Cutting mylar stencils with a silohuette cameo

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Cutting mylar stencils with a silohuette cameo

Postby teletypeguy » Fri Mar 29, 2013 2:57 am

Hey folks:

I saw this note from Laszlo buried in a pnp thread and wanted to start it as a new topic:

László Monda says:
February 21, 2013 at 11:36 pm
Instead of messing around with the solder paste dispenser I highly recommend you picking up a Silhouette Cameo.
So far I’ve had wonderful results with it. Created a short video and some pictures of the action at https://plus.google.com/photos/10643536 ... 0625134033
Also take a look at
http://www.idleloop.com/robotics/stencil/index.php https://github.com/pmonta/gerber2graphtec
http://hackaday.com/2012/12/27/diy-smd- ... ft-cutter/


Yes Laszlo, I too was impressed with the fine-pitch (even 0.5mm looked workable) stencils that Cathy was cutting with her cameo:
http://www.idleloop.com/robotics/cutter ... hp#stencil
http://www.idleloop.com/robotics/stencil/

I peeked at your pics/vid as well, but could not see close up -- how fine a pitch did you cut? What were your cut settings?

I just got a cameo for making stencils as well, and fired it up today with a sheet of mylar overhead transparency film. I used the eagle ULP file linked from Cathy's site, which very nicely extracted a dxf file for the cameo to open. Sadly, I was quite disappointed in the resulting stencil, and think perhaps I got a bum machine. I used the same settings Cathy used (blade depth 1, speed 1 = slowest, thickness 33 = max-force). Tweaking these didn't change my two fundamental problems: 1) a square shape is actually a right-leaning parollelogram, and 2) the straight sides are actually bowed out.

Here is a pic of simple 100-mil and 50-mil squares:
100-and-50-mil-squares.jpg


A 50-mil pitch SOIC and SOT23:
50mil-pitch-soic-and-sot23.jpg


A 0.65mm (26-mil) pitch TSSOP:
0.65mm-(26mil)-pitch-tssop.jpg


And a 0.5mm (20-mil) pitch HDMI connector with SOT23 for reference:
0.5mm-(20mil)-pitch-hdmi-and-sot23.jpg


Am I doing anything different than you? Any thoughts appreciated.
thx, gil smith
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Re: Cutting mylar stencils with a silohuette cameo

Postby royco » Fri Mar 29, 2013 11:11 am

I cut all my stencils for prototypes using my Silhouette SD, its an older machine that comes with replaceable needle caps to adjust cutting thickness. The settings I have that work perfectly (and I mean super clean cuts on kapton sheets from Mcmaster) are SPEED: 3 , THICKNESS: 14 and BLADE CAP: Yellow (middle). These are on Silhouette studio. I export dxf from diptrace, fix/adjust it on inkscape or coreldraw and open up the DXF in silhouette studio.

I also have a Cameo but have not successfully converted those settings into the newer adjustable blade that it comes with.

I think your material may be shifting while being cut and causing the slight angle. What is the thickness of the transparency film? The kapton film I use is 2 mils I think.

Here are some tips on getting it nice and clean.

1. Make sure you cutting mat is free from debris when you place your stencil sheet, I scrape it with an unused PCB to remove all of the left over cut kapton.

2. Once you placed your stencil film use another PCB or credit card to squeegee the trapped air and flatten it out. This is very important because once you have air packets in there the blade will rip closely placed cuts into one big hole.

IMG_1040a.jpg
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Re: Cutting mylar stencils with a silhouette cameo

Postby teletypeguy » Fri Mar 29, 2013 11:46 am

Hi royco:

Thanks for the feedback -- looks like everyone who cuts stencils has good luck, so I just need to find out what I am doing wrong.

First off, please pardon the spelling errors; I do indeed know how to spell parallelogram and silhouette (unfortunately I don't see a way to edit the original subject line), but it was pretty late last night. Also pardon the crappy pics as I didn't have my macro rings handy and had to resort to the remove-the-lens-and-hold-it-backwards trick (the combination of razor-thin dof and hand-held shooting makes it tricky to get a decent pic).

The material I used is clear mylar overhead-transparency sheet stock. Some have called it out as 3-mil, but when I checked with my micrometer I measured about 4-mil. I have three brands, all of which measure and cut the same.

