Cutting mylar stencils with a silohuette cameo

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Re: Cutting mylar stencils with a silohuette cameo

Postby teletypeguy » Thu Apr 04, 2013 3:37 pm

SUCCESS FINALLY!

I got a good stencil with gerber2graphtec, so it was not my machine, it was the Silhouette Studio software. The Sil-Studio sw cuts a rectangle in one pass, and just destroys the resolution of the cut. Even if the custom eagle ulp (which takes the cream layer and generates a dxf) is indeed "drawing" a rectangle as four separate cut lines, Sil-Studio looks like it just cuts all four sides in one pass and monkeys up the hole. I don't know how Cathy got the fine-pitch results that she did -- perhaps she used an older sil-studio version that cut four lines differently, idk.

Anyway, gerber2graphtec is awesome -- it is very slow, but I see why: it has a home area a bit outside the 0,0 hole pattern origin (which is at the top-right, not the lower-left as in sil studio). I could see it cut horizontal and vertical alignment cuts up in this home area, and I am guessing that it does this to align the knife (which simply rotates in the holder) before making cuts of a segment or two (I'll watch closer next time, it may home every segment). This makes a lot of sense as the knife is pre-positioned in one of four orientations before moving to a cut location, dropping down, and cutting a line segment, which could be as short as about 10-mils. I will post pics shortly.

The only thing I didn't like about gerber2graphtec is that it cut the stencil out of the mylar sheet with a outline about an inch larger on each side than the hole pattern -- I would rather have cut the outer mylar region myself to a larger size for easier stenciling. Not a deal-breaker though; I'm just being picky. I don't know how much work it would be to tweak the code to make this outline cut a bit bigger.

When first I plugged in the cameo this morning (it had not been plugged into this win7 machine until now), I could not find it as a printer in win7 control panel (but sil-studio saw it just fine). It showed up as undefined or something, as a "USB Printing Support" device, and not a printer that could be shared. A bit of googling told me to install the device driver on the install cd, which they provide really just to quiet the win messages that you get. This indeed made the device a printer that I could share and rename for the gerber2graphtec command line stuff to find, and it then worked great.

I had a bit of fun learning some python as I tweaked the file; I set it up to save the intermediate pdf, pic, and graphtec txt files (probably only want to keep the pdf), and for the first time in probably 20 years I wrote a batch file for windows.

The slow gerber2graphtec stencil cutting is definitely a start-before-you-go-to-lunch sort of thing, but that's no problem as I won't be cutting stencils all that often.

Thanks to everyone who helped out. The cameo will pay for itself soon; it cost me $270 at uscutter.com and included one blade, a 12x12 sticky cutting mat, a mat-scraper doo-hickey, a $10 card for some crafty-crap, and an assortment of adhesive vinyl and transfer film that the wife and kids will have fun turning into window signs and such (it's easy to make cut-out titles for those science fair boards now), and even an xacto knife. It also had a teflon sheet that you can use to iron-on that Dangerous Prototypes logo you printed on tee-shirt stock and die cut with the cameo. I also picked a 12x24 mat for larger stuff like chassis overlays (another test, later). The vinyl is on rolls and can be loaded without a mat so you can cut up to 10-feet long or so. It may be designed for cutting vinyl signs and doilies for scrapbooks, but it is a cool little machine and much more precise than the sil-studio sw would lead you to believe.

thanks,

gil
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Re: Cutting mylar stencils with a silohuette cameo

Postby jesuscf » Thu Apr 04, 2013 6:42 pm

Post by teletypeguy » Thu Apr 04, 2013 3:37 pm
SUCCESS FINALLY!


I am glad gerber2graphtec worked for you also!
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Re: Cutting mylar stencils with a silohuette cameo

Postby teletypeguy » Thu Apr 04, 2013 7:05 pm

Hey folks:

Here are some pics from cutting a stencil with gerber2graphtec on the cameo. Compare this to the sh%$ that sil-studio did in my OP.

The only cameo setting is the physical blade depth, which is set to 1 (minimum). The media is polyester (mylar) overhead transparency sheet from any office store. I measured it to be about 4-mils thick. The pics are of the cut sheet resting on a textured black powder-coated chassis.

