THE ARCHITECTURE OF 3D PRINTING - 03 TOLERANCES AND SNUG FIT

[Stefania Dinea 101]

I am Stefania Dinea, an architect who mixes 3D printing, VR, parametric design and blogging daily and I will share some of my 3D printing tips & tricks with you. This series is my overview about the process and my work-around. Please feel free to comment and add. 

 

PREVIOUS POST:

THE ARCHITECTURE OF 3D PRINTING - 01 TOPOGRAPHY

THE ARCHITECTURE OF 3D PRINTING - 02 MASSING

 

03  TOLERANCES AND SNUG FIT

 

Now that we know we will be printing in scale 1:400, would be good to be able to use one site for all 4 previous versions.

 

To print in scale 1:400 we need to alter the site, for that a simple edit in place of the floor slab we just did will do, or even easier, make a section box.

To print in the specified scale, we need to know how much will that translate to in scale 1:1 , also take into consideration the printing size - 180x180mm for the UM3 dual extrusion mode on.  All is left to do is introduce the factors in an online scale converter – or if you are up for it, old school math.

 

This being said, I will make sure the section box will be adjusted to box 72 x 72 m. Tip for this action is to work in parallel with the plan and the 3D view.

So how much is that in cura? As a percentage?

We will export again in these settings, and as said in the cura tips&tricks section, you will see that  if you use the xtl exporter and you set it in meters as export settings you will need a 250% scale up.

 

But this topic is about snug fit, for a snug fit you need to allow a tolerance offset, just like in reality. In the case of 3D printing it is between 0.3 and 0.5 - a skill you will learn to master by experience, trial and error. For this exercise I will use a 0.3 offset in scale 1:400.

As you footprint might remain the same, and your design will probably change specially in concept stage, begin by offsetting from your border line.

The result will look something like this:

However, you are not done yet, I generally recommend that the bottom is not let empty, but also as a part of the site, for that we will do another floor to cover the area under the proposed model.

 

In my case, it so happens that the new floor is placed under Level 1, and Level 1 is my zero floor, which works for me. If the scenarios would have been different I would have just offset the new floor in a + or – direction from the Revit Properties menu bar.

This is a section from Alternative 1 – you might want to check all alternatives just to make sure you don't need any extra information input.

 

I have noticed that the sides of my new cut-out are at level 0, therefore an adjustment is needed as well on the edges. Same routine as when you did the sloped floor – Modify sub elements – and add the desired point height.

 

The new result will look something like this:

So now you are ready to export the site and each option individually.

 

The site will be exported from Main Model, in meters as units. The same will be done with all the design options, one way to export any Revit element individually, for 3D printing is to Isolate Element in view.

Once your model looks like this, you are rready to export. Repeat the same rpoceedure for all elements.

However in the case of option 4 we have extra space between the volumes, you might want to fill in those extra gaps now. Place the new floor components also in Design option 4.

Don't forget to adjust the height and also to place the offset mentioned before.

 

Isolate the elements in view and again, export them separately from the rest.

 

3D PRINTED RESULT:

 

NEXT ON THIS SERIES:

04 ENTOURAGE

 

FILES FOR DOWNLOAD:

site.stl

alternativ 3-4.stl

alternativ 2-4.stl

alternativ 1-3.stl

alternativ 4-3.stl

alternativ 4 - extra site.stl

site.stl

Edited April 21, 2018 by Stefania Dinea

[SandervG 1,521]

Hi @Stefania Dinea , thanks again for taking the time to put this together. 
@Alex L, is it equally easy to do this in ArchiCad?

 

Something I just wondered since we're talking tolerances here, how do you usually go about details in your design that, after scaling it down 1:400, become too small to 3D print? I dunno, like railings in a balcony or details in windows / doors / furniture? Do you leave them out entirely, scale them up so they can be printed or make them separately, perhaps via a different route? I imagine the solution may vary per object but curious how you decide how to deal with it. 

[Alex L 29]

17 hours ago, SandervG said:

Hi @Stefania Dinea , thanks again for taking the time to put this together. 
@Alex L, is it equally easy to do this in ArchiCad?

