Whiz-Lock Screw
Whiz-Lock Screw
(OP)
I'm looking for design information for a 1/4-20 X 0.75 Whiz-Lock Screw as manufactured by MacLean-Fogg Co. Anyone have a link that gives design load capacity? I assume that the material is Grade 5 or equivalent.
thanks, Dik
thanks, Dik





RE: Whiz-Lock Screw
In my experience (almost 30 years) the Whiz-lok feature is more Marketing than actual performance. If you take a standard head design on a threaded fastener and load it up to the proper clamp load it works just as well. One situation where the Whiz-lok works well is bearing against softer die cast surfaces, where the serrations really dig in and prevent rotation. In most cases you can obtain better resistance to loosening if you use a thread rolling screw like a Taptite, plus you eliminate cross threading and the cost of tapping.
Dick
RE: Whiz-Lock Screw
Dik
RE: Whiz-Lock Screw
If loads vary then keeping the fastener from rotating may
instill a false sense of security.
http://www.boltscience.com/images/boltf6.jpg
http://www.boltscience.com/pages/vibloose.htm
RE: Whiz-Lock Screw
Dik
RE: Whiz-Lock Screw
If the client is having such a problem with loosening, then you need to first make sure that the parts are truly being tightened to their full capability. If they are still loosening, then you may need to resort to "band aids" to help prevent (not solve) the problem. Some of the things I would try would be lock nuts (nylock or deflected metal), or a thread adhesive (preapplied by the manufacturer is much less messy). Don't even contemplate using a 'lock washer' because they don't (lock that is). On joints that have small L/D ratios (less than 4 : 1) you sometimes are forced to use the band aid approach since there is not enough effective stretch avaiable in the bolts to keep them from loosening.
Dick