Free Type 1 gage study template
A Type 1 gage study checks a gage on its own: one operator measures one reference part about 50 times. Cg compares the gage's spread with 20% of the tolerance, and Cgk also counts its bias. Both at 1.33 or more is the usual pass. This Excel workbook calculates both, tests the bias and plots every reading against the reference value.
You'll repeat this study after a repair or a new setting master. Attach each workbook to the gage's record in Axiospec, next to its calibration history.
What's inside the workbook
Instructions
How to pick the reference part, take the readings and read Cg and Cgk, plus what K and L mean.
Blank study
Yellow cells for the reference value, both limits, the resolution and up to 50 readings. Cg, Cgk, %Var, the bias test and a run chart update as you type, once 25 readings are in.
Filled example
A digital bore gauge on a 25 mm setting ring. Cg is 1.42 and passes, Cgk is 1.24 and does not, and the bias is significant: a precise gage that reads high.
How to run a Type 1 study
- Pick a reference part with a known value, such as a setting ring or a calibrated master, ideally near the middle of the tolerance.
- Enter the reference value (Xm), both specification limits and the gage resolution.
- Measure the reference part 50 times (at least 25), removing and re-positioning the part or the gage between readings, and enter each reading.
- Read Cg and Cgk. Both at 1.33 or more is the usual acceptance criterion.
- If Cg passes and Cgk fails, the gage is precise but biased: check the setting or zero. If Cg fails, the gage scatters too much for this tolerance.
How to read the result
- Cg: the gage's spread (6 standard deviations) against 20% of the tolerance. Below 1.33, the gage scatters too much for this tolerance.
- Cgk: the same comparison with the bias taken off the allowed band. A passing Cg with a failing Cgk means the gage is precise but set wrong.
- %Var: the spread as a share of the tolerance. 15% or less matches a Cg of 1.33.
- Bias test: a t-test of the mean against the reference value. A p-value below 0.05 means the bias is real and not just scatter.
- Resolution: the gage's smallest step should be 5% of the tolerance or less, or the readings are too coarse to judge.
The formulas
Cg = 0.2T / 6s Cgk = (0.1T - |x̄ - Xm|) / 3s
T is the tolerance (USL - LSL), s the standard deviation of the readings, x̄ their mean and Xm the reference value. These use the usual defaults, K = 20% of the tolerance and L = 6, and the workbook lets you change both if your customer asks.
Run it before a Gage R&R
A Type 1 study looks at the gage alone. A Gage R&R adds operators and parts. Fix a gage that fails here before you spend operator time on a Gage R&R. When it passes, move on to the free Gage R&R template.
Keeping calibration records somewhere else?
Send us what you have, in any format, and we load it into Axiospec for you. We keep your instrument IDs and intervals. It usually takes a couple of business days, and it's free on every plan.
Checking bias and linearity on real instruments? Axiospec runs the AIAG MSA studies in the app and keeps each result with the instrument's own history.
Common questions
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What is a Type 1 gage study?
A study of the gage alone, usually done before a Gage R&R. One operator measures one reference part with a known value about 50 times. The spread of the readings gives Cg, and their average against the reference value gives the bias and Cgk, both compared with the tolerance.
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What is the difference between Cg and Cgk?
Cg looks only at how much the gage scatters. Cgk also counts the bias, how far the average reading sits from the reference value. A gage can have a good Cg and a poor Cgk when it is precise but set wrong.
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How many readings does a Type 1 study need?
50 is the usual recommendation and 25 a common minimum. The workbook takes up to 50 readings and shows results once 25 are in.
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Is the template free? Do I have to enter an email?
It is free, and there is no form. The download link is on this page.
A practical template, not a substitute for your customer's measurement system requirements. Check which K, L and acceptance limits your customer specifies before you rely on the result.
Keep the study with the gage
Axiospec captures Gage R&R, bias, and linearity studies against each instrument's tamper-evident history. Free under 50 instruments.
Got a gage list? Send it over and we load it for you, usually in a couple of business days. Free on every plan.