I’m reviewing over 70 GraviTrax add-ons from 7 Etsy shops. Each shop owner sent me
parts of THEIR choosing for these reviews. I evaluate each shop’s overall 3D print
quality, and then review each part individually. Parts gets scored in 4 key areas:
First, quality. This evaluates the part’s fit, operation, build quality, and ease of
use.
Second, utility. How USEFUL is this part in a marble run? Does it add new capability to
GraviTrax that you didn’t have before?
Third, fun. This is the part’s coolness factor and is my opinion of how much fun the
part will add to your marble runs!
And lastly, uniqueness. This doesn’t measure how good the part is, but whether the part
is an original design that you can’t get anywhere else. A generic design that is sold
by several Etsy shops gets a lower uniqueness score.
Hi! I’m Chris! Join me on my quest to find the world’s best 3D-printed add-ons for
GraviTrax marble runs!
In this video I review Etsy shop BackCorner3D. Look! The parts make a cute little Christmas
tree!
Just so you are aware, I purchased these parts at full price from the BackCorner3D shop in
2021.
Today we’re going to examine the following GraviTrax add-ons sold by the BackCorner3D
shop:
Vertical Corners See Saw
Fall & Catch
You can buy these parts from Wiebe’s Etsy store at this link: Etsy.com/shop/BackCorner3D
Let me start with a caveat: 3D printing is somewhat of an art. It’s not just the design
that counts, but how you print it. It can be difficult to dial in printer settings to
get a quality print. Many of these shop owners are improving their designs and print processes
over time, so the parts YOU receive may differ in design and quality from the parts reviewed
in this video. Be sure to talk to the shop owner if you have any questions. I’m simply
reviewing the parts I received at the time of this video.
First, let’s take a look at the overall quality of the 3D prints coming out of the
BackCorner3D shop.
Overall the print quality is pretty good. The parts are functional, with only a few
slight surface imperfections. There are not really any lines, but there is some slight
layer shifting from time to time. There is very little stringing or ghosting. Filament
quality is good. Overhangs are somewhat poor and irregular in places and sometimes exhibit
drooping, which in one case affected operation by preventing marbles from passing through
a tunnel. There is no noticeable elephant's foot. Bottom surfaces are smooth. Top surfaces
sometimes showed gaps and gooping. I’m giving BackCorner3D 3 ½ stars for overall print
quality.
Now let’s dive in for a look at the parts!
The first parts I’m reviewing from the BackCorner3D shop are the VERTICAL CORNERS.
The vertical corners are available in two styles from this shop: One with the exit below
the entrance, and the other with the exit offset 60 degrees clockwise from the entrance.
There are rail attachment points at the entrances and exits.
The vertical corners have a 2 height tile drop, and the marble falls down the center
of the piece, picking up speed.
On one of the pieces there was some filament drooping from the overhang inside the tunnel
where marbles would get stuck. I had to use a file to eliminate the overhang, and then
the marbles traveled through freely.
Marbles roll through these parts smoothly, and pick up speed from the drop in height.
The vertical corners not only change a marble’s direction abruptly, but accelerate the marble
as well. They can handle many marbles in quick succession, and seem to work reliably.
Here’s my score card rating for the VERTICAL CORNERS:
For quality I give 3 stars. The tiles are well printed, but since I had one where the
marble gets stuck in the tunnel, it’s clear that some improvement is needed in the printing
process. For utility I give 5 stars. These give you
new kinds of action for your marble run fun. For fun I give 5 stars. These pieces give
a snappy unexpected change of direction to marbles that is interesting and fun.
For uniqueness I give 1 star. These designs are on Thingiverse, and in other Etsy shops.
The second part I’m reviewing from the BackCorner3D shop is the SEE SAW. Its name rhymes with
YEE HAW! Which is something we say a lot down here in the American Southwest. Do you SEE
it? There, now you SAW it. You SEE it, and you SAW it. Hence the name…SEE SAW!
