No user serviceable parts inside

I'm trying to decide on case fastening/closing technology; solvent weld, snap, mechanical fasteners, etc.

*Despite* many things having "no user serviceable parts inside", it seems like many (a growing number of!) folks are actually disassembling bits of kit to fix/upgrade them in ways the OEM hadn't intended.

Having been on the consumer side of many of those efforts, I can sympathize; its annoying to have to replace something "just because" the manufacturer doesn't want to sell you a replacement component, or doesn't carry those components any more, or doesn't carry the model you'd be willing to buy AS a replacement!

[I don't want to have to deal with spare parts, etc.]

Of course, there are other reasons why a manufacturer may opt for a particular case-closure technology -- besides cost (environmental issues, strength, appearance, serviceability, etc.)

In the absence of other OVERWHELMING criteria, what's the "most friendly" (least annoying) approach? Simple "hardware" (straight

*through* the case vs. into PEM nuts, etc.)? [The least friendly would probably be solvent welded (at least for PLASTIC cases)]
Reply to
Don Y
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Are YOU planning on repairing your own products? If so, easy access might be a good idea.

That would be me. In the war against user repairable products, manufacturers have done their best using Apple adhesive technology (tar), and encapsulation (epoxy). Whatever it takes to protect their profits, err.... products.

Methinks you're straddling the fence. Basically, the problem boils down to whether you believe that the customer actually owns the product, to do with as he sees fit, or whether you are actually selling a license to use your product, restricted in any manner you see fit.

No, you don't want to deal with irate customers, self-repair hackers,

3rd party repair shops, and people trying to buy unique parts so they can clone your product.

UL approval, which intentionally limits user access to anything that might electrocute a user. The product can self destruct or even catch fire, but as long as it doesn't kill anyone, it's considered safe.

What does that mean? Quantity is a rather poor substitute for quality.

Conventional screw threads into PEM inserts are probably the best if everything is aligned. That the way most laptop bottoms are secured. The problems start when they're not misaligned, or some lunatic with an electric power screwdriver cross threads the PEM nut. The result is usually cracking the plastic supporting the PEM nut. I've done better with self tapping plastic screws if the plastic standoff is fairly thick. Extra points for using a double helix threaded screw, which are made for plastic:

Solvent welding or glue are almost a requirement for wall wart type power supplies. The idea is to keep the customer out so that they don't kill themselves. It can be done with screws, but the screw heads need to be covered with an escutcheon or buried under potting compound or similar goo.

Also, think about some kind of destructive indicator that clearly demonstrates that someone has opened the case.

--
Jeff Liebermann     jeffl@cruzio.com 
150 Felker St #D    http://www.LearnByDestroying.com 
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Reply to
Jeff Liebermann

Solvent welding would be difficult with a metal case, yes.

Easiest would be screws into PEM nuts. Second-easiest would be thread- forming screws into bosses in the case. If a user takes apart a plastic- cased device and screws it up -- well, tough. Just put a "warranty void if seal broken" on the thing, and let them suffer any consequences.

--
www.wescottdesign.com
Reply to
Tim Wescott

** The words in your heading are part of a serious **safety warning** - the complete version is like this:

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It has absolutely nothing to do with the device being repairable by someone with the skills and knowledge to do so.

Makers who use the warning want to protect themselves against possible legal claims when some dope opens up an appliance and thinks he or she can find the loose wore or blown fuse - and gets an electric shock or worse.

.... Phil

Reply to
Phil Allison

*I* can have "means" to access the parts that I would want to repair -- as well as "affordable" replacement cases (something to which a user wouldn't have access)

Even manufacturers of "licensed" products don't have their own "product police" that go around knocking on doors to see if you've tampered with "their" product. E.g., *despite* license terms to the contrary, there is nothing that prevents me from "reverse engineering" software, etc. (what I then *do* with the knowledge gained is a different issue)

I simply don't want to have to stock "replacement parts". Doing so puts you in a position of having to either supply all sorts of "basic components" (do you sell replacement screws? adhesive labels? MAC address stickers? etc.) at some outrageous markup ("Cripes! $5 for a set of replacement screws??") that never endears you to your customers.

*Or*, selling some smaller set of components at "reasonable" prices that adds to YOUR costs.

I'd be happy to let some third party pick up the "profit" from addressing the needs of those users -- and "justifying" his prices (and "quality") to them (as well as fielding their questions when something goes wrong!)

Other, OVERWHELMING criteria that would bias AGAINST having easy access would be things like: - device designed to be water-resistant to 50 fathoms - device contains toxic substances - device has lots of little parts held in place by the case - device houses high voltages "protected" exclusively by the case etc.

I've also seen over-torquing simply stripping the threads -- the screw effectively acting like a *drill* bit. At this point, the case is unsalvageable.

Hence my suggestion that *through* hardware is the most friendly (e.g., a COTS "bolt w/ nut") -- though most difficult to accept from an appearance perspective.

Screw into plastic has a limited number of cycles before the plastic gets to the point that it simply can't retain the screw. Think Jboxes in residences.

