Test Equipment Anonymous (TEA) group therapy thread

[mnementh]

I blame BREXIT. 

mnem
The Three Laws of Thermodynamics:
1. You can't win.
2. You can't break even.
3. You can't even get out of the game.

[Neomys Sapiens]

And I just discovered another specific facet of annoyance with TEA:
The cheaper you manage to aquire a piece of test equipment, the more it is guaranteed that you will be seriously fleeced when you attempt to complete it.
I got this Gaussmeter from Lake Shore Cryotronics, which did only cost me 80.-€. It is even like new and working nicely. It came with a axial probe. Just getting the transversal probe will cost me over 300.-, and then I still need a reference magnet and a zero-Gauss tunnel (a tube of solid µ-metal). Must wait somewhat , but hopefully lot long enough for LCS to raise their prices.

[Mr. Scram]

Please don't snip important context in order to make a point that turns out to have, um, more limited applicability that you imply.

In this case the context was...

Now, would you like to quantify your statements "much more brittle" and "not quite as long lasting"?

I have an SLA piece of mine which works perfectly, whereas the same PLA piece was so weak it broke during installation. The latter was no surprise whatsoever, snapping along the join between layers; I made it just to compare the dimensional accuracy.

I can also point to that SLA threaded handle; it is 4 years old and in perfect condition, despite being a little too thin walled. Would an HP MJF nylon pieces' surface smoothness and low friction would be acceptable for that screwthread? Who knows, without trying it.

Fundamentally engineering is about matching a material to the use. Different uses imply different materials may be applicable.

I don't think EEVBlog crowd is that easily confused about the context. SLA simply isn't that strong and tends to be not that stable from a chemical point of view. Modern resins are slowly improving either or both but it's no coincidence it's usually used for show or prototype pieces. I'll quote the SLA disadvantages section of 3dhubs. "SLA parts are generally brittle and not suitable for functional prototypes. The mechanical properties and visual appearance of SLA parts will degrade overtime when the parts are exposed to sunlight. Support structures are always required and post-processing is necessary to remove the visual marks left on the SLA part."

All printing processes have very distinct benefits and drawbacks and the trick is to match the right process with your use case or vice versa, as you say. The same applies to any engineering problem and picking the right solution and tooling for the job. None of that really matters if the solution we bumbled together happens to pan out though. It's not as if we're trying to build a Falcon 9. If that SLA part works for you it works.

https://www.3dhubs.com/knowledge-base/introduction-sla-3d-printing/#pros-cons

[mnementh]

And I just discovered another specific facet of annoyance with TEA:
The cheaper you manage to aquire a piece of test equipment, the more it is guaranteed that you will be seriously fleeced when you attempt to complete it.
I got this Gaussmeter from Lake Shore Cryotronics, which did only cost me 80.-€. It is even like new and working nicely. It came with a axial probe. Just getting the transversal probe will cost me over 300.-, and then I still need a reference magnet and a zero-Gauss tunnel (a tube of solid µ-metal). Must wait somewhat , but hopefully lot long enough for LCS to raise their prices.

Is this a factor of the difference in what it takes to make the transversal probe; ie this is a global issue, or are you saying that LCS is lowballing the core unit, and pricing the "everybody needs this" transversal probe absurdly high to make up the difference, like pretty much every squid-squeezing paper printer manufacturer selling ink by the gram like crack & crystal meth?

mnem
 

[tggzzz]

Please don't snip important context in order to make a point that turns out to have, um, more limited applicability that you imply.

In this case the context was...

Now, would you like to quantify your statements "much more brittle" and "not quite as long lasting"?

I have an SLA piece of mine which works perfectly, whereas the same PLA piece was so weak it broke during installation. The latter was no surprise whatsoever, snapping along the join between layers; I made it just to compare the dimensional accuracy.

I can also point to that SLA threaded handle; it is 4 years old and in perfect condition, despite being a little too thin walled. Would an HP MJF nylon pieces' surface smoothness and low friction would be acceptable for that screwthread? Who knows, without trying it.