A pic of resistors: 0402 (upper-left), 0805 (lower-left), 0603 (upper-right), 1206 (lower-right):
(the 0805 has closer-than-norm pads as we use it for solder-jumper also)
resistors.jpg


50-mil pitch SOIC and SOT23:
(26-mil-wide hole with 24-mil space)
50-mil-pitch-soic-and-sot-23.jpg


0.65mm (26-mil) TSSOP (bottom) and 25-mil QSOP (top):
(~15-mil-wide hole with ~11-mil space)
0.65mm-(26mil)-pitch-tssop-and-qsop.jpg


0.5mm (20-mil) hdmi conn and SOT23:
(~12-mil-wide hole with ~8-mil space)
0.5mm-(20-mil)-pitch-hdmi-conn-and-sot-23.jpg


Note that the holes are wider than they should be, but this is actually a stricter test, with thinner between-hole segments. I did not shrink the cream layer before generating gerber from eagle. Some folks have said to bring it in by about 2-mil (I presume that is per-side) which will probably be about right, and I will try that on my next stencil.

But just look at the thin bits of mylar between the 0.5mm pads! They must be only a few mils wide -- very accurate cutting indeed. I am quite pleased.

gil
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Re: Cutting mylar stencils with a silohuette cameo

Postby jesuscf » Thu Apr 04, 2013 8:38 pm

Teletypeguy, what brand/type of transparencies are you using? I am using Canon transparency type E. With this transparencies I am having some trouble getting some small hole sizes to open up.
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Re: Cutting mylar stencils with a silohuette cameo

Postby teletypeguy » Thu Apr 04, 2013 10:19 pm

Hi jesuscf:

I have three brands of transparency stock, but I won't be back in the office until Monday to get you actual product numbers. It may not be too relevant since they are probably circa 1995 or so, when I actually used an overhead projector for presentations! One of them is a 3M number-number, another is an Apollo somethin-somethin, and I forget the other one. Using a micrometer, they all measured about 4-mil thick. One was probably for a laser, and one for an inkjet... I tried cuts on all three and they seemed the same.

They don't prominently tell you what the specific material is for transparencies, but polyester (mylar) seems to be typical. I am not a plastics expert by any means -- in the past, for die-cut overlays, I have spec'd polycarbonate 0.010 material with 3M 467 adhesive, and for switch overlays (which would lead to cracks after a while in polycarbonate), I have spec'd polyester of probably 0.007 thickness. That is the extent of my professional plastics knowledge. Other than that my only experience in plastics is with PVC for plumbing and irrigation lines, and ABS for the poopy stuff :)

I have not tried Canon-brand transparency stock. You might just try another brand from the office supply store.

There is also some slightly-thicker (maybe 6-mil?) clear plastic stuff that is used for covers for reports 'n stuff. Also in the office supply store beside the binding machines and combs etc. I have not tried that yet but want to try one (as I have some of that, also left from years ago) just to try a thicker application of solder paste.

Let us know what you find out in materials. I will post the brands/models I have on hand when I get in next week.

thanks,

gil
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Re: Cutting mylar stencils with a silohuette cameo

Postby jesuscf » Fri Apr 05, 2013 3:25 pm

As I suspected, the type of transparency matters when cutting stencils with the Silhouette Cameo. For the two stencils below, I used one of the example Gerber files included with gerber2graphtec: test_0.5mm_0402.gbr.

For the first test I used a Canon type E transparency:

Canon_box (Small).jpg
Box of Canon Type E Transparencies.


The results are a bit disappointing as some of the small holes didn't clear out. You can see in the picture below:

Canon_milar (Small).jpg
Test stencil using Canon type E transparency.


For the second test I used Apollo Overhead Transparency Film. These transparencies are kind of "forbidden" at work because people put them in laser printers/copiers and they melt, ruining the equipment. Thankfully I managed to find a misplaced half box with this information inside:

Apollo_box (Small).jpg
Box of Apollo Overhead Transparency Film


These ones are not as rugged as the Canon transparencies, but the resulting stencils are excellent! All the holes cleared out without trouble and the cuts are cleaner.

Apollo_milar (Small).jpg
Test stencil using Apollo Overhead Transparency Film.


As you can see from the pictures above the results using the Apollo transparency are much better than results with the Canon type E transparency.

