EEVblog Electronics Community Forum
General => General Technical Chat => Topic started by: vixo on September 17, 2020, 09:49:34 am
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when making panels etc for LEDs, do they require any clearance? or are LEDs actually a little smaller than the standard sizes - 3mm, 5mm etc
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I don't know, but I would start by checking the data sheet.
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Im making the panel for someone else, i dont know what leds they will use - the panel is cut for both 3mm and 5mm, but exactly which ones i don't know
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I had to decide this a couple days ago and drilled 4mm holes for 3mm LEDs in an aluminum sheet metal panel: that is my smallest step drill.
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It is not the greatest photo but here is what the 3mm LEDs in 4mm holes looks like.
[attach=1]
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There is panel mount hardware for LEDs like this:
[attach=1]
Lets you adapt to slight variations in LED dimensions as well as securing the LED in place.
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Ask the <expletive> customer whether they need a push fit or a clearance fit. Warn them they may have to ream the holes if they need a push fit. For a clearance fit, 3.5mm and 5.5mm should do nicely as typically good quality LEDs have a diameter tolerance of 1 thou, (0.25mm). If your mill or drill press has a bit of runout and tends to drill oversize, you may need to go down to 3.2mm for the 3mm LEDs
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... typically good quality LEDs have a diameter tolerance of 1 thou, (0.25mm)....
The Everlight 3mm LED datasheet I recently looked at (Taipei, March 2006) gave 3+/-0.2mm (+/-8 thou).
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OUCH!! That (+/- 8 thou) would make a reliable push-fit impossible in any sort of rigid panel. WTF are they doing to get that sort of size variation? Are they running their encapsulation machine without maintenance till the mold's so worn it produces a vaguely cylindrical blob?
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I am puzzled why Everlight is lax about the diameter: it is a flat top, cylinder LED. The datasheet notes that "without special declared, the tolerance is±0.25mm."