What angle tolerances can machine shops typically hold?
What angle tolerances can machine shops typically hold?
(OP)
Hello, we spec an angular tolerance of plus/minus 0.5 degrees on our dwgs, but I know most shops can do better than that. Is plus/minus 0.1 degrees something most shops can hold without breaking a sweat? Thanks for any info, Scott





RE: What angle tolerances can machine shops typically hold?
RE: What angle tolerances can machine shops typically hold?
RE: What angle tolerances can machine shops typically hold?
yes it can. if the angle is very important. but beware cost will increase.
Mfgenggear
if it can be built it can be calculated.
if it can be calculated it can be built.
RE: What angle tolerances can machine shops typically hold?
RE: What angle tolerances can machine shops typically hold?
as the precision of the part increases so does the equipment required.
that is why part cost triples.
a grinding or lapping operation may be required depending on the size & requirement.
Mfgenggear
if it can be built it can be calculated.
if it can be calculated it can be built.
RE: What angle tolerances can machine shops typically hold?
-Dustin
Professional Engineer
Pretty good with SolidWorks
RE: What angle tolerances can machine shops typically hold?
Measuring an angle to within 1/2 degree can usually be done with a machinists protractor. To get better than that, you are probably looking at co-ordinate measuring systems or optical comparators. If you need the added percision, then they will find a way to measure it, but to put a tolerance on a dimension that is tighter than is needed just becasue "they should be able to hold that" is wrong.
If a valve seat needs to be within +/- 5 minutes (for the valve to pass pressure testing, say) then it needs to be specified as such. However, if chamfer can utilize +/- 5 degrees and still work, resorting to +/- 1/2 degree block tolerance just becasue "they should be able to hold that" is not good design practice.
rp
RE: What angle tolerances can machine shops typically hold?
RE: What angle tolerances can machine shops typically hold?
sin bar & precision indicators with increments of .0001", .0005" or .001"
optical comparator, the precision depending the system.
CMM
HTH
Mfgenggear
if it can be built it can be calculated.
if it can be calculated it can be built.
RE: What angle tolerances can machine shops typically hold?
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The Help for this program was created in Windows Help format, which depends on a feature that isn't included in this version of Windows.
RE: What angle tolerances can machine shops typically hold?
standard chamfers can be +/- 5 deg & can be held & easily inspected. for medium to small parts ok
in my current world with gears Inside Diameter centers have to be +/- .5 degrees 60 deg included angle.
it is used for tooling. we can hold it all day, we have specialized inspection equipment to verify it.
because this is used for inspecting & grinding, in other cases some special porting requires excessive close angle tolerance.
or for whatever reason. It must have a good rational.
if it's just an edge break or to remove a sharp corner & holds no purpose it is good to clarify
that an excessive close tolerance on a chamfer is not necessary. and should not done.
The way the question was ask by OP is can a angle be held at +/- .5 degree the answer is yes
if it is a very necessary function of the part.
sometime my answers are too brief.
HTH
Mfgenggear
if it can be built it can be calculated.
if it can be calculated it can be built.
RE: What angle tolerances can machine shops typically hold?
These days with CNC applications, a guy could specify +/- 1/4 degree without problems.
Regards,
Cockroach
RE: What angle tolerances can machine shops typically hold?
Ted
RE: What angle tolerances can machine shops typically hold?
what is the requirement of your part.
is it for required important angles ?
Mfgenggear
if it can be built it can be calculated.
if it can be calculated it can be built.
RE: What angle tolerances can machine shops typically hold?
If using any kind of default tolerance then really for every feature/dimension you place you need to think about if the default tolerance is appropriate (primarily function but also manufacturability and inspectability).
What is Engineering anyway: FAQ1088-1484: In layman terms, what is "engineering"?
RE: What angle tolerances can machine shops typically hold?
I would agree with the other posters- setting up a machine based on or validating precise angles is a PITA. A better approach is to use linear edge dimensions and/or a system of gauge points. Even CMM's can only validate surface geometry based on the Cartesian coordinates of several measured points.
CNC and CMM machines work off of X,Y,Z values. So forget about using angular dimensions whenever possible.