topic Re: Drawing: Dimension tolerance, specify both as E8 and Plus-Minus in 3D Part & Assembly Design

Drawing: Dimension tolerance, specify both as E8 and Plus-Minus

EddyVE — Wed, 16 Oct 2024 08:33:11 GMT

Hi,

I am still using Creo 4.0 M050.

When making 2D drawings of a part, I usually specify a dimension tolerance as 'Plus-Minus' or as a 'Letter-Number' combination (like H6, G7, E8 ...).
Sometimes I feel it is more appropriate to specify both.

The nuisance is that Creo puts the Letter-Number combination (E8 in this case) always behind the Plus-Minus numbers.

So, like this:

But I would prefer that the E8 comes immediately behind the nominal dimension, and in front of the Plus-Minus. Like Diam 3E8 +0.05/+0.10.
I couldn't find a way. Is this possible in Creo 4.0 ?

Re: Drawing: Dimension tolerance, specify both as E8 and Plus-Minus

BenLoosli — Wed, 16 Oct 2024 15:06:41 GMT

Doesn't the E8 specify a tolerance range? Why have 2 sets of tolerances for a dimension?

Re: Drawing: Dimension tolerance, specify both as E8 and Plus-Minus

pausob — Wed, 16 Oct 2024 17:27:33 GMT

Try the detailing settings discussed in thread ISO Standard Fits and Tolerances - where the dimensions show up more like what you want:

Re: Drawing: Dimension tolerance, specify both as E8 and Plus-Minus

EddyVE — Wed, 16 Oct 2024 17:29:42 GMT

Yes indeed. E8 specifies a tolerance range, The plus-Minus would be a numerical representation of that same (E8) tolerance ( I realise this is wrong in my example above because I quickly put it together).
The reason for specifying 'the same' in 2 different ways is for reasons of clarity for the manufacturer. As said above, I normally don't do it, but in some cases it gives additional information.

When the tolerance is specified on a hole diameter, the manufacturer simply has to use an E8 reamer to make a hole, according to the specifications. He doesn't need to know the plus-Minus values.
You can also specify E8 tolerances on something else than a round hole. A linear dimension for example. In that case, a reamer can not be used. So the manufacturer has to look up the numerical tolerance values of 'E8'. To save the manufacturer some time, sometimes a designer also specifies the numerical tolerances, next to E8.
So, it is simply a matter of 'more clarity' for the manufacturer. But you are indeed representing the same information twice, but in 2 different forms.

Re: Drawing: Dimension tolerance, specify both as E8 and Plus-Minus

EddyVE — Thu, 17 Oct 2024 14:30:31 GMT

The method as described in your link, works for me in Creo 4.0 .
Thank you so much!

Kind regards