hi
i designed a one sided pcd with a smd regulator on the back side
after that i printed out the pcb and make the holes but when i wanted to put in the part the first three pins are in right place but the rest keep getting off until the last pin does not even touch the copper of the pad
at first i think nothing of it , yeah a different manufacture it happens but then i get back to the kicad and check the rest of the part they had the same problem
and its not just the parts from kicad library, i had 3rd party footprints too
i even had designed a footprint my self and it still had the same problem
the printer did not descale the design i put reference lines and shape and rules
the worse part is that the silkscreen of the parts matches perfectly
im lost at this point , the deadline of the project was due to spring and we are already mid summer
so redesigning the thing in another software is my last option
thanks
since forum don’t let me upload rest of my images here i upload them in an image uploader. sorry for the inconvenient
https://ibb.co/27qHM4gX
https://ibb.co/q3ktftsF
I would double and triple check this. Printer software does all sorts of funky things with scaling.
Surely not . . . your pads are connected with lines not tracks !
It’s quite easy to check, put a rule on the board outline and see if its the correct size, any scaling error will be noticeable on the largest feature that can be measured, i.e. the board outline. 
Why don’t you just look at the files in KiCad? Use the measurement tools or look at the pad coordinates directly.
Read:
to find how to solve this problems yourself in probably few minutes.
that why there is a line and a circle in the first image
i checked them and they are exactly 1cm as they should be
the tracks are narrow (kicad default setting)
i change them in later projects but for now they somehow miraculously survived acid bath
Are you saying that these things (circle and line) measured at screen are ok and when printed are ok, but footprints measured at screen are ok, but when printed (together with those test shapes) change scale?
There is no such thing as exactly 1cm . . . we live in an analogue world, there is ALWAYS inaccuracy in measurements. What did you use to measure ? tape ? steel rule ? vernier ? measure a larger feature and any error will be larger and easier to measure.
yes exactly
even on the paper that i printed with correct measurements and correct sized silkscreen the pads are still off
and as you can see they are fine until the third pad (still slowly shifting but don’t cause problem at that point yet)
i know but as much as my eyes and my steel ruler tells me it is pretty much 1cm
the last pad of that connector in the picture is off by a whole 3mm
I don’t want to question your measuring skills too much, but the last pad is not off by 3mm. That type of connector usually has a spacing of 2.54mm (100mil). And you are not even close to being off by more than the spacing between the pads.
I used to etch my own circuit boards and had this problem many times and it was always an issue with the printer software scaling something. I think @RaptorUK had the right idea. Create an object that is at least 10cm or so large and then verify that it isn’t scaled.
its fine that you doubt my measuring skills ( i do too tbh)
all of the pads are like this not just the connector but thanks i will try a longer line for reference
Are you 1000% certain you have a 0.1" pitch footprint and a 2.54mm header? This discrepancy looks awfully close to what you’d see trying to put a 0.1" header into a 2.5mm pitch footprint.
I would try with a 20 pin DIP IC, these are always 0.1" pitch, unlike connectors, which have so many choices
That line and the circle are too small to measure accurately.
You also wrote:
With bigger things, it’s much easier to see small scale difference then with small things. A common cause of printing scale issues is with a “scale to fit (to paper)” somewhere in the printer stack.
Looking at the picture you posted on imgbb:
(I modified it a bit. I put the measurement close to the connector and make the picture smaller)
Footprints for these green connectors are a bit notorious. You can buy them with a pitch of 5mm, and with a pitch of 5.08mm.
If I take the footprint: Connector_Phoenix_MSTB / PhoenixContact_MSTBA_2,5_10-G-5,08_1x10_P5.08mm_Horizontal with 10 pins, then I measure 52.8mm in the footprint editor:
The pitch is also encoded in the footprint name. You have not mentioned the names of the footprints you are using. In the footprint I posted, it’s name has the pitch encoded as: P5.08mm.
And for the dual row header, it could also be the difference between a header with 2.5mm pitch and 2.54mm pitch.
And unfortunately things like this are quite common.
Inspect - Measure Tool is a quick way to add a scale ruler to your PCB
There is even a library dedicated to “Calibration_Scale” footprints.
Yes, but most are quite small. (But there are a few 100mm long scales).
My own preference for calibrating the printer is to draw a big rectangle and print it. Bigger is better, such as 200 by 250mm (But I’m not sure if 200mm is printable on 210mm wide A4). We don’t have “letter” sized paper here in the EU. Mabe an 180 by 250mm rectangle is safer to print. Ah well, a sheet of paper costs 2ct or so.
But my previous post shows that it is very likely wrongly chosen footprints. But printer scale should be verified too, especially as OP is apparently etching at home.
Euhm, here is the other picture he posted on that image site:
Also, printers are not designed to be very accurate, but only to generate neat looking pictures. Some mechanical CAD programs have built in functions to calibrate your printer (or better: distort the image before it’s sent to the printer). I have done this a few times for different printers, and printers tend to be up to 1% wrong in size, and with different errors in X and Y direction.