----- Original Message -----
From: "Dennis Storzek" <destorzek@...>
To: <STMFC@...>
Sent: Saturday, December 27, 2008 1:32 PM
Subject: [STMFC] Re: making the case for self-tapping screws


> --- In STMFC@..., Denny Anspach <danspach@...> wrote:
>>
>>
>> Truck makers make bushings peculiar to their truck bolsters?
>>
>> Denny
>>
>> Denny S. Anspach, MD
>> Sacramento
>>
>
> Doc,
>
> I fail to see why truck makers need to be responsible for other
> manufacturers' poorly designed body bolsters. The de facto standard in
> the hobby for the last forty years has been a clearance hole for a
> 1/8" dia. boss, so the truck doesn't pivot around the threads, and the
> screw can be tightened solid without binding the truck. If it wasn't
> for the fact that Kadee persists in adhering to the outdated and
> obsolete NMRA standard, the available trucks would have matched this
> standard 100%, at least before the recent wave of designed in China
> stuff started diverging again.
>
> There is no reason why resin kit makers can't mold the boss on their
> parts; I was even able to have it included on white metal parts. The
> fact that it might need to be removed to accommodate a few trucks is
> no excuse; it's easier for the modeler to carve it off rather than
> cobble it up from nothing.
>
> That being said, If you buy Accurail trucks, you get the added value
> of someone actually giving this some thought during the design
> process. Accurail trucks come with the clearance hole for the 1/8"
> boss, and so will fit most any other injection molded kit. The inside
> diameter of the screw head recess is designed to be a decent running
> fit on the ANSI standard dimensions for the pan head on a #2 screw;
> either a wood screw, type AB thread cutting screw (sheet metal screw)
> or machine screw. So, if you use pan head screws, the O.D. of the head
> should give acceptable results, although the standard for pan heads
> does provide wider tolerances that the molded bosses are usually held
> to. You can even trim the bushing off the ubiquitous Kadee #5 box, and
> you will find that the thickness of the Accurail truck bolster is such
> that the Kadee bushing is the proper length.
>
> Dennis Storzek
> Accurail, Inc.
>
>
>
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