Machsupport Forum
Mach Discussion => General Mach Discussion => Topic started by: ayprens on August 25, 2010, 06:12:32 AM
-
i want to make circle cutting but i failed. try all of CV settings.
g code example:
F400
G00 Z10
G00 X7.5 Y0
G00 Z1
G01 Z-0.5 F50
G02 X7.5 Y0 I-7.5 J0 F400
G01 Z-1 F50
G02 X7.5 Y0 I-7.5 J0 F400
i zoom toolpath screen. this is not a perfect circle. it is segmented. When i was cutting a circle, surface is choppy.
(http://img840.imageshack.us/img840/315/machh.jpg)
-
It is not possible to cut a true circle with a flatbed X-Y-Z CNC machine. Because the machine can only move in straight lines the circle must be comprised of straight lines and so is really just an approximation of a circle. (A CNC lathe would, of course be entirely different).
Mach outputs step and direction signals which are also a series of straight line moves - that is the way it works.
The circle quality starts to improve as you get more (shorter) lines up to the point where the GCode gets too long to be practical.
From tests using acrylic and relating to the optical quality of the edge I have found that a 50mm disc comprising 400 straight lines is about the minimum I would like to use. If the diameter of the disc is increased then so does the number of lines used and so on...
One trick with CAD is to draw many times full size then scale the GCode at run time.
Hope this helps.
Tweakie.
-
The code looks fine. When you zoom in on the cricle you will see it segmented and doesn't affect the actual cutting.
Like Tweakie said the X and Y are moving in small straight lines, but......
How close to a perfect circle you can cut is dependant on your machines systems components. The better the resolution,
lead screw quality, micro stepping all come into play.
RICH
-
i know perfect circle imposible for x.y.z machines. But my surface is very bad. i am using servo system. My mechanical equipment is very good.
i think my mach3 setting is wrong or circular interpolation is not enough. i send my setting file.
-
I think that by using circular interpolation you will only cut a circle with 40 sides but the edge finish will be good. If you are getting a poor edge finish then it is something else which is machine related and probably, as Rich has said, mechanical.
These two discs have been shown before but the one on the left has been cut with straight but wobbly lines (bad finish) whereas the one on the right has been cut with 40 straight lines, using circular interpolation (good finish).
Tweakie.
-
Your problem is likely to be you are using a pirate version of Mach.
Hood
-
I am using 3.042.040 version of mach with license.
i dont think so my problem about license.
i count 40 segmented lines at one circle.
-
You have a pirate licence.
Hood
-
no. i have my own license. i purchased myself from scott nichols.
do you think my license is fake. this is a very big problem.
-
I'm not arguing whether or not his license is legit. Just curious how it could effect working quality?
-
Bob,
I actually think it is either a bad pulse stream or a mechanical issue. I can however say with confidence that the licence being used is a pirated version. Should support be given for that? personally I think not but as I am not Artsoft I will leave that up to them. I do believe that ayprens may have good intentions and has made a mistake in this case but the licence being pirated is not in question
As for the graphics showing the segments, that is just the way the toolpath is drawn, if you wish to confirm for yourself load some code with an arc (G2, G3) zoom in to it and you will see the same.
Hood
-
I am curious how you know its pirated? I have my perfectly legal copy installed on three machines. Two of them I use for design work and just use Mach for dry running and reviewing the toolpaths. One is for actually driving my machine. Its my understanding that for personal use the license allows you to run Mach on multiple machines. I have copies of my license files stored in three places so I won't lose them and I can re-install on the fly if I have to, and I have had to when a machine needed to be replaced.
To the OP: Sorry about the thread jack, but this is of immense curiosity to me.
-
Bob, what you are doing is totally legitimate :)
There are tell tale signs stored in an xml and in this case the xml posted had these signs in it. I believe that the op may well have one or more legitimate licenses but in this case the one being used was not one of them.
I have suggested, by PM, that the OP contacts Scott at Artsoft and I am sure things will get sorted out, if they do then I will be more than happy to help to the best of my ability as I will feel I am not wasting my time :)
Also to let you understand I get PM's asking for support all of the time and at least 3 in the past week have been from new users (no forum posts at all ) who are using pirated versions.
Hood
-
There have recently been a number of ebay listed pirated copies which I have reported and they have eventually been withdrawn but I suspect there are lots of copies in circulation which are "Licensed To: PAPA FABIO".
Tweakie.
-
Tweakie, yes there are many pirate versions out there, Papa Fabio was at one time the most common but doesnt seem to crop up so much now.