Jesus
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Re: Cutting mylar stencils with a silohuette cameo

Postby teletypeguy » Fri Apr 05, 2013 7:35 pm

Hey Jesus:

Nice cuts. We need to compile a list of good vs. bad stock to use.

What was your blade setting? I just used the min of 1 since gerber2graphtec cuts the whole thing twice, and I heard that if your blade is deeper than it needs to be, you run the risk of snapping of a bit of the tip (ruining the blade -- not sure if that is true, as the cutting mat is soft, but I'll play nice).

Were the two stocks the same thickness? If so then one polymer must just be tougher than the other.

You got pretty good pics -- what lens is that?

thanks,

gil
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Re: Cutting mylar stencils with a silohuette cameo

Postby jesuscf » Fri Apr 05, 2013 8:04 pm

Gil,

I used a blade setting of 1 for both tests above. I also experimented with 2 and 3 blade settings with no damage to the cutter, but since the blade is kind of conical, the fine cuts came out a bit stretched out.

The two transparencies types I tested have the same thickness, about 4 mil. The Canon transparency is way tougher than the Apollo one. The Apollo transparency is way easier to cut when using an X-acto knife.

Lens? Whatever the Samsung Galaxy S3 built in camera has.

Jesus
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Re: Cutting mylar stencils with a silohuette cameo

Postby christof » Sun Apr 07, 2013 12:32 am

Hi everybody,

I'm using a Silhouette Portrait (SP) successfully under Win7 and Gerber2graphtec.
I confirm some distorsions if i use the original Silhouette Software instead ! Gerber2graphtec is really better.

So, I have to calibrate my SP using the matrice option ;
I need to extend Y axis up to 0.25%. X axis seem's to be ok.
Please let me know how to convert it into a matrice option, how do you proceed to calibrate yours ?

Thanks , Chris.
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Re: Cutting mylar stencils with a silohuette cameo

Postby jesuscf » Sun Apr 07, 2013 11:00 am

Post by christof » Sun Apr 07, 2013 12:32 am
So, I have to calibrate my SP using the matrice option ;
I need to extend Y axis up to 0.25%. X axis seem's to be ok.
Please let me know how to convert it into a matrice option, how do you proceed to calibrate yours ?


My Silhouette Cameo is spot on, at least for the small PCBs I am testing (max is 3000 mil by 2000 mil) so I didn't have to do any calibration. What I would suggest is to cut a test stencil with two long components (maybe connectors) in the X and Y axis. Measure the result and adjust using the --matrix option in Gerber2Graphtec.

You can use --matrix 1,0,0,1.0025 to compensate for the 0.25% error in the Y axis. I ran a couple of tests using the same Gerber file to see how this option works:

1-0-0-1.jpg
--matrix 1,0,0,1 (default setting)

1-0-0-1.3.jpg
--matrix 1,0,0,1.3


Jesus
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Re: Cutting mylar stencils with a silohuette cameo

Postby christof » Mon Apr 08, 2013 9:11 am

Yes it works fine like this. Thanks Jesus. Chris.
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Re: Cutting mylar stencils with a silohuette cameo

Postby jesuscf » Tue Apr 09, 2013 9:25 pm

Here are three more tests with different transparencies:

Staedtler_995AV_mylar.jpg
Staedtler 995AV transparency test.

Avery_5277_mylar.jpg
Avery 5277 transparency test.

3M_PP2200_mylar.jpg
3M PP2200 transparency test.


Both the Staedtler 995AV and Avery 5277 are good but not great: some distortion can be seen in the horizontal lines. Surprisingly, the 3M PP2200 transparency worked very well, almost as good as the Apollo write-on transparency.

Jesus
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Re: Cutting mylar stencils with a silohuette cameo

Postby 2blmaster » Thu May 16, 2013 2:42 pm

Hi everybody,

I just received my Silhouette Cameo after I got excited reading *this* thread :)

I use it together with the great gerber2graphtec tool
In principle it works as expected and according to what is promised here :)

But trying to print "large" (~10x10 cm²) stencils, I always find a "spot", where the rectangular shapes are "distorted", and not repeated exactly in the different cutting passes... (gerber files are okay!)

Please find a picture attached

Has any of you encountered similar things, or have an explanation for this?

Thanks a lot and cheers
Andre
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silhouette_stencil.jpg
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Re: Cutting mylar stencils with a silohuette cameo

Postby xl97 » Fri May 17, 2013 10:54 pm

hey gang..

