Fluke quality...

[Fungus]

How about olive oil?

Here in Spain we use it for everything from bicycle chains to salads.

[saturation]

To reduce the risk of stripping a threaded insert hole I first turn the screw counterclockwise by hand until it sits on the existing groove, it will fall or click into place which you can feel by hand.  It should then screw in as easy as when you unscrewed it.  If not easy, it might be in slightly off angle and is probably cutting another groove. Back out, insure the screw is straight then retry.  If you've cut multiple grooves already keep retrying until you find the smoothest one but never force it.

For Fluke cases, I have not yet stripped a screw hole so it doesn't hold, in 28+ yrs particularly the early models, which require the cases to be opened with each battery change.

Lubricant really isn't necessary and worse case, you do not want to make it easier to cut new grooves. 

In low quality gear, the plastic can be so bad that it deforms or existing grooves can simply break off, no fault of your own.  You can then fill the hole with crazy glue or Goop, whichever bonds better.  If it doesn't bond no worries, it will pop out, if it bonds, its hold.

Lastly but most involved, you can buy threaded inserts and new matching screws and replace the screws in toto.

[HighVoltage]

To reduce the risk of a stripping a threaded insert hole I first turn the screw counterclockwise by hand until it sits on the existing groove.  It should then screw in easily.  If not, it means its being screwed in slightly off angle and is probably cutting another groove. Back out, insure the screw is straight then retry.  If you've cut multiple grooves already keep retrying until you find the smoothest one but never force it.

+1
That is the key to success, not only for plastic threads but for all threads.

I also agree, never to use lubricants on any plastic threads.

[SeanB]

To reduce the risk of a stripping a threaded insert hole I first turn the screw counterclockwise by hand until it sits on the existing groove.  It should then screw in easily.  If not, it means its being screwed in slightly off angle and is probably cutting another groove. Back out, insure the screw is straight then retry.  If you've cut multiple grooves already keep retrying until you find the smoothest one but never force it.

For Fluke cases, I have not yet stripped a screw hole so it doesn't hold, in 28+ yrs particularly the early models, which require the cases to be opened with each battery change.

Lubricant really isn't necessary and worse case, you do not want to make it easier to cut new grooves. 

In cheap gear [particulary China], the plastic used is so bad that it deforms and soften so existing grooves can simply break off, no fault of your own.  You can then fill the hole with crazy glue or Goop, whichever bonds better.  If it doesn't bond no worries, it will pop out, if it bonds, its hold.

Lastly but most involved, you can buy threaded inserts and new matching screws and replace the screws in toto.

Lucky I have M3 and M4 recoil inserts, the taps and the insert tools. It does work, though often I also have to use some epoxy and a small diameter metal tube as an external brace for cracked plastic bosses. If you have older broken beyond repair equipment ( or old cellphones) you can strip the brass inserts out of them to use here, using a drop of epoxy to hold it in place.

[ManateeMafia]

I like the idea about using super glue or plastic epoxy to fill the hole. I have used a similar idea on anchor bolts for large equipment. A bolt wrapped in teflon tape was easy to remove and left plenty of threads to tighten.

Perhaps use some PTFE coated screws and insert them in the glue before it hardens?

[SeanB]

I like the idea about using super glue or plastic epoxy to fill the hole. I have used a similar idea on anchor bolts for large equipment. A bolt wrapped in teflon tape was easy to remove and left plenty of threads to tighten.

Perhaps use some PTFE coated screws and insert them in the glue before it hardens?

I just used bigger anchors, and a 2 pack construction epoxy as insurance.

For the epoxy release you do not need any PTFE, just take some silicone furniture polish and spray the bolt, then wipe it off leaving a light coat, or use silicone mould release from the boat chandlers. Works a charm, and is not going to harm any plastics, though keep it well away from where you are working, otherwise the epoxy will not stick to anything ever again.

The furniture polish works well for keeping building tools clean, just spray before use, and then afterwards wash them clean using water and a cloth, and spray again then put in storage. Cement will not stick on them easily then.

[BravoV]

To reduce the risk of a stripping a threaded insert hole I first turn the screw counterclockwise by hand until it sits on the existing groove.  It should then screw in easily.  If not, it means its being screwed in slightly off angle and is probably cutting another groove. Back out, insure the screw is straight then retry.  If you've cut multiple grooves already keep retrying until you find the smoothest one but never force it.

+1
That is the key to success, not only for plastic threads but for all threads.

