Dog leg slot in PCB is possible? - Page 1
Forum section: electronics / general

author: Faringdon
author_rank: Super Contributor
timestamp: August 20, 2023, 04:40:32 pm
content: Hi,Is it possible to produce a dog leg slot in a 1.6mm FR4, 2 layer PCB (NPTH), as in the attached.?

author: T3sl4co1l
author_rank: Super Contributor
timestamp: August 20, 2023, 04:43:53 pm
content: Yes?Check the width in the diagonal segment. It's still doable as-drawn and to-scale, but won't be as annoying if made consistent width.The inside corners will be radiused as well. Don't forget this on the diagonal segments.Tim

author: langwadt
author_rank: Super Contributor
timestamp: August 20, 2023, 04:48:03 pm
content: ffs, how do you even come up with such silly questions?

author: Faringdon
author_rank: Super Contributor
timestamp: August 20, 2023, 04:50:27 pm
content: Thanks, compared to a straight slot of 10mm and same width, how much more expensive would it be? (ie how much more costly, roughly, is it for the dog leg slot?).Or is it roughly the same cost as a straight slot of the same overall length?

author: T3sl4co1l
author_rank: Super Contributor
timestamp: August 20, 2023, 04:51:59 pm
content: Tool routes don't cost anything.Tool changes, and smaller tools, cost extra.Tim

author: mikeselectricstuff
author_rank: Super Contributor
timestamp: August 20, 2023, 04:55:02 pm
content: Unless you're into very high volumes, details like this make no difference to cost as long as you don't go thin enough to use a nonstandard cutter.Don't forget that they will usually be routing round the whole perimeter, so a few cm of slots makes little difference

author: HwAoRrDk
author_rank: Super Contributor
timestamp: August 21, 2023, 10:33:13 am
content: "Sorry Mr. Faringdon, if you want anything other than slots at 90° increments, it's going to cost you an extra £0.05 per degree, per slot, per board."

author: Psi
author_rank: Super Contributor
timestamp: August 21, 2023, 11:09:23 am
content: As long as it's just a path for the router to follow it wont matter how long it is or how much of a drunk path it takes.The path can even come back on itself and cut out a section, if you wanted.Now, if you wanted the diagonal section of your path to be 1mm but the horizontal parts to be 3mm then you would need 3 separate route paths.2x 3mm ones, and 1x 1mm one. with them overlapping, which is fine.They wouldn't charge more for this either at our volumes. It's pretty normal to have a few slots and a few sizes on a PCB.If you had 100 individual route paths on the PCB and they were all the same size they probably wouldn't charge more either. Since they just tell the machine to do it and it does it. Though there can be a small charge sometimes for excessive drilling/routing. It would depend on the size of your PCB.But... if you wanted 100 route paths all with difference size holes from 1mm to 11mm in 0.1mm steps. Then first they would probably look at you funny, and then they would definitely increase the price.Mainly because the machine would spend most of its time going back and forward to the automatic tool changer rather than cutting slots. So it would be quite slow and also the tool charger might not be able to hold 100 bits at once, so they might have to stop/start it a few times and have the operator come by and swap the router bits tray around a few times. So they would definitely charge more for that.

author: T3sl4co1l
author_rank: Super Contributor
timestamp: August 21, 2023, 05:24:41 pm
content: Well, depends how accurate you want them. The smaller ones would be drilled, for sure.If you don't mind the bumpy outline of a full-speed router, all of those are doable with a 1mm end mill, just does an ever-increasing wiggle inside the hole and that's your finished size. Maybe just changing to 2mm when available to speed things up. If you do mind the bumpy outline, it's still possible they just program a slower approach and feedrate, perhaps load sharper tools, and that solves most of the roughness; or a rough pass--finishing pass is done; or the machine is calibrated better to local features for better positioning and dimensional (and perhaps even roundness) tolerance.Under 0.005" (0.127mm) board-edge (rout) tolerance is generally custom (read: cost will go up some).Tim