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Author Topic: Need help with 4th axis continuous motion code  (Read 23608 times)

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Offline TT350

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Need help with 4th axis continuous motion code
« on: May 20, 2009, 06:47:16 PM »
Hi Guy's,

I have a job in the shop that requires some tight tolerances for some round holes  +/-.0001.  
I tried doing this in one set up but I'm getting a variation of .00015 between the X & Y axis.
The holes are not round.  
This job should really be done in a Lathe, but all I have is a manual Lathe in the shop and I have to make 30 parts to make so
I'm going to try to do this job in the mill.  
This is an adapter plate with 2 sets of hole patterns and some counter bores and alignment steps.
What I would like to do is sit my 4th axis up and rotate the 4th axis as I move the end mill across one axis (X or Y) as a 4th axis turns my part.
If one of you guy's could just show me a little piece of code that would rotate my 4th axis continuously, I can take it from there.

Here's a Youtube clip of what I'm trying to do. You will have to watch it about half way through to see what I'm talking about.
http://www.youtube.com/watch?v=vooVKTdCrQw&feature=related


Thanks for your time,
Chris

vmax549

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Re: Need help with 4th axis continuous motion code
« Reply #1 on: May 20, 2009, 09:58:13 PM »
UNless you have a very tight/rigid commercial grade machine and climate control I wish you all the luck. I see more tolerance change than that by just letting the machine warm up.

Just a thought, (;-) TP
Re: Need help with 4th axis continuous motion code
« Reply #2 on: May 21, 2009, 02:53:55 AM »
Look like the 1/4 slot drill is not really the right tool to do the job and as  I can see, feedrate is way too high for a finish pass. A brand new 1 inch end mil would do the job better

This kind of tolerance can only be achieve in a room where temperature will be very stable.

Even end mill do not have this kind of tolerance unless you buy very precise end mill.

Only my humble opinion, Jeff

Offline TT350

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Re: Need help with 4th axis continuous motion code
« Reply #3 on: May 21, 2009, 04:32:52 AM »
Is there anybody that would be so kind as to post a little peace of code to help me out?
Re: Need help with 4th axis continuous motion code
« Reply #4 on: May 21, 2009, 05:24:39 AM »
I'm a newbie here.
As I understand it Mach has no ability to do a true continuous movement or rotation of any axe. Workarounds is possible but this doesn't give ideal results. One limitation is that the rotation of the "continuous rotation" axe has to stop between every line of g-code. If your tool end of movement isn't in air then the stop of rotation will happen with your tool still into the work piece.
Say you want to face of a work piece with an end mill while the work piece rotates, leaving a circular "edge" in the center. You do something like this: X50 A3600. Your end mill feeds 50mm across the work piece while the work piece rotates 10 full turns. However you want the work piece to rotate one full turn after the X feed stops. Your next line of code will be: A360. And there is no way to retract the end mill from the work piece before the rotation stops after this line of code. So the rotation stops and your next line may be X0. This lead to the end mill "resting" against the edge of the work piece, with the spindle running, for a short moment before it moves off. This may produce a mark on the edge of the work piece.

Here is two topics which may be of interest for you.
http://www.machsupport.com/forum/index.php/topic,11438.0.html
http://www.machsupport.com/forum/index.php/topic,11422.msg72469.html#msg72469

« Last Edit: May 21, 2009, 05:26:45 AM by SteinarN »

vmax549

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Re: Need help with 4th axis continuous motion code
« Reply #5 on: May 21, 2009, 09:56:38 AM »
SOrry but there is NO such thing as continiuos rotation CODE for the 4th axis. YOu have to program the rotation just like you program the other 3 axis as part of the total movement. Mach will interpolate the moves so all axis work together but that is about as far as it goes.

AS to the tool marks that is why you do leadins and leadouts. Also with CV on it tends to smooth out the actually stops to just a slowdown or No slowdown and a continous feed across the stop points.

Sorry (;-( But that is about how it works for ALL controllers

(;-) TP
« Last Edit: May 21, 2009, 10:00:15 AM by vmax549 »

Offline docltf

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Re: Need help with 4th axis continuous motion code
« Reply #6 on: May 21, 2009, 12:05:08 PM »
if your hardware will allow it .this includes switches ,relays ,motors ,drivers etc.you can try making a new profile where you turn the spindle on and off like a pump.then you config  your 4th as both A-axis and spindle.then you can turn
your 4th on with M3.that way you can switch the rotary with code.you have to be carful with the code because when you use the rotory as spindle you loose 4th location.good luck trying to hold 5-diget tol with multi fluted tools.
they come with the bang and miss action buitl in.

bill

Offline TT350

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Re: Need help with 4th axis continuous motion code
« Reply #7 on: May 29, 2009, 04:08:55 PM »
I wrote the code by hand with deadly accurate results!

N4 M5M6 T4
N5 G43 H4
N6  M03 S2500
M08
G00 Y0.0 X-3.56
Z-.01
G01 X-3.5 A-35 F100
A-410
Z-3.56 A-420
G00 Z.312
G01`X-2.4975 A-1490 F100
A-1880
X-1.320 A-1900
Z.400
X-1.2
Z-.01
X-1.25 A-1920
A-2290
A-2340 X-1.2
G92 A0.0
M9 M5
M30





vmax549

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Re: Need help with 4th axis continuous motion code
« Reply #8 on: May 29, 2009, 06:22:49 PM »
yea but that is NOT +/- .0001 tolerance. You can't get that type of  measurement  with a caliper by hand. (;-)

BUT a really nice looking part.

Good job, (;-) TP

Offline TT350

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Re: Need help with 4th axis continuous motion code
« Reply #9 on: May 29, 2009, 06:50:41 PM »
My bad +/-.0002

The little lip that is 4.495 is .063 tall.

So how would take that measurement and what would you use?