Automatic Bolt Detection from Steel Drawings
Counting bolts from a shop drawing set is one of the most tedious parts of steel estimating. A single beam might have 4 bolts at the left end and 6 at the right. Multiply that by 150 beams and you are manually counting over a thousand bolt locations — and one miscount throws off your hardware order.
SteelFlo now reads bolt specifications directly from your drawings.
What Gets Extracted
For every connection detected, SteelFlo captures:
- Count — how many bolts at this connection
- Diameter — 3/4", 7/8", 1", M20, M24
- Grade — A325, A490, A307, Grade 8.8, Grade 10.9, Grade 4.6
- Hole type — Standard (STD), Short Slotted (SSL), Long Slotted (LSL), Oversized (OVS)
These roll up automatically. If your drawing set has 48 shear connections each with 4 bolts, your BOM shows "192x 3/4" A325 Bolts" — one line item, ready for procurement.
US and International Specifications
Steel is a global industry. A fabricator in Texas uses A325 bolts. A shop in Melbourne uses Grade 8.8. A UK fabricator uses M20 10.9. SteelFlo handles all of them because it reads what is on the drawing, not what it expects to find.
The text scan recognizes callout formats from multiple conventions:
| Convention | Example Callout | What SteelFlo Reads | |---|---|---| | US AISC | 4-3/4" A325 | 4 bolts, 3/4" dia, A325 | | US AISC | 6-7/8" A490 BOLTS | 6 bolts, 7/8" dia, A490 | | Metric | 4-M20 8.8 | 4 bolts, M20 dia, Grade 8.8 | | UK/EU | 6-M24 10.9 | 6 bolts, M24 dia, Grade 10.9 |
Hole Patterns vs. Bolt Counts
Shop drawings show both bolt holes (as circles with dimension strings) and bolt specifications (as text callouts). SteelFlo detects both:
- Text callouts like "4-3/4 A325 STD" are caught by the text scan
- Visual hole patterns on the drawing are identified by the vision AI
When both sources agree, confidence increases. When they differ, both are shown so you can make the call.
Non-bolt holes — erection pin holes, drain holes, and access holes — are tracked separately so they do not inflate your bolt count.
From Drawing to Order
The traditional workflow: read the drawing, write down bolt specs, enter them into a spreadsheet, cross-reference with your supplier's catalog, generate a purchase order.
The SteelFlo workflow: upload the drawing, review the detected connections, confirm, export. Your bolt counts are in the BOM alongside your steel members. One file, one export, one source of truth.
No more sticky notes. No more missed connections on page 47.