External thread
Bolt, shaft, screw, plug, or male machine element
Engineering drawing tool
Thread Dimension Drawing Generator
Select a published thread or define a custom mating pair. The tool draws the internal and external profiles together, preserves their diameter-to-pitch proportions, and highlights fit or geometry conflicts.
Made for more than fasteners Machine elements, lead screws, closures, fittings, repairs, and custom fits.
1 · Define the thread
Choose a standard and designation
Designation Calculating…
Standard basis Calculating…
When this series fits
When this tolerance fits
Checking geometry Calculating the selected profile.
Disclaimer: Use calculations at your own risk. For critical applications, verify results against your governing standards/specifications.
2 · Compare the mating profiles
Dimensioned thread drawings
Both drawings use the same selected geometry. Blue identifies the external member; orange identifies the internal member and sectioned material.
Internal thread
Nut, bore, housing, sleeve, fitting, or female machine element
3 · Read the dimensions
Current design values
Basic profile values are calculated from the selected geometry. Fit envelopes are design aids and must be checked against the applicable standard before release or inspection.
4 · Prepare and inspect
Manufacturing guidance
These values help with early design and process planning. Tooling, material, coating, engagement length, thread-forming method, and inspection requirements can all change the correct production dimensions.
What the selector covers
The catalog brings general-purpose metric M and MJ, Unified UN and UNJ, NPT and NPTF, BSPP and BSPT, Whitworth, ACME and Stub ACME, metric trapezoidal, and buttress forms into one drawing workflow. Preferred, fine, extra-fine, constant-pitch, and special selections are labeled inside the pitch dropdown instead of being spread across a lookup chart.
Some standards define additional limits by engagement length, material group, coating, gage plane, lead, number of starts, or application-specific practice. Custom mode covers exploratory geometry, but it does not convert an unlisted combination into a standardized designation.
How drawing scale works
Each profile expands to use the available drawing area while preserving the proportion between major diameter, pitch, and thread depth. That makes a coarse form visibly coarser than a fine form at the same nominal diameter. The small profile inset is intentionally magnified so the included angle remains readable.
FAQ
Why can I select an option that has a geometry warning?
Custom machine-element work sometimes begins outside preferred standard combinations. The tool leaves those selections available, marks the conflict clearly, and lets you inspect why the root, crest, core, allowance, or tolerance envelope needs review.
Does a finer pitch always create a better fit?
No. Fine pitch can reduce lead and thread depth, but it may be less tolerant of damage, contamination, or cross-threading. Fit class and pitch solve different design problems.
Can the SVG be placed on an engineering drawing?
Yes, as a visual or reference detail. Add the governing thread designation, standard, inspection method, and any application-specific requirements in the released drawing notes.