Documation TM200 card reader - pinch roller restoration

[Guy Dunphy]

At 07:21 PM 16/10/2018 -0400, you wrote:
>    > From: Guy Dunphy
>
>    > The mechanics has no adjustment or spring tension on the pinch roller
>    > positions. ... all the spring is in the rubber of the rollers.
>    > But how much squish?
>    > ...
>    > I'm hoping someone might have some knowledge of how much punch card
>    > reader pinch rollers should press against capstans. Does 0.2mm squish
>    > seem right
>
>To produce a given force on the card, the dimensional amount of squish needed
>would depend on the rigidity of the material, no? A stiff material would
>need/want less than something soft, I would think.


Yes absolutely! This is why I chose a casting silicone product with (supposedly)
a duro of 60 Shore A. Which is close to car tire rubber (60 to 70.) 
Since the original rollers were rubber, I'd assumed they probably used some
standard grade of rubber and were fairly stiff too.

It's also why the mold structure I'm making will hopefully allow repeated
attempts using different materials if first try doesn't work.

Later today I'll post the photo of the rollers, with dimensions derivation.
It implies the original rollers are fairly stiff material.

Guy