Author Topic: 14 x 14 mm not quite right?  (Read 3109 times)

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Offline Eszett

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14 x 14 mm not quite right?
« on: Sat, 25 June 2022, 10:42:56 »
I made a switch plate with 14 x 14 mm cutouts. I thought this is standard. But it turned out that switches don't fit in because they have these bumps here https://i.imgur.com/BnaXPny.png If i sand these bumps off the switches fit in quite well. not too tight, not too loose. What did I miss there? Is 14 x 14.5mm the cutout I should order, rather?

if I try to jam them in anyway the amount of force I have to apply is sick, maybe the hot swap sockets add up to that. Anyway it doesn't feel healthy. I guess I have to order 14 x 14.5 cutouts next.
« Last Edit: Sat, 25 June 2022, 11:20:41 by Eszett »

Offline suicidal_orange

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Re: 14 x 14 mm not quite right?
« Reply #1 on: Sat, 25 June 2022, 12:05:40 »
Those little bumps are supposed to clip under the plate to stop the switch falling out so they might require a bit of pressure but not too much, 14mm is the correct hole size.

Where did you order from and have you accurately measured the holes?  Could be the wrong allowance for kerf (cutter thickness) meaning the holes are smaller than you specified.
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Offline Eszett

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Re: 14 x 14 mm not quite right?
« Reply #2 on: Sat, 25 June 2022, 12:50:54 »
I don't have precision calipers right here yet, maybe tomorrow. But AFAIK the cutouts are exactly 14x14, since it's a FR4 plate and cuts are pretty darn exact. However, I already plan to order new plates, with little 5mm x 1mm salients in the spot where the bumps would take hold. That should nullify the bumps, while keeping the support for the switches still intact.
« Last Edit: Sat, 25 June 2022, 12:56:27 by Eszett »

Online Rob27shred

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Re: 14 x 14 mm not quite right?
« Reply #3 on: Sat, 25 June 2022, 14:24:16 »
I don't have precision calipers right here yet, maybe tomorrow. But AFAIK the cutouts are exactly 14x14, since it's a FR4 plate and cuts are pretty darn exact. However, I already plan to order new plates, with little 5mm x 1mm salients in the spot where the bumps would take hold. That should nullify the bumps, while keeping the support for the switches still intact.

Yep that's the way to go, plates need to have that little cutout in the thickness of the plate to accommodate the bumps that lock the switches in AFAIK. Without them the switches will want to push themselves back out & feel like they're a little too big for the cutout IME.

Offline fohat.digs

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Re: 14 x 14 mm not quite right?
« Reply #4 on: Sat, 25 June 2022, 14:30:01 »

Could be the wrong allowance for kerf (cutter thickness)


I have been stung by this conundrum so many times in my life. 14mm to the outside of the blade is not the same as 14mm to the inside.
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Offline AuthenticDanger

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Re: 14 x 14 mm not quite right?
« Reply #5 on: Sat, 25 June 2022, 15:07:19 »
How thick is your plate?
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Offline Findecanor

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Re: 14 x 14 mm not quite right?
« Reply #6 on: Sat, 25 June 2022, 17:33:59 »
The plate should be 1.5±0.1 mm thick. A common thickness of FR4 is 1.6 mm, which is at the high end of that interval, and you shouldn't use too thick layers of copper and soldermask at the top and bottom of the switch hole where the snaps go.

Offline Eszett

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Re: 14 x 14 mm not quite right?
« Reply #7 on: Sun, 26 June 2022, 00:53:16 »
Yes it's a FR4 with standard 1.6 mm.


Quote
Yep that's the way to go, plates need to have that little cutout in the thickness of the plate to accommodate the bumps that lock the switches in AFAIK. Without them the switches will want to push themselves back out & feel like they're a little too big for the cutout IME.
Do you refer to the 5mm x 1mm salients? Not sure but I never saw them before ..??
« Last Edit: Sun, 26 June 2022, 04:28:09 by Eszett »