resizing a pcb  - Page 1
Forum section: electronics / general

author: Deathwish
author_rank: Unknown
timestamp: August 21, 2015, 10:43:52 pm
content: I have a pcb in jpg format on my pc. if i print it out it fits an A4 page !, not exactly what I want. I need to resize it so it comes out to it's proper size, does anyone know of anything that will do this, my only way of knowing the correct size is going to be by resizing it so the dip pins come out at 2.54 apart.

author: T3sl4co1l
author_rank: Super Contributor
timestamp: August 21, 2015, 11:11:40 pm
content: It's in the wrong format for about three reasons...Best you can do now is keep printing it at different scales / fit-to-widths and see how close you can get it.Back in the day, I used gerb2tiff at 600 DPI output, saved TIF as 2-color PNG (with DPI scale included, optionally), embedded that in a PDF at net size, and printed that at 100% (not "reduce to margins", which shaves about 5% off -- I've already made the margins!).Ultimate accuracy is limited by paper, which shrinks and expands nonuniformly due to temperature and humidity. One region might be in perfect registration with another layer (top vs. bottom, or drill, or..), but rarely so across the length of a full board.Tim

author: Deathwish
author_rank: Unknown
timestamp: August 21, 2015, 11:15:51 pm
content: Thanks Tim. Guess it's going to be a long slog.

author: Wilksey
author_rank: Super Contributor
timestamp: August 21, 2015, 11:40:47 pm
content: I presume you don't have the original PCB files?Do you have the means to recreate the PCB as it would be less hassle!

author: Aodhan145
author_rank: Frequent Contributor
timestamp: August 21, 2015, 11:51:48 pm
content: Open the jpg in photoshop. Then print at 100% size or 600 dpi.

author: tautech
author_rank: Super Contributor
timestamp: August 22, 2015, 12:17:12 am
content: Quote from: Deathwish on August 21, 2015, 10:43:52 pmMeasurement of your printed copy and simple maths should indicate the image scaling required.If you know the external measurement it is supposed to be this should be very simple if you have a printer that allows scaling.Otherwise do the layout again in one of the many free PCB cad programs available.

author: Deathwish
author_rank: Unknown
timestamp: August 22, 2015, 12:25:30 am
content: It has no references as to actual size, it is in fact the hakko 936 pcb that the late Tom Hammond put up on his site.

author: tautech
author_rank: Super Contributor
timestamp: August 22, 2015, 12:33:52 am
content: Measure the image DIP pins overall, compare with physical DIP and do the maths = scaling %. Easy.

author: T3sl4co1l
author_rank: Super Contributor
timestamp: August 22, 2015, 10:01:11 am
content: Quote from: Aodhan145 on August 21, 2015, 11:51:48 pmThat's the trick. See, JPG is a raster image format, nothing else. It has no scale information. It is equally valid to print a JPG at 1mm or 1km width, and call that "100% scale". No matter if it's 1 pixel wide or 1,000,000.Even more subtle:Even if the full JPG image represents a standard film size (say, a 3x5" print), that doesn't mean the thing photographed is at the same scale, too. A photo of a PCB could be at any distance and scale.Probably a combination of these is at work. Tautech's suggestion is really the only thing you can do. Once you get that calibration (and verify it with a real print, at the correct scale), I would suggest saving it in a format which does include size or DPI information, such as PNG, or embedded in a PDF.Tim

author: Deathwish
author_rank: Unknown
timestamp: August 22, 2015, 10:02:33 am
content: the original file is a pdf file but it still prints at almost a full size A4 page whatever i do

author: tautech
author_rank: Super Contributor
timestamp: August 22, 2015, 10:09:23 am
content: Quote from: T3sl4co1l on August 22, 2015, 10:01:11 amQuote from: Deathwish on August 22, 2015, 10:02:33 amOr get a decent printer that allows scaling.

