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Another Option for Isolation Routing

dl1ebn
Sat, 16 Nov 2019 11:57:01 GMT

[Begin](//muut.com/u/flatcam/s2/:flatcam:GuF3:begin.jpg.jpg)

dl1ebn
Sat, 16 Nov 2019 12:19:02 GMT

[End](end.jpg) Hello Marius, sorry for the message before without any text. I hit the "Post" Button by accident. Both Pictures, "Begin.JPG" and "End.JPG" show the same pcb isolation routing. Begin is the solder Pad on the starting point of the trace and End is the solder pad at the other End of the same trace. If you take a look on the pad at the beginning of the outline, you see on the right side that the routing tool started to travel upwards on he solder pad. directly at the same point you see the end of the routing. there is a little offset between begin and end of the routing process. This little offset end very often in a microscopic rest of copper that causes shortcuts. This problem mainly occurs when the solder pad has a circle geometry. My request is, if it would be possible to generate some kind of overlap between begin and ending point of the outline? I assume that the offset is a result of the load cycle that changes on the milling tool exactly at the end of its way through the copper layer. This change makes the milling tool being bend. If there would be an overlap, the offset could be compensated and it would possibly avoid the microscopic copper parts. The offset described above never appears if the solder pad does not contain the beginning or ending of the outline trace. I also tried to decrease the milling speed and increase the spinning of the spindle. Both didn't have a remarkable effect. Regards Norbert, DL1EBN [End](//muut.com/u/flatcam/s2/:flatcam:1GtF:end.jpg.jpg)

Marius Stanciu
Sat, 16 Nov 2019 13:05:02 GMT

Hi Norbert, What you see is the result of interpolating a circle into lines. The used algorithm compare the start point and the calculated point from the end of the last line and if they are not the same (due of inherent cumulative calculation errors) it will add a last line connecting the start with the calculated end in order to have a complete isolation. In short, it's all about calculation errors due of limited decimals in the float numbers. There is an option available in Geometry, if you change the Application Level to Advanced (in Preferences -> General), named *Recut 1st pt.* which will cut over the end point. May be what you need. Best regards, Marius

dl1ebn
Sat, 16 Nov 2019 13:32:44 GMT

Hello Marius, thanks for the explanation. I will try that. Hopefully it's available in the LINUX version. I will report the results. Regards Norbert, DL1EBN

Marius Stanciu
Sat, 16 Nov 2019 13:34:33 GMT

There are no differences between the code that run in Linux and the one in other OS's except that in Windows there is a association between Gerber/Excellon files and FlatCAM that allow starting FlatCAM and opening the file by double clicking on the file.

dl1ebn
Sat, 16 Nov 2019 15:33:24 GMT

OK. Thanks. I#m really looking forward to the newly generated files. Except of the problem described, I'm really glad to have access to such an outstanding piece of software. Thank you!!

dl1ebn
Mon, 09 Dec 2019 00:21:43 GMT

Hello Marius, I tried out the "Recut 1st pt" option. Unluckily it does not doe what I expected. The Offset between 1st and last point disappeared, but there is an extremely small "leftover" [Mill-Fault](//muut.com/u/flatcam/s2/:flatcam:URiJ:millfault.jpg.jpg) . If you look at the image attached, you will see what I mean. What you see there happens at 99% of all milled solder pads. It's a lot of additional work to check all solder pads with the microscope and eliminate these little bridges. I think, the solution could be to generate some kind of overlap (maybe three or four segments) to make sure that everything is completely outlined. Regards Norbert, DL1EBN

Marius Stanciu
Mon, 09 Dec 2019 01:22:25 GMT

Hi Norbert, It may be that what you see is the result of your router backlash. You should check it first. I may add a parameter to set how many points in the path to overlap. Right now only the first point in the path is overlapped and if this point is in a curve, because the curve is interpolated in many lines, the actual over-cut will be very small.

Marius Stanciu
Tue, 10 Dec 2019 03:38:01 GMT

BTW Norbert, I just expanded the Re-cut option in the following way. I've added a new option named Re-cut length. If it's value is 0 then the behavior is as before: at the end of the path the CNC will cut again until the first point in the path no matter what the length is. If the Recut length value is not zero then at the end of the path, the router will cut as many points in path as needed until the distance from the start of the path (along the path) is equal with the Recut length value. That should cover almost all use cases if not all.

dl1ebn
Sun, 01 Mar 2020 12:41:50 GMT

Hello Marius, excuse me please for being offline that long. But there was a lot of work to be done. However, I have some further Questions: You said I should check out if there is a backlash of my router bit. Maybe, but I don't know how to find that out. While milling I can't see the router bit. Even if, I think it will be that small, that I'm not able to see that. Do you have an idea how to measure or watch the backlash if there is any? I inserted a value for the the Re-Cut Option. I stumbled over the predefined value of this Re-Cut. It has four decimals. As far as I understood, the value represents the number of steps to be Re-Cut. Am I right if I use the numbers in front of the decimal point? I did install different versions of Python, including the actual one. I do not get the Linux version of FlatCAM to be installed. I always have the same error messages than before. What I did not do is replacing the Python Version by the latest one. There is a parallel installation of different versions. I understood, that it could cause problems if there is software dependent on a special version of Python. I have software dependent on Python but I don't know if it runs into problems when the version changes. Would it be possible for you to take a look on the LINUX Version of FlatCAM that LINUX users have the advantage of the improved preferences specially the post processor and Re-Cut stuff ? Up to now LINUX allows version 8.5 only. Regards Norbert, DL1EBN PS: I have different PCB-projects to be milled. I will try the latest tools (unluckily under WINDOWS) within the next days.

Marius Stanciu
Sun, 01 Mar 2020 16:53:39 GMT

Hi Norbert, Backlash is a complex topic and I also don't know much on how to effectively measure it as I am not a machinist. When in doubt, for my CNC machine it is easier and cheaper to just replace the parts involved with parts ordered on Aliexpress (machined SFU1604 ball leadscrew). Yet, there are a lot of resources over Internet, you could look for example to this YouTube video: https://www.youtube.com/watch?v=d5uw2kKDuM4 The number of decimals used in FlatCAM can now be adjusted in Edit -> Preferences -> App Preferences -> Precision. The value in Re-Cut means that at the end of a isolation of a polygon, the application will make a secondary move over the same path, crossing the end and advancing on the same path (already isolated) over a distance equal with the one entered in the Re-Cut field. The app does not know how many points there will be only that it will follow the path until it reach that distance (over the path). If the value is zero then the app will will do the overlap crossing only until the first point. Through points I am referring to the point s that result from interpolating a circle into a number of lines. Basically a circle will be made into a sequence of fused lines, therefore there will be a number of points of discontinuity (where the lines change direction). I hope this answer your question. Regarding the error you have running FlatCAM beta under Linux, that is a complex situation as all things under Linux are. Maybe because there are so many different flavors of Linux and it also require that you are familiar with this OS. Your Linux may be older, or you may have conflicting packages ... It's hellish .... I myself have only a passing acquaintance with Linux, but I do manage to get it running every time if I need to do it. Yet I am always doing it on a vanilla, just installed/copied, virtual machine. That means that while possible you may need to study more. Unfortunately I can't help you because basically I will have to do what you need to do: search over Internet and step by step solve the problems you encounter. And your problems may be specific to your setup. Best regards, Marius