Cutting mylar stencils with a silohuette cameo

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Re: Cutting mylar stencils with a silohuette cameo

Postby teletypeguy » Sun May 19, 2013 7:17 pm

...continuing:

Some of the paste smeared -- no big whoop -- it'll reflow nicely even if the pins all look shorted right now. You are more concerned with just having enough of it more or less. Some of those SOIC pads look a little long? I made a hybrid part so I can use normal 150-mil parts, or the wider 209-mil SOP/EIJ parts. Likewise, my MAX202 is able to use the 150-mil narrow or 300-mil wide parts. Why have procurement problems in the future?
ctrl-assy-7.jpg


Tweezers for the small bits (an old fart like me will put on two pairs of reading glasses).
ctrl-assy-8.jpg


Little suction thingy for chips.
ctrl-assy-9.jpg


Time to fry this puppy up on my Tilt-n-Drain Griddle from Walmart. Turned out great!
ctrl-assy-10.jpg
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Re: Cutting mylar stencils with a silohuette cameo

Postby xl97 » Sun May 19, 2013 9:11 pm

nice job!.. I do same.. except, I use a toaster over, not a hot griddle.. :)



I am doing another test run..

bigger piece of mylar in there now..

ran same .bat as posted before..

(I get the same stupid ENTRY POINT error about pstoedit)..

oh, and to comment,.... I have installed all apps in their default locations as well.. no deviation (not sure why or what that errors means)..

I opened by .brd file.. edited out the DIMENSIONS layer... (so it doesnt cut the pcb outline)..

started cut @ 7:45 pm..

my file is no bigger than the size of a US quarter.. (a ATmega328P-Au chip and a couple 0603 leds/resistor footprints..)

last time I sent it to cutter it took over 4 hours..and I had to cancel it..

lets see what happens this time! (from what i could tell form last test.. the cuts were AMAZING!.. and if only 2 hours wait.. Im happy as heck with it!)

would be nice to figure out a way to get the file 'centered' somehow though..

:)
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Re: Cutting mylar stencils with a silohuette cameo

Postby xl97 » Sun May 19, 2013 10:20 pm

test cut 2:

MUCH faster!.. (went upstairs for a few..came down it was done.. but as mentioned its a really small and simple layout)

I had the blade set @ "2".. and some of the holes were ripped/merged together.. (ie: one long hole)

re-doing the same cut at blade setting of: '1'


Test Cut #3:

Resources:
* all apps install as default set-ups
* created directory C:\gerber-files-to-cut (files here are my .bat file and the gerber file I want convert/cut)
* copied gerbertographtec folder to - C:\gerber-files-to-cut\gerber2graphtec (where all default gerbertographtec files reside.. I have only added .py extension and edited those two lines for 'paths' I believe it was for )
* printer shared out correctly (Cameo)
* edited .bat file with my info (computer name)


Settings:
* Blade setting: 1
* Using mat (yes)


File:
* created using CADSoft Eagle
* iTeadStudio CAM file to generate GERBER files (thats usually who I use for pcb fab)
* 0603 footprints & ATmega328P-AU SMD chip



Results:

Total Cut Time: 28 minutes! (no complaints!..on time that is)

* Still getting: "The procedure entry point ?construct@?$allocator@VVPath@Magik@@@std@@QAEXPAVVPath@Magik@@$$QAV34@@Z could not be located in the dynamic CORE_RL_Magik++.dll"

* (Still) Did "NOT" cut all the way through on all holes,....... (using an exacto to push on them..still didnt pop them through.. feeling the backside, its mostly smooth, showing cut didnt penetrate in most areas/holes) what can I do if blade setting 1 isnt enough and blade setting 2 is too much?

* The holes for the ATmega328P-AU chip have VERY little space between the pads... (I got better pad 'spacing' doing trying it with the ULP script that exports a .dxf file for you to use in the Silhouette Studio software from here: http://www.idleloop.com/robotics/cutter ... hp#stencil)... but of course the rest of it cuts like KAKA (slanted squares, rounded bottoms..etc)

maybe trying to compensate for it prior to export by this 'shrinking of the cream layer pads'?

* In Eagle I deleted the Dimensions layer before generating my GERBER files.... it no longer 'cuts this' PCB outline as a result.. (which is NOT the 1" board outline you were commenting on).



Off Topic:

Q1: I saw you mention something about shrinking the cream layers before export? How do you do that?

