Both pcbway and jlcpcb will cleanly cut your entire board outline with no panelization tabs. You can draw any arbitrary shape in your edge.cuts and get it in one clean continuous cut.
oshpark leaves rat bites that you have to sand down and clean up if the board outline matters to you. Worse, if you have castellated half holes, the rat bites can land right in the middle of what was supposed to be edge contacts.
I have boards that are small like the size of a dip28, where the entire length of the two long sides are castellated, and they are edge contacts to fit in a socket, not for soldering, and the entire board snaps into a carrier so essentially all 4 sides need to be clean and match the drawing. I have to sand and clean up oshpark boards, and live with a little bit of defect in the castellated holes. I don't have to do anything with jlc or pcbway boards. They arrive perfectly clean edged and ready to use.
I have one board that is only about 1cm square, but not square, it has a complicated outline, and both jlc and pcbway just pop it out with no fuss the same as any other order for the same nothing cost. I don't know how they even hold on to the tiny board to cut the outline. It does appear to be traditionally routered, not laser or water jet.
I guess I shouldn't be so amazed at the size, given how common tiny pcbs are, for example the little page counter chips on my printers toner cartridges are only about 1/3 the size of these, although simple square edged.
Here's a step-by-step video about how JLCPCB makes PCB's. The link goes directly to that step at 21:09: https://youtu.be/ljOoGyCso8s?t=1269 It looks like in this case they are using a CNC router to make the cuts, and a vacuum table to keep the PCB's in place (it's a table with a grid of tiny holes that has vacuum inside to suck the PCB's onto the table).
I don't know exactly why but I can't watch that guy for more than a few seconds. But those machines are sure cool. I'm criticizing him, or myself, not you just to be clear.
I've orderdered several times from oshpark because over the last 5 or so years I've iterated the design slightly many times. From oshpark I have received different results at different times from the same board outline. One time was a single rat bite in the middle of the short ends, leaving the castellations fully clear. Another time was two rat bites on each end at the corners, but on the short sides, again leaving the long sides clear. But most of the time the tabs are placed randomly other than being spaced apart.
Even the buggered ones were usable, it's just that one was usable after cleaning up, and still slightly uncosmetic even after cleaning up because you can only sand down not fill in, while the other was not only usable but fully cosmetic right out of the box.
I give all my boards nice rounded corners now just because apparently it's free so why not.
It's even functional not just cosmetic in this case. Any time a part has to fit into another part, there has to be some relief either on the inside or outside part, they can't both have perfectly sharp inside and outside corners and fit into each other. It's often not possible, and usually not desirable because of stress riser reasons, to manufacture perfectly sharp inside corners, and so you need the outside corner of the inside part to be cut down. Or, if the outside of the inside part must have a sharp corner, then you need to cut out extra relief in the inside corner of the outside part, like adding a round hole centered on the corner, both for stress-riser reasons and just to ensure the part will always be able to fit without interferance.
Like the inside corner on the left edge of this pic:
https://github.com/bkw777/WP-2_IC-Card/blob/master/COVER/WP-...
There's a connector body with square edges that fits into that part, so there's a little extra cutaway right in the inside corner.
In the carrier part above, the drawing for the carrier has simple imaginary perfect inside corners, and in real life the printer doesn't quite make a knife-edge inside corner of course. And the pcb has slightly rounded outside corners. If the fab couldn't do it for me with the router, I'd do it by sanding.
I would say those two particular projects (rex and teeprom) are a special case with needs that most people won't need to worry about, so I'm not saying oshpark is a bad choice. It's just a difference, and the whole point of the article was to compare and show differences.
oshpark leaves rat bites that you have to sand down and clean up if the board outline matters to you. Worse, if you have castellated half holes, the rat bites can land right in the middle of what was supposed to be edge contacts.
I have boards that are small like the size of a dip28, where the entire length of the two long sides are castellated, and they are edge contacts to fit in a socket, not for soldering, and the entire board snaps into a carrier so essentially all 4 sides need to be clean and match the drawing. I have to sand and clean up oshpark boards, and live with a little bit of defect in the castellated holes. I don't have to do anything with jlc or pcbway boards. They arrive perfectly clean edged and ready to use.
I have one board that is only about 1cm square, but not square, it has a complicated outline, and both jlc and pcbway just pop it out with no fuss the same as any other order for the same nothing cost. I don't know how they even hold on to the tiny board to cut the outline. It does appear to be traditionally routered, not laser or water jet.
https://github.com/bkw777/TPDD_Cable
pics of an earlier version with slightly different outline. https://photos.app.goo.gl/TdYxGhzK94KT9rS78
I guess I shouldn't be so amazed at the size, given how common tiny pcbs are, for example the little page counter chips on my printers toner cartridges are only about 1/3 the size of these, although simple square edged.