(05-01-2018, 09:01 PM)Mark Atkinson Wrote: Hello All,Mark, as a former fastener person....to be a bit pedantic..(sorry)... R or S indicates the strength (S is close to metric 8.8 I recall) "High Tensile" is a bit fuzzy as a description. The recommended tightening torque is a good indication & if you feel stretch then they could be a bit iffy! I don't have a list of recommended tightening torques to hand...they vary whether threads are lubricated or not, of course.
I am having nasty quality issues with some newly acquired BSF fasteners, specifically that they will not take sufficient torque before stripping the thread. They are ‘R’ grade, which indicates they are supposed to be HT. I have also found the nut supplied with them to have undersized heads, so that they do not work with standard BSF tools.
A 1/4 BSF grade R should be able to take up to 8.2 ft.lbs torque, but these are failing before they are anywhere near that load.
They appear to be from two separate manufacturers LPS and SB.
I am fortunate that I have sufficient feel when tightening fasteners to recognise when a thread is stretching and seldom have problems, but, made up for that today with several set screws failing during assembly and before I had started to nip them up!
Frighteningly expensive, they came from a recognised supplier of BSF fasteners, who I will speak to on Monday.
This could be a nasty safety issue for someone who has not detected the fasteners weakness.
Please may I ask if anyone else has had a similar experience.
Regards, Mark
Mind you we used to break the heads off a 10.32 R quality hex head bolt that was put into an aluminium Rivnut to show that our Rivnuts were more than suitable for many uses! (3/8 BSF aluminium Rivnuts were used to hold the winch onto a Landrover Chassis in the 50/60/70's!).
I'll see if I can identify LPS & SB. It is normally a good sign if there is a head mark & a strength letter.
What thread size? What A/F dimension on the nuts. As an aside, Stainless fasteners are also no substitute for S grades where there is any significant load (seat mountings perhaps), but probably ok to hold bodywork together!
(05-01-2018, 10:01 PM)David.H Wrote:(05-01-2018, 09:01 PM)Mark Atkinson Wrote: Hello All,Mark, as a former fastener person....to be a bit pedantic..(sorry)... R or S indicates the strength (S is close to metric 8.8 I recall) "High Tensile" is a bit fuzzy as a description. The recommended tightening torque is a good indication & if you feel stretch then they could be a bit iffy! I don't have a list of recommended tightening torques to hand...they vary whether threads are lubricated or not, of course.
I am having nasty quality issues with some newly acquired BSF fasteners, specifically that they will not take sufficient torque before stripping the thread. They are ‘R’ grade, which indicates they are supposed to be HT. I have also found the nut supplied with them to have undersized heads, so that they do not work with standard BSF tools.
A 1/4 BSF grade R should be able to take up to 8.2 ft.lbs torque, but these are failing before they are anywhere near that load.
They appear to be from two separate manufacturers LPS and SB.
I am fortunate that I have sufficient feel when tightening fasteners to recognise when a thread is stretching and seldom have problems, but, made up for that today with several set screws failing during assembly and before I had started to nip them up!
Frighteningly expensive, they came from a recognised supplier of BSF fasteners, who I will speak to on Monday.
This could be a nasty safety issue for someone who has not detected the fasteners weakness.
Please may I ask if anyone else has had a similar experience.
Regards, Mark
Mind you we used to break the heads off a 10.32 R quality hex head bolt that was put into an aluminium Rivnut to show that our Rivnuts were more than suitable for many uses! (3/8 BSF aluminium Rivnuts were used to hold the winch onto a Landrover Chassis in the 50/60/70's!).
I'll see if I can identify LPS & SB. It is normally a good sign if there is a head mark & a strength letter.
What thread size? What A/F dimension on the nuts. As an aside, Stainless fasteners are also no substitute for S grades where there is any significant load (seat mountings perhaps), but probably ok to hold bodywork together!
The manufacturers appear to be : LPS Lakshmi Precision Screw Co. Rohtak Haryana India 124001. Big Company, automotive supplier with good branded products. Will certainly have good QC ratings.
SB are closer to home! Smith Bullough in Wigan. They are ISO 9001 approved.
Both should know what they are doing.
Nuts sound more fishy!