Exact placement of holes on boards


#1

Steps I took that resulted in the problem:

during the build of a board, i was trying to place holes in designated spaces according to a Hensel junction box data sheet (Attached). i placed the holes on the board according to the X and Y coordinates for the holes i wanted to use.

What I expected should have happened instead:

i expected the holes to be in the proper position according the Hansel data sheet. the holes are off and when i hover over the location of the holes the X Y coordinates listed at the bottom right of the window are off by a few mm.

My version of Fritzing and my operating system:

Fritzing 0.9.3 Beta
MacOS X 10.11.6

Please also attach any files that help explaining this problem
large_Controller.fzz (14.0 KB)

data sheet for Hensel junction box


#2

How did you place them, did you use the mouse pointer - you have to turn off snap to grid - or by the Inspector coordinates.


#3

initially i placed them using the inspector coordinates, then found out the measurements were off, so i used the mouse pointer coordinates to place the holes and components. i also turned off SNAP and the GRID but still could not get the exact placement of the items.


#4

It is best to use the snap grid set at 0.1", 0.05", and 0.025" and drag the parts and traces. 0.05" works very well for most, but if you need to get the traces a little closer together, set it at 0.025. You can also hold the Shift key down when dragging a bend point and the starting side of the trace will snap at 0, 45, and 90 deg. If you hold down the Ctrl key down, then grab the bend point, the snap grid will be turned off for fine alignments when the connector does not line up with the grid.


Auto-relocating of part placement problems
#5

If it’s out it’s only by a touch, which could be because I’m eyeing things up.

I click on the left mounting hole, unlock, and change x coordinate to 1.0. It locks on 1.001" - It tends to snap to certain numbers -
I click on right mounting hole. unlock, and change x coordinate to 3.952. - 75mm divided by 25.4 plus 1 - It locks on 3.952"
I zoom in to max zoom, to get more accuracy, and put the mouse pointer on the left edge of the left hole copper and get 1.306".
I now do the left edge of the right hole copper and get 4.258"
4.258 - 1.306 = 2.952"
2.952 x 25.4 = 74.98mm
It’s a touch out, but one hole did lock on 1.001".

It’s pretty much std practice to go from edge to edge of same sized hole because you can’t get accuracy guessing the centres.

I know there is a bug when locating PCB, like you enter 2.0 and it changes to 2.001, but it wasn’t that important for me to have it that accurate.


#6

Having the same problem here. It’s not just 0.001mm off, it’s more like 0.1mm

If I type 0mm as the origin for an imported silkscreen layer, for example, it will move to 0.082mm

Kind of a fundamental thing for a design program to get right.


#7

In the future it might be, but this is not that kind of program.

There is probably a 0.1mm manufacturing tolerance on the part being fitted, why does it have to be so accurate.
I did engine machining for 20 years and can understand the need for accuracy, but the free play in the mounting holes will probably have that much movement as it’s not even the thickness of 2 sheets of paper.