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Author Topic: Wrapper and toolpath view  (Read 12780 times)

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Offline docltf

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Re: Wrapper and toolpath view
« Reply #10 on: March 06, 2009, 09:50:02 AM »
Sage

have you tried a higher velocity on your A axis ,something like 2000 and make your pulse width wider.what are your settings for the X and Y. i did a air cut with your code today on my machine
and it ran well.

bill

Offline Sage

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Re: Wrapper and toolpath view
« Reply #11 on: March 06, 2009, 10:39:28 AM »
Running in air might be fine.
How's the balance between X speed and A rotation  speed for you?
60ipm for X is crazy fast for a 1/16 cutter.
Put some metal under it and see what happens for you.

I tried faster A velocity when I first set it up but the motor was losing steps on start up on G0's. I could try tuning the acceleration a bit to compensate. I somehow doubt there is going to be a stepper speed that s going to suffice with the rotary motor working into a 90:1 gear ratio compared to the X and  which are just driving ball screws.

My X and Y are set to 20000 steps per and a velocity of 50 ipmin. That gives me a G0 of about twice what I can turn the handle (mill drill) at which keeps me out of trouble.

As a test I purposly de-tuned my X axis to slow it down. That helped balance things for the wrapper code but obvioulsy that isn't a good solution. Or maybe it's all I can do to have a separate XML for this application.

What kind of rotary setup do you have??


You mention setting pulse width wider. Where is that done? I'm scheptical on that becuause I use Gecko drivers and their going to drive the motor how they see fit. I'm not losing any pulses from Mach to the drivers. That interface is solid.
I just think I'm driving the motor too fast for it's abilities to overcome the 90:1 ratio compared to the direct drive of the X axis.



Sage
« Last Edit: March 06, 2009, 10:41:01 AM by Sage »

Offline docltf

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Re: Wrapper and toolpath view
« Reply #12 on: March 06, 2009, 08:17:43 PM »
Sage
 the air cut i did looked pretty smooth and balanced.i did not have to change the feed rate in the code .my machine is not set to operate that fast.so it just ran at my maximum settings.I also use small cuttters at times,the smallest
is .0075 ,have not killed one yet,but have killed plenty .03125 playing with differant feed rate for differant materials.the A axis on my machine is 600 steps per degree.the X axis is 3200 steps per inch.in your post you mention your
X axis is 20000 steps per.does that per, mean inch?it might be your X axis is maxing out your A . try reducing your microstepping on X by half.the pulse width is for time balance between driver and computer.you will find it in motor
tuning.when i first set my A axis up the motor would not act properly.the motor was the same as the motor on Z axis .X Y and Z were running well. drove me nuts! so i set the A axis as spindle in ports and pins.then started to play with
pulse width running the motor as a constant speed spindle.the motor smoothed out and acted properly at a pulse width of 9 . my old setting was 5 and i thought my machine was pretty smooth.now it is real smooth.between mach,
my computer and the drivers ,setting my pulse width at 9 runs it the best.if i have to use my backup computer that pulse width has to be set at 3 to do the same thing.

bill

Offline Sage

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Re: Wrapper and toolpath view
« Reply #13 on: March 07, 2009, 02:27:42 PM »
I have no control, over the microstepping. The Gecko drivers are fixed at 10 microsteps per input step pulse. Likewise the pulse width makes no difference with a Gecko. It's an edge triggered device therefore pulse width will have no effect.

20,000 steps per inch is not unreasonable for X and Y.

I have 0.2" per revolution ball screws. So the math is.

200 step motors x 10 microsteps = 2000 steps per revolution.
1 revolution is 0.2" of table travel.
0.2" / 2000 = .0001 or 1 tenth thou per step (10 steps per thou). I wouldn't want a step any bigger.

The A axis is not being slowed by X. The contrary is true. In a combined instruction the X is slowed down considerably waiting for A.

Consider:

G0 X1 A1
where X is 1 inch and A is one degree. Being that the two are on the same line of code they must complete at the same time to form a diagonal, therefore the X has a whole inch to move and the A has only one degree. You can figure out the the linear distance of one degree on a 6" rotary table as 6 x 3.1415 = 18".   18/360 is only .05 inches.  X must be slowed down about 20x  to be linear with A. (1/.05)
This has been proven when I run the wrapper code. Combined lines wi X and A don't need modification, X-only lines need a big reduction in the feed rate and A only lines I can practically run at G0 speeds since My A is so slow.

