Guide · Measurement tools
Calipers, dial indicators and feeler gauges for printer work
Resolution, accuracy and repeatability explained with Mitutoyo's published specs, what NIST says about extra digits, and why measuring one wall misleads flow tuning.
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Picks that fit
- VINCA DCLA‑0605 IP54 digital caliper, 6 in / 150 mmCheck price on Amazon
- VINCA DMCA‑0105 IP64 digital outside micrometer, 0‑1 in / 0‑25 mmCheck price on Amazon
- Clockwise Tools DPIR‑0105 IP65 digital indicator, 0‑1 in / 25.4 mmCheck price on Amazon
Short answer
Buy a caliper by its published accuracy, not its number of digits: Mitutoyo's 150 mm caliper reads to 0.01 mm but is specified at ±0.02 mm. Use calipers for parts and filament, a dial indicator for small height changes, and feeler gauges for gaps. Do not tune flow by measuring a single printed wall.
Picks that fitAll picks and how to choose
- VINCA DCLA‑0605 IP54 digital caliper, 6 in / 150 mmCheck price on Amazon
- VINCA DMCA‑0105 IP64 digital outside micrometer, 0‑1 in / 0‑25 mmCheck price on Amazon
- Clockwise Tools DPIR‑0105 IP65 digital indicator, 0‑1 in / 25.4 mmCheck price on Amazon
Resolution, accuracy and repeatability
Three figures on a spec sheet mean different things:
- Resolution: the smallest step the display shows.
- Accuracy: how far a reading may be from the true value.
- Repeatability: how closely repeated readings of the same thing agree.
Mitutoyo's 150 mm ABSOLUTE Digimatic caliper is a clear example. Mitutoyo lists it with 0.01 mm resolution, ±0.02 mm accuracy and 0.01 mm repeatability.[1] The display shows hundredths, but a single reading can be two hundredths off.
More digits are not more accuracy
A metrology paper on NIST's site finds that finite instrument resolution combined with measurement noise produces a spread of results, with no simple formula linking that spread to the measurement uncertainty.[2] The same paper found that the spread of readings depends strongly on where the true value sits relative to the instrument's resolution step.[2] The papers are general metrology, not about printers, but the point carries: a listing that shows only display resolution tells you nothing about accuracy.
What a caliper measures
Mitutoyo says its ABSOLUTE Digimatic caliper measures outside, inside, depth and step dimensions.[3] The stated accuracy applies to all four. On a printer, that covers filament diameter, printed parts and the length of filament between two marks during E-steps calibration.
Picks that fit2 products
For parts, filament and E-steps marks, choose the 6 in / 150 mm VINCA DCLA-0605 caliper. For filament diameter, choose VINCA's 0-1 in / 0-25 mm DMCA-0105 micrometer.
More on choosing
Compare the accuracy each maker publishes, not the display digits. On Amazon, check that 'Ships from / Sold by' shows Amazon.com or Clockwise Tools, VINCA's maker.
VINCA DCLA‑0605 IP54 digital caliper, 6 in / 150 mm
VINCA DMCA‑0105 IP64 digital outside micrometer, 0‑1 in / 0‑25 mm
Dial indicators
A dial indicator reads small changes in height or position against a fixed reference. Mitutoyo lists its 2046A with 0.01 mm graduations, a 0-10 mm range, ±0.013 mm accuracy and a measuring force of 1.4 N or less.[4] Variants of the same model can have different accuracy or force, so compare by exact order number.
Indicators are themselves checked against a reference. Starrett describes its indicator tester as a tool for calibrating dial test indicators, reading directly to 0.0001 in (0.002 mm) over ranges up to 1 in (25 mm).[5] That is a calibration instrument, not a hobby purchase.
Picks that fit1 product
Choose the 0-1 in / 25.4 mm DPIR-0105. It needs a magnetic base or a printed mount to read a bed or gantry, and neither comes with it.
More on choosing
On Amazon, check that 'Ships from / Sold by' shows Amazon.com or Clockwise Tools.
Clockwise Tools DPIR‑0105 IP65 digital indicator, 0‑1 in / 25.4 mm
Feeler gauges
A feeler gauge set is a stack of leaves of known thickness for checking gaps. Mitutoyo makes its feeler gages from carbon steel, and its 184-303S set has 28 leaves from 0.05 to 1 mm.[6] We could not read a reliable per-leaf tolerance from Mitutoyo's page, so we do not quote one.
| Tool | Good for on a printer | Spec to look for |
|---|---|---|
| Caliper | Parts, filament, marks for E-steps | Accuracy, not just resolution |
| Dial indicator | Small height or position changes | Graduation, range, accuracy, exact order number |
| Feeler gauge | Gaps | Leaf range and material |
Why one wall misleads flow tuning
The ellis3dp.com print tuning guide argues that measuring one- or two-wall cube walls with calipers is an unreliable way to set extrusion multiplier, because layer wobble and filament variation inflate the reading.[7] It prefers judging a printed top surface in 1-2% then 0.5% steps.[8]
The expected width is not what many people assume either. In Slic3r-based slicers, two 0.4 mm perimeters at 0.2 mm layer height come out to about 0.757 mm, not 0.8 mm.[7] Other slicers and settings differ. A ±0.02 mm caliper reading of a wobbly wall cannot settle a few percent of flow.
Next
Questions
Do I need a caliper that reads to 0.01 mm?
Reading to 0.01 mm is resolution, not accuracy. Mitutoyo lists its 150 mm ABSOLUTE Digimatic caliper with 0.01 mm resolution but ±0.02 mm accuracy. Look for a published accuracy figure, not just the display.[1]
Can I tune flow by measuring a single wall with calipers?
The ellis3dp.com guide argues against it: layer wobble and filament variation inflate the reading. It prefers judging a printed top surface in small steps.[7]
What is a dial indicator for on a 3D printer?
It reads small changes in height or position against a fixed reference as you move a part past it. Mitutoyo lists its 2046A with 0.01 mm graduations over 0-10 mm and ±0.013 mm accuracy.[4]
Why does my two-wall test print measure 0.76 mm instead of 0.8 mm?
The ellis3dp.com guide explains that in Slic3r-based slicers two 0.4 mm perimeters at 0.2 mm layer height come out to about 0.757 mm, because of how the slicer spaces them.[7]