I also agree, never to use lubricants on any plastic threads.

+2  , slow counterclockwise turn while maintain the screw straight, until the 1st "click", where thread hit the exact start groove, then start the clockwise turn to fasten while the fingers still sensing if its derailing from the groove on the 1st few turns.

[nanofrog]

To reduce the risk of a stripping a threaded insert hole I first turn the screw counterclockwise by hand until it sits on the existing groove.  It should then screw in easily.  If not, it means its being screwed in slightly off angle and is probably cutting another groove. Back out, insure the screw is straight then retry.  If you've cut multiple grooves already keep retrying until you find the smoothest one but never force it.

+1
That is the key to success, not only for plastic threads but for all threads.

+2  , slow counterclockwise turn while maintain the screw straight, until the 1st "click", where thread hit the exact start groove, then start the clockwise turn to fasten while the fingers still sensing if its derailing from the groove on the 1st few turns.

+3 

[Robomeds]

One issue with an old meter like this is we don't know what chemicals it was exposed to over the years.  I used to work with rugged battery packs.  Tough as all get out in drop and impact.  If we wanted to open them without damaging the electronics inside we just sprayed them down with brake cleaner.  The plastics just crumbled.  No idea if this is P90's case but it looks like it could explain the Amazon posting.  Self tappers into plastic is OK if you aren't opening them all the time or if you are careful when you do open them.  We have no idea if P90's was ever abused (cross threaded, lover sized screw etc).  Actually, given that Fluke was expecting this to be the method for changing the battery I'll go with wasn't treated with caution when removing the back cover. 

I do agree with those who think that inserts are darn near mandatory if you expect people to remove the back cover to change the battery.  Fluke addressed that with the 87-3 which was released what, near 20 years back?  I'm willing to overlook fuse doors held on with self tappers as you shouldn't be blowing fuses that much.  So the 87-5 still has user serviceable parts behind self tappers.  The comment about the 27/28 meters using self tappers is a non-issue in my book.  Those have no user serviceable parts inside.  Yes, we love to open things just for the heck of it, but the fuses and batteries are all accessed via a panel held with machine screws/inserts.

Thinking about CAT ratings etc, I don't at all like the idea of gluing in machine screw standoffs inside of the meter.  A plastic screw boss is non-conductive so no fear of voltage inside of the meter finding a case screw.  A threaded insert is buried deep in plastic so again no issues with conductive paths.  I can't say the same for a user added threaded boss.  Like so many safety things 99.9% (maybe 99.99+%) will never care (won't operate in a high risk area or high risk will never result in an event that tested the meter's safety features) but you would hate to be the one that did care. 

[P90]

One issue with an old meter like this is we don't know what chemicals it was exposed to over the years.  I used to work with rugged battery packs.  Tough as all get out in drop and impact.  If we wanted to open them without damaging the electronics inside we just sprayed them down with brake cleaner.  The plastics just crumbled.  No idea if this is P90's case but it looks like it could explain the Amazon posting.  Self tappers into plastic is OK if you aren't opening them all the time or if you are careful when you do open them.  We have no idea if P90's was ever abused (cross threaded, lover sized screw etc).  Actually, given that Fluke was expecting this to be the method for changing the battery I'll go with wasn't treated with caution when removing the back cover. 

I do agree with those who think that inserts are darn near mandatory if you expect people to remove the back cover to change the battery.  Fluke addressed that with the 87-3 which was released what, near 20 years back?  I'm willing to overlook fuse doors held on with self tappers as you shouldn't be blowing fuses that much.  So the 87-5 still has user serviceable parts behind self tappers.  The comment about the 27/28 meters using self tappers is a non-issue in my book.  Those have no user serviceable parts inside.  Yes, we love to open things just for the heck of it, but the fuses and batteries are all accessed via a panel held with machine screws/inserts.

Thinking about CAT ratings etc, I don't at all like the idea of gluing in machine screw standoffs inside of the meter.  A plastic screw boss is non-conductive so no fear of voltage inside of the meter finding a case screw.  A threaded insert is buried deep in plastic so again no issues with conductive paths.  I can't say the same for a user added threaded boss.  Like so many safety things 99.9% (maybe 99.99+%) will never care (won't operate in a high risk area or high risk will never result in an event that tested the meter's safety features) but you would hate to be the one that did care.

