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Posted by T.Alan Kraus on March 7, 2008, 12:57 pm
Please log in for more thread options Rex wrote:
> woodworker88 wrote:
>
>>
>>> What is the usual finish for hydraulic master cylinders internal bores.
>>> Say a brake master cylinder. Would reaming be good enough? Material
>>> is 303
>>>
>>> cheers
>>> T.Alan
>>
>>
>> Usually they are honed with a Sunnen hone. Usually the point is to
>> remove any striations or rings (lines going either along the length of
>> the cylinder or around the bore).
>
>
> Well, yes, but a certain fine finish is desirable, and a mirror finish
> is not.
Yes I researched that and found out that there are two issues at play.
One is the obvious piston seal deterioration by friction with a rough
bore surface, the other is an increased stiction for the o ring seal
when the bore surface is too smooth. These two issues work against each
other and there is a happy medium. Somewhere I saw the figure of 20
micro inches or an Ra of 5. Can anyone confirm or shoot this down?
cheers
T.Alan
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> Say a brake master cylinder. Would reaming be good enough? Material is 303