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Author Topic: PLASMA SPEED  (Read 5269 times)

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« on: April 09, 2009, 02:38:28 PM »
Hi everyone .... well I am new here but not with mach !
well the thing is that how can we make the movement faster in plasma  mode ? and I need the machine be more accurate while its on full speed ! the thing is that when I select the exact stop at the motion mode option the movement will be very slow  but very accurate ! but I want the machine use the constant velocity so I can have the speed ! My feed rate is at 18000 but when I select exact stop I think it turns to 100 ! its that slow !
so the find out that when I use PLASMA mode its much better ! but I need a bit more speed ! while when it reaches arc or movement of Z it slows down for more accuracy in details ! by the way I make 3D moulds !
thank you for reading my post and I am looking forward for your reply !!!!....  ::) ;) :)
« Reply #1 on: April 09, 2009, 02:56:01 PM »
Well the thing is, that when cutting with plasma, you need mach to run in Constant velocity, this comes with some tradeoffs, mainly being that the corners get rounded off as to keep the velocity constant.
The only thing to get this to be better is with higher accelerations, which sometimes machines cant handle much acceleration (machine starts to flex, vibrate or even destroy itself) or the motors cant deliver enough force to generate this accelerations.

If your machine can handle it, try increasing your accelerations.



« Reply #2 on: April 09, 2009, 03:55:57 PM »
First the machine has to be capable of extreme accellaration to do good 3d work FAST. Most cam generated code tends to be short segmented code. THEN for each bock the machine has to process it speeds up and slows down from start to stop. THIS alone will slow the machine dramatically.

IT takes a very fast and rigid machine to do this well and FAST at the same time.  CV is a must to produce smooth code. TO do CV well the machine has to be able to accel very fast to prevent rounding of the corners.

SO you can have your cake and eat it too  BUT it tends to be expense to buy or build that type of cake.

Hope that helps, (;-) TP

« Reply #3 on: April 10, 2009, 05:11:57 AM »
hi ! well thanks for your reply !!!
okey .. I have set my accelerations for ...... x= 1000 y = 5000 z= 5000   which I can rise them to 25000 and my machie can handele it  ! but I think in some cases it will be too jerky  ! by the way will it be make too masive jerks if I use exact stop ? I think it will be ! and other thing is that will it destory its self when I use these kind of accelerations ?

one more thing is that when I use PLASMA mode dies it round off some corners or miss some steps ? or it just speeds up at 180 angle and when it comes to any corners it slows down and use slower aacceleration to make the arcs or corners or use the Z !
thanks again...... :o ;D ;)
« Reply #4 on: April 10, 2009, 06:16:56 AM »
hi .. okay... here is a pic of my machine and some my work ! as you can see I can use very high speed which it does not harm my material or my tool ! but the thing is when I use the CV mode it round off my arcs and I think some miss steps ! I have set my CV distance at 180 ...and the feed rate is +1 which its off alwayz ! .
Now I wanted to know that is there a solution or setting for me that you recommend to use high speed while it preserve the details and not jerk the machine !
by the way last time I used exact stop option and increased my acceleration to see how it can handle it ! what happend was that I had a massive jerk at the corners ! it looks like it stops and go and stop and go for each segments ! I think the out put for arcs for mach from my program which I use ARTCAM it uses polyline and not arcs !
By the way in the post processor for MACH3 I have 2 option which one of them written ATC at the end which I don't understand the difference between match3gb-arcs-mm.(tap) and match3gb-arcs-mm ATC.(tap) !!!! what ATC stand for ?
thanks a million again for your concern and kindness.......
« Reply #5 on: April 10, 2009, 02:39:44 PM »
First of all, i think plasma mode was intended just for plasma cutters. So i believe that setting should be off.
If you want precision you should stick to exact stop since there is no way to remove the corner rounding completely, even with high acceleration.
But as you say, exact stop is too slow, even with high accelerations. Specially, ive heard ARTCAM  outputs many tiny little segments in their posts, you could try increasing the lookahead lines, although i think you will still see little increase in performance.

Your machine looks rigid, but only you can be the judge of your machine handling such jerks.

« Reply #6 on: April 12, 2009, 01:34:44 AM »
thanks fernando  :-*
well first of all I wanted to know is how much I can increase my lookahead line ? I mean can I set it to 500 for example or 700 ! ? or is it I should rise it 50 to 50 ? (like 250 - 300 - 350 ) ! mine is 200 right now !
second thing is that is there a way that I can convert my artcam post to something else so I can have more smoother and of course MORE SPEED machine !
thanks a million :-*
« Reply #7 on: April 13, 2009, 10:51:21 AM »
Well, 200 is a fairly good amount, you could try increasing it 100 by 100 and see if it makes any improvement, if it doesnt, then drop it back to 200.

Id like to know too if the artcam post can be improved, a friend of mine has the same problem.