FULL EXPLANATION HERE: https://www.reddit.com/r/FDMminiatures/comments/1v0rerw/introducing_the_curling_tower_a_simple_solution/

 

 

 

 

 

This is a “Curling Tower” - A Model designed to combat “Curling”, especially when printing Miniatures. 

 

 

 

What happened here? 

When 3D Printing Miniatures with an FDM Printer, we run into some unique issues. One of which is the fact that even though it takes a long time to finish the print, the time spent on each individual layer is fairly short. Ideally, by the time the current layer starts printing, the previous one should have cooled down as much as possible. Now, if you're printing something large this isn't a problem - By the time the nozzle circles back to the starting point of the next layer, the previous one will have solidified.

 

But, as you can probably guess, this isn't always the case for miniatures. It usually doesn't affect the entire model - Most of them are still large enough that the Layers will have enough time to cool down. Where it becomes an issue is with "isolated" parts of the model - Parts that are either only partially connected to the Model, or only become fully connected throughout the print. Examples of partially connected isolated parts are but are not limited to Swords raised towards the sky, Staffs and other weapons. Examples of isolated parts that only become fully connected throughout the print, are usually legs or similar body-parts. 

 

 

But what exactly is Curling, and why is it such an issue?

 

When printing these isolated parts, the time spent on each layer is very short - So short that by the time, say Layer 100 starts, Layer 99 hasn't fully solidified yet. The heat of the Nozzle as well as the new layer of filament being placed on top of the previous Layer will re-soften the material further, causing the layer to be slightly lifted upwards. If this happened only once, it wouldn't be a major issue - The lift per layer is relatively small. But if it happens over multiple layers it becomes a problem. Eventually the filament will be curled enough for the Nozzle to slam into it, at which point it will most likely break of that part and ruin the print. With print times reaching the double digits, this is - as you can imagine - moderately upsetting. 

 

 

So how do we fix it? 
There are four common solutions to curling:

1. 
   Since Curling is caused by filament not cooling quickly enough, the easiest way is to simply increase the speed of the cooling fans. However, since most HQ Profiles already have these maxed out, this is unlikely to help most people. However: If they are already maxed out, but you still run into the issue - Make sure that they are actually clean. The fans on my A1 were stuffed with dust, which significantly lowered the cooling effect. If it's been a while since you last cleaned the fans, or never cleaned them at all, now might be a good start. 
2. 
   If the fans are clean and already running at 100% speed, we might need to give them a little help by lowering our printing temperature. Filament leaving the nozzle at 220° will take longer to cool down than filament leaving the nozzle at 200°. The problem here is that you can only go so low before you start creating new issues, namely Nozzle Clogs. If you are already operating in the 195-200 range, you don't have much room left. 
3. 
   If the problem is caused because the surface of the model is too small, we could simply increase the size of the Model. By upscaling it until the "vulnerable" part of the model has enough surface area for it to be printed with regular infill as opposed Solid Infill, the likelyhood of it warping becomes substantially smaller. Of course, this solution substantially increases print time and if you're printing Wargaming Proxies where scale matters, it's not suited for you at all.
4.  
   Printing multiple models. Following the same logic as Solution #3, instead of going for Model Size, we aim to increase the total print volume. By introducing at least a second Model to our print and print by layer, we can give each layer a cooling-buffer. As the printer finishes the Layer on Model A, Model B will have more time to cool down and vice versa. This solution also drasticially increases print-time, and comes with the downside of not only introducing additional risks in case the print fails somewhere, but also the simple fact that not everyone wants or needs multiple models.

 

While all those four solutions work, I wasn't satisfied with any of them. The first two are limited by Hardware which, in some cases, simply isn't enough. The other two force you to print something other than what you actually wanted to print. So, I wanted to use a compromise. 

 

 

The Curling Tower - It's just a simple, hollow, square tower with thin walls. The idea here is simple - You print it alongside your actual model, with some distance between the two. Once the Printer has finished a layer for the Model, it will move to the Tower, giving the Filament on the Model enough time to cool down. Now, you might be thinking - That's just Solution #4 again, printing with more than one model at the same time. 

 

And you're right - But there is a catch.

 

Because the Curling Tower is much more basic than any miniature, there isn't a whole lot that can go wrong with it. It's "safer" to print alongside your actual print, because there can't be any failed supports, harsh overhangs or even curling. And, because it's such a simple design - it will add significantly less time to the total print duration than a second, actual miniature would. 

 

But the real difference and big advantage, is that the Tower is adjustable. Remember when I said that Curling mostly affects the isolated parts of the model? In this case, it's the leg of the Skeleton - You don't need to print the entire Tower. You can just match the height of the tower to the point where the isolated part re-connects with the model and is out of the "Danger Zone"

 

This means that you will have all the benefits of the "Cooling Buffer" that Solution #4 gives you, at a fraction of the increase in print time and material waste. To give you some numbers: 

• 
  Skelly without Tower or 2nd Model to serve as a Cooling Buffer: 3h45m 
• 
  Skelly with a 2nd Skelly as a Cooling Buffer: 6h56m 
• 
  Skelly with a Curling Tower equal to the Model Height: 4h54m
• 
  4h54 Skelly with a Curling Tower adjusted to the "Danger Zone": 4h14m

That's an increase of only 13% when compared to the 86% increase you'd get when printing with a 2nd model.

Now, is this something that you should use for all of your prints? No, of course not - Although in theory, it should also very slightly improve Overhangs for the same reason it fixes Curling - By giving them more time to cool before the next layer is added on top. But this is primarily meant as a tool for models that have a lot of isolated parts, or if you are struggling with Curling and none of the other solutions work out for you. So next time you're running into Curling even though your fans are already maxed out - Give this one a try.