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No Output GCode with GND Polygon

Posted by Anonymous User 
Anonymous User
No Output GCode with GND Polygon
November 06, 2013 08:30AM
Awesome Phorum Folks,

I have a few questions, the first is the most important.....

1. When outputting my gcode when I have a GND polygon setup for the bottom layer the only gcode output I get is for the orphans. I may use this term incorrectly. There are several areas between pads and lines that does not get filled in, very small areas. These areas are the only output I get. If I remove the polygon and re-run pcbgcode it works fine. I have tried turning orphans on and off. Since using the polygon is saving the system from forming about a dozen extra routes I would hate to lose it. It looks fine in Eagle.

2. Is there a nice good thread or web page to refer to for milling the second side of a PCB. I will be starting my first dual sided board and have read "a little" about using the alignment pin method. Just trying to find the best method for flipping the board and keeping things aligned without re-zeroing x and y.

Mike
Re: No Output GCode with GND Polygon
November 06, 2013 09:21AM
Mike,
I cannot help you with your first question as I have had no problems with doing ground planes. Sorry

As to the second question, I will tell you how I do it and you can see if it will help you.
First off, I modified my post processor so that all TOP work is done in G54 offset and all BOTTOM work is done in G55 work offset.
Then I home my machine and made a small program to cut a pocket (about 1/16" deep) in my spoil board and later vacuumn chuck that is slighly bigger than the board size that I use. Because I cut the pocket I know I know exactly where the lower left and right coordinates are. I move my spindle to the lower left and issue a G54 G92 X0 Y0 and this sets the origin point for G54 offset. Repeat doing the same thing at the lower right corner for G55 and that origin is set. Then I save These fixture offsets to a file. Now because on my machine which is dedicated to pcb work and the fixture is never removed, all I have to do when I boot up is home the machine, load the offset table for pcb work and am ready to go.

In use, the raw PCB stock (for top work is slid into the pocket so the lower left corner is in that corner of the fixture. and when flipped, the lower right corner is aligned to the lower right corner of the fixture. As your using the same corner of the stock for alignment and the pocket was machined straight on the machine, your aligned!

Hope this helps.
Re: No Output GCode with GND Polygon
November 06, 2013 10:12AM
Can you post a screen shot for issue 1?
Maybe a picture of what you see in Eagle, and a picture of what you see in the previewer in pcb-gcode.

Regards,
JJ

[www.pcbgcode.org]
[groups.yahoo.com]
[www.facebook.com]
Anonymous User
Re: No Output GCode with GND Polygon
November 06, 2013 12:40PM
Countrly_Bubba, thank you.

JJ, here are some pics of the board and GCODE Wizard top and bottom etch. If I remove the polygon and perform the same output then I will get the correct bottom etch outlines.
Attachments:
open | download - Board_PolyProps.PNG (96.9 KB)
open | download - GCODE_Props.PNG (106.5 KB)
open | download - GCODE_Props.PNG (106.5 KB)
open | download - top_etch.PNG (39 KB)
open | download - bottom_etch.PNG (3.8 KB)
Re: No Output GCode with GND Polygon
November 06, 2013 01:13PM
I'm afraid you'll have to talk to the gcode wizard guy about this.

Regards,
JJ

[www.pcbgcode.org]
[groups.yahoo.com]
[www.facebook.com]
Anonymous User
Re: No Output GCode with GND Polygon
November 06, 2013 01:37PM
JJ,

It is the same thing for the preview output, attached are the code outputs. The TOP etch is 124KB and the BOTTOM is 9KB.

I purchased the wizard so that what I am used for viewing now, but it is the same for both.

To show a little better I made the poly on half of the board diagonally, and half of the output is blank and the other fine.

In addition, thanks for all the help so far.

Mike
Attachments:
open | download - Viewer_TOP.PNG (82.2 KB)
open | download - Viewer_Bottom.PNG (63.4 KB)
open | download - Bottom_Viewer_HalfPoly.PNG (76.2 KB)
Re: No Output GCode with GND Polygon
November 06, 2013 05:07PM
Very interesting.
I assume you are creating the polygon using Draw Polygon, then doing a Ratsnest and the result looks like the first attachment.
Then in the previewer, I see the second attachment.

So, I guess the first question is, do you see the isolated tracks in the polygon in Eagle as in my first attachment?

