Drawing Callout: "Holes must be in line" No Tolerance specified

[jdm2008]

As the title says. I have the following callout on a drawing: "Holes must be in line after welding". How far out of line should I allow these holes to be before rejecting them. My first thought is to simply use the tolerance of the diameter. Because holes are specified in line so a straight shaft can go through.
However I do not believe this standard is legitimitized by the print. Is this specification simply incomplete?

 

[Jim Wynne]

Re: "Holes must be in line" No Tolerance specified

As the title says. I have the following callout on a drawing: "Holes must be in line after welding". How far out of line should I allow these holes to be before rejecting them. My first thought is to simply use the tolerance of the diameter. Because holes are specified in line so a straight shaft can go through.
However I do not believe this standard is legitimitized by the print. Is this specification simply incomplete?

Without seeing the drawing, I'd say it's certainly incomplete. You would need to know two things: "In line" with what? and what constitutes "not in line." There might be other specifications that could guide you, such as the positions of the two holes on their respective pieces, and position specification for welding. If the holes are within tolerance position-wise on their respective piece parts, and the pieces are correctly aligned for welding, the holes should "line up."

In all cases, when drawing ambiguities exist, it's best to query the customer.

 

[jdm2008]

Re: "Holes must be in line" No Tolerance specified

Without seeing the drawing, I'd say it's certainly incomplete. You would need to know two things: "In line" with what? and what constitutes "not in line." There might be other specifications that could guide you, such as the positions of the two holes on their respective pieces, and position specification for welding. If the holes are within tolerance position-wise on their respective piece parts, and the pieces are correctly aligned for welding, the holes should "line up."

In all cases, when drawing ambiguities exist, it's best to query the customer.

Here is the drawing. Unfortunately this is an old drawing from an in-house designer(94) and he's not around anymore.

 

[Wes Bucey]

Jim's advice holds true for most situations involving ambiguous or unclear drawings, instructions, or other requirements from a customer - clear these up as part of the Contract Review process, if possible, not once you have agreed to do something for a price.

 

[Jim Wynne]

Re: "Holes must be in line" No Tolerance specified

Here is the drawing. Unfortunately this is an old drawing from an in-house designer(94) and he's not around anymore.

Not much help there, I'm afraid. If this is an in-house print, is there an engineer who "owns" it now? Is this something that has been made before?

 

[jdm2008]

It is currently being made and we are having several assembly and end use issues(including the holes among others), with the application. There is an owner, but for all practical purposes the owner will soon be me .
I am trying to determine the what specification the manufacturer(This part is sometimes made in house, sometimes sent out) is being held to, with regards to the hole, or whether he is not held to any spec because the drawing is icomplete.

 

[Jim Wynne]

It is currently being made and we are having several assembly and end use issues(including the holes among others), with the application. There is an owner, but for all practical purposes the owner will soon be me .
I am trying to determine the what specification the manufacturer(This part is sometimes made in house, sometimes sent out) is being held to, with regards to the hole, or whether he is not held to any spec because the drawing is icomplete.

Sounds like a job for the Reverse Engineering Department.

 

[Wes Bucey]

It is currently being made and we are having several assembly and end use issues(including the holes among others), with the application. There is an owner, but for all practical purposes the owner will soon be me .
I am trying to determine the what specification the manufacturer(This part is sometimes made in house, sometimes sent out) is being held to, with regards to the hole, or whether he is not held to any spec because the drawing is incomplete.

Rarely, but often enough that we formulated a process, we would encounter a customer who didn't have the details we craved. In which case, we resorted to "reverse engineering," concentrating on form, fit, and function of a product, especially related to its fit with mating parts.

My own mechanical engineering skills date back to compasses, T-squares, and straight edges, but certainly "someone" in the supply chain you deal with can supply answers about the fit and function of the product you are fabricating. With that information, an up-to-date mechanical engineer can help formulate the necessary tolerances for a successful product.

 

[Ninja]

...I am trying to determine the what specification the manufacturer(This part is sometimes made in house, sometimes sent out) is being held to, with regards to the hole, or whether he is not held to any spec because the drawing is icomplete.

You're probably already thinking this way, but just in case you're not...

Don't put all the focus on what spec was held before. As you stated above, there are some issues with was has been done.

Save some (most?) of the focus for what the part NEEDS in order to have the issues stop. If this is the last bit that should have been done years ago and wasn't...do it now. Then update the drawing.

 

[Wes Bucey]

You're probably already thinking this way, but just in case you're not...

Don't put all the focus on what spec was held before. As you stated above, there are some issues with was has been done.

Save some (most?) of the focus for what the part NEEDS in order to have the issues stop. If this is the last bit that should have been done years ago and wasn't...do it now. Then update the drawing.

"needs" is exactly the issue! Thanks for simplifying the matter.