If You’ve Ever Hammered a Dowel Pin, You'll Know this Struggle

You know what’s super chill? Spending a day cutting 100 holes and realizing half your pins don’t fit.

If you’ve ever wrestled with tolerance stackups, clearance fits that turned into interference fits, or reamers that just feel like they’re gaslighting you—this one’s for you.

We just made a guide on ISO Limits & Fits—but this time, it’s for actual humans.

🔧 What you’ll learn (minus the jargon):

• What H7/g6 actually means

• Why the letter “H” is everyone’s best friend

• How to choose a reamer size when your dowel pins come from the chaos dimension

• The difference between allowance and clearance (hint: it’s not just vibes)

• How to use the ISO system to design parts that… y’know, fit

🎯 First: What’s a Tolerance Zone?

Every real-world part has variation—no hole is exactly 10.000000 mm, and no shaft,is perfectly round. That’s where tolerances come in.

Think of a tolerance zone like a football goalpost. Your target dimension is the center, but as long as the actual part lands anywhere between the uprights—the upper and lower limits—it’s good. Manufacturing isn’t perfect, but if you stay in the zone, the part passes.

5 minute engineering drawings with Drafter

We’re building a tool that lets you go from 3D model to manufacturing-ready 2D drawing in minutes—not hours. No more clicking through a hundred dropdowns or babysitting your title block. Just fast, clean drawings with proper GD&T, ready to send to the shop.

Whether you’re designing aerospace components or bike parts, Drafter gets you to a drawing faster than your coffee gets cold.

We’re already working with teams in aerospace, robotics, automotive, medical devices, and energy—basically anywhere engineers are tired of wasting time on the boring stuff.

We'd love your feedback! If there are specific resources or tools you'd like Drafter to create, please reach out anytime. Your input directly shapes the tools we build.

Happy engineering,

The Drafter Team