Re: Seeking correct EuroCard dimensions
On 2017-07-29 01:16, David Griffith via cctalk wrote: I'm trying to verify the correct dimensions for a 160mm x 100mm EuroCard. I figured this would be simple: 160 millimeters by 100 millimeters. But when I submitted a template to the Kicad project at https://github.com/KiCad/kicad-library/pull/1441. I was told that I need to trim the board back by .15mm, citing this document: https://www.elma.com/-/media/general-web-content-files/resources/pdfs/us-corporate-dimensions-of-pcbs-d.ashx?la=en=13B1EAF4FF743087F8B7E87BB10A1D20C44C40BD This doesn't seem to make sense to me. I always thought that the bearing surfaces on the card cage would be spaced slightly more than the card width. What's going on here? What am I missing? The VMEbus spec says the same, tolerance is [+ 0, - 0.3mm] so take the .15mm off and you're good ;-) Actually look at the connectors & grid, so you need to take of .075mm of each edge, so the connector area stays the same ...
Re: Seeking correct EuroCard dimensions
On Fri, Jul 28, 2017 at 5:16 PM, David Griffith via cctalk < cctalk@classiccmp.org> wrote: > > I'm trying to verify the correct dimensions for a 160mm x 100mm EuroCard. > I figured this would be simple: 160 millimeters by 100 millimeters. But > when I submitted a template to the Kicad project at > https://github.com/KiCad/kicad-library/pull/1441. > > > I was told that I need to trim the board back by .15mm, citing this > document: https://www.elma.com/-/media/general-web-content-files/resou > rces/pdfs/us-corporate-dimensions-of-pcbs-d.ashx?la=en= > 13B1EAF4FF743087F8B7E87BB10A1D20C44C40BD > > This doesn't seem to make sense to me. I always thought that the bearing > surfaces on the card cage would be spaced slightly more than the card > width. What's going on here? What am I missing? I think what they're saying is that the board size specs have a tolerance of +0.0/-0.3mm, so you should spec 0.15mm less than nominal to be right in the middle of the tolerance range, so that any positive tolerance variation from manufacturing should still be within the specification. I'm in the process of designing some 220x100 mm Eurocards myself, and hadn't previously given the tolerance limit of +0.0mm any consideration. I think the advice to trim 0.15mm is good. Eric
Seeking correct EuroCard dimensions
I'm trying to verify the correct dimensions for a 160mm x 100mm EuroCard. I figured this would be simple: 160 millimeters by 100 millimeters. But when I submitted a template to the Kicad project at https://github.com/KiCad/kicad-library/pull/1441. I was told that I need to trim the board back by .15mm, citing this document: https://www.elma.com/-/media/general-web-content-files/resources/pdfs/us-corporate-dimensions-of-pcbs-d.ashx?la=en=13B1EAF4FF743087F8B7E87BB10A1D20C44C40BD This doesn't seem to make sense to me. I always thought that the bearing surfaces on the card cage would be spaced slightly more than the card width. What's going on here? What am I missing? -- David Griffith d...@661.org A: Because it fouls the order in which people normally read text. Q: Why is top-posting such a bad thing? A: Top-posting. Q: What is the most annoying thing in e-mail?