Q2: Curiosity is getting the better of me.. what is the PCB for in your posts?? haha


this is a nice trick!! (I dig this!)
quote: "I made a hybrid part so I can use normal 150-mil parts, or the wider 209-mil SOP/EIJ parts. Likewise, my MAX202 is able to use the 150-mil narrow or 300-mil wide parts. Why have procurement problems in the future?"


Im going to pick up some of that Apollo write-on transparency sheets.. ($50 a pack.. YIKES!) see if it yields better results than this mylar.. :(

4mil is getting to be thick for fine pitch parts though!.. I dont think Id' wanna use thicker than 4mil... (depends on the components I guess) :)

guess I just keep on playing around?

thanks!
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Re: Cutting mylar stencils with a silohuette cameo

Postby teletypeguy » Sun May 19, 2013 10:28 pm

You can look at your solderpaste gerber in gcprevue before you cut it, but note that editing the DIMENSIONS layer in your eagle board file will have NO effect on your cameo cut. Gerber2graphtec only looks at the outer BOUNDS of ACTUAL CUTS (see the generated pdf), and adds 1 inch extra on all sides to trim it out of the sheet (you can change this trim number in the py file).

Unless your board is large, I don't know why you care where the stencil is "centered" on your sheet of cheap throw-away mylar. As long as your board fits in the 8.5x11 inch sheet, you will be happy to have it cut for you, and you will happily throw the scrap away.

As for the incredibly-long time it takes, if you watch the knife, it will very often move to the upper-right corner for what Peter calls a "training" cut -- this orients the blade (which rotates freely in the holder), to get in the correct position for the next cut or two. This is, I think, the key to the program's cut accuracy. When I cut small rectangles with sil-studio, I could see the effect of the knife rotating as the cut transitioned 90-degrees, and it resulted in totally unusable stencils. Peter's program may be slow, but it works very, very well.

Previously, I cut a small stencil that took a half-hour. The 4.5x4.75-inch one of which I just posted pictures, took two hours. If you have a little board and it is going for four hours, there may be something wrong. It does look like the board should be cut twice though, so if you see it doing the same cuts twice I think that is normal. If it is cutting them more than once, well, i dunno...

gil
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Re: Cutting mylar stencils with a silohuette cameo

Postby xl97 » Sun May 19, 2013 10:53 pm

I think we were both posting at the same time.. LOL

I understand why its so accurate.. goes back to 'home' before each cut!..

I only asked about the placement, because if I want some more meat on my actual stencil.. I have to move some off the matt.. not a big deal or a deal breaker..

and Im not sure where 'connecting' on this Dimensions layer thing.. LOL (although I explained a bit more/better above)..

example my PCB has an ODD shape...... a circle PCB for example.. that 'shape' I want pcb to be cut is in the Dimensions layer....

for the stencil I dont need my PCB outline (the circle) cut.. I only need (like you explained) the 1" in border from the PUTER BOUNDS of ACTUAL CUTS...

cutting out the shape of my pcb defeats the purpose of having a stencil.. hard to smear paste over a sheet/stencil thats the same size/shape as your PCB.. in my first cuts.. this layer was in there.. as I took same gerbers I sent to fab house.. I needed to remove this layer, re-export and use that in my gerbertographtec tests.. :)


I need to somehow fix the spacing (maybe the 2mil shrink of cream layer you mentioned in previous post will help this?) in my ATmega328P-AU pads... (done through Eagle somehow Im assuming?)


yes.. my latest, smaller pcb cut time did take roughly half an hour too.. (which is even better!)

I thikn it gives the BEST cuts as far as 'straight and positioning'... I just need to get full cuts.. so its a 'real' stencil!! lol..

maybe shrinking cream layer and going to blade setting of: 2?


thanks!
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Re: Cutting mylar stencils with a silohuette cameo

Postby teletypeguy » Sun May 19, 2013 11:14 pm

I just looked at my solderpaste gerber in gcprevue, and there is no board outline from the dimensions layer. I don't know what might be different about your itead cam export, but it must be different than mine. I just use the standard eagle CAM-processor (I get my boards at myro, but gerbers are gerbers). I also use an older eagle version 4.16 on XP, as years ago we paid a shit-load of money for the full pro version (as we needed big boards with 6+ layers), and with the autorouter (which we have only used once), and have really never needed to spend another thousand bucks to upgrade it (except for a few more-recent libraries we can't open).
To export gerbers:
File/CAM-processor
File/Open/Job
(select our 6/4/2-layer.cam file, which just defines solderpaste-top as a .SPT, RS274X...)
Process-Job...