 

Something I just wondered since we're talking tolerances here, how do you usually go about details in your design that, after scaling it down 1:400, become too small to 3D print? I dunno, like railings in a balcony or details in windows / doors / furniture? Do you leave them out entirely, scale them up so they can be printed or make them separately, perhaps via a different route? I imagine the solution may vary per object but curious how you decide how to deal with it. 

Not being familiar with Revit I couldn't do a fair comparison but it is very easy in ArchiCAD, we made a very simple site as a quick test.

 

We didn't use any tolerance in ArciCAD instead scaling the insert by 0.5mm on the X and Y axis, leaving the z axis.

Admittedly this is cheating but at the scale we printed the distortion to contours created is not noticeable and for real sites Stefania's tolerance method is probably better by allowing an increase in site size.

 

Archicad doesn't require any cheats to get meshes to work in Cura and a simple solid element operation created our site recess

you can see the imported meshes below ()obviously the insert needed to be printed separately if you are using our cheat by scaling the horizontal size of the insert (OK on a test, probably not so good on an actual building!)

 

Below you can see the printed objects (excuse the silver PLA - not very architectural!)

 

With regards to detail; there becomes a point as you suggest where detail is too small to print, often Cura will remove these bits. Generally a model will need a bit of tuning before printing, or else generating with 3D printing in mind, I have not yet go to grips with curtain walling out of archicad, this is my next task!

Edited May 1, 2018 by Alex L
Added bit answering other question!

[Stefania Dinea 101]

15 hours ago, SandervG said:

Hi @Stefania Dinea , thanks again for taking the time to put this together. 
@Alex L, is it equally easy to do this in ArchiCad?

 

Something I just wondered since we're talking tolerances here, how do you usually go about details in your design that, after scaling it down 1:400, become too small to 3D print? I dunno, like railings in a balcony or details in windows / doors / furniture? Do you leave them out entirely, scale them up so they can be printed or make them separately, perhaps via a different route? I imagine the solution may vary per object but curious how you decide how to deal with it. 

 

Hej @SandervG and @Alex L, in my xp, revit families do become too small to print, by that I refer specially to furniture, which in general are very thin, like 12 mm thick , because as a good BIM family, it respects reality. Scaling it down  makes it vanish in thin air and therefore unprintable. However, next I have entourage on the plate for the what can your software print "challenge"

 

Alex, the model looks greats, and I said before - so gelous. 

Edited May 1, 2018 by Stefania Dinea

[SandervG 1,521]

Yes!! The entourage will be a good one

So I suppose there is a minimal scale you can work with then, and details that won't survive this are left out. ?

 

Regarding the guide above, I had another question.

On 4/21/2018 at 8:40 PM, Stefania Dinea said:

Now that we know we will be printing in scale 1:400

I was looking through the past guides but I don't think I saw the reference where we decided this was going to be the scale. Is 1:400 an industry standard?

 

What tolerances do you keep when you have divided a building up in parts, and needs to fit tight when put together? Do you also start with .3? 

 

[Stefania Dinea 101]

1 minute ago, SandervG said:

Yes!! The entourage will be a good one

So I suppose there is a minimal scale you can work with then, and details that won't survive this are left out. ?

 

Regarding the guide above, I had another question.

I was looking through the past guides but I don't think I saw the reference where we decided this was going to be the scale. Is 1:400 an industry standard?

 

What tolerances do you keep when you have divided a building up in parts, and needs to fit tight when put together? Do you also start with .3? 

 

 

I will post the entourage today or tomorrow, since I will be away the next weeks, so i am unable to handle it from Friday on, just a quick peak at comments and debates. 

 

I used it from the a swedish reference, in the sense that site plans are usually delivered scale 1:400 for building permits - and this first chapter is about that, of course you can go even smaller, like 1:1000, but this was my choice for now. So it has some base in my professional reality. 

 

Yes, I always start with .3, I have noticed that with .3 I can never fail, weather it is buildings or jewellery. But again, that is my experience.