I am Thijs Roumen, Hasso Plattner Institute.
Our software tool "kerfCanceler" allows modifying cutting plans
so that they not only work when fabricated on the laser cutter
they were designed for, but also on other machines that remove
much more or much less material.
The most interesting models made by laser cutting are models with
mechanisms
such as this bearing which holds an axle in place.
To make this possible, the designer carefully tuned the
size of the cutout, so as to precisely hold the axle in
place.
This tuning however, tends to get lost when somebody
fabricates the same model on a different machine. Let's look at
what happens when we add more kerf.
The axle wobbles in the bearing
which causes the pinion to fail to engage with the rack
and the slider to get misaligned as a result.
So while people can download this model from the internet,
ultimately, it turns out to be useless, as it simply does not
work when fabricated elsewhere.
One way to solve this is to let users input their curve into an
editor and export a 2d cutting plan accordingly, software
systems like flat fab and kyube enable such workflow.
With springFit, we made press-fit joins and mounts kerf
tolerant using cantilever springs.
In this paper, we extend that idea by also handling loose fit
such as the bearing we've seen before.
We achieve that by inserting such crescent-shaped inserts.
This is how they work
we jammed the inset in place
which then holds the bearing with just the right fit.
We call these mechanisms kerf-canceling mechanisms.
mechanisms with an additional inset that maintain their
functionality independent of the kerf of the machine they are
fabricated on.
We've made a range of mechanisms kerf-cancelling, such as
bearings as we just saw, sliding mechanisms
The kerf-canceling bearing consists of two designed
elements, the jammer and the inverse scaler.
If we look at the jammer in isolation, we see that the shape
of the outside is a Nautilus spiral
we place an inset with the same shape inside that cutout.
But kerf makes that inset smaller.
We can still lock the inset in place by rotating it.
Because of the self similarity of the Nautilus spiral. This
makes the inset lock in place depending on the amount of kerf
applied to the model.
The inverse scaler in turn, holds the axle in place.
The shape of the inverse scaler is the same as that of the
jammer but flipped.
So as more kerf results in more rotation of the jammer. The
inverse scaler now narrows down the cutout by exactly the same
amount
which results in a bearing of consistent size, even with
increasing amounts of kerf.
We also modified this slider to become kerf-canceling.
The slit gets wider because of kerf resulting in a loose
carriage.
We solve this by adding springs next to the slit and inserting
two jammers to jam it in place. This narrows down the slit by
exactly the amount of material removed due to kerf.
The last kerf related problem is the pinion that failed to engage
with the rack.
We place a wedge next to it which pushes the spring sideways
by exactly one time kerf
resulting in gears that engage well, like what you see here in
this multi-stage gearbox.
So these mechanisms combined, allow me to make that microscope
work independent of the amount of kerf applied to the
mechanisms.
Let's look at how our software tool kerfCanceler achieves that
kerfCanceler runs in the browser uses just load to SVG file right
into the editor.
When the file is loaded kerfCanceler analyzes the
geometry in the model to determine what are contours in
the model. Given that the contours are typically not part
of the mechanisms themselves, kerfCanceler greys them out. To
put the focus on the actual mechanisms.
kerfCanceler then guessed what mechanisms go were based on
circular cutouts in the model.
kerfCanceler therefore relies on user inputs to get all the
mechanisms in place.
These, for example, are not bearings but glare holes when
you look through in the microscope, and this big one
here just holds a petri dish in place instead of being a bearing
itself. So let me just remove those incisions with the "remove
mechanism" tool.
I can use group convert to convert multiple dimensions of
the same size at the same time.
The next piece of information that is not included in the 2d
coding plan is which bearings hold the gear in place. By using
the gear tool, the user can place the gear in the right
location.
Finally, the sliding mechanism is also not guessed ahead of
time by kerfCanceler.
but are relatively rare. If kerfCanceler would turn every
rectangular cutout into a sliding mechanism, it would
result in a lot of false positives.
Therefore, kerfCanceler relies on users to place these sliding
mechanisms in the model using this lighting tool.
Right now, kerfCanceler has converted all mechanisms to
kerf-canceling equivalence. And given that we've been editing an
SVG file all along, we can send the file right to the laser
cutter
to produce the microscope.
Finally, by calling the headless implementation of springFit,
kerfCanceler converts the microscope to a completely
portable model.
We evaluate our system by comparing the amount of friction
and play of our bearings to plain bearings, which are simple
circular cutouts in a plate while varying the amount of kerf
of the cut.
Looking at the bearing performance, we see that the
kerf-canceling bearings are stable across variations in
kerf.
Only at the point where the kerf of our laser cutter is the same
as the amount of kerf that we added to the model does the
plain bearing outperform the kerf-canceling equivalent,
which makes sense because this is a bearing that is optimized
for the machine at hand.
We see similar results when looking at the amount of play.
The kerf-canceling bearings stayed consistent as the kerf
varied
while the play in the plain bearing increased linearly with
the amount of kerf.
In conclusion,
SpringFit allowed us to make joints and mounts tolerant to
kerf variations.
kerfCanceler expands this by also tackling loose fit.
My goal is to make models for laser cutting portable
and portability in the context of laser cutting is a measure of
how easily a laser cutting
model can be transferred from one laser cutting environment to
another. A laser cutting environment consists of all
parameters that influence the quality of the resulting cut,
The combination of kerfCanceler and springFit, allow me to take
models with any fit, and make them work on any laser cutter.
Here's a great piece of Assembler code, it allows me to
play a tone on my machine.
But in order for this to work, it writes to machine specific
registers and to machine specific ports.
portability in the context of computer science made source
code valuable, as it can now be shared and used by others
a prerequisite for more advanced collaboration such as re mixing
or modifying models made by others. I think that by enabling
the same transition towards portability in the context of
fabrication, we can truly stand on the shoulders of giants and
truly increase the complexity of what the community makes.
Thank you for your attention