Of course! IME, "tinkerers" are willing to eat their failures (instead of trying to return a TAMPERED product for "warranty repair"). The goal is to make it easier for them to achieve their tinkering WITHOUT getting to a point where they have to resort to a complete replacement.

[I.e., I suspect many would be TICKLED if they could buy a new case AT COST -- as insurance against the inevitable mechanical or cosmetic damage that their tinkering is likely to promote]
Reply to
Don Y

Screws that finish just below the surface that and fit a No.2 Phillips screwdriver, with triangular arrow-heads that indicate the apropriate screw positions (if there are non-closure screws).

no, least friendly is potted with alumina fill.

Solvent welded is easy to open. once you get the knack, certainly easier than screws obscured by a glued-on metal front facing. Easier in many cases than spring-loaded hooking clips.

--
This email has not been checked by half-arsed antivirus software
Reply to
Jasen Betts

Do you really think that a consumer electronics manufacturer would keep a spare parts inventory after the production run (which may last only 3 to 6 months) ? After all, a spare part inventory would be a capital investment, which doesn't ever pay back.

There are large lots (several reels) of components sold on EBay. One source is from device manufactures who have ordered too many components or the production run has been cut short. Previously these components would has been used as a spare part inventory, but are now sold on EBay.

The trend seems to be that "inventory" is a dirty word due to the capital tied to it.

Of course, this causes a lot of problems for equipment manufacturers that must give a long warranty time, such as 10 years :-(.

Reply to
upsidedown

** Wot utter crap.

Manufacturers and importers are required by consumer LAW to have essential spare parts available for the expected service life of equipment they sell.

They are not required to make them available to owners or third parties, but usually do and sell them with LARGE profit margins attached.

Spares may be individual components, sub-assemblies or whole circuit boards.

They do not have to supply "garden variety" parts as spares, but only parts that are special to the equipment and not available in small quantities elsewhere.

.... Phil

Reply to
Phil Allison

Might they choose to repay the price or offer a "better replacement"? I suspect in some cases that would be more economic.

Reply to
Tom Gardner

** Sorry, cannot discuss your unexplained hypothetical.

The bone has no flesh on it.

.... Phil

Reply to
Phil Allison

The trend is that consumer products often depend on some external service that disappears or changes after a while, making the product redundant and in need of replacing it.

For example, a radio depends on the transmission of radio programmes in a format that the radio can demodulate. In the days of AM and FM those formats did not change for many decades, and if a change was made it was made in a backward-compatible way (FM stereo, color TV). So you could be interested in repairing your radio or TV even when it was a decade old.

Today, the formats change every couple of years. DAB has already been replaced by DAB+ for example. This makes your DAB radio a useless device now.

Similar developments make older computer-like devices obsolete because there is no supported operating system for them anymore, or because they cannot handle the load of today's software. Even when you could repair your smartphone or tablet, you would not want to do that because it already was too slow or was incompatible with today's standards iOS and Android.

This is the ideal world for manufacturers, because they don't need to support all that equipment anymore even when it would be economically sound to repair it.

Reply to
Rob

Or the whole product.

Based on expected early infant mortality rates, some CE (China Export) companies are willing to send a replacement product even without requiring a faulty product to be returned.

Retaining a few fully assembled product for warranty replacement may be easier than maintaining an inventory for individual components.

Reply to
upsidedown

"Better replacement": we had been using a fully populated +5 V PCI card for years. Suddenly without any warning or change of the card type number a new lot of Universal PCI (+5/+3.3 V) cards with a single ASIC were delivered. Unfortunately, the software driver was not compatible with the old version. In addition, the consumption on the

+3.3 V line was too high, bringing it down, while there were plenty of power available on the +5 supply.

This was a quite nasty surprise, when there are only hours or a few days available for replacement once every (few) a years.

Reply to
upsidedown

Use common screws and you don't need to.

It really isn't. Fit a wider screw, use a bit of glue, use a nut & bolt etc

A label or foot over it is one option

but then you're condoning user repairs.

NT

Reply to
tabbypurr

Since you're planning on doing the same thing you don't sound very sympathetic. What, the device is to be a throwawy ?

If you have kids, eventually a landfill will fall on their house.

Reply to
jurb6006

On the off chance he really has a valid reason to do this I will mention th e Pioneer trap switch. Pioneer plasma TVs used to have a switch that was op ened (or closed, whichever) when the back was removed. you had to know this otherwise if you don't put tape on it ad plug it in it will never work aga in until you call the factory and get the procedure to reactivate it. It wa s not even in the service manual though you can get it online. They used th e excuse that there was proprietary CODECs or some shit.

Reply to
jurb6006

That assumes people can read. Can't assume that here though now with texting more kids actually want to learn to read, mainly so they can be on the net at school instead of paying attention.

Reply to
jurb6006

al spare parts available for the expected service >life of equipment they s ell. "

Not in the US. These days when you buy things, if the place you buy it from is any good they will tell you to save the box so you can ship it back for a warranty replacement. At your expense of course, which can be significan t if it is like a 60" plasma TV.

But for a while now, like decades, it has been the policy of the US governm ent not to protect the Citizens from anything and to exploit and real attac k to get more draconian laws supported.

