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Author Topic: cutting an arc on the outside of a rotary axis  (Read 3414 times)

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cutting an arc on the outside of a rotary axis
« on: July 05, 2009, 07:28:44 PM »
Hello everyone.
     Trying something new and I wanted to consult the mass's first. I am planning a part that will require me to cut an arc on the outside of a rotating part mounted in my rotary table on my mill. meaning that the two axis along wich the arc will be cut is the X and the A ( as apposed to the usual X and Y). I think a dabbled in this before but was wondering what the approach should be. Will it work if the A axis is set up as angular? can I give mach an angle and a distance with which to interpolate the arc or do I need to fiddle with some settings first?
any help will be welcomed.

CB
Re: cutting an arc on the outside of a rotary axis
« Reply #1 on: July 05, 2009, 09:24:37 PM »
You can tell mach3 that the A axis is a rotary Axis and go to the MDI page, and type G0 or G1 A90 to get a 90 degrees of rotation

Menu - Config, General config, check A is angular.

I don't know what kind of an arc you are trying to machine.

If this is an ellipse, you'll have to draw it in a cam software in order to get the right displacement and that feed are synchronize with others Axis.

Re: cutting an arc on the outside of a rotary axis
« Reply #2 on: July 06, 2009, 06:21:50 AM »
I am trying to machine a series of half circles along the outside circumference of a ring shaped piece of stock. so my question is. Will a G02 command work if I include a A axis word instead of the usual Y as an example

G02 x0 A36 (degress) R.5

instead of say

G02 X0 Y-.5 R.5

or should I use a "I,J or K" comand format of some kind instead. Or something else. not really sure how the controller would know what to do with the angular information.
So basically I am hoping to not have to change a bunch of settings to trick mach into thinking the A axis is linear. was hoping to find someone out there who has done this with out using a CAM software to generate arc segments. instead of using a simple Arc command.

CB

vmax549

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Re: cutting an arc on the outside of a rotary axis
« Reply #3 on: July 07, 2009, 06:19:59 PM »
I don't think Mach has 4th axis interpolation. I believe it is just x/y y/z x/z.

But you could do a swapaxis      A=Y   Just have to do a ratio of diameter and distance to do the code values.     That way you do not have to reset the steps values.  Figure out how far you program the Y to do an exact 360 deg and that is your window to work in with Y distance. IF you were to program 4 arcs take the toal movement and divide by 4 this would be the Y value of the arc

Just a thought, (;-) TP
Re: cutting an arc on the outside of a rotary axis
« Reply #4 on: July 07, 2009, 08:00:27 PM »
yeah I figured that would be the answer I got. Unfrtunately it is a bit trickier than that. I would definately have to change the step values on the motors because the rotary is a stepper and the Y axis is a servo and the steps per differential is huge. I really dont like messing with the settings once I get everything working correctly. I can of live by the moto. "If it aint broke, dont break it". guess unless anyone else has a better idea I will have to decide if I wanna go that route.
thanks

vmax549

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Re: cutting an arc on the outside of a rotary axis
« Reply #5 on: July 07, 2009, 08:22:53 PM »
YOU do not have to change step values. You just have to understand the relationship of distance when you swapaxis.

After you swap then rotate the A(thru y) until it rotes 360 degs. Then look at the distance traveled in the dro. this is one complete revolution or the max distnace of Y you have to work with. If the distance was say 2" and you needed to make 4 arcs equal distance then each arc would be .5" in y.

Just a thought, (;-) TP