author: TheElectricChicken
author_rank: Frequent Contributor
timestamp: August 22, 2015, 10:21:34 am
content: Quote from: Deathwish on August 21, 2015, 10:43:52 pmI can resize attachments in my sleep, if you have any file that prints out correctly then put it, along with the bad one, attached to a message and next time I nod off I'll fix it for you.

author: Aodhan145
author_rank: Frequent Contributor
timestamp: August 22, 2015, 10:48:40 am
content: Quote from: Deathwish on August 22, 2015, 10:02:33 amPrint att 100% with the pdf it is one of the settings inadobe acrobat

author: Deathwish
author_rank: Unknown
timestamp: August 22, 2015, 11:36:39 am
content: you can find it herehttp://dalincom.ru/datasheet/HAKKO_936_schematic.pdf

author: TheElectricChicken
author_rank: Frequent Contributor
timestamp: August 22, 2015, 11:53:39 am
content: Ok I have loaded that one, now I need one that is the right size to compare. Any other circuit board picture that prints correctly for you and I'll line up the chips.

author: Deathwish
author_rank: Unknown
timestamp: August 22, 2015, 12:14:54 pm
content: No I havent tried any others, that is in fact the only board i really want to try making for the fun of seeing if it works

author: Aodhan145
author_rank: Frequent Contributor
timestamp: August 22, 2015, 12:44:02 pm
content: I will scale it save as png then you can print it out.Both my printers are out of ink.

author: Zero999
author_rank: Super Contributor
timestamp: August 22, 2015, 12:57:19 pm
content: Quote from: T3sl4co1l on August 22, 2015, 10:01:11 amIt's also lossy compression so the edges of lines will be blurred.You might be able to fix that in imaging editing software and saving to a format which doesn't distort it such as TIFF or PNG. To avoid the file being extremely large you can use 1-bit monochrome format.

author: Deathwish
author_rank: Unknown
timestamp: August 22, 2015, 01:02:40 pm
content: Thanks everyone, if it works we will have to make it available for others to use

author: Aodhan145
author_rank: Frequent Contributor
timestamp: August 22, 2015, 01:09:19 pm
content: Is that the only board on a hakko 936? I might build one.

author: TheElectricChicken
author_rank: Frequent Contributor
timestamp: August 22, 2015, 01:24:13 pm
content: I don't have anything to compare it to yet. I kind of need something that you are able to print out with some success. You can however tell me how big you need it compared to how big it is.Also, because of the rough edges of the tracks, I thought it best not to reduce it in image software, because it gets even worse (blurry) so enlarging the page it is on and then allowing the printer software to do it MIGHT be the go, but I can image enhance too if that doesn't work. But the size is a good idea for now.

author: Balaur
author_rank: Unknown
timestamp: August 22, 2015, 01:27:10 pm
content: The PCB from the original PDF file is vector. Why do you would want to go through the hassle of making a bitmap file and printing that one?Just print the PDF page at the correct scale. The print dialog of Acrobat has a "Custom Scale" option. Use it!To roughly estimate the required scaling factor, I measured the distance between the pins of the DIP IC. My calculations point to a factor of 49.1%.

author: TheElectricChicken
author_rank: Frequent Contributor
timestamp: August 22, 2015, 01:32:05 pm
content: Quote from: Balaur on August 22, 2015, 01:27:10 pmcannot print here., Didn't realize it was vector until you mentioned it,working.....

author: TheElectricChicken
author_rank: Frequent Contributor
timestamp: August 22, 2015, 01:53:01 pm
content: ergh. took pictures of the enlarged vector, stitched them together, scaled that. Turned out the same. Then scaled to .49, somewhat blurry. Ergh. well, how is it going for size at least.

author: Aodhan145
author_rank: Frequent Contributor
timestamp: August 22, 2015, 02:39:40 pm
content: Quote from: TheElectricChicken on August 22, 2015, 01:32:05 pmPrint it as a PDF with the correct scalling, upload the pdf. then everyone can just print to 100% scale. Why is something simple getting so complicated?

author: Deathwish
author_rank: Unknown
timestamp: August 22, 2015, 02:59:34 pm
content: complicated ?, have you ever visited the time nuts threads, now that is complicated.