Fundamentally engineering is about matching a material to the use. Different uses imply different materials may be applicable.

I don't think EEVBlog crowd is that easily confused about the context. SLA simply isn't that strong and tends to be not that stable from a chemical point of view. Modern resins are slowly improving either or both but it's no coincidence it's usually used for show or prototype pieces. I'll quote the SLA disadvantages section of 3dhubs. "SLA parts are generally brittle and not suitable for functional prototypes. The mechanical properties and visual appearance of SLA parts will degrade overtime when the parts are exposed to sunlight. Support structures are always required and post-processing is necessary to remove the visual marks left on the SLA part."

All printing processes have very distinct benefits and drawbacks and the trick is to match the right process with your use case or vice versa, as you say. The same applies to any engineering problem and picking the right solution and tooling for the job. None of that really matters if the solution we bumbled together happens to pan out though. It's not as if we're trying to build a Falcon 9. If that SLA part works for you it works.

https://www.3dhubs.com/knowledge-base/introduction-sla-3d-printing/#pros-cons

Nonetheless snipping context is liable to mislead and is unnecessary; this isn't stackexchange or edaboard, thank deity.

Your contention about this relative strength of PLA vs SLA is unsubstantiated and contradicted in my experience and examples.

I too have doubts about SLAs long term stability, it isn't a wonder material. I also have doubts about PLAs long term stability. But if PLA isn't strong enough when manufactured, it isn't going to get any stronger!

[Neomys Sapiens]

And I just discovered another specific facet of annoyance with TEA:
The cheaper you manage to aquire a piece of test equipment, the more it is guaranteed that you will be seriously fleeced when you attempt to complete it.
I got this Gaussmeter from Lake Shore Cryotronics, which did only cost me 80.-€. It is even like new and working nicely. It came with a axial probe. Just getting the transversal probe will cost me over 300.-, and then I still need a reference magnet and a zero-Gauss tunnel (a tube of solid µ-metal). Must wait somewhat , but hopefully lot long enough for LCS to raise their prices.

Is this a factor of the difference in what it takes to make the transversal probe; ie this is a global issue, or are you saying that LCS is lowballing the core unit, and pricing the "everybody needs this" transversal probe absurdly high to make up the difference, like pretty much every squid-squeezing paper printer manufacturer selling ink by the gram like crack & crystal meth?

mnem
 

Nope. I think it is only the factor of surprise on my side. It was a serious 'jammy git' candidate.

[drussell]

I think I would probably use a 3DP mostly for things like making the patterns to do sand casting with metal.

I know everyone's use cases are different, but I really can't think of enough plastic parts I would want to actually print directly to justify buying a printer.... 

Now, if I ever get around to finding myself some refractory cement to build my self a little used oil burner mini-foundry or something....  Heh... Heh... 

[tautech]

I think I would probably use a 3DP mostly for things like making the patterns to do sand casting with metal.

I know everyone's use cases are different, but I really can't think of enough plastic parts I would want to actually print directly to justify buying a printer.... 

Now, if I ever get around to finding myself some refractory cement to build my self a little used oil burner mini-foundry or something....  Heh... Heh... 

A DIY LPG lance and a few fire bricks is easier.

[Cerebus]

Your contention about this relative strength of PLA vs SLA is unsubstantiated and contradicted in my experience and examples.

I too have doubts about SLAs long term stability, it isn't a wonder material. I also have doubts about PLAs long term stability. But if PLA isn't strong enough when manufactured, it isn't going to get any stronger!

OK. I'm confused. PLA (polylactic acid) is a material. SLA (stereolithography) is a process, which can use many different resins. So surely any comparison is a chalk and cheese one unless someone mentions what particular SLA resin is being compared.