Yes, it is a clean cutting mat. Everything is brand-new. After each cut I did scrape all the little bits off the mat, and did ensure that there were no bubbles when putting the mylar on the sticky mat.

I wonder also whether the mat is slipping, but I am not sure whether that would result in the parallelogram shapes -- when the rollers are driving the mat out (towards the front), it is cutting a line from front-to-back, but the line is veering to the right as if the knife-head is not stationary on its horizontal track, or as if the mat is moving to the left. When cutting in the opposite direction, it is the opposite (as if the mat is moving to the right as it drives inwards). If the mat was just not being gripped well, I would expect less-predicatable movements, I would think. As for the bowed-out lines, I don't really have an explanation yet.

I need to try some more tests when I get back in Monday -- hopefully I will be able to solve this, as it looks like a dandy little machine.
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Re: Cutting mylar stencils with a silohuette cameo

Postby mondalaci » Sat Mar 30, 2013 8:44 pm

Hey Gil,

The relevant thing to note is that I haven't ever used the bundled Silhouette Studio software because I use Linux and it's not available on Linux. Even if I could have used it I wouldn't because I'm fairly sure that it's not optimized for super-precise cuts like for fine-pitch stencils. Intead I rather used the https://github.com/pmonta/gerber2graphtec script. I don't know how much of a command line guy you are but this tool basically receives gerber files and outputs Graphtec files that can be directly sent to the cutter.

I'm fairly certain that the generated Graphtec file takes a LOT longer to cut than what Silhouette Studio would have done because the cutter recalibrates (goes to the origin coordinates) very often, moves slowly and only draws horizontal or vertical lines in one pass instead of turning from horizontal to vertical in one pass (and mess up corners).

Right now I'm unable to shoot close-ups because I'm away from my cutter but I'll be able to make some pretty pictures about a week later if you want me to, but let's just say that I couldn't be more satisfied with the result.

Cheers,
Laci
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Re: Cutting stencils (and overlays) with a cameo

Postby teletypeguy » Sun Mar 31, 2013 11:59 am

Hi Laci:

Thanks for the feedback. There are two things I want to do with the cameo: cut smt stencils, and cut overlays for rear-panels on products.

Your graphtec stencil solution sounds nice. Going slowly should definitely help. In sil-studio, with the slowest speed of 1, it still seems way too fast to me. The dxf files from the eagle ulp supposedly break a rectangle into four lines, to get around the rounded-corner thing. I have macs and win machines but never got into linux. I did do unix many years ago when I worked at cray research, so that will tell you what an old fart I am.

STENCILS:
The stencil thing is, of course, demanding on the cameo machine, but many folks have had good results even to 0.5mm, so I am optimistic. I need to find out if I have a user problem, feed/slipping problem, or a defective machine. The eagle ulp extracts the cream layer into separate cuts in a dxf file, which sil-studio imports and cuts. The Sil-Studio software does provide for small holes, down to a resolution of 5-mil at least, iirc. Gotta figure out my problem.

CHASSIS OVERLAYS:
For overlays, the Sil-Studio software has, for "drawing" the cut layer, the important tools I need like in adobe illustrator -- precision sizing and movements of circles and rectangles, copy-paste-exactly-in-front-and-move-precisely, etc. It has a print-and-cut feature which lets you import a graphic (eg: jpg), and print it out to an inkjet or other printer, adding registration marks. You then load the printed piece into the cameo, and send it the cut file -- it optically locates the reg marks and cuts precisely on your image. It was designed so you could print out a cute unicorn or some crafty thing and cut around it, but it is much more capable than that if I understand this correctly. I have yet to try this, but here is the plan:
- my rear-panel drawings are in illustrator at the moment, which has a low-res jpg export, but:
- I can open the ai file in photoshop and save a hi-res jpg (600dpi is about the max I could import into sil-studio)
- my file has thin (1-mil) hairlines for the connector openings and the outer box that need to be cut, and the image to print.
- the main image is, of course, the lettering that identifies the connectors, logo, whatever -- can be full color gradients or a pic of my kids beside the connectors.
- print this from sil-studio to my inkjet (which can do 11x17 for big overlays) on inkjet-ready, adhesive-backed plastic sheets
- add the cutlines in sil-studio for the connector openings and outside edge -- have done this and it is easy to line up with the hairlines, and can be very precise.
- load the sheet and cut. Going to try this next week.

thanks,

gil
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Re: Cutting mylar stencils with a silohuette cameo

Postby mondalaci » Sun Mar 31, 2013 1:05 pm

Hey Gil,

No matter what operating system you're using, I'm pretty sure that you should be able to make the gerber2graphtec tool work. It might not be the most user friendly application out there but it does work. So far I only cut stencils out of gerber files using this tool so it's all I know. If you have any specific questions, feel free to ask me.

