"N_Cook" wrote in message
...
I need to do a hub-pulling type operation on a small piece of equipment
that is not made to be taken apart, so no purpose-made anchor points. There
are 8 off , 1mm tapped holes with 5 threads per hole , in the aluminium
available (used for undemanding normal fixing to the chassis) , if I drill
a plate to take 8 screws . The only screws of that thread I have are brass,
probably preferable to steel anyway. For a similar hub-pulling where there
was purchase , after heating (limited as to amount that can be used ),
required about 4Kg of force to extract. Would 4Kg , assuming even
distributed loading over the 8 screws be above or below the stripping force
?
I found these sites but not applicable for my purpose it would seem

www.tribology-abc.com/calculators/e3_6e.htm
http://www.roymech.co.uk/Useful_Tabl...ead_Calcs.html

I would be leery of using these screws for even this kind of light pulling.
Even if a single 1 mm screw in a 1.25mm deep hole in aluminum can hold 0.5
kg (I do not know; I have not done the calculation), I know from experience
it is very easy to strip an M1X0.25 screw in aluminum even when torquing for
preloading. Don't forget the preload and load together have to be less than
the strength of the thread. If you do not have any preload (i.e. the screws
are loose) then there is a good chance the force will not be evenly
distributed among the screws when you pull.

I think I would try to use a method that used some sort of temporary tape or
adhesive that is compatible with the moderately high temperature you need.
If there is a large enough flat area to mount to, perhaps just viscous high
temp grease between the hub and the pulling plate would provide enough
suction force when pulled straight up.