A vast subject...
Hello!
I drew two pieces that fit together, side by side, and I'm at the drawing stage with tolerance. and I ask myself questions.
My question is the following: When creating parts and assembling, add directly to the part the -0.1mm that fits well or you draw them side by side. The rest in doing so has the drawing.
Thank you in advance.
Hello
Personally, I always put the tolerances in the 3D model.
Indeed, with 3D, we design everything directly as we used to do on the drawing board (in 2D).
I haven't checked but there is feedback for all the modifications made in the MEP reflected in the 3D. So your 3D ends up having the same tôlérances. (to check that for the odds it's also true retro-feedback). Anyway, if you use the assistance for the piercings and the functions are automatically in the 3D model.
I also think it's good hygiene because it's a safe bet that in less than 20 years 2D will have almost disappeared for new designs.
All this will be done with the MDB technique of 3D dimensioning and no more 2D plans.
The arrival of millennials and the digital generation will accelerate the movement, especially since the elders (including the baby boomers) will retire.
Exit the old people, with autocrad as a parting gift and the old drawing board that is used to display the menus in the canteen ;-)
Kind regards
ok it's very clear thank you
Hello
Including tolerance in 3D leaves me a little perplexed; I understand that this has its advantages, but isn't tolerance dependent on the precision of the machine or tool that will machine the part? In which case, if the machine differs, the tolerance will differ with. And in 20 years, to take your example, @Zozo_mp, It is a safe bet that the precision of machining will be greatly increased, even with zero tolerance.
I would say that it all depends on whether you want to display the acceptable margin of error for the part to be viable or indicate the range of variation that the part is likely to have when it leaves the factory.
Cdt
Personally I do both.... Hence my question. For parts that will be produced on a 3D printer, I included it directly in the 3D because it is a step that is transmitted.
As for the parts in conventional machining, indeed, I was leaning towards a "side for side" drawing THEN only tolerance on the drawing.
The question remains open...
Agree with our friend @ Zozo
Question why create dimensions in the drawing
since normally all the refs of the drawing are from the parts or assembly
And all the drawings are in theory and practice dependent on the 3 Ds
@+;-)
Hello gt22
If I want to keep a part with precise dimensions and only add the margins of error on the drawings, isn't there a way to dissociate the MEP tolerances from the 3D dimensions?
To my knowledge
it's from 3D to the drawing
but nothing prevents you from creating dimensions in the drawing with tolerance or not
and these dimensions will remain inoperative in 3D
After all, it also depends
for which type of part
Meca / sheet metal work / piping / welded cons / etc
and the size, the material of these said pieces
See this link among others
https://www.usinenouvelle.com/article/le-tolerancement-en-quete-d-efficacite.N39237
@+
@gt22: Unfortunately, I don't have access to the entire article but I think I got the essence of the message:)
Hello jojo4008
This deserves discussion for several reasons (at least that's my point of view)
1° As far as 3D printing is concerned, it is not because we have to generate WWTP that we should set the tolerances in advance.
Moreover, the WWTP is no longer of the design but almost of the fab. In addition, the respect of tolerances and especially the repeatability of tolerances is very random in 3D printing and depends a lot on the technique (powder or wire). In powder technique, it is 0.1 mm and still not everywhere and the repeatability is between 0.3 and rather 0.5 over short distances.
2° if there are tolerances and standards, including GPS dimensioning - which very few have mastered - it is not for fun, but because it meets a specific mechanical need.
3° precision is expensive because between making a hole in an aluminum plate with a Clarkson cutter is 0.05 mm (a simple bore drill guarantees you depending on the diameter between 0.05 and 0.07mm, and for more precision, it is the boring head (outside of CNC).
4° precision requires a tempered metrology service with temperature-stabilized parts.
I've seen too many plans with dimensions 0.05 for screw passages or as in aviation 0.05 for push button passages to name a few.
To come back to the discussion, should we tolerate in the 3D plan I say "yes" but intelligently.
I put a general tolerancing at 0.5 mm or 2mm depending on the size and mode of Fab and specific tolerances when necessary (typically the very famous H7 and its friend g6). Moreover, it would be pointless to set tolerances when the dimension chains would not be controlled.
It all depends on whether you are using precision mechanical assemblies, typically shafts with bearings and gears in all directions, and thermal or pressure constraints, or whether you are making wheelbarrows or even mechanically welded.
As for thinking that the precision of machines becoming so exceptional that we are popular (to quote @Sylk precision of machining will be greatly increased, even with zero tolerance.), well that's an illusion. Because even with current CNCs, the hourly cost of a machine is high, because the programs have to be prepared in advance and the metrology still reveals discrepancies.
So, the debate seems to me to be more about 3D prints or when you want precision, you have to do rework.
So, the plan is only the reflection of what we want to do in the end, but without forgetting anything about the purpose, or the machining constraints depending on the equipment of the workshop or the subcontractor.
Kind regards