i have a note on a drawing wich says "face of fitting must be perpendicular to axis of thread within plus or minus 0 deg 10', how do i put that into a tol box?
Scott, GD&T works differently from plus-minus tolerancing-especially with respect to angles.
The upshot is that it doesn't tolerance angled features with allowances for deviation in degrees.
In your case, you define the tolerance as the space between two planes perpendicular to Datum A that youre surface has to land inside.
The entirety of GD&T is based on these theoretical volumes that say where the feature has to be when it's inspected so specifying ± degrees is not supported. If you need to tolerance the face that way, use a regular angular dimension.
Also, Datum B isn't really serviing much of a purpose. You've already qualified the counterbore. Finally, concentricity doesn't do what you think it does. Concentricity is for defining the center of rotation of an irregular form like an extruded prism. It's rarely used correctly. If this part is stationary in it's application, use position with a diameter symbol. If the part rotates or acts as an idler or cam, use runnout.
finally, if you're going to be designing using GD&T and not just applying notes other engineers give you you should by a book on Y14.5 and ideally: take a class. The standards books are sold by ASME and they're expensive. IHS Drawing Requirements Manual 9.0 combines several standards into one book. TechEase offers pretty good training.
First question that pops into my mind is how in the heck did that get inspected? If it is getting inspected, that will be a clue as to how the control frame should be constructed. If not then the fitting face should be defined as a datum surface. Then you can assign a positional callout to the thread to the global datums and further define the position with either an angle or positional callout to the flange datum. personally I would use the positional since it is the easiest to measure. You will need to calculate what the positional error would be relative to the reference surface for 0deg 10' for the thread depth.
how do i type plus minus and the deg symbol into the tol block?
Actually you don't and I am mistaken as far as using an angle callout unless you dimension the centerline from the flange surface. You can use a perpendicular callout and then define the tolerance in the control frame. The tolerance defines the distance between two planes that are symmetric to the center line of the hole. You will need to calculate the maximum angle and resulting displacement and define the postion of the planes using that.
how do i put the drawing into this post?
Upper right corner "Advanced...", Then Bottom right corner "Attach Files". Either a pdf, unattached drawing or attach both the part and drawing file otherwise the sheet will be blank.
Unless you just want the image in the post itself then click the camera icon in the toolbar....
here is the part i am talking about
in the tolerance frame, hold the "Alt" button and type in 241 using the key pad for the ± and 248 for the ° symbols.
go here for a list https://forum.solidworks.com/docs/DOC-1205
Can't say as I'm aware that it's OK to have plus or minus or degrees in a CF. Plaese correct me if I'm wrong. Any ASME Y14 people out there? Handy though...
I can appreciate your frustration if you are simply updating the print to GD&T because I can't believe that part was ever inspected to those dimensions. Here's what I am talking about: 0 deg 10' = .166 deg; take the tangent and multiply by the width of the surface of the flange (about .5") and that's .0015". Plus or minus .0015" as measured from a threaded surface. Consider the surface area on the flange with the chamfers and slots. Then consider how are you goung the establish the dimension of the thread? Center line, minor, major or pitch diameter? And that's a standard thread callout too so not much to work with.
I don't want to come off as though I'm ambushing you here just that those tolerances are not realistic and you have an opportunity to fix it. If you want to let it ride, assuming this is a mostly turned part my suggestions are:
You won't be using a plus or minus anything in a GD&T control frame if you take my suggestions or not and it will be expressed in inches (in your case).
Hope I'm not coming off as too harsh. Not my intent at all.....
not at all harold, i work with military drawings. they are all rediculous with tolerances. i will take your advice, im sure the shop will appreciate it.
ok, heres my updated drawing
Just my observations:
- If the surface is to be perpendicular to "axis" A, then the datum A callout needs to be in line with the dimension callout. By having datum A on the extension line and not in line with the dimension you are stating the OD surface as datum A.
- why is there a .85 depth callout for the center Ø.275-.278 hole and a depth callout for the thread? the thread is thru and therefore no way to inspect to the noted depth.
ok, i made those changes, wich dims should be basic?
ok, i just asked the inspection engineer and he said the perpendiculer call out is ok but he said the others should be changed to concentric with T.I.R after the .005 and .007 tol. would you agree?
I would go with what your company's inspection engineer wants. After all he is the guy that has to check it and has the best knowledge of the requirements for the customer and your company.
Good point Anna. Even, If the inspection engineer is calling for concentricity instead of runnout or position, he's still probably inspecting it with a Dial indicator or gauge pin. I haven't seen anybody ever measure pairs of opposing points and compare the computed median axis to the datum reference frame.
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