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Author Topic: 4th axis - GCode degrees vs distance  (Read 19872 times)

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Offline RICH

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Re: 4th axis - GCode degrees vs distance
« Reply #10 on: March 02, 2010, 11:07:30 PM »
Greg,
From my 53 page vault of info on a rotary axis:

Quote
The checkbox for linear/angular only tells an axis not to convert when switching from mm to inch, other than that it
has no purpose. A, B and C are always rotary axis.. So using an IJ with an A axis is an error in syntax, though still legal, the missing Y in this
case woudl simply be interpreted as the current Y location, and the A would just be a linearised motion on that axis during the movement of the XY
in the XY plane arc.
Art

I was experimenting a fair amount with the rotary ( in my case a stepper driving the spindle on the lathe ) for constant turning motion , as an indexer, as rotary in angular, and also as rotary using linear ie; the steps per inch relative to a diameter, then slaving them to say the Z axis.
You need seperate profiles for rotary and linear. Then there is swap axis via a macro but that had faults ( swaps pins but not the tuning units ?) ............
Then you consider the different combinations of feedrates, the feedrate modes, slaving ect and it all can become rather confusing..... ???

Angular does make sense and helps to keep ones sanity.  ;)

RICH
« Last Edit: March 02, 2010, 11:12:08 PM by RICH »

Offline Greolt

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Re: 4th axis - GCode degrees vs distance
« Reply #11 on: March 03, 2010, 02:44:23 AM »
Ahh........ that is the info from Art that I remembered reading but had forgotten the detail.

"The checkbox for linear/angular only tells an axis not to convert when switching from mm to inch, other than that it
has no purpose. A, B and C are always rotary axis.."


Thanks Rich

Greg

Offline bowber

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Re: 4th axis - GCode degrees vs distance
« Reply #12 on: March 03, 2010, 04:20:32 PM »
Set the rotary to angular, like someone has already said the only true way to set it is angular.
There is a setting in mach to tell it the diameter so it can sort out the feedrate via linear units though.

Steve
Re: 4th axis - GCode degrees vs distance
« Reply #13 on: March 08, 2010, 05:47:37 PM »
Have a look at the Mach manual page 93 at the bottom.
No you can't say 1 degree is now 1 inch, unless that is calculated to equal that.
But A B C can be linear. That's what the book says?
Hey THANKS 4 all the help in advance. I'll need more than you'll ever expect!!!


www.cravenpottery.com

Offline RICH

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Re: 4th axis - GCode degrees vs distance
« Reply #14 on: March 08, 2010, 09:25:01 PM »
Quote
There is a setting in mach to tell it the diameter so it can sort out the feedrate via linear units though.

The Rotation RADIUS was changed from diameter, see the Setting ( Alt 6 ) screen in Mach Mill.
 
You can use the rotary as linear but requires changing the steps per  in motor tuning and also velocity based on a set diameter.
In my fooling around, it was slaved to the x & z axis on the lathe. Then I did coordinated moves, but, all hand coding.

RICH
Re: 4th axis - GCode degrees vs distance
« Reply #15 on: March 09, 2010, 02:09:03 PM »
Thanks to all that have responded.  Now I am more throughly confused than ever ;)

PointCloud,  'Why would you want do do that!!!'  Probably because I don't know what I am doing.

Query.  I have a tube that I wish to do the following.  Put a logo on with a diamond drag point that was drawn with a Vectric product and assumes a linear relationship.  I want the logo to remain proportional regardless of the tube size. Then continue with adding a geometric design (e.g. greek key) to the circumference which is defined in radial terms so that regardless of size there are always the same number of repititions on the circumference.

It seems as though I will have to change profiles to accomplish this kind of task and I have no problem with that.  I just was trying to find out what the limitations are in Mach.  Love the program.  Love the help you guys give.  Hopefully I will have my A-axis put togehter in the next few months and then I will have a whole slew of new questions for  everyone.

Thanks,

RT

Offline Greolt

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Re: 4th axis - GCode degrees vs distance
« Reply #16 on: March 09, 2010, 02:46:51 PM »
Have a look at the Mach manual page 93 at the bottom.
No you can't say 1 degree is now 1 inch, unless that is calculated to equal that.
But A B C can be linear. That's what the book says?

Mach is used to control many varied machines.

Take for example, a hot wire foam cutter.  These typically have four axis, all of which are linear.

In the context of this thread, the 4th axis being discussed is a rotational axis, not linear.

Greg
Re: 4th axis - GCode degrees vs distance
« Reply #17 on: March 09, 2010, 03:35:55 PM »
greolt. you said that a b c were always radial. LOL...
 the question was can he change it between linear and radial. The answer is YES, but you have to make sure of what you are doing. If it rotates then you put in angle values, if it is linear then you put in a linear distance..

Checking or Unchecking the box will require your axis to be setup accordingly...

Hey THANKS 4 all the help in advance. I'll need more than you'll ever expect!!!


www.cravenpottery.com
Re: 4th axis - GCode degrees vs distance
« Reply #18 on: March 09, 2010, 03:49:26 PM »
font=Verdana]Query.  I have a tube that I wish to do the following.  Put a logo on with a diamond drag point that was drawn with a Vectric product and assumes a linear relationship.  I want the logo to remain proportional regardless of the tube size. Then continue with adding a geometric design (e.g. greek key) to the circumference which is defined in radial terms so that regardless of size there are always the same number of repititions on the circumference."""""

It seems as though I will have to change profiles to accomplish this kind of task and I have no problem with that.  I just was trying to find out what the limitations are in Mach.  Love the program.  Love the help you guys give.  Hopefully I will have my A-axis put togehter in the next few months and then I will have a whole slew of new questions for  everyone.[/font]


I am thinking that you need to use a 4 axis cad/cam software to interpret this into a more functioning work? You can do this with many different name brands of software... I use rhinocam, in my case I would simple wrap your art around a tube and use a v-carve or a pencil tracing function to get my code? I also would not use a drag point on a radial surface but a streight tip. As to proportioning, and tube size... Proportions could remain the same, and you'd juse use a larger tube prior to code writing...

A drag point will continually try to drift down hill on a round surface...
Check out the CNC zone.com for some great insight to cad/cam machining software, there are lots of them. Some free and some $15k+..

« Last Edit: March 09, 2010, 03:56:46 PM by pointcloud »
Hey THANKS 4 all the help in advance. I'll need more than you'll ever expect!!!


www.cravenpottery.com

Offline Greolt

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Re: 4th axis - GCode degrees vs distance
« Reply #19 on: March 09, 2010, 05:37:28 PM »
greolt. you said that a b c were always radial. LOL...

No I did not actually say that. Art did. ;D

Sorry, I should have made it clearer that I was quoting Art. (the quote in blue above)

The part of that quote being relevant to the OP's question about units on a rotational axis and the point that I tried to make (not very well it seems) was,

 ".....other than that it has no purpose....."

Greg
« Last Edit: March 09, 2010, 06:42:56 PM by Greolt »