Let me play around with it a bit when I get some time. Maybe I can improve the A performance.


Sage


« Last Edit: March 07, 2009, 02:29:56 PM by Sage »

Offline Chip

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Re: Wrapper and toolpath view
« Reply #14 on: March 07, 2009, 04:26:01 PM »
Hi, Sage

Using the G-code you posted, Wouldn't using F60 for your cut speed be an excessive value for cutting with a small cutter anyway.

Set it to a realistic value for the type of material your cutting, Make sure your using "Diameter for Federate" in Config, Tool-Path.

I think your masking Mach3's ability to work as it should, Tune your Velocity's & Acceleration's with G0 moves till they skip then back them down a little.

Would think your A axis Acceleration could be higher.

Just Thinking Hear, Chip

Offline Sage

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Re: Wrapper and toolpath view
« Reply #15 on: March 08, 2009, 09:22:01 AM »
I didn't program the F60. Wrapper did.
You're missing the point. I guess I tend to provide more info than people care to read.
YES F60 IS excessive for X moves but it's also - at the same time - too slow for A moves given my current A configuration.
There is only one F speed code programmed in the code produce by the wrapper program.
For me, the speed resulting from G0 is closer to a desireable speed for A moves  and a 1/16 cutter (just bit fast).


I agree that it might be possible to modify my A configuration BUT as I already mentioned I went through the process of tuning it until it skips and backing off a bit. I doubt there is any all encompassing F speed that will satisfy my hardware arangement.
I haven't really st down and thought about it too much. I'm sort of busy right now. I'll have to ponder it more.

I'd like to hear from someone else using a 90:1 ratio rotory axis and what motors and setting they have.

Sage
« Last Edit: March 08, 2009, 09:25:10 AM by Sage »

Offline ger21

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Re: Wrapper and toolpath view
« Reply #16 on: March 08, 2009, 09:28:38 AM »
Sounds like the bottom line is that you want different feedrates for the rotary and linear axis. Is that correct? I don't think Mach3 can do this. It tries to move the tool at the commanded feedrate, no matter where it's going. The A diameter and Use Diameter settings allow it to do this.

The problem seems to be that your A axis is just too slow.
Gerry

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Offline Sage

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Re: Wrapper and toolpath view
« Reply #17 on: March 08, 2009, 02:27:13 PM »
Mach is doing a good job slowing the X down to accommodate the slow A when X and A commands are on the same line. This is absolutley required since otherwise a proper diagonal would not be possible - so no I don't WANT (or need) different feed rates when moving in X and A together but I do NEED a different rate for the lines with separate X and A moves.
I'd still like to hear from someone with a similar setup (A axis 90:1) and what settings they have for A axis and the results they get running the sample program. I can't see there being a single feed rate that can possibly work for both X and A.
 As I mentioned before I have no problems with A the way it is. Until now I've never had a reason to move X  and A together in sync. I've cut gears before but that's only a position A and then cut X sort of function and it makes no difference how long A takes. Since the two commands are always on separate lines of code I can adjust the Feed rate for all A position commands.

Let's hear from others using rotary tables .


Sage

Offline Sage

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Re: Wrapper and toolpath view
« Reply #18 on: March 08, 2009, 02:30:40 PM »
PS> What is this "Use diameter" setting you are mentioning. I seeit in the settings and have it checked but where ids the diameter of anything entered in a mill program? SO what is Mach using to calculate anything referenced to diameter?

Maybe someone can explain what Mach is going to do with (or without) such information.


Sage

Offline ger21

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Re: Wrapper and toolpath view
« Reply #19 on: March 08, 2009, 04:17:08 PM »
You enter the diameter of your part on the settings page, and Mach uses it to caclulate feedrates.
Gerry

2010 Screenset
http://www.thecncwoodworker.com/2010.html

JointCAM Dovetail and Box Joint software
http://www.g-forcecnc.com/jointcam.html