[pure-silver] Re: WTB Dry Mount Press

Quoting DarkroomMagic <info@xxxxxxxxxxxxxxxx>:

> All a lot easier said than done. These imperial nuts are tough to get even
> in the US (little to no chance here in Germany). These nuts are very thin

In Munich a good source of imperial nuts and bolts is Schrauben Central
Preisinger near Viktualienmarkt. There are, I'm sure, other similar shops
in most German urban areas--- I recall a few, as well, when I lived in Berlin
and have seen similar shops in Frankfurt.

> (just 3 mm). There is no nylon replacement nut available and there is no
> space or clearance to add any washers or add counter-nuts. Also, since the
> housing is aluminum and the bolts are steel, I'm not sure if grease could

Are we talking about the same model I have: 210-M ?

> make things worse and cause corrosion? I remember side strip on automotive
> doors falling off, because the door was aluminum and the fasteners were out
> of steel.

This is what one does all the time. In bicycles the typical crank interface
is an aluminum arm press-fited onto a steel axle. Forces climbing a mountain
or in a sprint are quite large. Elite cyclists can generate beyond 1500 watts
of power for short periods of time acting on a crank arm of between 165mm 
(track) to as long as 180mm.

Its important that the parts are correctly fastened.

The general formula for calculating torque is:
Torque = 0.2 x nominal diameter of screw x load where load is 80% of yield
strength. Torque for bolts with nuts may be slightly higher. The load depends
upon the friction cooeficient of the screw (and the material into which the
fastener is attached) and the depth of the thread. Lubrication and/or platings
can effect torque values by as much as 25%. Some platings increase torque and
some actually decrease it.

The use of lubricants is especially valuable where steel bolts go into aluminium
components. The lubricant helps to prevent galling of the threads on assembly,
helps to prevent galvanic corrosion in service and helps with removal.


A good reference is:

http://www.bsn.com/Cycling/other/tm584c.html
(my local copy of the "CORROSION CONTROL AND TREATMENT MANUAL" from the
John F. Kennedy Space Center (KSC) )





> 
> Anyway, none of these action should be required for a press, retailing
> around $2,000. It functions well as a dry-mount press, and I don't know of a

Its a specialized "machine" with, I'd expect, some margins..

> better one, but the mechanical design leaves something to be desired as far
> as quality is concerned.


-- 
-- 
Edward C. Zimmermann, Basis Systeme netzwerk, Munich
Office Leo (R&D):
   Leopoldstrasse 53-55, D-80802 Munich,
   Federal Republic of Germany
http://www.nonmonotonic.net
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