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Re: Cutting mylar stencils with a silohuette cameo

Postby teletypeguy » Sun Mar 31, 2013 3:09 pm

Hi Laci:

I peeked at the gerber2graphtec stuff, and while the command-line operation doesn't bother me, I don't have a linux machine (except macs), and I still don't see an easy way to run it on windows. The scripts are in python, and, well, I only know monty python. Then there is the whole windows filename slash-vs-backslash thing that dates back to the days when gates and seattle computing ripped-off digital research's cp/m...but I digress.

However, maybe it would be cleaner on a mac, what with linux under the hood and all. From the github page it looks like it needs xcode and some other stuff loaded, but it might not be too bad. Any thoughts on running it on mac? I have a mini-server with lion, and laptops with earlier osx versions. I'd be up for trying it if you think it's worth a try.

thanks,

gil
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Re: Cutting mylar stencils with a silohuette cameo

Postby mondalaci » Sun Mar 31, 2013 6:06 pm

Gil,

Yes, a Mac would definitely be a better choice than Windows because of its Unix legacy. The README file does a decent job at listing the dependencies and giving some instructions for Mac. I don't have any better idea, unfortunately.
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Re: Cutting mylar stencils with a silohuette cameo

Postby teletypeguy » Mon Apr 01, 2013 1:02 am

Hi royco:

I cut all my stencils for prototypes using my Silhouette SD, its an older machine that comes with replaceable needle caps to adjust cutting thickness. The settings I have that work perfectly (and I mean super clean cuts on kapton sheets from Mcmaster) are SPEED: 3 , THICKNESS: 14 and BLADE CAP: Yellow (middle). These are on Silhouette studio. I export dxf from diptrace, fix/adjust it on inkscape or coreldraw and open up the DXF in silhouette studio.


I don't know anything about the SD machine, but I think it has similar capabilities as the cameo. Is sil-studio the same for both machines? If so, your SD at speed=3 is cutting better than my cameo at speed=1.

Why kapton? I don't know anything about that polymer except that it is apparently dandy for spacesuits. Is it more dimensionally-stable than a garden-variety polyester (mylar), or polycarbonate? Does it cut better?

What is the smallest stencil pitch you are cutting? What is the thickest material you can cut?

thanks,

gil
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Re: Cutting mylar stencils with a silohuette cameo

Postby jesuscf » Mon Apr 01, 2013 6:23 pm

teletypeguy » Fri Mar 29, 2013 2:57 am

I just got a cameo for making stencils as well, and fired it up today with a sheet of mylar overhead transparency film. I used the eagle ULP file linked from Cathy's site, which very nicely extracted a dxf file for the cameo to open. Sadly, I was quite disappointed in the resulting stencil, and think perhaps I got a bum machine. I used the same settings Cathy used (blade depth 1, speed 1 = slowest, thickness 33 = max-force). Tweaking these didn't change my two fundamental problems: 1) a square shape is actually a right-leaning parollelogram, and 2) the straight sides are actually bowed out.


I also got a Silhouette Cameo a couple of days ago with similar distorted results for my first tests. The problem is that the Silhouette Cameo is not very precise when cutting traces at 90 degrees. If you draw your solder paste holes using only individual trace lines the results are considerably better. For instance, instead of using trace rectangles to cut the pads use four trace lines. Cathy mentioned in her page that she used a custom dxf exporter for Eagle. I think that the converter is using only lines and no rectangles. I don't used Eagle, so I used a PNG file exported from gerbv which I loaded in Silhouette Studio. When I used the auto-trace with the Silhouette Studio, the program put a bunch of rectangles. After cutting, the holes looked exactly like your pictures. Then I drew the rectangles using only lines and the results are very good, very similar to what Cathy reported.
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Re: Cutting mylar stencils with a silohuette cameo

Postby jesuscf » Wed Apr 03, 2013 1:02 am

After a few small hacks I got gerber2graphtec working on Windows 7. First, I had to install Python (version 2.7.3, version 3.x.x may not work), gerbv (version 2.6.0), pstoedit (version 3.61), and ghostscript (version 9.07). I download these programs from:

http://www.python.org/
http://sourceforge.net/projects/gerbv/files/gerbv/gerbv-2.6.0/
http://www.pstoedit.net/
http://www.ghostscript.com/download/gsdnld.html

I downloaded gerber2graphtec from

https://github.com/pmonta/gerber2graphtec

by clicking the 'Download this repository as a zip file' button. I unzipped the downloaded file to a folder, say 'C:\gerber2graphtec-master'.

