[TR] How to tell the size of bolt or setscrew from the part number

Chris Kantarjiev cak at dimebank.com
Wed Jun 17 14:51:33 MDT 2020


On 6/17/20 1:48 PM, Chris Kantarjiev wrote:
Oh, I should have also said: these are all UNF threaded.
> You're on the right track, but not quite right.
>
> The first time I saw this system explained was in TRF's TR250 manual.
>
> HU is a "set screw" - fully threaded.
> HB is a "bolt" - partially threaded.
> HN is a nut.
> JF is a jam nut (thin)
> LN is a slotted nut (castle nut)
> TN is a thin nyloc nut
> YN is a thick nyloc nut
> WL is a split lock washer
> WP is a plain (flat) washer
>
> By default, it's grade 5 hardware. Bolts that have part numbers 
> outside this system are special in some way - stronger, or have a 
> shoulder, or an unusually threaded section. For example, the bolts 
> that connect drive shaft flanges are not in this system (and I prefer 
> to use AN hardware for them, but that's a different discussion).
>
> For bolts, the first digit indicates the *wrench* size, and the 
> second/third digit indicated the length in 1/16" increments. So HU704 
> takes a 7/16 wrench (so it's a 1/4" bolt) and is 1/2" long.
>
> For nuts, the last two digit indicates the wrench size.
>
> For washers, the last two digits indicates the wrench size of the 
> associated through bolt/nut.




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