then go down. My Tangentail setting is 35 deg and +400, so when running with the z down at +200 the tangential setting will retract to -200 if >35 deg moves.

My A Axis steps/per are the same as yours 5.55555555555 etc. I have got some gears and timing belt to make it a 10 steps/per but have not found the time to set it up.

So the key here is to take a look at your feedrates and set your z codes large enough so that it creates some dwell time for the z to get up, the A to rotate and get down all before the machine starts to feed again.

There is an issue with Mach 3 in tangential also. The tangentail moves only work well on G1 moves. So if you have any G0 moves in your code change these to G0. I have found that the A will rotate when the Z is down on the job when a G0 is present.

Iam praying for the Mach guys to work this bug out in some future updates.

I have set my A axis to high vel and acc setting as you have however due to the little bug with rapid moves it has been no point to run it so fast

If you need an other help, I can check my machine settings and get back to you.
Re: Tangential Knife Setup
« Reply #4 on: December 09, 2009, 11:52:59 AM »
Thank you. The information is very helpful. Could you email me your xml file?. I want to see how you did your outputs.  A sample G cvode file would be helpful also.
If a time delay is required for your system have you thought about inserting a G4 command for a dwell?
So if I understand correctly what you are doing with the pneumatic cylinder you are setting the 2.5D in the general config menu and you a re using tangential. Then in you G code file you are setting the Z up Z+200 and Z-200 for down. Then when a Z value is - how do you have your config file set to activate the relay?
I understand the indexer A axis  and was surprised to hear that the tangential only works on G1 commands . I thought they fixed that. Are you using the latest lockdown version?
Re: Tangential Knife Setup
« Reply #5 on: December 10, 2009, 02:46:44 PM »
thank you for the info, this is a simple gcode of a triangle, no G0 commands in the drawing triangle; the rotation of my A axis is working OK but not lift at vertex.

G0 X0.000 Y0.000 F1000.000
G0 X30.000 Y-58.875 Z-10.000
G1   Z0.500 F600.000
G1 X47.250 Y-18.375  F800.000
X72.750 Y-58.875
G0   Z-10.000
G0 X0.000 Y0.000
G0 Z-10.000
G0 X0 Y0

The A axis change to 66.1 then 302.4 then 180 degrees it is ok but the Z axis not change to 1 at vertex.
The parameters in xml is lift angle+45 and lift z 1, I tried to change this but nothing happens .
What am I doing wrong?