Why the 3D Benchy Isn’t the Best Test Print for Tuning Your 3D Printer

Many people in our community showcase how they achieve a high-speed, high-quality 3DBenchy. While I genuinely appreciate seeing these fast Benchy shredders, I’ve learned that the 3DBenchy isn’t the best model for tuning a high-speed printer. Consequently, I stopped using it once I began fine-tuning my T250 slicer profiles.

So what's my issue with it? Here's a sliced benchy on my current fast quality profile:

It only takes about 1.6 to 2.8 seconds to print each hull layer, leaving almost no time for them to cool. As soon as a layer starts to wobble, you’ll see artifacts on the hull that can ruin the entire print.

So let's analyse how fast we can print an outer perimeter without artefacts:

I began a test series by printing cylinders in spiral mode at layer heights ranging from 0.05 mm to 0.3 mm. Starting at a print speed of 100 mm/s, I increased the speed by 1 mm/s every 0.1 mm as long as there were no visible artifacts. Once artifacts did appear i stopped the print and I measured the cylinder height with a caliper. Here are the results I found:

The results indicate that as the layer height increases, the minimum layer time must also increase to avoid artifacts on the outer perimeter. For example, with a 30×30 mm cylinder printed at a 0.1 mm layer height, the required minimum layer time is at least 0.4 seconds.

But in this scenario, each layer was stacked perfectly on top of the previous one, which is the easiest case. How do overhangs affect the minimum layer time?

In my second test series I printed the same cylinders but this time wit different angles to simulate worst case overhangs from 0° to 72°. Here are the results:

I was surprised by my findings. Even the smallest overhangs required a 50% increase in minimum layer time, while 48° overhangs needed almost 300% more to print properly.

With that in mind lets go back to our 3D Benchy. Those who have been reading carefully might already have noticed that the hull line in the example above features about a 30° overhang, with a minimum layer time of 1.6 seconds. Which will be too much for our part cooling.

Anyone following my 3D printer journey knows my straightforward tuning approach: Find the current bottleneck, create a solution to fix it, then push the printer to its next limit—where the next bottleneck (and the next challenge) appears.

So we have to optimise our part cooling, right?

While this strategy is generally a good idea, it can still hit a dead end. I’ve tested it myself by cranking the CPAP power up to 100% and experimenting with other slicer settings I thought might boost cooling performance:

Even with maximum CPAP cooling and maximum Side Blower Cooling I was only able to increase the average printing speed by 30% which is huge but you can clearly see the diminishing returns here.

So I started to increase the diameter of the circles to increase the minimal layer time of the prints to see how they affect the overall printing speed. And yes I printed many circles:

The results turned out to be surprisingly interesting for me:

A print with a wider diameter can be completed faster. After determining the maximum error-free speed, I used those values to calculate the minimum layer time based on both diameter and speed. Interestingly (or perhaps not surprisingly), as soon as the minimum layer time fell below 0.8 seconds, the print began to fail.

And yes I was curious where the limit was which lead to the initial video of this post.

But let’s return to my initial thought about the 3D Benchy. Let’s be honest: most of the things we print aren’t nearly as small as a Benchy, nor do they feature such steep or complex overhangs. In my experience, typical prints are simply not as demanding as the 3D Benchy.

Optimizing a slicer profile just for the Benchy often means slowing down print times overall, which I believe is the wrong way to go. That’s why I swapped out the standard Benchy for a 200% scaled version. With that increase in size, the minimal layer time jumps to about 3.8 to 5.4 seconds for the hull, creating a more realistic print scenario.

Matt