Rope/gear blog
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Blog dates in yymmdd format
250916 Slightly dirty nylon webbing is ~20% weaker. https://hwstock.org/rope/dirtywebbing/
250913 Fall on a Munter is softer than a fall on hardened knot https://hwstock.org/rope/munterfall/
250905 Undersampling force peaks in drop tests? https://hwstock.org/rope/undersample/
250821 A curious concern about shockloading; rockclimbers and the alternate reality. https://hwstock.org/rope/shockload/
250819 UV exposure and nylon webbing. https://hwstock.org/rope/UVnylon/
250812 DEET and nylon ropes. https://hwstock.org/rope/DEET/
2507132 Absurd things with thin slick rope-- Munter with twist, autoblock, ascending thin Amsteel. https://hwstock.org/rope/absurd/
250711 Ascending a "4mm" cord with schwabish knots. https://hwstock.org/rope/ascend4mm/
250706 "No-Twist Munter" force in Hanging Raps on Thin Spyderline and Amsteel. https://hwstock.org/rope/notwistmunter/
250703 Length of tapered tail in bury splices: does it matter (to me)? https://hwstock.org/rope/tails/
250206 (Updated 250630) Raps on thin lines: forces at the anchor in "dynamic" moves https://hwstock.org/rope/thinrapforce/
250209 Releasable anchors and forces required for accidental release. https://hwstock.org/rope/releasable/
250121 Making a knot-block not dangerous https://hwstock.org/rope/knotblock/knotblock.jpg
250116 Hasty Harness and the dreaded square knot! https://hwstock.org/rope/hastysquare/
250114 Sewn vs. Figure 8 loops in 6mm nylon cord. https://hwstock.org/rope/sewn_v_fig8
241218 Apparent forces felt by top-belayer when rope is run over rock. https://hwstock.org/rope/capstan/
241128 Hand-sewn loops in webbing: number of UHMWPE stitches needed to reach optimum strength. https://hwstock.org/rope/sewnweb/
241101 Does heat typical of cleaning weaken PET ropes? https://hwstock.org/rope/heatPET/
241025 Loss of strength in canyon ropes-- dirt vs. long-term underwater. https://hwstock.org/rope/strengthlosscanyon/
240516 Ropes running over a bare sling (no quicklink)...what actually matters? https://hwstock.org/rope/slingmelt/
240322 Hand-Sewn Loops: Break at 196% for 16mm Webbing, 167% for 5 mm Cord https://hwstock.org/rope/dogbone/
240315 Knots for Amsteel (Dyneema) for "Smooth Operator" in Canyons https://hwstock.org/rope/smooth/
240201Titanium vs. Aluminum for rappel devices-- a matter of thermal conductivity. https://hwstock.org/rope/Ti_vs_Al/
231210  Sewn Amsteel stronger than end-for-end splice https://hwstock.org/rope/sewnamsteel2/
231129 Girth-hitched Amsteel Eye Breaks at 77% on Carabiner, 100% on 2" pipe. https://hwstock.org/rope/girth_amsteel/
231027 Strength of sewn loops girth-hitched in dyneema/HMPE  https://hwstock.org/rope/sewn_loop_girth/
231005 Why so much hate for small quicklinks? https://hwstock.org/rope/3_16ths_rapide2/
230909 Abrasion tests on 1/8" Amsteel and PET cord. https://hwstock.org/rope/abrasion/
230829 Rapping and acsnding on coreshot ropes: ATC and mechanical ascender versus hitches https://hwstock.org/rope/coreshot2/
230811 More about sewing cords. https://hwstock.org/rope/sewing/
230719 Dyneema is slippery... but when and where? https://hwstock.org/rope/binerpulley/
230624 The relative resistance of slings to cuts by rocks. https://hwstock.org/rope/rockcut/
230304 Will raps on thin Amsteel Dyneema kill you? https://hwstock.org/rope/willdyneemakillyou/
230221 Critter damage to Dyneema vs. Nylon/polyester. https://hwstock.org/rope/critter/
221031 What happens when you rap over core-shot ropes with Dyneema cores? https://hwstock.org/rope/rap_core_shot/
220806 Would short sheaths make Amsteel knottable? https://hwstock.org/rope/sheathed_amsteel/
220805 Break test of sewn eye in 2500 lb bs Amsteel. https://hwstock.org/rope/sewn_amsteel/
220719 Break test of Trilene "Knot" in Amsteel (Dyneema). https://hwstock.org/rope/amsteeltrilene/
220614 Breaking a 4 mm, sewn, eye-to-eye prusik used for schwabisch knots. https://hwstock.org/rope/eye2eye/
220612 Can an EDK be used to join two webbing straps for an "easy" rap? https://hwstock.org/rope/edk15mm/
220611 Do urethane coatings weaken knots in rope? https://hwstock.org/rope/coatknot/
220608 Amsteel left in sun 3 years breaks at least at 80% original strength. https://hwstock.org/rope/oldamsteel.htm
220608 Titan tech cord (dyneema core): knotted versus sewn. https://hwstock.org/rope/titansew.htm
220507 Can you trust a cord girth-hitched to the bottom biner hole of an ascender? https://hwstock.org/rope/girth.htm
220504 4mm Dyneema and tiny quicklink against 10.2mm nylon dynamic rope: https://hwstock.org/3_16ths_quicklink_pull_test/
220315 Thoughts on butterfly knots and core-shots https://hwstock.org/rope/butterflies.htm
220101 Dyneema Rap Chronicles: https://hwstock.org/dyneema/dnew
180724 UIAA drop tests and "Sharpie" pen middle marks for nylon ropes. http://hwstock.org/rope/UIAA-middle.pdf
160510 Thoughts on fixed ropes http://hwstock.org/fixed.htm

This is not a site for comprehensive, 100-sample statistical tests; I rarely break or otherwise test more than 5 replicates. Most of my reports describe one-off tests, on gear I sew or splice. I am very consistent in the ways I make soft goods, which have fairly obvious failure modes. There are a few thermal tests on hard-soft systems, but few break tests of hard goods (e.g. small quicklinks) which break at forces I cannot measure (the practical limit of my fast load cell in 5000 lbs).

The linescale 3, used as a loadcell in many of these tests, seems to have an inherent "slop" of about +/- 15 lbs at the low end, up to my body weight (about 150 lbs).  I get much better low-end (5-300 lbs)  reproducibility with cheap hanging/crane scales; but these sample at 2 Hz at best, whereas the linescale can sample up to 1280 Hz. At low sampling rates (e.g. 10 Hz), the linescale 3 has pretty good agreement with calibrated hanging scales (the error should not depend on the sampling rate, and the instrument does no averaging, so this may be observer bias). At  forces above 1000 lbs, the linescale 3 seems to be about 2% accurate. When I tested tested the linescale in a static pull against a 6000 lb cranescale, it was within 1-2%. Note I use either my car or a come-along to supply force; the strain rate is fast compared to ASTM D4268, but slow compared to most climbing applications. Tensile strength often increases with strain rate.