Regards,
JJ

[www.pcbgcode.org]
[groups.yahoo.com]
[www.facebook.com]



Edited 1 time(s). Last edit at 11/06/2013 05:08PM by admin.
Attachments:
open | download - Screen Shot 2013-11-06 at 7.51.08 PM.png (42.7 KB)
open | download - Screen Shot 2013-11-06 at 7.52.29 PM.png (125.4 KB)
Re: No Output GCode with GND Polygon
November 06, 2013 05:19PM
Also, if I may suggest: you'll want to make your tracks a lot wider unless you have a great mill / router with vacuum hold-down, really flat stock, low spindle run-out (you get the idea).

Go to Tools | DRC | Restring and change the Min and Max track widths. When you click the Check button, all the tracks will be resized.

You can also change the default width in Edit | Net Classes, but I think that only applies to newly-drawn tracks.

Regards,
JJ

[www.pcbgcode.org]
[groups.yahoo.com]
[www.facebook.com]
Anonymous User
Re: No Output GCode with GND Polygon
November 06, 2013 07:53PM
JJ,

First Post : The answer is no, I even did it in the order your stated. I have been creating the polygon, then auto routing, then running pcb gcode.

Second Post : I have not actually milled my first PCB yet, this circuit was going to be my second. I have developed a quick and dirty single sided one with the same settings. In order to make any decent board it seems you need to be able to route between pads. (Wrong Thought it Seems)

Interesting enough I tried playing with doubling the line width and spacing to prevent between pad routing. I then created the polygon and rats nested and believe it or not I got a great output.

However, the pads needed for that polygon (GND) are not connected in this version.

It did not blank out everything though.

I need to play around with some settings it seems.

If you look at he very bottom right side pad, it is a ground. You can see in the Eagle board snapshot it is connected to the ground plane. In the pcbgcode output it is completely isolated top and bottom.

I like the new setup though, thanks.

Mike
Attachments:
open | download - Eagle Board with Poly.PNG (45.6 KB)
open | download - New Bottom Etch.PNG (98.1 KB)
open | download - New Top Etch.PNG (89.5 KB)
Anonymous User
Re: No Output GCode with GND Polygon
November 06, 2013 07:57PM
In addition, I do not have either of the setup you call out.

I have a TAIG Mill, no vacuum, flat stock will be typical of getting double sided PCB stock from eBay, and spindle runout is not horrible on this mill.
Re: No Output GCode with GND Polygon
November 07, 2013 06:12AM
Okay, looking at the Eagle screen shot and the new bottom etch picture, it appears that the thermals are too small to be isolated, and are being ignored.

After much searching, here is how to increase the isolation of thermals:
Go to Tools | DRC | Supply
There you will find Thermal - Isolate which you can increase. I left the Restring checkbox checked. After clicking the Check button, then clicking Ratsnest, the isolation around the thermal I was looking at increased.

Regards,
JJ

[www.pcbgcode.org]
[groups.yahoo.com]
[www.facebook.com]
Anonymous User
Re: No Output GCode with GND Polygon
November 07, 2013 07:49AM
JJ,

Thanks a million, I increased the thermal isolation and it indeed started showing up.

I am still wondering why the first event happened, but it does not matter since the current settings are working fine. Well, on paper I should say.

Now to get out some copper clad boards and see what my mill can handle.

I need to do some research on a fixture to place my board onto, I have been doing my other non PCB jobs secured to plywood which was secured to the table.

Mike
Re: No Output GCode with GND Polygon
November 07, 2013 08:00AM
Mike,
Before I made the vacuum chuck, I used a piece of MDF and double sided tape. Milled my pocked to be sure it was flat on the bottom and away we went. Main reason I switched to the vaccum chuck was I got tired of trying to clean all the "sticky" off the boards and it also holds the boards flatter.
Anonymous User
Re: No Output GCode with GND Polygon
November 07, 2013 09:22AM
Country_Bubba,

Thanks I will look into some vacuum chucks, for now I plan to use the same type of pocket into some MDF as you suggested.

I am really interested to see the type of tolerances I can keep without messing up the traces.

Do you cut a new pocket for different size PCB blanks?

Thanks for the suggestions.

Mike
Re: No Output GCode with GND Polygon
November 07, 2013 09:34AM
Mike,
No, so far (I only have two similar sized board stocks), I cut one size pocket in the derlin base that will hold both boards. I cover the unused portion of the chuck with packing tape to minimize leakage. I also found the board stock I got off ebay has a warp in it so I seal the edges with tape also and the vacuum pulls it down real tight (27" vacuum). The tape also helps when I get to drilling as there will be vacuum leaks as I drill.

I only have a small 3 CFM vacuum pump so leakage is a concern.
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