It was not exposed to chemicals nor was it abused, if fact it's been used far less than any of my other meters, and they don't have any of these plastics issues. I never over tighten any of the screws in anything, I'm very cautious. In fact, that's why it's not a good idea to lube screws, since you end up over tightening them.

[BMack]

I have a bunch of Fluke meters and never had an issue with any one of them...until I bought a used Fluke 12. It was in great shape, works well but the posts broke after I put a new battery in, the plastic seems to have become brittle over time. It doesn't look like it was abused or had chemicals applied at all. Posts didn't have visible cracks when I removed the screws and I'm quite gentle when I put any screws in plastic. The OP isn't just making this up...but it's also not what I'd call common. It happens, still the best DMMs on the market.

[Ig_sherwood]

Expensive multimeter VS Expensive multimeter ,
can you figure out who is better 
 

[BravoV]

Expensive multimeter VS Expensive multimeter ,
can you figure out who of them is better 
 

And in between  ....

An unique combination of both, mixed of thread inserts and self taps in a single box , an expensive meter too, its Agilent/Keysight U1213A clamp meter, images below part of -> U1213A teardown.

[P90]

Expensive multimeter VS Expensive multimeter ,
can you figure out who of them is better 
 

And in between  ....

An unique combination of both, mixed of thread inserts and self taps in a single box , an expensive meter too, its Agilent/Keysight U1213A clamp meter, images below part of -> U1213A teardown.

I have a somewhat similar UEI clamp meter that has 3 screws total in order to remove the back half, 2 with brass inserts, and the third treads into plastic...  genius...   
 

[saturation]

Come to think of it, I vaguely recall there was a recall of the 80 series in the early 1990s, but I cannot be sure.  I think it did have something to do with the plastic case.  If true, Fluke would consider such an issue a defect.

In 2012,  The 28-II EX were recalled because the screw back plastic could crack the chassis.

http://www.fluke.com/fluke/sgen/support/safety/28-II-EX-Recall.htm

[ericloewe]

Expensive multimeter VS Expensive multimeter ,
can you figure out who of them is better 
 

And in between  ....

An unique combination of both, mixed of thread inserts and self taps in a single box , an expensive meter too, its Agilent/Keysight U1213A clamp meter, images below part of -> U1213A teardown.

It's not really unusual. Metal threaded insert for the frequently-accessed compartment, cheaper self-tapping screws for the rest.

[kaz911]

Fluke is great for all but...

1. all "ScopeMeter" bw lcd Screens (Lines on screen - covers ALL product lines like EtherScope, 43b, 12x series, 190/190b series and all deviations)

2. ANYTHING rechargeable (high "off" battery load killing batteries - and no external battery on/off switch - and supercap issue on 28x series)

3. And I agree - plastic screen frames on all instruments - cheap plastic - sorry. My 3 YO Fluke 725 - plastic disintegrated. No solvents used on it - no excessive heat - just crappy quality plastic. My old 743b which is probably about 12 years old - the screen frame is fine.

But in the Marine Environment I have seen a lot of really bad plastic and a lot of really good plastic. The good plastics from Navico(Simrad/Lowrance), Raymarine (Flir) and Garmin lasts for decades and stays white - and does not chip/break - where the cheap non super UV versions gets yellow after a year or two (Maretron, Hummingbird and a lot of other small companies) - Another year or two and it starts chipping - and another year and it has disintegrated completely. You might see the same at home with light switches, thermostats etc. even if the sun does not reach them directly. Both heat & UV impacts plastic lifetime. Salt water does also have an impact as I think the salt helps take the moisture out of the plastic?

[LabSpokane]

It's not a "bad plastic" problem. It's a fundamental plastics-engineering problem.

Folks, the plastic screw bosses are cracking because the base plastic is polycarbonate or a polycarbonate blend. It is not "bad" plastic. These plastics are typically classed as engineering resins because they are tough and flexible.  The plastic is simply being inappropriately used. There are only two safe ways to put a screw into a polycarbonate boss: use an insert or use a thread-cutting screw.

The reason why PC bosses break is that PC and its blends don't endure hoop stress well.

Under no circumstances should cyanoacrylate glues be used on PC or PC blends. That has a real chance of degrading the plastic and causing it to disintegrate.

Flukes continued lack of use of threaded inserts or other, better means of battery access has been a decades-long disappointment with no excuses given the price point and Fluke's available resources.

 

P.S.

Lubricating the screws will do nothing to help this cracking. It is entirely due to the fact that PC is a high-modulus material and responds to extended periods of strain by cracking instead of stretching.

