Mechanical Drawing Notes
Mechanical Drawing Notes
(OP)
So I am trying to make mechanical drawings for a part that I need made but I don't know how to make the notes for the bearing to be press fit inside of it. How do I do this if I have a bearing with an outside diameter of 100mm?





RE: Mechanical Drawing Notes
Dan
www.eltronresearch.com
Dan's Blog
RE: Mechanical Drawing Notes
What is Engineering anyway: FAQ1088-1484: In layman terms, what is "engineering"?
RE: Mechanical Drawing Notes
Okay, so if I pick out one of their bearings that has an OD of 100 mm and I choose the housing fit that I want and it says use tolerance P7 what do I do?
RE: Mechanical Drawing Notes
RE: Mechanical Drawing Notes
Dan
www.eltronresearch.com
Dan's Blog
RE: Mechanical Drawing Notes
RE: Mechanical Drawing Notes
What drawing standards are you working to/where are you located?
What is Engineering anyway: FAQ1088-1484: In layman terms, what is "engineering"?
RE: Mechanical Drawing Notes
RE: Mechanical Drawing Notes
Unfortunately I don,t know an English version, but maybe this explains a little
RE: Mechanical Drawing Notes
Rerig
RE: Mechanical Drawing Notes
Dan
www.eltronresearch.com
Dan's Blog
RE: Mechanical Drawing Notes
A learned skill that will be valuable in your career is to identify who might know the things you need to know don't but, and ask them your questions. Nobody expects you to know everything.
As an example, the applications engineers at SKF. Most manufacturers of engineered equipment have them, and that's what they are there for.
Of course you did start here, so that's good:)
Regards,
Mike
RE: Mechanical Drawing Notes
htt
http://www.wisetool.com/fit.htm
h
http://www.lmgtfy.com/?q=fits+and+tolerances
TygerDawg
Blue Technik LLC
Virtuoso Robotics Engineering
www.bluetechnik.com
RE: Mechanical Drawing Notes
P7 is a bore tolerance. (Bores use capital letters, shaft tolerances are lower case letters , p, k, n, r , etc). On a 100 mm bearing It would result in a theoretical interference fit with the bearing outer race of 14 to 54 microns ( ~ 0.0005 inch to roughly 0.002 inch ) . Those are diametral fits, not radial.
Beyond the size there are equally important tolerances for shoulder runout, bore and journal coaxiality (relative runout is sometimes recommended as easier to gage), roundness and cylindricity, etc.
The info is online and in most catalogs, but I'd talk to an application engineer until you are real comfortable with all the design steps. It takes a while.
These days machine more machine shops are familiar with the ISO fit designators. I think it is smart to include a copy of the appropriate hunk of the ISO fit table right on the drawing. It sure beats having a whiny pillow fight about mysterious or imaginary tables when parts are the wrong size.
RE: Mechanical Drawing Notes
Who is going to press fit the bearing, you, or the fabricator?
This affects how your drawing is presented.
A dig for SKF here. If you need info like the tolerances on the OD of your bearing, buy your bearings from people who publish this information. Better yet, buy your bearings from people who publish handbooks telling you how to analyze your bearings and design and tolerance the mounts. SKF might cost more, but if they support your engineering, you will get your job done right, the first time.
RE: Mechanical Drawing Notes
Ted
RE: Mechanical Drawing Notes