What Is a Buttress Thread?
A buttress thread (German: Sägengewinde, “saw thread”) is built to carry a high axial load in one direction. One flank, the load flank, is nearly perpendicular to the axis. The other flank slopes away steeply. That shape gives a buttress thread more one-way load capacity than a symmetrical trapezoidal or Acme thread of the same size, with lower friction on the load side.
Typical applications include screw presses, jacks and lifting spindles, vices and clamping devices, machine-tool collets, and closures on pressure vessels and pipe equipment. In Europe the metric buttress thread is standardised in DIN 513 (Part 1 profile, Part 2 nominal dimensions, Part 3 deviations and tolerances).
Key point for buyers: because the profile is asymmetric, a buttress gauge only fits one way. The drawing or RFQ must show which direction the load flank faces, otherwise the gauge cannot be made correctly.
How to Read an S Thread Designation
A DIN 513 buttress thread is written as S + nominal diameter x pitch, with extra codes when needed:
| Callout | Meaning |
|---|---|
| S 52 x 8 | Metric buttress, 52 mm nominal diameter, 8 mm pitch, single start, right hand |
| S 52 x 8 LH | Same thread, left hand |
| S 52 x 16 P8 | Two-start thread: lead 16 mm, pitch 8 mm |
| S 52 x 8 – 7H / 7e | Tolerance class 7H for the internal thread, 7e for the external thread |
Basic profile data per DIN 513:
| Parameter | Value / formula |
|---|---|
| Load flank angle | 3° |
| Clearance flank angle | 30° |
| Included angle | 33° |
| Pitch diameter d2 = D2 | d − 0.75 P |
| Minor diameter, external thread d3 | d − 1.735534 P |
| Minor diameter, internal thread D1 | d − 1.5 P |
DIN 513 Buttress Thread Size Chart (40–80 mm, standard pitch)
Nominal dimensions for common sizes with their standard pitch. Values in mm, calculated from the DIN 513 formulas above. Fine and coarse pitches also exist for each diameter, for example S 52 x 3 and S 52 x 12.
| Designation | Nominal d (mm) | Pitch P (mm) | Pitch dia. d2 = D2 | Minor dia. ext. d3 | Minor dia. int. D1 |
|---|---|---|---|---|---|
| S 40 x 7 | 40 | 7 | 34.750 | 27.851 | 29.500 |
| S 44 x 7 | 44 | 7 | 38.750 | 31.851 | 33.500 |
| S 48 x 8 | 48 | 8 | 42.000 | 34.116 | 36.000 |
| S 50 x 8 | 50 | 8 | 44.000 | 36.116 | 38.000 |
| S 52 x 8 | 52 | 8 | 46.000 | 38.116 | 40.000 |
| S 55 x 9 | 55 | 9 | 48.250 | 39.380 | 41.500 |
| S 60 x 9 | 60 | 9 | 53.250 | 44.380 | 46.500 |
| S 65 x 10 | 65 | 10 | 57.500 | 47.645 | 50.000 |
| S 70 x 10 | 70 | 10 | 62.500 | 52.645 | 55.000 |
| S 80 x 10 | 80 | 10 | 72.500 | 62.645 | 65.000 |
Non-Standard Sizes: The S 58 x 8 Example
Many buttress threads on machines and presses are special sizes. S 58 x 8 is a good example. The DIN 513 diameter series runs 52, 55 and 60 mm, and the 8 mm pitch is listed for 46–52 mm, so 58 x 8 does not appear in the common size tables.
That does not mean the gauge cannot be made. The basic dimensions can still be calculated from the DIN 513 formulas:
| S 58 x 8 (calculated) | mm |
|---|---|
| Nominal diameter d | 58.000 |
| Pitch diameter d2 = D2 | 52.000 |
| Minor diameter, external d3 | 44.116 |
| Minor diameter, internal D1 | 46.000 |
Before production: for a special size, the tolerance limits and any deviations from the standard profile should be confirmed from your part drawing. We send the gauge limits for your approval before grinding starts.
Tolerance Classes for Buttress Thread Gauges
DIN 513-3 sets the deviations and tolerances for metric buttress threads. In practice, internal threads are usually specified as 7H and external threads as 7e. The “e” position puts a small fundamental deviation on the external thread, leaving clearance for lubrication and running fit. Some drawings use other classes, so always gauge to the class on the drawing. Our guide to thread tolerance classes explains the H/e position system in more detail.
Types of Buttress Thread Gauges
| Gauge | Inspects | Notes |
|---|---|---|
| GO/NO-GO thread plug gauge | Internal buttress threads (nuts, housings), e.g. 7H | GO checks full profile and assembly; NO-GO checks the maximum pitch diameter. See thread plug gauges. |
| GO/NO-GO thread ring gauge | External buttress threads (spindles, screws), e.g. 7e | Solid or adjustable rings. See thread ring gauges. |
| Setting / check plug | Ring gauges | Used to set adjustable rings and verify ring wear. |
| Custom profile gauge | Special or modified buttress profiles | Made from your drawing. See custom thread gauges. |
Buttress gauges are usually made from hardened gauge steel such as GCr15 or Cr12MoV, hardened to around 58–64 HRC and ground on the thread flanks. Each GO and NO-GO member is marked with size, pitch, class, direction and GO or NO-GO so it cannot be confused at the bench.
If you also inspect symmetrical power-transmission threads, compare our guides on trapezoidal (Tr) thread gauges and Acme thread gauges. Inch buttress threads to ASME B1.9 use a different profile (7° load flank, 45° clearance flank) and need their own gauges.
How to Order Buttress Thread Gauges
Include the following on your RFQ for an accurate quote on the first reply:
| Item | Example |
|---|---|
| Thread callout | S 58 x 8, or S 52 x 16 P8 for multi-start |
| Hand and starts | RH / LH, single or multi-start |
| Tolerance class | 7H plug, 7e ring, or as per drawing |
| Gauge members | GO only, NO-GO only, or GO + NO-GO set; check plug if needed |
| Load-flank direction | Shown on drawing or sketch |
| Material and hardness | e.g. GCr15 or Cr12MoV, 60–64 HRC |
| Documentation | Inspection report with measured values, calibration certificate |
| Quantity and delivery | Number of sets, destination country, target date |
Buttress Thread Gauge FAQ
Free PDF: Thread Gauge Selection Guide & Tolerance Chart
4H–7H / 6g–6e chart, fundamental deviations, 2A/2B vs 3A/3B, gauges by standard and an ordering checklist.
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