A good drawing review checks six things in order: the title block and notes, the datums, the dimensions and basic dimensions, every feature control frame, the general tolerances, and whether inspection can actually measure what the drawing asks for. Below are 20 checks, one line each, written to ASME Y14.5-2018 so you can print them and work through the next drawing on your desk. After the list, you'll find the reasoning behind the checks that catch the most expensive mistakes.
The 20 checks
Work through the groups in order. A wrong datum scheme makes every frame that references it wrong too, so there's no point checking position tolerances before the datums are right.
Title block and notes
Datums
Dimensions and basic dimensions
Feature control frames
General tolerances
Inspection
Why the tricky checks matter
Most of the list is housekeeping. A handful of checks catch errors that look harmless on the screen and cost real money on the floor. Here is what goes wrong when each one is missed.
| Problem on the drawing | What it causes | Fix |
|---|---|---|
| No edition named in the title block | Supplier and customer argue over which rules apply | Name the standard and year in the title block or notes |
| Datum on a non-functional surface | Parts pass inspection and don't fit the assembly | Pick the surfaces that locate the part when it's installed |
| Datum symbol on a centerline | No defined feature to contact, so each inspector sets up differently | Attach the symbol to the hole, shaft, or slot itself |
| Position with no basic dimensions | The tolerance zone has no defined location | Add basic dimensions from the referenced datums |
| MMC on a flat surface | The modifier has no meaning, and the frame is invalid | Remove it, or apply the control to a feature of size |
| Flatness larger than the size tolerance | The flatness callout controls nothing | Tighten it or delete it |
Datum order is a design decision
The order of the datum letters in a frame is the order the part is located when it's inspected. For example, a bracket that bolts down on its bottom face and is located by two dowel pins should usually have the bottom face as primary and the pin holes after it. Swap the order and the inspector fixtures the part a different way, and a part that would assemble fine can measure out of tolerance, or the reverse.
Concentricity and symmetry are gone
The 2018 edition dropped both symbols. In the standard's wording, as quoted by GD&T Basics, the two symbols "are no longer supported" because other characteristics give more direct control with a well-defined meaning. If your drawing references 2018 and still shows either symbol, replace it, usually with position or runout depending on what the function needs. If the drawing references 2009, the symbols are still legal under that edition, which is another reason check 1 matters.
Refinements must be smaller
For an individual feature of size, Rule #1 already limits form. A flat face of a 0.500 plus or minus 0.005 thick plate can't be out of flat by more than the 0.010 size tolerance unless the drawing overrides the rule. A flatness tolerance of 0.015 on that face adds nothing. Run the same arithmetic for orientation, since a perpendicularity tolerance also limits the flatness of the face it controls.
Modifiers need a size to modify
MMC and LMC tie the tolerance to the actual size of a feature. A flat face has no size, so there is nothing to modify. Runout is always applied regardless of feature size, so a modifier in a runout frame is also wrong. Both errors show up when someone copies a frame from a hole callout to a face.
How to run the review
A checklist works best when the review itself has a routine. A few habits make it stick:
That last point is where the checklist stops helping. A checker can catch a datum on a centerline every time. Teaching the people who draw it why it's wrong is what stops it showing up.
When the same checks keep failing
If your checkers keep marking up the same errors, the team needs a shared understanding of the standard, applied to your own parts. There are three ways we can help, priced from our GD&T training page:
| Option | What it covers | Price |
|---|---|---|
| Half-day refresher and drawing review | About 3.5 hours on-site, reviewing your own drawings with the team | $2,500 for up to 12 participants |
| 2-day GD&T course | About 14 hours on-site, from reading frames to stack-ups, ending with a drawing review | $8,000 for up to 8, then $300 each, up to 16 |
| Monthly lunch-and-learn | Two 90-minute sessions a month on current drawings and questions | $1,200 per month |
For a team that already uses GD&T, the half-day refresher is the natural fit for this checklist. At full size it works out to about $208 per person ($2,500 divided by 12). We review a set of your drawings beforehand, and the session works through the errors that keep coming back. If the team is newer to GD&T, see what a 2-day course should cover. If you're weighing training against individual credentials, GD&T certification or team training compares the two. Engineers working on their own skills can book one-on-one GD&T tutoring.
Next step
Send us a few of your drawings, redacted if needed, along with your team size and timing. We reply within one business day with a proposal or a few questions. Request a proposal for the half-day refresher and drawing review, or see all corporate training programs.
