Fastener humor - special screws

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Originally Posted By: justintendo
some good ones there! 903 would be a hot seller im sure!


As long as it isn't used for a blind hole...and the chips from drilling/tapping don't clog the threads...then it might actually work!
 
Originally Posted By: justintendo
some good ones there! 903 would be a hot seller im sure!


They are real - just very expensive
 
898...flatmate in Uni wanted to hang something on a vertical wooden post...told him to grab my toolbox, and found him hammering woodscrews in...he graduated first class honours in engineering.

881 - used in British Steam turbines.
887 - used in british turbines (there's another one called a "cheese head", which has a ridiculously large "cheese" head so that the flat bladed screwdriver is less likely to mangle it.

891, 892, 896, 897 - when we built Mount Piper, the HVAC company had a lot of ductwork stuff manufactured off site, and installed on site. The inspector noticed that only 1/3 of the bolts and nuts were installed, climbed a ladder and checked...the holes were misaligned (and needed an 875 really). Two days later, they told him it had been fixed.
Expecting them to have slotted the holes, and weakened the joint, he found them to be really good looking. But the back didn't match the front...they epoxied heads on one side and cut off bolts with nuts the other.

894, you can get structural lock washers like that, anti run back and can check crush for right pre-tension.
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900, you can get torque limiting screws...usually snap off

893 - sort of already exist, in aerospace.

910, drawer handles come with those, break off to length.

905, with LH thread and right hand thread are used in rigging levelling equipment.

But the loser is the "superbolt"...When I was in turbines, the salesmen for these would be around all the time...

Design of steam turbine casing joints is quite specific, the bolt is installed at 0.15% strain, and the joint integrity relies on the effective length of the bolt being known, and the nut being a solid, square anchor point/end stop...we tension them by induction heating the stud (or hydraulic stretch), then rotating the nut through a specified rotation to get the strain correct.

These introduce "ease", but include additional elastiicity, and misalignment potential...I feel sorry for those fooled into them.

MJT-landing-page2_newlogo.png
 
Originally Posted By: Shannow
898...flatmate in Uni wanted to hang something on a vertical wooden post...told him to grab my toolbox, and found him hammering woodscrews in...he graduated first class honours in engineering.

881 - used in British Steam turbines.
887 - used in british turbines (there's another one called a "cheese head", which has a ridiculously large "cheese" head so that the flat bladed screwdriver is less likely to mangle it.

891, 892, 896, 897 - when we built Mount Piper, the HVAC company had a lot of ductwork stuff manufactured off site, and installed on site. The inspector noticed that only 1/3 of the bolts and nuts were installed, climbed a ladder and checked...the holes were misaligned (and needed an 875 really). Two days later, they told him it had been fixed.
Expecting them to have slotted the holes, and weakened the joint, he found them to be really good looking. But the back didn't match the front...they epoxied heads on one side and cut off bolts with nuts the other.

894, you can get structural lock washers like that, anti run back and can check crush for right pre-tension.
10-22122011-068240L.gif


900, you can get torque limiting screws...usually snap off

893 - sort of already exist, in aerospace.

910, drawer handles come with those, break off to length.

905, with LH thread and right hand thread are used in rigging levelling equipment.

But the loser is the "superbolt"...When I was in turbines, the salesmen for these would be around all the time...

Design of steam turbine casing joints is quite specific, the bolt is installed at 0.15% strain, and the joint integrity relies on the effective length of the bolt being known, and the nut being a solid, square anchor point/end stop...we tension them by induction heating the stud (or hydraulic stretch), then rotating the nut through a specified rotation to get the strain correct.

These introduce "ease", but include additional elastiicity, and misalignment potential...I feel sorry for those fooled into them.

MJT-landing-page2_newlogo.png




Super Bolts are great when used for the right application. We used them to bolt the flanges (3in. dia. studs, 48 in. dia. flanges) to the universal joints on large rolling mills. Prior to that, we had to use a hydraulic torque wrench suspended from an overhead crane.
 
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