To shrink the solderpaste (which I think is important for the cameo cuts), open your board in eagle, click on DRC, click the MASKS tab -- it has settings for STOP (solderMASK), and CREAM (SolderPASTE) layers. They do the opposite:
--- when you select a positive number for the STOP layer, it makes the mask wider, so your soldermask has some clearance around your pads to compensate for soldermask registration.
--- when you select a positive number for the CREAM layer, it makes the mask narrower, so you can compensate for stencil registration, and also the spreading of the gooey, oozing, disgusting, solderpaste, by shrinking it a bit.
I have STOP set to 5mil-min/100%/5-mil-max (so it is always 5mil wider).
I have CREAM set to 2mil-min/100%/2-mil-max (so it is always 2mil narrower).

If you have tight holes blowing out, it might be helped by shrinking the cream layer. However, even if the paste spreads across all of the pins in one giant rectangle, it will likely reflow quite nicely with no shorts.

As jesuscf pointed out, not all transparency film cuts the same. He had good luck with Apollo write-on stuff (and bad luck with Canaon) -- I am using Apollo Inkjet stuff, but have tried 3M and Highland (also 3M) sheets, and they were all much the same for me (the Apollo probably a tad better). I can't comment on current prices as all three boxes of this stuff has been sitting in the closet since the late 90s, when we actually gave presentations with overhead projectors :)
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Re: Cutting mylar stencils with a silohuette cameo

Postby teletypeguy » Sun May 19, 2013 11:26 pm

In Peter's gerber2graphtec.py program is a line that sets the 1-inch border around the cut boundaries:
border = (1,1)

which you can change for a 2-inch border:
border = (2,2)

If it is also cutting out your board outline, you have a problem with your CAM processor's gerber generation (which should not include the Dimensions layer).
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Re: Cutting mylar stencils with a silohuette cameo

Postby 2blmaster » Mon May 20, 2013 7:30 am

Hi all,

I solved my recent problem with the Cameo (see ~2 pages backwards), not cutting every area of the stencil correctly.

I did so, by modifying the optimize.py of the gerber2graphtec tool.
The tool by default adds *plenty* of "knife-positioning" cuts just outside the area of the stencil. This takes a lot of time, and also needs to move the cutting mat back and forth again and again. Somehow (??) my cutter messed up with that, and made the cuts not straight...

I modified the python code to just do a single "training" cut per cutting angle that is used in the file, and then do all cuts with this angle in a row. This needs the mat to be moved completely only once per angle.

I don't know, whether Peter (author of gerber2graphtec) added this by purpose or not (already contacted him), but for me it works reasonably faster and better without the zounds of training cuts in between.

Please find my modified version attached - maybe it is useful for some of you.

Cheers
Andre
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Re: Cutting mylar stencils with a silohuette cameo

Postby timb » Mon May 20, 2013 12:42 pm

Awesome, thanks for that Andre! I was wondering why it was re-homing the blade after every cut.

I got gerber2graphtec working (Mac OS X 10.8) on the Silhouette SD last night by simply adding the USB PID to the file. It cut beautifully! I'll give it a test on my CraftRobo Pro later this afternoon, but I don't see any reason it won't work.

Now, the CraftRobo actually has a parallel port on it in addition to USB, so I'm wondering if I could hook a print server to it for wireless printing. It's a JetDirect, so that should be a RAW transport...
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Re: Cutting mylar stencils with a silohuette cameo

Postby xl97 » Mon May 20, 2013 12:54 pm

I havent been able to get a clean cut all the way through using blade setting of 1..

a setting of: 2 rips corners..and merges small pads together..

any ideas on a fix or work around at this point

Windows XP
stock set-up
using .bat file posted

Im going to try and shrink the cream layer tonight (alot) and try a blade setting of two again..

(since setting 1 doesnt make it all the way through)

@2blmaster -

anything this there (optimize.py file) or pressure or thickness settings?


Im stuck in between the IDLE LOOP approach and the GERBERTORAPHTEC approach..