I 'too' just got a new Silhouette Cameo..

and mostly to do SMT solder paste stencils! (as well as vinyl stickers and stencil for etching on glass..etc..etc)

I have a few small pieces of mylar I cut off some other solder paste stencils I ordered on-line a while back to 'test with'.

I tried the .ulp file direct export of .dxf file from Eagle (which is the PCB design software I use)... but when I printed.. I wasnt too happy with the results..

cuts were ok in some places.. jagged in other? (and this is a TINY/small pcb.. about size of US quarter or so.. with 0603 footprint parts and ATmega328P-AU main chip)

so Im hoping this gerbertographtec approach yields better results.


Summary:

Machine: Silhouette Cameo
OS: Windows XP
Medium cutting: mylar (3mil)

Downloaded all apps listed above (Phyton, Gerbv, pstoedit, Ghostscript..etc)

installed gerbertographtec in C: root directory... edited the file to add .py extension as well added in the two lines above.

I go to CMD prompt.. and run this:



C:\Documents and Settings\whispers>C:\gerber2graphtec-master>gerber2graphtec.py test.gbr > result.txt

'C:\gerber2graphtec-master' is not recognized as an internal or external command, operable program or batch file.


I even tried executing that from inside the directory (cd to the folder).. same error..

what am I doing wrong?


thanks!
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Re: Cutting mylar stencils with a silohuette cameo

Postby xl97 » Sat May 18, 2013 11:00 am

Well a new day... and still trying! :)

I cant get ANYWHERE with those command lines posted.. not sure if those are for WINDOWS or not?

I dont recognize the > stuff in there?

so I tried to remove those and use slashes like Windows does for its pathing..

and it looks like Im getting a step closer.. but still more odd errors:

C:\Documents and Settings\whispers>C:\gerber2graphtec-master>gerber2graphtec.py
test.gbr > result.txt
'C:\gerber2graphtec-master' is not recognized as an internal or external command operable program or batch file.


C:\>C:\gerber2graphtec-master\gerber2graphtec.py
usage: gerber2graphtec [options] paste.gbr >/dev/usb/lp0

options:
--offset x,y translate to device coordinates x,y (inches)
--border bx,by leave a border around the bounding box of the gerber file
--matrix a,b,c,d transform coordinates by [a b;c d]
--speed s[,s2[,s3]] use speed s in device units; s2,s3 for multiple passes
--force f[,f2[,f3]] use force f in device units; f2,f3 for multiple passes
--cut_mode [0|1] 0 for highest accuracy (fine pitch), 1 for highest speed

defaults:
--offset 4.0,0.5 suitable for letter size (portrait) on the Cameo, fed as "me
dia" not "mat"
--border 1,1 1-inch border in x and y around gerber bounding box
--matrix 1,0,0,1 identity linear transform for scale and skew calibration
--speed 2,2 use two passes, speed 2 in each pass
--force 8,30 use force 8 for first pass, force 30 for second pass
--cut_mode 0 highest accuracy


C:\>C:\gerber2graphtec-master\gerber2graphtec.py test.gbr > result.txt
'C:/Program' is not recognized as an internal or external command,
operable program or batch file.

Problem during opening C:\Program Files\pstoedit\drvmagick.dll:The specified mod
ule could not be found.

Problem during opening of pstoedit driver plugin: C:\Program Files\pstoedit\drvm
agick.dll. This is no problem as long the driver in this library is not needed.
Possibly you need to install further libraries and/or extend the LD_LIBRARY_PATH
(*nix) or PATH (Windows) environment variables.
Could not open file _tmp_gerber.pdf for input
Traceback (most recent call last):
File "C:\gerber2graphtec-master\gerber2graphtec.py", line 104, in <module>
strokes = pic.read_pic(temp_pic)
File "C:\gerber2graphtec-master\pic.py", line 5, in read_pic
f = open(filename,"r")
IOError: [Errno 2] No such file or directory: '_tmp_gerber.pic'



Anybody help out with some suggestions for WINDOWS users to get this up and running?

How does this 'command line' stuff actually find or use the Eagle file you want to use as the source for cutting?

Needs to be in some directory with it?

(command line stuff is kaka!) lol


thanks!
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