Chris Gammel's "Never Trust the Autorouter shirt" on Teespring - Page 1
Forum section: electronics / general

author: Christe4nM
author_rank: Unknown
timestamp: May 24, 2014, 05:05:39 pm
content: You might've seen Chris wearing this T-shirthere. He's made it available throughTeespring. I think it's a great one and sometimes you just have to let your nerd out, so I've ordered.edit: typo

author: linux-works
author_rank: Super Contributor
timestamp: May 24, 2014, 05:27:33 pm
content: nice idea, but I don't like the shirt. the point could have been made better with a simpler, less busy graphic and still have been funny.that just looks like a mess, which I realize is sort of the point, but still ...

author: zapta
author_rank: Super Contributor
timestamp: May 24, 2014, 05:40:50 pm
content: Quote from: Christe4nM on May 24, 2014, 05:05:39 pmCould have on the back a nice manual routing of the same board.BTW, I am happy with Eagle's auto router.

author: VK3DRB
author_rank: Super Contributor
timestamp: May 25, 2014, 08:06:25 am
content: I like it. And it is true to a point. Generally I don't use autorouters, but sometimes I do autoroute small areas of a PCB when it gets tricky... Sort of like hints in a game of chess. The aim is to limit the numbers of visa or track lengths and to save time. Always of course go back and review the results.Not long ago we got a PCB back and two internal nets had a short. Track to a pad. The spacing had violated the rules, but Altium had not detected it with the DRC! I can only conclude it was a bug in Altium. There was nothing wrong with the rules. User beware. Fortunately it was only a prototype PCB and drilling a tiny hole fixed it.

author: Psi
author_rank: Super Contributor
timestamp: May 25, 2014, 08:33:01 am
content: The text and graphics are a bit 'in ya face' and could be smaller, but i like the idea. As well as having a hand routed version on the back.

author: TerraHertz
author_rank: Super Contributor
timestamp: May 26, 2014, 01:43:14 am
content: The trouble with now needing glasses for close-up work, reading, etc, is that I can't wear t-shirts that don't have a pocket. One of those little surprises that getting old springs on us.Shouldn't that t-shirt be green?Also, looks like he trusted the auto component place a bit too much as well.

author: Forced Perfect
author_rank: Contributor
timestamp: May 30, 2014, 02:56:49 pm
content: I agree he could have made a much simpler version to get the point across, I have ordered one but I already dread explaining it to the people at work (none of which know anything about electronics). A simple auto vs. manual of something simple like a 555 organ or something would have gotten the point across much clearer to people who don't get the joke.Despite it not being "PCB green", I like the colour.

author: zapta
author_rank: Super Contributor
timestamp: May 30, 2014, 08:37:32 pm
content: Quote from: Forced Perfect on May 30, 2014, 02:56:49 pm+1I spent a few years developing auto routing algorithms. One simple test case we often used is this one:Conventional one-layer-at-the time greedy algorithms had difficulty finding the wire length wise optimal solution (above). For example, they ended up with something like the one below, and if A, E, D, F were on the routing boundary, they could not find a planar solution at all (e.g. if you make a greedy route of A-B and C-D, you have no clearance to route E-F between B and C).Probably not the most intuitive example of bad auto routing but the shirt could have something simple along these lines.BTW, I love the eagle auto router. I route manually the critical nets and let it does the rest of the work and when lazy I don't even clean up for aesthetic.

author: linux-works
author_rank: Super Contributor
timestamp: May 30, 2014, 10:00:51 pm
content: zapta: you're hired. please re-do the shirt with your ideas and let us know when its buyable(seriously)

author: zapta
author_rank: Super Contributor
timestamp: May 30, 2014, 10:32:44 pm
content: Quote from: linux-works on May 30, 2014, 10:00:51 pmMy graphic design skills are non exist ;- but here is it how eagle handle this problem. Would be interesting to see what other auto routers doManual routing:Eagle auto router:A topological router like this one has better chance of finding the optimal solutionhttp://www.ssalewski.de/Router.html.en(A very impressive site BTW. I don't know that person).

author: jancumps
author_rank: Unknown
timestamp: May 30, 2014, 10:42:11 pm
content: I keep wondering: does the BenchBudEE fail if you autoroute it. If it's proven to fail, I'm going to order that shirt.