A quick survey suggests that SLA materials seems to range from a rather nebulous "standard", "transparent", "durable", "ceramic reinforced" of unnamed chemistry  with ultimate tensile strengths ranging from 31-75 MPa, Young's modulus of 1.3-4.1 GPa, all the way through to familiar engineering materials of ABS, Nylon, SBR/TPR. For reference the first set of material properties I can find for PLA are UTS=26.4 Mpa,  and Young's modulus of 2.3 GPa.

I can't find figures for long term stability for any of these materials that are useful for objective comparison, they're all "n out of 10" type comparative scores and I'm suspicious whether those amount to anything more than pure hand-waving.

Just to put those into perspective, typical properties for more familiar materials:

Material	UTS (MPa)	Tensile Modulus (GPa)
Nylon 66 (average, unreinforced)	61.6	2.3
Aluminium (1050-H14)	105	70
Low Carbon Steel (EN1A)	480	207

Both the metals are selected for being the 'weakest' of their elemental ilk in everyday commercial use.


I'd have preferred to quote tensile yield strengths (or proof strength) rather than UTS, generally that's a much more useful parameter to design around, but the 3PD type folks only seem (in general) to list UTS for their materials.

[Mr. Scram]

Nonetheless snipping context is liable to mislead and is unnecessary; this isn't stackexchange or edaboard, thank deity.

Your contention about this relative strength of PLA vs SLA is unsubstantiated and contradicted in my experience and examples.

I too have doubts about SLAs long term stability, it isn't a wonder material. I also have doubts about PLAs long term stability. But if PLA isn't strong enough when manufactured, it isn't going to get any stronger!

PLA is a printing material and SLA is a printing technique. The discussion was about FDM versus SLA. The implied assumption PLA is involved is not unreasonable as it's still the popular beginner material for FDM but FDM can print a whole host of plastics, almost all of them with better mechanical properties and stability. To get some proper parts you'd need to move to something like the aforementioned MJF process, providing the material matches your needs. If you want to make train models SLA prints of your average resin should be fine as that's essentially a cosmetic application but it's not ideal for functional or mechanical parts for reasons mentioned. None of the available resins change this although things are slowly improving.

We've been over the snipping matter a couple of times before. It hasn't caused any confusion. The full contect is preserved in the original post and the reply for everyone to see. It prevents inane repetition and visual clutter. I'm sorry to hear it upsets you but I don't feel that responsibility is on my end. Here too repetition is outliving its usefulness.

[Kosmic]

Crap, one of the seller on ebay accepted my lowball offer on one of those old Fluke shunt 

They are really not helping.

[Cerebus]

Crap, one of the seller on ebay accepted my lowball offer on one of those old Fluke shunt 

Oh, how terrible for you. I'm sure we all sympathise deeply with your troubling plight.

Mum, mum look! I did manage to keep a straight face.

[Kosmic]

Crap, one of the seller on ebay accepted my lowball offer on one of those old Fluke shunt 

Oh, how terrible for you. I'm sure we all sympathise deeply with your troubling plight.

Mum, mum look! I did manage to keep a straight face.

Ha thank you. it's a good thing we're all in this together 

[Cerebus]

Question for all of you. What common object, other than a ruler, would one use for scale in a photograph that is universal? Yeah, a ruler works but it doesn't have that same visceral feel that, say, a box of matches does.

For the Brits, a standard box of matches would work, but the "standard box of matches" varies in size around the world. A packet of Gitanes is the same size the world over but most people don't have a pack of French Cancer Sticks to hand. A bunch of keys? Pretty universal but you don't really want to embed the key profile of your front door key in a photo for publication. I've been over a few other things in my mind and discounted all of them as not universal enough. Pencil? The ubiquitous Bic? Too long and thin. Cups and cutlery are too variable in size.

I finally hit on a standard pack of playing cards. Right kind of scale, the same size all over the world, something that fits in the hand.

So, can anyone else think of a common household object that is truly universal worldwide, and that fits the bill better than a pack of cards? Thoughts? Something obvious that I've missed?

[0culus]

Clearly, you don't reddit, because the answer is obviously a banana. 

[tautech]

Bic lighter.