1.) not the best 'cuts' as far as alignment/straight, but all the way through, and good spacing
other
2.) great 'looking' cuts, bad spacing (maybe fixable before export in Eagle).and didnt cut through the mylar all the way.. =(
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Re: Cutting mylar stencils with a silohuette cameo

Postby timb » Mon May 20, 2013 1:56 pm

@xl97 Have you tried physically adjusting the blade? If you pop it out of the holder, you should be able to adjust blade depth by twisting the cap.
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Re: Cutting mylar stencils with a silohuette cameo

Postby xl97 » Mon May 20, 2013 2:19 pm

yep! :)

if you are referring to the 'rachetting' blade..yes..

I have tried blade settings 1 & 2


"I havent been able to get a clean cut all the way through using blade setting of 1..

a setting of: 2 rips corners..and merges small pads together.."


or is there another way to adjust it, using this gerbertographtec Python approach?
as far as I know thats the only way to adjust the blade using this method..right? :)

In Silhouette Studio I know there are settings for speed & thickness/pressure... but not using this .bat file/Python script approach. (or did I miss it?) :)


1 'looks nice' but just doesnt cut all the way through.

see if I can shrink things.. and try blade 2 again..

this is the same mylar that Pololu.com uses for their stencils..

Hoping to pick up some of the Apollo write-on transparencies tonight though.. (they are expensive though, so I hope this works out!) lol
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Re: Cutting mylar stencils with a silohuette cameo

Postby timb » Mon May 20, 2013 4:28 pm

Oh, yeah you can set blade pressure with gerber2graphtec using the --force command.

"--force f[,f2[,f3]] use force f in device units; f2,f3 for multiple passes"

So, --force 5,10,15 will do one pass at pressure 5, another at 10 and another at 15.

Edit: The default is a first pass at 8 and a second pass at 30.
Last edited by timb on Mon May 20, 2013 6:12 pm, edited 2 times in total.
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Re: Cutting mylar stencils with a silohuette cameo

Postby xl97 » Mon May 20, 2013 4:55 pm

hmm..

thanks for that!!

I'll have to poke around more I guess..

1.) Im on Windows.. (so Im never sure if this is applies to windows or only Linux/mac people...seems ot be edit to script..so shouldnt matter?)

2.) if you (dare) read back on my posts.. I could never get a command line to work from a CMD prompt....
I always got error(s), after error(s) (I believe this was because I originally thought the > needed to be replaced for / because of the Windows pathing/file system).. it was until I used the .bat file posted that I was even able to get past (most) errors..and actually send anything to the Cameo to be cut..

*I still am getting some GerbV error about an Entry Point..etc..etc and Image_Magik++.dll dynamic library..etc..


Here is the .bat file I am using

@echo off
rem This is for printer named "Cameo" which must be named and shared in control panel.
rem This is for computer named "hacker"
echo.
echo This script will send gerber file to Cameo for cutting solder stencil.
echo Generates intermediate files .pdf, .pic, and .graphtec.txt
echo.
echo Set your Cameo blade to 1 and turn cutter on.
echo Load mylar sheet (landscape) at upper-left corner of mat.
echo.
set /p filename= Enter filename of gerber (eg: test.spt or board.gbr):
gerber2graphtec\gerber2graphtec.py %filename% > %filename%.graphtec.txt
copy /B %filename%.graphtec.txt \\hacker\Cameo



--force f[,f2[,f3]] use force f in device units; f2,f3 for multiple passes"
Im guessing I need to add this parameter to/after the gerbertographtect.py?

gerber2graphtec\gerber2graphtec.py--force 33, 33 %filename% > %filename%.graphtec.txt

for two passes at full pressure? (for example)

also where did you find this --force info?

readme? in some file> some documentation I havent seen perhaps?
edit: found 'em..

offset = (4,0.5)
border = (1,1)
matrix = (1,0,0,1)
speed = [2,2]
force = [8,30]
cut_mode = 0

what is CUT MODE?

thanks!
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Re: Cutting mylar stencils with a silohuette cameo

Postby timb » Mon May 20, 2013 7:00 pm

Yes, put it after gerber2graphtec.py, but add a space. (gerber2graphtec.py --force 10,20)

You want the first pass to be lower pressure, which will give you a more accurate shape as it will score on the first pass and actually do the cut on the second.

cut_mode 0 will increase precision at the expense of speed and 1 will sacrafice precision for the sake of a faster cut.

Here's where some of the info is located: https://github.com/pmonta/gerber2graphtec

The rest came from the command line:

timbmba:gerber2graphtec timb$ ./gerber2graphtec
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 "media" 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
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