Hey guys, Welcome to part 3 of my Easy, Step by Step
guide to 3D Resin Printing.
Today we’re going to look at Screen resolution and I probably get more questions about this
than any other subject.
2K, 4K, 6K, 8K or whatever…
what does it all mean?
And what’s all this XY Micron business?
Before I start, I just want to give a quick thanks to those that have hit that YouTube
Thanks button making very thoughtful donations of appreciation, and also, of course, to my
Patrons, without who I simply wouldn’t be able to run this Channel.
When it comes to resolution, 2K, 4K, 6K, etc, the chances are this is nothing new and is
most likely something you’ve already experienced.
TV’s, cell phones, cameras or tablets, they’ve all been shouting about improved screen resolution
for years.
Most people understand the concept of pixels, especially in relation to the devices I’ve
just mentioned.
Pixels are tiny areas or illumination which, when activated in controlled patterns, form
images that we recognise.
In a given area, the more pixels there are, the clearer and sharper the image becomes.
And that’s exactly what happens in your TV or phone.
So higher resolution can be thought of as squeezing more pixels into the same size screen.
The density of pixels in often measured in PPI or pixels per square inch, and higher
numbers mean greater density and finer, sharper images.
However, whilst this is a useful concept, this information is not always provided by
printer companies.
What is available for resin printers is typically numbers like 2K, 4K, 8K, etc.
K stands for one thousand, so 2K is 2000, 4K is 4000, etc, and these numbers relate
to pixels.
So a 4K printer has 4000 pixels.
An 8K printer has 8000 pixels.
And when I say “has” it relates to the longer length of the screen.
If we look at the Elegoo Mars 3 Pro which you saw me set up in the last video, its screen
displays 4098 pixels across this longer edge of its screen, which is commonly called the
X Axis.
When we round down this number to the nearest thousand, it gives us 4000 or 4K, and sure
enough the Mars 3 Pro is a 4K printer.
Of course, the screen also has a shorter side or width, and this is called the Y axis, and
this holds 2560 pixels.
But let’s be honest, this doesn’t sound as impressive, so marketing gurus spout the
bigger number and congratulate themselves on a job well done.
So, more pixels in a given area means more detail, and if a printer says 4K it must have
loads of pixels and consequently print in much finer detail, right?
Unfortunately, no.
Remember what I said about Pixels Per Inch?
Well, THAT defines sharper details in a way we can easily understand, and as such it’s
rarely shown.
The K number or screen resolution as it is often referred to merely tells us how many
pixels fit within the longer X axis of the screen.
I understand this sounds confusing as I’ve tried to explain it dozens of times to viewers.
So let’s look at an example.
We’ll use the Elegoo Saturn, just because we’ve already used the Elegoo.
The Saturn is a MUCH bigger printer than the Mars, designed to print bigger models.
As such it has a bigger build plate, a bigger resin tray and of course, a bigger Screen.
Now the Saturn is happy to advertise itself as a 4K printer.
So it must print equally as well as the Mars, right?
No.
Not really.
The much bigger screen of the Saturn has an X axis measuring 3840 pixels which, rounding
up to the nearest thousand makes it a 4K printer, just like the Mars 3 Pro.
But the Saturn has 4000 pixels over a much longer area.
Think again in terms of pixels per inch.
It cannot print fine detail as well because in has a lower PPI as my maths shows here.
Calculating the PPI of a digital screen is accomplished by dividing the diagonal pixel
value by its diagonal measurement in inches.
Now I don’t have the exact dimensions of these screens but thanks to most slicer software,
I do have accurate data for the build plates and whilst this won’t be exact, it’s good
enough for what we’re doing here.
And if you’re not a big a fan of Pythagoras Theorem, don’t worry, I’ve got you covered
as I’ll explain in a moment.
But for now, you can hopefully see that even though both screens are 4K, there’s a marked
difference in PPI, and a higher PPI means better finer display or, in our case, better
finer printing.
So this knowledge is very useful to have, which is probably why most companies don’t
provide it.
A more increasingly common unit of comparison is XY Resolution, measured in Microns.
Now, we know that X is the long edge of the screen and Y is the shorter width.
What the XY Resolution does is combine the number of pixels on an axis with its physical
metric measurement, and through a little maths achieves the XY Resolution.
Here I’ve applied this calculation to the Mars 3 Pro and sure enough this gives us a
value of 35 microns, where a micron is one thousandth of a metre, also known as a micrometre
– though micron is more common.
And yes, the Mars 3 Pro tells us that it has a XY Resolution of 35 microns.
So let’s compare once again using the data from the Saturn.
And yes, 50 microns.
In the case of XY resolution, the smaller the number, theoretically the finer the print,
unlike pixels per inch where a higher number would mean a finer print.
Hence lots of confused and mis-informed potential customers, unwittingly pliable for clever
sounding sales techniques.
But hopefully for you, that will not apply.
You now know that a K Resolution merely expresses how many pixels fit along the X axis, a larger
PPI figure is better than a small one and, conversely a lower XY Resolution is better
than a high one.
And if maths isn’t your thing and you need to calculate these numbers, I’ve added a
dedicated page to my website that will do it for you.
And if you use it, please consider a small donation.
Even a little helps a lot.
Now, just as your feeling fairly confident, there’s a third axis to consider, the vertical
Z axis.
Now I’m British and pronounce this letter Zed normally, but for 3D printing I’ve found
it more helpful to adopt the vernacular Zee.
Pretty much the entire printing industry doesn’t want us to think about Z measurements and
as such it’s NOT covered in PPI, XY resolution or K valued screen resolution, and the reason
behind this is largely the technology.
Vertical movement tends to be controlled by a screw thread and governed by a stepper motor,
and whilst these are pretty good, as they are reasonably inexpensive mechanical devices,
they are limited to printing a layer height thickness of 10 microns, or 0.01mm, and as
such the industry pretty much wants us to print at 50 microns, or 0.05mm, which is still
pretty damn thin when you think of it as 1/20th of a millimetre.
Now you will usually find this information amongst the specs of these printers, but because
it’s fairly limited by technology right now, no one makes a big fuss about it.
The Z Layer Height can in fact make a big difference when printing, as reducing this
can lessen the number of visible layer lines, especially in smaller prints.
And for this reason, we’ll probably cover the topic of Layer Heights in another video.
But right now, pretty much all manufacturers have the same restrictions placed upon them
with Z Height, and as such it seems XY measurements are pretty much the industry focus, with smaller
micron values meaning better quality prints.
There are other factors at play when it comes to perfect printing, like model angle, support
positions, resin choice & temperature, and more things than we can shake a stick-shaped-print
at.
And, of course, just because you now know how to assess which printer should print more
finely, it doesn’t mean that you should pick the best spec printer available.
Genuinely, it might not be suited to your needs, and for that reason in the next video,
we’ll be asking Which Printer Should You Buy.
So until next time, thanks for watching and happy printing.