I thought I'd start a new thread regarding the proper way touse dual dimensions on drawing. First off, I strongly dislike dualdimensions, but the company I'm contracting for insists my drawingsconform to their company standard. My hands are tied, though I willquestion their decision for using them...
So, I understand now, though I had not previously given it anythought, how dual dimensions create contradictory specifications.Simple example- You have ".039/.035 [1/0.9]" on a drawing- the partcomes in at .0393", do you reject it? it's outside of the .039",but still inside of 1mm (which is approximately .03937"). Is thereany precedence for calling out the alternate units as reference?That would indicate that the inspector should inspect the parts tothe primary units, and ignore the tolerance on the alternate unit.
I can see why some companies use them. Most US CNC machines alloperate in inches. Most of the tooling available in the US is madein inches (end mills, drills, reams, etc..). So, if you give amachinist a drawing in mm, you are forcing them to convert unitswhich costs time (which = \$\$).
BM
SolidworksDrawings And Detailing
So, I understand now, though I had not previously given it anythought, how dual dimensions create contradictory specifications.Simple example- You have ".039/.035 [1/0.9]" on a drawing- the partcomes in at .0393", do you reject it? it's outside of the .039",but still inside of 1mm (which is approximately .03937"). Is thereany precedence for calling out the alternate units as reference?That would indicate that the inspector should inspect the parts tothe primary units, and ignore the tolerance on the alternate unit.
I can see why some companies use them. Most US CNC machines alloperate in inches. Most of the tooling available in the US is madein inches (end mills, drills, reams, etc..). So, if you give amachinist a drawing in mm, you are forcing them to convert unitswhich costs time (which = \$\$).
BM
SolidworksDrawings And Detailing