Reply to
jurb6006

I got a problem right now with a customer who simply does not want the new and improved version. We don't have the parts and already sent him the newe r version which he tried out and does not want. He sent it back. He describ ed what he didn't like about it, so what are we going to do ? Has yet to be determined. I think I can scare up another of that model.

Another problem is that even though we are running out of parts for this li ke two year old model, people are still selling new ones online and on eBay . If they get forced into a refund by eBay I imagine we are going to have t o issue a refund, on a product sold before we even bought the company.

Reply to
jurb6006

One of my friends was building a product that required a highly customized case. The problem was that he had to order a substantial quantity of cases in order to keep the cost down. The result was an over-supply that filled his garage and part of his house. I suggested that he ship a spare case with each product to reduce the storage costs. He hasn't asked my advice since then.

I suggest you print the poster and hang it on the wall as a reminder of what you customers are probably thinking.

Yeah, I know how that works. At several former employers, I calculated the cost of shipping an empty box. The box would contain no product or parts, but would carry the cost of all the overhead, handling, boxing, documentation, paperwork, billing, credit check, inspection, QA, shipping, labeling, debt retirement, taxes, executive slush fund, political contributions, etc. It varied by company, but my guess(tm) is that it currently is about $75. That sets the minimum cost of shipping a single screw to a customer.

However, tossing in additional screws did not increase the cost much. One screw or 100 screws were almost the same cost to the customer. That also set a minimum order charge, which was the main defense against getting nickel and dimed to death by customers doing their own repairs. It was not unusual for someone to order 100 screws, even if they only needed one. Set a minimum order size and you'll probably be ok.

Good luck finding such a 3rd party parts vendor. What I did at one employer was setup a 2nd source parts list for customers demanding repair parts sources in the unlikely event of having my employer go bankrupt. Basically, they wouldn't buy the overpriced product with some reassurance that it could be repaired forever. That worked well for commodity parts, but not so well for PCB's, molded parts, and special order parts. So, we found a 3rd party warehouse that would carry just these parts at outrageous prices. It worked. Therefore, I suggest that you supply your customers with Digikey or Mouser part numbers, and only deal with the few unique parts either yourself, or through some 3rd party (eBay vendor, fulfillment house, parts warehouse, etc).

Ok, got it. Assisting or enabling a customer in performing an unsafe repair would not be a good idea. You could try including a legal document that indemnifies you from any subsequent or consequential damage, but those are difficult and expensive to enforce. I guess the simplest approach is that you can be sued for helping a customer hurt themselves, but you cannot be easily sued for refusing to help them and NOT supplying them with the parts they need. Welcome to the throw away products business.

Yep. Give the user an electric screwdriver and that's exactly what will happen. I see if often in the computer repair biz. I do have electric and pneumatic screw drivers, but they're only used to remove screws, not install them.

The problem with self tapping screws in plastic is that the mounting boss needs to be rather wide and deep. Manufacturers of these screws specify minimum design specs, which often become the values used in the product. If the self tapping screw is sufficiently long, it will take considerable force and effort to strip it. If the mounting boss is sufficiently wide, it won't crack.

If you're going into plastic, the brass threaded PEM style inserts have the advantage of being shallower and requiring a smaller mounting boss. At the design minimums, it doesn't take much to crack the plastic boss and spin out the threaded insert. Which is appropriate is a design decision. If you have the room, I suggest self tapping screws. If you lack the space, use threaded inserts. However, if you can use a sheet metal mounting plate, with press fit PEM fasteners, I would consider that preferential and much better than either self tapping and threaded inserts.

Agreed. However, such packaging is not often possible. Most of the radio products I worked on were a PCB mounted on a sheet metal chassis or shield. All the case fasteners were to PEM nuts in this shield. That worked just fine for large boxes, but wasn't practical for small radios, such as pagers, handhelds, and "thin" radios. So, we were forced to make the same decisions that you're facing now.

I'm looking around my desk at all the eJunk. Most of the plastic case devices that use screw type fasteners (drop in chargers, cordless phones, digital clock, SIP phone, TV remotes, calculators, mouse, etc) use self tapping fasteners. The only one I found that uses threaded inserts are several 2way radios and my better computah keyboards. You might want to make a similar survey of everything within reach. I think you'll find self tapping to be far more popular.

So, how many assembly/disassembly cycles would you expect you product to survive? What percentage of your sales would you expect to require repeated disassembly? How many self-stripping case mounting screws can you break or leave out and still have a safe and functional case? With robotic assembly, the cost of an extra fastener is trivial.

No, your goal is to do all that without killing the tinkerer. Your product may have had thousands of successful repairs and rebuilds, but it only takes one fatality to ruin your day. Welcome to defensive design.

I really think you should consider shipping a spare case with each product. If the serial number is on the case, move it elsewhere. Or, you could sell a repair, rebuild or refurbishing kit, that includes the case, screws, and cosmetic parts.

--
Jeff Liebermann     jeffl@cruzio.com 
150 Felker St #D    http://www.LearnByDestroying.com 
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Reply to
Jeff Liebermann

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