Would you use an ABS 19" Rack Case? - Page 1
Forum section: electronics / projects

author: made2hack
author_rank: Frequent Contributor
timestamp: March 26, 2024, 10:02:42 am
content: Hi all,I've got a few questions regarding using an ABS 19" Rack Case (1U if it matters). Essentially the question comes down to whether plastic is a good alternative to the more common sheet steel rack case?The electronics going in are a few ASIC boards and a thin client board. Possible external PSU, but maybe internal.Considerations:- Grounding:In a steel case, you would connect the GND wire to chassis GND in the event a live wire gets disconnected and touches the case, the GND wire would trip a breaker. This is no longer a consideration since ABS is an insulator, so does the GND wire thus become redundant? Are there still grounding issues / needs?In optical use cases (think fiber distribution), not really a concern.- Static Electricity:Can there be a build-up of static electricity in the case? Are there any ESD considerations using a plastic case? If so, is passive vs active cooling a concern (ex: does a spinning fan create static electricity)?- Thermals:Due to the insulating properties of plastic, would I conceivably see higher temps as opposed to a steel case where there would be some heat transfer through the material? I assume with active cooling this would be mitigated, but what about passive cooling (think heatsinks only)?- Durability:Obviously plastic is less durable than steel. But, if the rack is only ever installed and left in place for a long time, does this really matter? I mean, you're not mounting/unmounting it daily. I imagine this is not that much of a concern, but I figured I would add it.So what is your opinion on using an ABS plastic rack as opposed to steel? If I've overlooked something critical, please mention it.Thanks in advance!

author: madires
author_rank: Super Contributor
timestamp: March 26, 2024, 11:36:29 am
content: One important topic is missing:- mechanical load/stressRackmount units are usually mounted at the front using brackets. The case has to bear the mechanical load. There can be also stress by vibrations, caused by the device itself (fans), other devices or AC air flow.Regarding thermals, the case will need venting holes in any case, i.e. front, back and/or sides. Top or bottom doesn't make much sense because other devices can be mounted directly above or beneath. Passive cooling would be a plus as the small 40mm fans won't last long.

author: made2hack
author_rank: Frequent Contributor
timestamp: March 26, 2024, 11:59:39 am
content: Quote from: madires on March 26, 2024, 11:36:29 amYes, you're right about this, I hadn't considered the continuous mechanical needs.

author: nvmR
author_rank: Regular Contributor
timestamp: March 26, 2024, 01:51:09 pm
content: While it is possible, sheet metal 1U chassis can be manufactured relatively cheaply. So why? Plastic would have hidden cost overheads in the durability sense, and other issues which add complexity, such as need for inserts, etc.

author: pope
author_rank: Frequent Contributor
timestamp: March 26, 2024, 01:59:41 pm
content: Do they even exist?

author: CaptDon
author_rank: Super Contributor
timestamp: March 26, 2024, 02:16:21 pm
content: You will probably find a 2U case is far more common than a 1U and may even be cheaper? The ABS cases for D.J. work and such usually have metal rack rails which are bolted or riveted to the side walls of the case. It is too easy to strip out ABS plastic so they quality manufacturers installed metal rack rails. You may have to install your own support system for the rear of your devices. I use angle brackets and sometimes wooden spacers. If you need only a 1U case but opt for the 2U you can install a blank plate or better yet a ventilation plate.

author: made2hack
author_rank: Frequent Contributor
timestamp: March 26, 2024, 02:55:36 pm
content: Quote from: pope on March 26, 2024, 01:59:41 pmHere's an example:https://www.tme.eu/ro/en/details/g17081ubk/19inch-enclosures/gainta/

author: nvmR
author_rank: Regular Contributor
timestamp: March 26, 2024, 03:59:39 pm
content: Now on the one hand, it has a nice stock, so someone must be using it.On the other hand, what is the expectation of the user? Make a custom pcb with the specific mounting holes and custom panel? You would need to either cut holes in the back, or connect a power supply on the front. Sounds like a headache, and going full custom would be better.If it is a one-off, maybe this is a good idea. Any more, and the customization will be too much of a hassle.

author: Haenk
author_rank: Super Contributor
timestamp: March 26, 2024, 05:39:56 pm
content: The ears are made out of metal, as long as the contents is lightweight, that should work out. ABS will last pretty long. However - No shielding, no grounding.