After that, I renamed gerber2graphtec to gerber2graphtec.py to run the program directly from a command window. Then I edited the two lines that convert the Gerber file to pic format in gerber2graphtec.py from:

Code: Select all
os.system("gerbv --export=pdf --output=%s --border=0 %s" % (temp_pdf,input_filename))
os.system("pstoedit -f pic %s %s 2>/dev/null" % (temp_pdf,temp_pic))


to:

Code: Select all
os.system("\"C:/Program Files (x86)/gerbv-2.6.0/bin/gerbv\" --export=pdf --output=%s --border=0 %s" % (temp_pdf,input_filename))
os.system("\"C:/Program Files/pstoedit/pstoedit\" -q -f pic %s %s" % (temp_pdf,temp_pic))


since neither the installation programs for gerbv nor pstoedit added their executable folders to the path. Finally, I shared the Silhouette Cameo 'printer' by right clicking on its icon in the 'Control Panel\Hardware and Sound\Devices and Printers' folder, selecting the 'Sharing' tab, clicking 'Share this printer' and setting its sharing name to 'Cameo'. To run the program and cut I typed in a command prompt:

Code: Select all
C:\gerber2graphtec-master>gerber2graphtec.py test.gbr > result.txt
C:\gerber2graphtec-master>copy /B result.txt \\JCF-PC\Cameo


where JCF-PC is the name of my computer as it appears on 'Control Panel\System and Security\System'. (Of course, you'll have to put the name of YOUR computer, not mine!) Half a noisy hour later I had a perfect stencil!

Also, typing

Code: Select all
C:\gerber2graphtec-master>gerber2graphtec.py test.gbr > \\[YOUR COMPUTER NAME]\Cameo


should work as well, but I hadn't tried it.
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Re: Cutting mylar stencils with a silhouette cameo

Postby teletypeguy » Thu Apr 04, 2013 12:01 am

Hey jesuscf:

Thanks for your posts. It was good to hear that someone else was seeing the same thing I was with the cameo. Here's an update:

I called silhouette-america tech support asking why I am seeing the rotated rectangles and squares with bowed-out edges. The first call ended since I didn't have the latest version of sil-studio. So I loaded it, and gee, same thing. So I called back and they wanted pics and such, which I was happy to provide, and I fired off an email with pics, a dxf file and the resulting studio file, and another studio file in which I used their drawing tools to create arrays of squares. I told them I have tried two different knives, that the knife was properly seated and clamped, that the mat is loaded properly and centered with the rollers in the proper position, and that the mat release lever was in the clamped position. I told them that the mat was very secure under the rollers (I could not move it after load), and that I had the latest sil-studio software. I told them that I was cutting polyester (mylar) overhead transparency sheets that I mic'd to about 0.004", that my blade depth was the minimum (1), that the speed was the slowest (1), and that I tried force (thickness) settings over a varying range, with the same result. I told them that I tried cutting on 0.007" (65lb) cardstock, at settings appropriate for that media, with the same result. I told them that many other folks with cameos are cutting rectangles down to 10-mil-wide with 10-mil space (~0.5mm pitch). I told them I would be happy with rectangles that were 15-mil-wide with 10-mil space (TSSOP ~0.65mm pitch). I told them that I could not even do rectangles that were 25-mil-wide with 25-mil space (SOIC 50-mil pitch) with the test I ran.

They replied, "Can you confirm whether you see this problem with a sheet of regular printer paper?" Which I did, and told them so, and I will never load thin paper again as it not only gets ripped up, but leaves a fibrous mess on the mat.

Then they requested pictures of my media loaded on the mat, and pics of me loading the mat into the machine. I replied that I would not be at the machine until Thursday, and asked how either a slightly-rotated media sheet or even a rotated mat load would result in the hole-to-hole pattern problems, and that I did not care how the entire pattern was oriented wrt to media edges.