author: TheElectricChicken
author_rank: Frequent Contributor
timestamp: August 22, 2015, 03:49:23 pm
content: Quote from: Aodhan145 on August 22, 2015, 02:39:40 pmwell, I have no printer, don't know the scale, and so I wait for anyone to suggest the scale compared to what I've uploaded. If the task is such a trifle, perhaps you can assist in a practical manner ?

author: Balaur
author_rank: Unknown
timestamp: August 22, 2015, 04:18:13 pm
content: No idea if it's the right scale or notTry it at your own risks.

author: SeanB
author_rank: Super Contributor
timestamp: August 22, 2015, 04:30:25 pm
content: Opened the PDF in Gimp and measured, then cropped page2 and changed the resolution after measuring the DIP leads spacing. Was 100 DPI now 210DPI, so YMMV on it.Kind of liking this new GIMP version, even though it annoyingly only will save in certain file formats, to get the more common file types you have to export it. But it does the job well enough, still getting to know just how much it can do. Works for pretty much all image manipulation I do in any case.

author: TheElectricChicken
author_rank: Frequent Contributor
timestamp: August 22, 2015, 04:48:43 pm
content: Quote from: SeanB on August 22, 2015, 04:30:25 pmI know what you mean ! I just don't understand why they have to come up with such silly ideas. I wish they'd take more note of the community and throw out the crazy person who secretly works for photoshop. I hope the whole export silliness disappears in the next version. And never detach a dock ! they never go back as far as i can see. (grumble) still, it beats everything commercial !

author: Deathwish
author_rank: Unknown
timestamp: August 22, 2015, 05:27:08 pm
content: sean, your sizes are off, they show me 2.4 between dip pins not 2.54 , any chance you can re do it ?.

author: SeanB
author_rank: Super Contributor
timestamp: August 22, 2015, 05:35:54 pm
content: Quote from: Deathwish on August 22, 2015, 05:27:08 pmTry now.....Changed to imperial and did it again slightly larger.

author: Deathwish
author_rank: Unknown
timestamp: August 22, 2015, 05:43:46 pm
content: What did you do ??, its gone massive

author: Deathwish
author_rank: Unknown
timestamp: August 22, 2015, 05:46:48 pm
content: I appreciate the help, but I have to sleep a while, so bbl ok.

author: SeanB
author_rank: Super Contributor
timestamp: August 22, 2015, 06:00:06 pm
content: Have a siesta and try this one.

author: con-f-use
author_rank: Unknown
timestamp: August 22, 2015, 08:48:09 pm
content: Quote from: Deathwish on August 22, 2015, 11:36:39 amOn page 5, you find components overlayed with the layout. Look up the size of the AC05D in the datasheet, then scale...

author: Deathwish
author_rank: Unknown
timestamp: August 23, 2015, 02:46:45 am
content: I think I am going to play with re doing it in eagle / cadence and outputting it to gerber copying the original pcb layout and design. could take a year or so though.

author: Bob F.
author_rank: Regular Contributor
timestamp: August 23, 2015, 03:38:54 am
content: Are you sure you can't scale it on the printer? I don't think I've ever unable to scale a printout on a printer's Properties settings. There is practically always an output scaling option somewhere - example below. The available step sizes (usually whole percentage points) may be too course in this case however.

author: Deathwish
author_rank: Unknown
timestamp: August 23, 2015, 03:41:14 am
content: I looked but I cant find it , its only a epson , I really want a HP laserjet 4 like I used to have for my pcb artwork. but right now I am still buying hardware etc.

author: sleemanj
author_rank: Super Contributor
timestamp: August 23, 2015, 07:32:23 am
content: PDF attached with the copper image which has been scaled so that the pins in the middle are 2.54mm pitch. Imported into gimp at 1200dpi, exported to a PDF page.Print this PDF WITHOUT ANY SCALING (common mistake, PDF viewers often "fit to page" or similar by default, make sure you turn that setting off, I use Evince on my ubuntu machine).