+/+ Tolerances

Sergiozal · 发表于 2022-7-7 23:05:20

Hello! I want to use tolerances that are, for instace, 230G6 (+0.044/+0,015) but the tolerances types available are just +/-.
I could just add a Mtext besides the dimensions, but I think it is not the best way to do it.
Thank you

JD Mather · 发表于 2022-7-7 23:19:40

You can do ++ or -- tolerances in AutoCAD - keep looking.

nukecad · 发表于 2022-7-7 23:24:18

Dont put mtext beside the dimension, thats a messy way of doing it especially if you later want to move or stretch your dimensions.

You can have +0.044 -0.015 as a tolerance, look a bit more at your dimension tolerance options, but I think that this always 'stacks' the tolerances one above the other.

If you want them to display as in your post then you could use the dimension PREFIX and SUFFIX options to add text to a dimension; that way it stays with the dimension value if you move or stretch it.

You can do it either as you set up the dimension style, or as an override to a dimension style, or after you have placed the dimension select it and use the PROPERTIES pop up to set it there.

dbroada · 发表于 2022-7-7 23:29:26

I have never worked at a place that likes the machinist to do the sums - they have all preferred the draughtsman to put the upper and lower sizes on the drawing. Doing that in the dimension style is easy but as I'm at home I can't check on the setting required.

Sergiozal · 发表于 2022-7-7 23:42:09

@JD Mather: I had tried a lot, but now I figured out how. It is just use the deviation and put minus sign on the upper value to make -/- and + sign on the lower value to have +/+

@Nukecad: That´s why I wanted to find out how to do it. I had a lot of trouble with dimensions made on the " easy way" by previous draughtsmen

@Dbroada: I do agree with you, in one of the places I worked they had this standard, but here the machinists are used to do the maths. For the engineers for other hand it is better to look directly to the ISO tolerance range.

Thank you for your answers!
Regards from Brazil

nukecad · 发表于 2022-7-7 23:45:11

The best way to do it - Nobody on the shop floor can say that they made a mistake with the tolerance calculation because the drawing was not clear about it.

Sergiozal · 发表于 2022-7-7 23:54:19

Just a correction on my previous post: Autocad thinks in a strange way, so here is how it will work: only the "-" signal affects the tolerance.

If you want -/- tolerance:
Use "deviation" and put the upper tolerance "-" sign

If you want to do +/+ tolerance:
Use "deviation" and put the lower tolerance "-" sign

It is strange but works out! I hope someone else can also be helped by my trial and error experience.

Lazer · 发表于 2022-7-8 00:05:12

I am with dbroada on this, on a drawing the other day noticed it had 16mm +.2/+.1, the shop floor have made errors on this part due to the way the tolerance is on the drawing. Where does this method come from?

Patrick Hughes · 发表于 2022-7-8 00:07:37

There are times when a +/- tolerance is more desirable. The base dimension being the "target" with the tolerances being the acceptable deviation (obviously).

When using upper/lower tolerancing the machinist does not have a target so much as he has a range.

A tolerance isn't necissarily there for the machinst - it's there for the inspector.

[综合讨论] +/+ Tolerances

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