Author Topic: Powder coated steel workbench top  (Read 430 times)

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Offline kylehunter

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Powder coated steel workbench top
« on: June 05, 2021, 11:26:56 am »
So I'm going to be changing some of our workbenches soon. We currently use a mix of wood and ESD dissipative tops, but they are pretty old and worn out. All of our tops have ESD mats grounded to earth. I was wondering, does anyone see any issues with using a powder coated steel top like this: https://www.grainger.com/product/GRAINGER-APPROVED-Workbench-Top-4TW35? It will have powder coated steel legs as well. They are a decent bit cheaper than a solid wood top or even some plastic laminates.

Ultimately, since we will have a nice ESD mat on the surface, it shouldn't really matter what is under it right? I can earth ground the metal top and legs too, but typically powder coated steel isn't super conductive.

Thanks!
« Last Edit: June 05, 2021, 11:28:58 am by kylehunter »
 

Offline Tomorokoshi

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Re: Powder coated steel workbench top
« Reply #1 on: June 05, 2021, 05:11:38 pm »
1. Powdercoat will scratch.

2. Powdercoat breaks down at ~500 V to ~1000 V.

3. Charge can accumulate on the powdercoat surface.

4. It might bang like a drumhead. No mention about the gauge.

Wood block tables should hold up just fine as long as ME's don't spill oil all over it or interns don't drill through it.
 

Offline Simon

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Re: Powder coated steel workbench top
« Reply #2 on: June 05, 2021, 05:33:21 pm »
i take it that is thin steal with returns folded around the edge to 1.5" or that is some dams heavy metal. So yea might not be too pleasant as a lab bench. I don't have the experience but I assume that grounding the bench is a good start and with ESD matt on it would be OK. Where I have been working is all plastic or carpet, the only electricalish person on the shop floor prides himself in never having on issue with ESD as though it's a skill and refused to take precautions.....
 

Offline jbb

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Re: Powder coated steel workbench top
« Reply #3 on: June 05, 2021, 09:41:19 pm »
I don’t know about static accumulation on the powder coat, but an ESD mat on the top would help.

It’s a good idea to ground a metal bench. And I would say it’s necessary if you go past, say, 50V. Be aware that bolted/screwed joins between metal parts (eg bench top to legs) are an awkward situation; you can’t depend on them to conduct, and you also can’t depend on them to insulate. If working >50V, suggest earth bonding wires to connect all the separate metal bits together.
 

Offline kylehunter

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Re: Powder coated steel workbench top
« Reply #4 on: June 05, 2021, 11:06:03 pm »
Thanks for the input guys! Everything stated makes sense. I think I'll just go back to the wood idea. That's how we've always done it in the past anyway.
 

Offline wizard69

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Re: Powder coated steel workbench top
« Reply #5 on: June 05, 2021, 11:29:50 pm »
I wouldn't go the steel route due to the safety issue.   By the way yes I know how incredibly high the price on wood products have become.   

As for powder coating there are lots of variants there but a common theme is that they are hard to repair and eventually you will need too.    Wood on the other hand can be sanded down or a sacrificial layer added on top.   Beyond that the metal is conductive but at the same time powder coating is very stubborn to clean up for good ground bonding.   This variably in your ability to bond to powder coated metals makes the bench unsafe for high voltage work.   Then you have the human factors issues of the edges not being comfortable.

Now considering some of the issues above you might want to consider benches (largely the legs) that at mostly welded together and painted afterward.    A good urethane or epoxy finish is very durable.   The "mostly welded" being everything but height adjustability in the legs.   Welding makes the assembly one piece and thus easy to ground.   The top can then be covered with an insulating laminate or even a prefabbed kitchen counter top

So I'm going to be changing some of our workbenches soon. We currently use a mix of wood and ESD dissipative tops, but they are pretty old and worn out. All of our tops have ESD mats grounded to earth. I was wondering, does anyone see any issues with using a powder coated steel top like this: https://www.grainger.com/product/GRAINGER-APPROVED-Workbench-Top-4TW35? It will have powder coated steel legs as well. They are a decent bit cheaper than a solid wood top or even some plastic laminates.

Ultimately, since we will have a nice ESD mat on the surface, it shouldn't really matter what is under it right?
Actually this can matter a lot.   Exposed metal is a safety issue and eventually, no matter how you coat the metal, the coating will wear off or simply not be able to withstand an applied voltage.   
Quote
I can earth ground the metal top and legs too, but typically powder coated steel isn't super conductive.

Thanks!
The inability of powder coating to conduct (when new) is a two edge sword.   It makes a complete bonding of the frame difficult and even harder to assure bonding over time.

If you are in a sufficiently large city there should be high quality sheet metal and fabrication shops around.   They can easily build tailored, welded, steel frames upon which you can put wooden tops.   Solid wood tops, commonly call bench tops can be self supporting but particle board kitchen counter tops often require support.   Even particle board counter tops can be made self supporting with a little wood under the particle board.   I'd avoid an all steel top unless you have a proven need for a big ground plane as part of the bench.   I'd avoid plastic due to the issues with static.   

Note that there are a lot of suppliers of lab quality benches designed for this purpose.   They are not cheap though.    This highlights the truth that you get what you pay for.   A fab shop should be able to knock a frame together fairly quick and cheap relative to one of these high end lab benches.   You will however lose out on built in features and flexibility.    You will also need a working drawing of what you want.

There are alternative sources for bench tops too.   Consider going to a used office equipment store that has Steelcase and similar office furniture.   The tops for this furniture is often a very stable and a self supporting wood product.   For a couple of benches you might even get matched colors.   I've recycled such office equipment into work benches both at home and at work.   They can be an incredibly good choice when purchased at a discount, used; at auctions or office equipment stores.   You can simply cut to size and attach some legs.   

Simple legs can be had at McMaster-Carr (as an example) https://www.mcmaster.com/bench-legs/?SrchEntryWebPart_InpBox=bench+legs.   However these are not optimized for electronics benches as there are no provisions for posts to support shelves (if you need them).    They are though readily available and cheaper than custom electronics lab bench systems.   So I'm not suggesting these for a traditional electronics bench but they might be suitable for a specific use case.

Also another way to a bench top is softwoods laminated together to form a laminated bench top.   hobby wood workers have taken this approach in the past to save money over hardwood tops, however the price of lumber has inflated so much I'm not sure it it makes sense.  in any event you might want to contact a cabinet or counter top shop for a quote and to see if they are even willing to go this route.   You could DIY a top this way also if you have the time and equipment.

In any event I've just touched on a couple of alternative ways to a lab bench.   Some of these may not be dirt cheap low end solutions but they can result in sturdy equipment.   however if you become creative enough and spend some time in non traditional places you can get a good bench at a lower than commercial price.

One more fact.   The edges of benches are a huge factor in user comfort and also complaints.   One approach we used was to attach 3/4" thick PVC edging with a big round over to soften the square edge.   this was for workers doing optical work but similar to an electronics tech sitting at a bench for hours on end.   This was a reto fit on composite wood with laminated tops.   The PVC was screwed and glued into position.   If you are doing wood tops, well any top really, a large radius round over is highly suggested at the operator station.   Doing it before hand is far better than a retro fit.
« Last Edit: June 05, 2021, 11:32:15 pm by wizard69 »
 

Offline Simon

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Re: Powder coated steel workbench top
« Reply #6 on: June 06, 2021, 05:27:32 am »
Where I worked we made steel box section frames and put wood on top.
 


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