curiousmechanical
Mechanical
Hello Everyone,
I have a question about tolerancing methods used on drawings. I work at a custom machinery job shop where we fabricate parts/machines from outside customer's drawings and our own in-house drawings (created by yours truly). Because I deal with a lot of other people's drawings I see many ways to tolerance parts. The most common that I see are the following 3 methods:
1. People who tolerance their parts using the standard +.000/-.005, +.001/-.001, +.0000/-.0005,...etc. This method seems like they just go with their gut feeling and use multiples of .0005", .001", and .005".
2. Other people just put the nominal dimension on the print and specify the type of fit that they want with a mating part. ex. "0.250" Dia. THRU for Light Press Fit with Shaft A." The guys in the shop seem to like this method the best because it gives them the freedom to size things however they want (within reason) as long as the parts fit together properly.
3. Then I see other people who use very specific toleranced dimensions. They use the American Standard Fits Listed in the Machinery Handbook. ex. h7, s7, etc. I really like this style of dimensioning for two reasons.
a.) I like that I can give two parts to two different people and know that they will fit the way I want them to and the two people don't need to work together to obtain the desired fit between the parts. That just doesn't seem right to me. Although, it seems to be so common in the job shop atmosphere...
b.) Also, I really like using some kind of standard method of generating tolerances rather than going with my random gut feeling as in method #1. I like to be consistent. Although, because the tolerances are always oddball numbers, the guys in the shop always complain and ask me "where the heck did you come up with that tolerance?" I tried to explain that I was using "standard fits," but they seem to give me the common attitude such as: "You guys think all the answers are in those books" or "Books are not always right” or “You are over-tolerancing the parts.”
What is the proper way for me to be dimensioning my parts, in my specific atmosphere? I really don't want to use method two because it seems lazy. On the other hand, I don't want to use method three if it is not necessary or if everyone will think I am trying to just be fancy for the sake of being fancy.
Any suggestions?
Thanks everyone!
I have a question about tolerancing methods used on drawings. I work at a custom machinery job shop where we fabricate parts/machines from outside customer's drawings and our own in-house drawings (created by yours truly). Because I deal with a lot of other people's drawings I see many ways to tolerance parts. The most common that I see are the following 3 methods:
1. People who tolerance their parts using the standard +.000/-.005, +.001/-.001, +.0000/-.0005,...etc. This method seems like they just go with their gut feeling and use multiples of .0005", .001", and .005".
2. Other people just put the nominal dimension on the print and specify the type of fit that they want with a mating part. ex. "0.250" Dia. THRU for Light Press Fit with Shaft A." The guys in the shop seem to like this method the best because it gives them the freedom to size things however they want (within reason) as long as the parts fit together properly.
3. Then I see other people who use very specific toleranced dimensions. They use the American Standard Fits Listed in the Machinery Handbook. ex. h7, s7, etc. I really like this style of dimensioning for two reasons.
a.) I like that I can give two parts to two different people and know that they will fit the way I want them to and the two people don't need to work together to obtain the desired fit between the parts. That just doesn't seem right to me. Although, it seems to be so common in the job shop atmosphere...
b.) Also, I really like using some kind of standard method of generating tolerances rather than going with my random gut feeling as in method #1. I like to be consistent. Although, because the tolerances are always oddball numbers, the guys in the shop always complain and ask me "where the heck did you come up with that tolerance?" I tried to explain that I was using "standard fits," but they seem to give me the common attitude such as: "You guys think all the answers are in those books" or "Books are not always right” or “You are over-tolerancing the parts.”
What is the proper way for me to be dimensioning my parts, in my specific atmosphere? I really don't want to use method two because it seems lazy. On the other hand, I don't want to use method three if it is not necessary or if everyone will think I am trying to just be fancy for the sake of being fancy.
Any suggestions?
Thanks everyone!