[mnementh]

BIC lighters come in a large and a mini version, plus a few weird novelty sizes rare enough to discount as bell-end candidates, so built-in confusion. Typically a penny or a dime have equivalents pretty close to the same size the world around.

This general conundrum is the reason why a lot of nerds shoot videos and pics over a cutting mat. Then the only thing you have to figure out is if they’re using the side gridded in CM or Dumbfuckistan units. 

mnem
 

[0culus]

[...] Dumbfuckistan units. 

mnem
 

OK, is this really necessary? 


...not saying Imperial units are good mind you. I like my powers of 10. 

[mnementh]

And I just discovered another specific facet of annoyance with TEA:
The cheaper you manage to aquire a piece of test equipment, the more it is guaranteed that you will be seriously fleeced when you attempt to complete it.
I got this Gaussmeter from Lake Shore Cryotronics, which did only cost me 80.-€. It is even like new and working nicely. It came with a axial probe. Just getting the transversal probe will cost me over 300.-, and then I still need a reference magnet and a zero-Gauss tunnel (a tube of solid µ-metal). Must wait somewhat , but hopefully lot long enough for LCS to raise their prices.

Is this a factor of the difference in what it takes to make the transversal probe; ie this is a global issue, or are you saying that LCS is lowballing the core unit, and pricing the "everybody needs this" transversal probe absurdly high to make up the difference, like pretty much every squid-squeezing paper printer manufacturer selling ink by the gram like crack & crystal meth?

mnem
 

Nope. I think it is only the factor of surprise on my side. It was a serious 'jammy git' candidate.

Well then! 

I gotcha... a bit of a “white elephant” syndrome. You got 90% of a Cadillac for 80 quid, but that other 10% is still gonna cost you a painful chunk of change. 

mnem
 

[0culus]

It's double trouble. With apologies to @nixiefreqq...sorry this may be more awesomeness than you can handle at once. 

[mnementh]

[...] Dumbfuckistan units. 

mnem
 

OK, is this really necessary? 


...not saying Imperial units are good mind you. I like my powers of 10. 

Yes. Yes, it REALLY IS necessary.  Kill them with fire. 

mnem
And shoot the ashes into the sun. On a rocket programmed in a mix of both units.  

[0culus]

[...] Dumbfuckistan units. 

mnem
 

OK, is this really necessary? 


...not saying Imperial units are good mind you. I like my powers of 10. 

Yes. Yes, it REALLY IS necessary.  Kill them with fire. 

mnem
And shoot the ashes into the sun. On a rocket programmed in a mix of both units.  

What if you miss? 

[tautech]

BIC lighters come in a large and a mini version, plus a few weird novelty sizes rare enough to discount as bell-end candidates, so built-in confusion. Typically a penny or a dime have equivalents pretty close to the same size the world around.

This general conundrum is the reason why a lot of nerds shoot videos and pics over a cutting mat. Then the only thing you have to figure out is if they’re using the side gridded in CM or Dumbfuckistan units. 

mnem
 

Nope, add a Bic to a pic and most anyone would expect the standard normal size not some midget or gorilla sized thing.
Coins as a size ref, you gotta be kidding.
Downunder, where the f**k am I gunna find a nickel to see now big/small it is ?
More hope using a dwagons claw for size comparison. 

Cutting mats OTOH are more universal but I ain't ever got one in a pocket whereas I do a Bic.

[0culus]

Use a pocket protector. I bet those are fairly universally sized. 


Except no one probably knows what they are anymore except for hardcore nerds.

[bitseeker]

Crap, one of the seller on ebay accepted my lowball offer on one of those old Fluke shunt 

They are really not helping.

Good catch, Kosmic. Now, you need an 8100A to go with it, like this. Side-by-side, the output of the shunt is right next to the input of the DMM.

The only thing I don't like about the A90 is the handle. It's the newer style that doesn't have a rotating crossbar. As a result, it doesn't fold under the enclosure like the early 8100A can (later 8100A also have the annoying handle).