How do you call for ??

[arto]

How do you call for a surface to be machined by a large cutter, so that there's no "shingle" effect?
i.e.: We had a 63 finish metal-to-metal low pressure steam sealing turbine flange surface. An outside vendor machined one side with a relatively large cutter [so it overhung the edges], thus it was "perfect." The mating surface was done on a different machine, with a smaller cutter - this required a back&forth tool path, which gave a 8" wide "Clapboard" that had to be handworked.

How would you call for this on a drawing so that it doesn't get missed??
Thanks
Arto

 

[Abrasive]

I was wondering if the shingling effect was simply a visual phenomena or a characteristics that can be measured with a surface profilometer. The underlying concern here is whether the type of surface you describe affects the functionality of the workpiece. Visual effects are concerned with the "lay" of the surface characteristics and are easily detected visually by not easily quantified. David Whitehouse's new book on surface metrology (Surfaces and their Measurement) has a set of symbols that can be used to specify the lay (p. 80). You can find a general discussion of the topic in the book.
If the concern here is the functional change caused by the different milling processes, then the solution might be to specify a specific surface parameter.

 

[stressriser]

Usually, a symbol is denoted with the surface finish symbol. For example, crosshatch marks mean that the surface must be lapped to the specific finish. The letter "C" means that the marks are circular relative to the center, much like the marks you would get from a lathe. It sounds like you are getting a multidirectional pattern, denoted by the letter "M". If this is not what you desire, consult a surface finish guide. The charachteristic lay is always added to the surface finish symbol.

stressriser

 

[ryano]

the problem you have is not uncommon in workshop environs however on the drawing you need to accurately specify what you weant done in your case specify on the drawing a radial surface this will denote the cutter must be truly flat then on your machining symbol from the top leader line ie the longest 60 degree add a special note minimum cutter diameter to exceed total surface width one pass per cut