Drill Chart

[Ripper]

Good Morning all,

I have been trying to create a chart that would allow me to select a drill size, to creating a feature, but when the feature is display on the drawing, I would like it to control the tolerance range of the hole.

Example

I would pick 1/4 drill from the chart, and on the drawing it would display as the following Dia. symbol .248-.247.

Thanks in advance!

 

[Ripper]

?????????????

 

[fcsuper]

Although it would be nice, I think you are getting too much into process whether than just designing the parts as the final product that you require. I know this isn't what you asked for, but just my 2 seconds.

 

[HelenG]

You do know that for the most part, drills cut slightly oversize. You would be very unlikely to get that size hole from a 1/4" drill. A "D" size drill at .246 would probably get you close to .248/.247 or a 6.30mm drill which is .248. I realize this is not what you asked for but that is why the drill charts in the hole wizzard just list standard drills. You can always add the tolerance in the drawing itself but you need to be reasonable about what size hole to expect unless you intend to ream it to the right size.

 

[Ody_Mech_Engr]

Drill Charts

As the previous post mentioned, drill tolerances are not included as a default for a very good reason. The tolerance is not specific to a drill and is most often not a plus and minus tolerance versus the nominal dimension. Actually, the hole tolerance is most often influenced by the equipment making the hole, the material, the drill quality (i.e. dull, sharp, type of point, helix, etc.), and of course the drill size.

Generally you would expect a range with the hole at the nominal size to slightly oversize. Just how much really does depend on what you want and what you need. Reaming is the only way to get a more precise hole diameter, but you need to drill undersize then ream. This is expensive and should only be used when required.