| roh | hey wolfgang | 02:18 |
|---|---|---|
| wolfspraul | roh: hi | 02:19 |
| wolfspraul | I wanted to keep in touch over the cases... | 02:19 |
| wolfspraul | we talked about L/ON/R already, that's clear | 02:20 |
| wolfspraul | my next worry was the button tolerances on the inside of the case, maybe you saw it | 02:20 |
| roh | nope | 02:20 |
| wolfspraul | I don't have enough cases to look at though, you know better how you feel about it | 02:20 |
| wolfspraul | ah OK, then I repeat | 02:20 |
| wolfspraul | so here is my concern: | 02:20 |
| wolfspraul | the button is made out of 3 pieces now, the big one on the inside preventing the button to fall out, and pushing it against the electrical switch | 02:21 |
| roh | i am quite busy these days with the move.. my status is: i ordered the metal, and contacted the laser contractor | 02:21 |
| wolfspraul | but I've had quite some problems with cases where after screwing them together, the pressure on the switch was so high that the buttons were stuck | 02:21 |
| wolfspraul | sure great, I totally trust the things is moving on your side | 02:21 |
| wolfspraul | I'm not worried about that | 02:21 |
| wolfspraul | I just want to give some more feedback | 02:21 |
| wolfspraul | this one is about 'stuck buttons' | 02:21 |
| roh | havent heard back from the laser guy, but he said on the phone already he will be on the road the next too weeks (about a week ago). | 02:21 |
| wolfspraul | the thing is that we are talking about 0.1/0.2 mm issues, so I'm not sure whether we should change anything, or maybe that would make things even worse | 02:22 |
| roh | i think the 'stuck button' thing will go away or be 'different' with the better machine (laser optics is more precise) | 02:22 |
| wolfspraul | ok. do you understand my concern first of all? | 02:23 |
| wolfspraul | I am also wondering about tolerances on the PCB side | 02:23 |
| wolfspraul | maybe if we make 80 sets, we will have 5-10 or so where some buttons will just be stuck | 02:23 |
| wolfspraul | we could try to find a thinner inner plastic piece | 02:23 |
| wolfspraul | or we could move the electrical switch on the pcb into the board a few mil | 02:24 |
| wolfspraul | but then what we have now is not bad, so we can easily make something worse than it is now... | 02:24 |
| roh | so if my test runs will show some 'tolerance issues' i will widen the button holes some fractions of a mm | 02:24 |
| wolfspraul | I'm talking about the thickness of the larger plastic piece | 02:25 |
| wolfspraul | the one that sits between the acrylic (on the inside) and the electrical switch | 02:25 |
| roh | that one is 1.0mm. | 02:25 |
| roh | i use 'precision acrylic' there to get real 1.0mm, since regular one has so much tolerance | 02:25 |
| wolfspraul | should we move the switch into the pcb a few mil? | 02:26 |
| roh | it also depends on the fitting of the sides. | 02:26 |
| roh | not neccessary, i can move out the side panel a bit if neccessary | 02:26 |
| wolfspraul | ok, that's a good point | 02:26 |
| wolfspraul | I'd rather not make mechanical changes on the pcb, otherwise it will get messy over time | 02:27 |
| roh | so i guess its easier to keep the button where it is, which would also make the cases 'more universal' | 02:27 |
| wolfspraul | definitely | 02:27 |
| roh | i will redo all the mechanical tests anyhow when i do the testrun on the other machine. no worries | 02:27 |
| wolfspraul | so then just remember this issue, and let's keep an eye onit | 02:27 |
| wolfspraul | it's a pretty nasty problem once it hits the user | 02:28 |
| wolfspraul | they will reassemble the case, tighten the screws: suddenly the box won't boot anymore | 02:28 |
| wolfspraul | and then it's hard to fix too | 02:28 |
| wolfspraul | I am also wondering whether the electrical switches loosen over time | 02:28 |
| wolfspraul | i.e. the pressure to make them connect will go down? | 02:28 |
| wolfspraul | there is probably a tolerance in that pressure too, so some of them may click/connect with less pressure than others | 02:29 |
| roh | hm. dunno. | 02:29 |
| wolfspraul | oh well :-) | 02:29 |
| roh | i think the mechanical 'distance from not pushed to pushed' should be spec-ed anywhere | 02:29 |
| wolfspraul | ideally in a 'unpressed state' (with button from outside), the force applied to the electrical switch should be exactly 0 | 02:29 |
| roh | and i would wonder if it would change much | 02:30 |
| wolfspraul | but the distance between 1.0mm plastic and electrical switch should also be 0 | 02:30 |
| wolfspraul | of course that's very hard to achieve | 02:30 |
| roh | i could just 'make it a bit wobblier | 02:30 |
| wolfspraul | if there is a small gap, yes I guess it would be wobblier | 02:30 |
| wolfspraul | I think in many cases we do in fact exert some pressure on the electrical switch, even if the user does not press the buttons | 02:30 |
| roh | i did quite some tries to get it 'right' maybe tolerances in reality are just a bit bigger than the 2 pcbs i have | 02:31 |
| wolfspraul | I may also be looking at old cases | 02:31 |
| wolfspraul | mine are from December | 02:31 |
| roh | i tried this stuff with the rc1 mechanical prototype and the rc2 i have | 02:31 |
| roh | will just give it some more slack and see what happens | 02:32 |
| wolfspraul | also we have to make sure that there is no glue residue coming out from between the 2 smaller button pieces and the larger one | 02:32 |
| roh | i will try another glueing method | 02:32 |
| wolfspraul | because if there is, it is exactly at the point that it will move the 1.0mm one further into the case | 02:32 |
| roh | there is some chemical which softens the surface of acryllic and it is intended to be used for glueing | 02:33 |
| roh | will do some tests with it and see if i can pre-glue the stuff properly.. maybe by using some fixture (thinking of an metal with a hole, which would be unaffected by the chemical) | 02:34 |
| roh | Tetrahydrofuran or Dichlormethan | 02:37 |
| roh | i think i have seen some of the latter when packing the 'special glue box' earlier | 02:37 |
| roh | http://www.tektorum.de/innenarchitektur-design/641-womit-plexiglas-kleben.html | 02:38 |
| wolfspraul | wow yes, lots of options | 02:42 |
| roh | will test and report what happens | 02:51 |
| roh | as soon as i find some time between packing moving and unpacking stuff and machines ;) | 02:57 |
| roh | still tearing down walls and mounting electric circuits. | 02:57 |
| lekernel | wolfspraul: PCB tolerances are usually small... they need to when you have this kind of track density and component pitch | 13:45 |
| wolfspraul | yes true, I wasn't very precise - I meant the positioning of the electrical switch on the pcb, and tolerances within the switch itself | 13:55 |
| wolfspraul | but roh already gave me some confidence, so we won't change anything on that side, if needed we can move the entire side out a little | 13:55 |
| --- Sun Apr 17 2011 | 00:00 | |
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