Spiggot Tolerance

[LabOwl]

Hi
I am looking for information on spiggot tolerances. Can you please refer me to an appropriate source or if you have a rule of thumb that I can use, please let me know.
My specific application is a locating spiggot between an adaptor plate and a pump column.
Thanks in advance.

 

[diamondjim]

You might specify some size range that
you are interested in. What kind of equipment
can you use to manufacture the parts?
I assume the two mating parts are critical
and you are not using dowel pins or other
alignment pins. How much runout does your
turning or grinding machine produce in that
particular size range?

 

[LabOwl]

diamondjim
The size range that I am interested in is 250mm to 350mm. We are using a lathe to manufacture the part. There is no dowel or other alignment pins used. There would be no runout during the machining operation. Hope this helps.
tia

 

[diamondjim]

I do not know if you are producing mucho parts
and want to ensure all components fit together
or if you are using matched assemblies.
Matched assembly tolerances can be tighter.

By using a nominal size i.e the maximum bore
size of the shaft and allowing only a minus
tolerance of whatever magnitude you feel your
machinists can produce without scrapping parts.
Say .06mm Then make the bore size the nominal
size with a nominal plus tolerances. If you
do have runout the nominal bore must include
the runout differences and the small effect of
oil or grease on these surfaces. You must have
great equipment that does not produce runout
of some magnitude. Do the spigot diameters
have to be sealed with an oring or caulking
compoound?

 

[LabOwl]

The part that is being manufactured is a once only part. The spigot is used to locate an adaptor piece between the coloumn of a vertically mounted submerged centrifugal pump and the motor. The spigot diameter does not have to be sealed as the flanged surfaces are sealed. I have decided to allow a maximum of 0.2mm tolerance.