The calipers don't lie or do they? I'll cut a long story short, was using Lidl calipers worth about £10. Seemed reliable enough. Then I bought some new larger 300mm ones from eBay for around £30. . Turns out the lidl calipers measure very small objects 2mm or so too large. They measure mid sized objects 20mm or so too small. They measure large objects 120mm or so, spot on. I can't rule out that they might have been damaged at some point but I've handled them fairly carefully. Sounds crazy but its worth checking your calipers measure accurately over a range of different object sizes before taking your printer apart to work out why its not printing objects the right size! Does anyone know where you buy calibrated objects of known dimensions to test these things? The objects would have to be to the 1/100 of a millimetre accurate? https://reprap.org/forum/read.php?1,702795,702795#msg-702795 Sat, 10 Oct 2026 23:15:45 -0400 Phorum 5.2.23 https://reprap.org/forum/read.php?1,702795,703180#msg-703180 Re: The calipers don't lie or do they? https://reprap.org/forum/read.php?1,702795,703180#msg-703180
Here are my finding comparing the two calipers to real precision machinist instruments (starrett brand)

Cheap calipers have poor repeatability. Go slow with them and they are generally within .1mm. (I have reworked and scraped mine to increase smoothness, which also increased reputability quite a bit surprisingly, still not perfect) You also have to watch out as the battery draining causes wild readings as well as what you described above. I replace my caliper battery at least every 12 months if not sooner, I buy the batteries at thee same place I bought my import calipers 50cent a battery is not bad.

The better calipers have much better reepeatability and are usually good for .01mm (their max resolution)

starrett measuring equipment has repetability in the .001mm range if they are specked as such. My starrett paper gauge caliper (0-10mm range) is so sensitive that the needle jumps around with just my heart rate. Those can reliably do .001mm or better, want to measure a spec of dust? they can do that as well. Do you need to? Not for a 3d printer you dont. Have a jewlers lathe? Or a mill that can hold that kind of acuracy? Then these tools become not only a nice to have, but a necessity.

With all this said, the best 3d printers in the market can struggle to hold +-.1mm accuracy (try =- .2mm is very typical if not worse). This is due to minuscule filament variation which includes undersized, oversize and oval filament.]]> jaguarking11 General Thu, 25 Aug 2016 16:30:58 -0400 https://reprap.org/forum/read.php?1,702795,703139#msg-703139 Re: The calipers don't lie or do they? https://reprap.org/forum/read.php?1,702795,703139#msg-703139 Translated it means if you use garbage to measure your results will be garbage.]]> Srek General Thu, 25 Aug 2016 13:23:24 -0400 https://reprap.org/forum/read.php?1,702795,703091#msg-703091 Re: The calipers don't lie or do they? https://reprap.org/forum/read.php?1,702795,703091#msg-703091 Much better than drill bits.]]> Andy1989 General Thu, 25 Aug 2016 09:38:28 -0400 https://reprap.org/forum/read.php?1,702795,703053#msg-703053 Re: The calipers don't lie or do they? https://reprap.org/forum/read.php?1,702795,703053#msg-703053 tmorris9 General Thu, 25 Aug 2016 05:20:46 -0400 https://reprap.org/forum/read.php?1,702795,702830#msg-702830 Re: The calipers don't lie or do they? https://reprap.org/forum/read.php?1,702795,702830#msg-702830 www.amazon.com]

as with anything else, the less you spend, the less you can trust them...]]> the_digital_dentist General Tue, 23 Aug 2016 22:53:55 -0400 https://reprap.org/forum/read.php?1,702795,702827#msg-702827 Re: The calipers don't lie or do they? https://reprap.org/forum/read.php?1,702795,702827#msg-702827
Hint: Using the thumbwheel is not the best way.

p.s. Most micrometer sets come with accurate test blocks.]]> etfrench General Tue, 23 Aug 2016 22:06:46 -0400 https://reprap.org/forum/read.php?1,702795,702808#msg-702808 Re: The calipers don't lie or do they? https://reprap.org/forum/read.php?1,702795,702808#msg-702808 DjDemonD General Tue, 23 Aug 2016 17:35:57 -0400 https://reprap.org/forum/read.php?1,702795,702805#msg-702805 Re: The calipers don't lie or do they? https://reprap.org/forum/read.php?1,702795,702805#msg-702805
Quote
frankvdh
But .001mm accuracy?

... no - he wanted only 0.01mm (ten microns) ;)]]> VDX General Tue, 23 Aug 2016 17:29:58 -0400 https://reprap.org/forum/read.php?1,702795,702803#msg-702803 Re: The calipers don't lie or do they? https://reprap.org/forum/read.php?1,702795,702803#msg-702803
Quote
DjDemonD
Does anyone know where you buy calibrated objects of known dimensions to test these things? The objects would have to be to the 1/100 of a millimetre accurate?

Coins? E.g a US quarter has a diameter of .955 inches (24.26 mm) and a thickness of .069 inches (1.75 mm). But it has a milled edge, so maybe a nickel or cent would be better? I did try a Google search, but couldn't find out how accurately coins are manufactured. [www.usmint.gov]

But .001mm accuracy?

Most metals have a coefficient of thermal expansion of between about 10 and 20 *1E-6/degree Kelvin. So a 10mm cube at 20C would be a 10.00015mm cube at 21C. If your ambient temperature range is more than about 10C, you're going to need your calibration cubes made of titanium or tungsten or quartz or similar.

How accurate is your printer? If you have a fairly typical 80 steps/mm, then the absolute best accuracy you can do is .0125mm. And when you factor in play, momentum, and other kinds of errors, I'd be surprised to get better than 0.1mm.]]> frankvdh General Tue, 23 Aug 2016 17:24:39 -0400 https://reprap.org/forum/read.php?1,702795,702797#msg-702797 Re: The calipers don't lie or do they? https://reprap.org/forum/read.php?1,702795,702797#msg-702797 You can use metric drill bits and measure them to see how close you are on small things.]]> Floyd General Tue, 23 Aug 2016 16:33:03 -0400 https://reprap.org/forum/read.php?1,702795,702795#msg-702795 The calipers don't lie or do they? https://reprap.org/forum/read.php?1,702795,702795#msg-702795 Then I bought some new larger 300mm ones from eBay for around £30.
.
Turns out the lidl calipers measure very small objects 2mm or so too large.
They measure mid sized objects 20mm or so too small.
They measure large objects 120mm or so, spot on.

I can't rule out that they might have been damaged at some point but I've handled them fairly carefully.

Sounds crazy but its worth checking your calipers measure accurately over a range of different object sizes before taking your printer apart to work out why its not printing objects the right size!

Does anyone know where you buy calibrated objects of known dimensions to test these things? The objects would have to be to the 1/100 of a millimetre accurate?]]> DjDemonD General Tue, 23 Aug 2016 16:26:43 -0400