They replied that if it cannot be resolved, that they will swap out the machine, which is great, but am now wondering whether that will result in the same problem.

I asked them if they had tried cutting the test files that I sent them, to see if it happened on one of their machines, whether they had a test file for me to try cutting, whether four line segments cut differently than a rectangle, how I could change a rectangle in sil-studio to four lines, and whether there was any special mode I could use to cut much slower than speed 1.

They replied that my hole sizes were too small to cut well on this material type (it is the same on all materials). Maybe they tried cutting my test files, I am not certain. They didn't answer any of my other questions, but asked me to cut some squares that are 1" and 0.5" size. Not sure what that will tell them. I am certain this is just going to end up with an answer of "not our problem; it's not designed for that use." Which is true, but I think they are missing a technical market. I'm feeling like my questions were not escalated to someone who could actually recognize the error and offer a solution, but it may never get that far. I can likely get them to swap out the machine, but I am not convinced that will help.

I am wondering whether the dxf file exported by the eagle ulp actually has four cut lines instead of a rectangle. I don't have autocad, and have only looked at it with an online dxf viewer. When the dxf is imported into sil-studio, I can only select it as a rectangle, not line segments, so perhaps it was not actually four lines, or perhaps the sil-studio import converted it into a rectangle. If that is the case, it would explain why it cut just like the test of studio-drawn squares.

I was actually happy to hear that you saw the same problem and found a solution. I am trying your fix, but I will continue this in another post.

thanks,

gil
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Re: Cutting mylar stencils with a silhouette cameo

Postby teletypeguy » Thu Apr 04, 2013 12:10 am

Hi jesuscf:

First, a thanks also to mondalaci who pointed out the gerber2graphtec script as a solution. I don't care whether it is slow -- even if it takes an hour to cut a stencil, I will be happy.

OK jesuscf, I have been working through your win7 scheme for doing this. On a win7 machine, I loaded all the programs you listed (python 2.7.3, gerbv 2.6.0, pstoedit 3.61, ghostscript 9.07). I installed them all in their default locations. I downloaded the gerber2graphtec stuff into a folder at c:, added the .pf extension and edited the file as you indicated. So far so good.

I opened a command window, did a cd to that directory, and tried to issue the first command line. Unfortunately, it complained that "'gerbv' is not recognized as an internal or external command..." and printed some traceback stuff and exited. I would have pasted it in here but it seems that even in 2013, microsoft has not provided a way to copy or paste in a command window (sheesh).

Also, even though I have installed the sil-studio program, there is no cameo printer in my system control panel. That may just be since I don't have it here to plug in, IDK. When I plug it in tomorrow, I will look for the cameo printer and share it so the script can find it, but it was not needed for the first command line test, so I have another issue to resolve.

Do you have any idea why the script is complaining about gerbv? Both gerbv and pstoedit are installed in the exact same places on c: as your system, so the edited lines should be identical to yours.

I am a bit stumped, and not particularly fluent in the command line. I presume there is a way to explicitly append the locations of gerbv and pstoedit to the path, but I am not certain just how.

Anyway, I am hoping I am close to being able to try this out when I get into the office in the morning.

thanks for your detailed post -- I hope to get this running soon to see if my little machine will work.

gil
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Re: Cutting mylar stencils with a silhouette cameo

Postby teletypeguy » Thu Apr 04, 2013 12:25 am

Ahh, user-problem. Just noticed that while I had edited the .py file with your tweaks, I neglected to save it before running the command line test. Yes, the first command line worked fine and generated the result.txt file.

Will try it out in the morning and let you know how it cuts!

thanks again,

gil
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Re: Cutting mylar stencils with a silhouette cameo

Postby Sjaak » Thu Apr 04, 2013 4:29 am

teletypeguy wrote:I opened a command window, did a cd to that directory, and tried to issue the first command line. Unfortunately, it complained that "'gerbv' is not recognized as an internal or external command..." and printed some traceback stuff and exited. I would have pasted it in here but it seems that even in 2013, microsoft has not provided a way to copy or paste in a command window (sheesh).


try right-click on the cmd box, mark. now you select the things in the box with the mouse cursor, right click, it is copied.. it even has a select all option :D

If the buffer is too small right click the topleft corner, properties, layout, buffersize.
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