Hood
-
In how many segments (or how long each) would Mach 3 draw a 50mm diameter circle? This is just to get an idea of the precision of the software.
-
How close to a perfect circle you can cut is dependant on your machines systems components.
Promech, it is better than your machine.
RICH
-
In how many segments (or how long each) would Mach 3 draw a 50mm diameter circle? This is just to get an idea of the precision of the software.
In the toolpath window you will see the segments but on the work itself you should not. The Toolpath is drawn that way to conserve resources and you only really see the segmentation if you zoom in. As Rich said the machine will determine the accuracy of a circle and not what you see in the toolpath window.
Hood
-
In how many segments (or how long each) would Mach 3 draw a 50mm diameter circle?
Since this may of interest to licensed users i will post something which will provide a perspective on the question
along with the Gcode. ;) Thus is gives insight into what is written in the ARC Motion write up on page 4.
Got to go, so probably tonight.
RICH
-
I am retrofitting a 20 year old industrial lathe which has few hours of work on it (it belonged to a university). I am sure the machine itself is still the limitation. But since the subject was brought up I am curious about Mach´s resolution with simultaneuous movements in X and Z. Maybe the limitation would be related to the steps/per configuration in the Axis Tunning Section? In this case it would be neglegible (about 0.0025mm for me).
-
I am retrofitting a 20 year old industrial lathe which has few hours of work on it (it belonged to a university).
Interesting, mine was the same, came from Hull Uni I believe and was used for testing the longevity of carbide v ceramic v CBN inserts I think.
Hood
-
Discussion was interesting about the license ;D
Surprise opponent
Amir
-
Amir
strange choice of words, well to be honest not really when its you that said them ;)
The new licensing scheme will make it much more difficult to run Mach from a pirate licence ;)
Hood
-
Didn't know there were so many pirate licences out there. And that is for a reasonably priced software that anybody who can afford buying a couple of motor drives for his machine should be able to afford the cost of Mach3. Just hard to imagine what could have been if Mach was priced in the range of some of the leading CAD programs.
Daniel
-
EMC would be a lot more popular. LOL.
-
:D Probably so
Daniel
-
I am curious about Mach´s resolution with simultaneuous movements in X and Z. Maybe the limitation would be related to the steps/per configuration
My engraving machine steps per inch is 253360. Resolution is 1/253360=0.000004" but practicaly speaking it's around 0.000040", but then i had difficulty actualy measuring and confirming that, so i will just just say that you can check a .0001" indication with 10 jog steps.
To bad the spindle with the sharpest point can only scribe a .004 or so line width as that limits the heigth of the engraving.
As far as the lathe goes, when i was doing threading tests,measurements were done on the scribed lines to .0001". The Z lathe axis steps per unit are
20320, thus resolution is under a tenth, so lets just say 0.0001". That can be confirmed easily over different increments / total length or whatever.
Now the X axis is 12700, thus it's resolution is like half the Z , but that X axis screw is a high grade ball screw and can match the Z any day of the week.
But practicaly speaking, all of the above means nothing, if at the end of the machining, the shaft is bigger than the hole and won't go in.... ;D
RICH
-
One thing worth thinking of, for internal holes at least just using a large cutter will virtually eliminate any steps in the edges.
I wasn't aware that pirated licenses caused such miserable problems, it's a rather dramatic security measure :/ My machine was fitted with a new computer a few weeks ago, increasing the pulse speed and making rather better progress, but the computer has since packed up and died causing a great deal of misery. I think it was just a crappy computer rather than license issues. I did have a license on the old computer but ti disn't seem to install properly on the new one and it stayed in demo mode. Odd.
-
One thing worth thinking of, for internal holes at least just using a large cutter will virtually eliminate any steps in the edges.
I wasn't aware that pirated licenses caused such miserable problems, it's a rather dramatic security measure :/ My machine was fitted with a new computer a few weeks ago, increasing the pulse speed and making rather better progress, but the computer has since packed up and died causing a great deal of misery. I think it was just a crappy computer rather than license issues. I did have a license on the old computer but ti disn't seem to install properly on the new one and it stayed in demo mode. Odd.
If you read post number 10 you will see I think it is more likely nothing to do with the pirate version. Having said that there is no telling what a hacked driver or code will do so it is definitely possible that a hacked version of Mach can act up.
As to your licence issue, if you have copied over the Mach1Lic.dat and placed it in the Mach3 directory it should work fine, if it doesnt then contact Scott at license@machsupport.com with your purchase details and I am sure you will get sorted out with a replacement.
Hood