[P90]

I have decided to get rid of all my Fluke meters.

[Ig_sherwood]

Im just amazed by peoples around here.
I mean ,why do you like when companies like Fluke rape's you?
The price of their meter are bloody expensive and the quality build for that price is not really well.
Im also wondering about how in some $40 taiwanese multimeter i can find all metal thread's for the screws ,but not here for circa 400/500 bucks!!!
and of course we are talking about FLUKE !!!!
This is just incredible !!!
Just incredible !!!

However the fault is also yours ,because no one of you are telling to fluke about this big mistake.

Don't be like a sheep ,because you can't justify plastic threads, this such obvious lack of quality !!!

You can't fix it with grease,lubrificant ecc,ecc,ecc,ecc,ecc...so please stop talks bullshit about this plastic threads,them simply sucks,end of the questions !!!

Many of you can send to them an letter ,go to their forum's to start speaking about this very nasty problem.

P.S im getting out with my brand new fluke and with fluke in general,if anyone is interested ,you can contact me in PM.

[kaz911]

Well om the plus side for the Fluke 28x meters are they are extremly precise even after 6-8 years. I had my 6 year one in for calibration - and the meter was 100% within spec - and not very much off original cal certificate.

And much other Fluke gear the story is the same. I have a really battered 743B  that I think is 14 years old - which I bought broken and fixed - and it is still bang on on every single parameter. Sourcing or measuring - spot on - and it is great for validating temperature probes - it is darn precise and very stable compared to most other temperature sensor measurement systems I have tried.

That is why I like my Fluke meters despite their moronic battery life and super-cap issues they usually wont acknowledge. For the MEASUREMENTs - and you can order every single part inside the case from their spare parts department. So WHEN the screen clip goes on a 725 - the replacement part no is in the manual.

[BravoV]

It's not really unusual. Metal threaded insert for the frequently-accessed compartment, cheaper self-tapping screws for the rest.

It is, that meter has 3 screws, 1st one for securing the battery compartment uses metal threaded insert, and the other two for the whole back cover is using two mixed types, go figure. 

[Someone]

It was not exposed to chemicals nor was it abused, if fact it's been used far less than any of my other meters, and they don't have any of these plastics issues. I never over tighten any of the screws in anything, I'm very cautious. In fact, that's why it's not a good idea to lube screws, since you end up over tightening them.

You still haven't mentioned how and where it was stored, there must be some difference between it and your other meters. Or perhaps you got unlucky and the batch of plastic was bad?

[joeqsmith]

Expensive multimeter VS Expensive multimeter ,
can you figure out who is better 
 

Hard to tell much from your picture.  Meter on the left uses a small glass fuse for the low current.  I only see glass used in the cheapest of meters, not the high end ones.  The 10A fuse is 500V rated and also doubt is has a high break current.   Funny to see wires soldered into PCB.  Not the ones for the connectors but the brown / white pair.  What's up with that?  The black jumper reminds me of some of those crap single sided PCBs with all the jumpers on them.    I've had some fun with meters having poor creepage distances like the meter shown.   Meter on right has a stripped hole someone bunged up? 

I've never ran any Gossen products and have no idea how they would fair against the others I have looked at.   I can't believe the meter on the left represents what they are selling today.  I have ran a few Asian made Flukes and these have all been some of the most electrically robust meters I have looked at.  Too bad I can't say that about the 87V. 

[Someone]

Expensive multimeter VS Expensive multimeter ,
can you figure out who is better 
 

Hard to tell much from your picture.  Meter on the left uses a small glass fuse for the low current.  I only see glass used in the cheapest of meters, not the high end ones.  The 10A fuse is 500V rated and also doubt is has a high break current.   Funny to see wires soldered into PCB.  Not the ones for the connectors but the brown / white pair.  What's up with that?  The black jumper reminds me of some of those crap single sided PCBs with all the jumpers on them.    I've had some fun with meters having poor creepage distances like the meter shown.   Meter on right has a stripped hole someone bunged up? 

I've never ran any Gossen products and have no idea how they would fair against the others I have looked at.   I can't believe the meter on the left represents what they are selling today.  I have ran a few Asian made Flukes and these have all been some of the most electrically robust meters I have looked at.  Too bad I can't say that about the 87V.

The threaded inserts also look to be pressed in place rather than moulded into the plastic, so the residual stresses are still there and they can pull out. Not a lot better for screws that are rarely taken in/out.