The see saw is not quite what you might think from the name. It’s not a lever with 2 identical
ends hinged in the center. Instead, the fulcrum is offset to the side, and one end contains
a pocket for placing a weight marble. The piece is essentially an open-top tiptube where
the marbles enter and exit the same side. The See Saw must have a marble inserted in
the back pocket as a counterbalance weight. This pocket sticks out beyond the edge of
the piece, which could cause it to interfere with marble tiles in an adjacent space. But
there is plenty of clearance if the only thing in the adjacent space is a stack of height
tiles, or Schrodinger’s cat.
I set up the see saw with the incoming tile at 3 ½ height tiles tall, and the exit tile
at ½ height tile tall. This means the see saw drops marbles 3 height tiles total. And
since marbles can exit at ½ height tile height when the see saw is on the baseplate, you
can slope output ramps to ensure your marbles make it all the way out from under a clear
baseplate.
The see saw fills up with 3 marbles. The 3rd marble triggers the SEE, and then the marbles
roll out, triggering the SAW. It both SEES and SAWS, hence the name SEE SAW.
The see saw’s base ring sits very loosely on top of other tiles. I’d recommend the
shop owner see if improvement could be made to the tile’s base grip.
Since the see saw deposits marbles in the same direction from which they came, this
means the piece must be used with a balcony or clear platform, or possibly a Pro tunnel
pillar. It also means the exiting marbles SEE the same scenery that they SAW when entering.
Hence the name, SEE SAW.
Here’s my score card rating for the SEE SAW:
For Quality I give 4 stars. The piece works pretty well, even though it sits loosely on
its base. For Utility, I give 5 stars. These pieces
give you a new capability of a tiptube where marbles enter and exit the same side.
For Fun, I give 4 stars. It’s pretty fun to be able to collect marbles and see them
spill out. Plus, since the top is open, you can see how many marbles are inside, unlike
the GraviTrax tiptube. For uniqueness I give 5 stars. I looked to
SEE, but I SAW no other Etsy shops selling this piece. Get it? SEE SAW?
The third and final part I’m reviewing from the BackCorner3D shop is the FALL AND CATCH.
The FALL AND CATCH is a combo of two inserts that fit in GraviTrax base tiles, a 6-entrance
funnel, and a catcher base. This is my favorite GraviTrax add-on from this shop.
The FALL AND CATCH inserts both integrate well into GraviTrax base tiles. They sit at
a height that matches the entrances, so marbles will not encounter a ledge. They don’t fit
too tightly or too loosely. In just a moment, I’ll play a slo mo clip showing just how
much the catcher insert moves when a marble hits it.
The inserts can also be used with the base tile from a straight tunnel piece.
Setting the funnel over the catcher, the pair works well together. Marbles fall reliably
from the funnel and are caught by the base insert, which routes the marbles out a single
side exit. I was surprised to discover that even if the funnel piece was 14 height tiles
above the base, the marbles fell straight down into the catcher remarkably well. You
can see the catcher has a nice wide funnel opening that directs marbles into the entrance.
I tried substituting a GraviTrax vortex on top, and the results were not as good. The
vortex allows more lateral movement of the falling marble, causing the marble to sometimes
miss the catcher. The GraviTrax freefall insert similarly allows a wider trajectory where
the falling marble misses the catcher.
So why is the FALL AND CATCH funnel so much better? It turns out that the hole diameter
of the Fall and Catch funnel is smaller than the hole in the GraviTrax vortex. You can
see that when I hold them together. Do you see that green ridge when looking through
the vortex at the smaller diameter hole of the FALL AND CATCH funnel? It seems that this
smaller hole helps the marble fall straight down. I wonder if the GraviTrax funnel could
have similarly reduced the size of the center hole? It would be interesting to run some
tests with the GraviTrax funnel, by adding a 3D printed plate underneath with a smaller
diameter hole.
The catcher piece is really good, but could have been better if it was designed to allow
a GraviTrax base tile to be placed on top. The square shape doesn’t really match well
with the hexagonal shape of GraviTrax pieces. I’d recommend the shop owner consider modifying
the catcher to allow the funnel piece or a GraviTrax vortex to sit directly on top. The
current design requires you to use the FALL AND CATCH catcher with a clear platform or
balcony in most cases.
The FALL AND CATCH catcher’s internal ramp is well designed. It is really effective in
redirecting the marble’s downward acceleration into sideways speed out of the exit. The marble
travels quite a ways afterwards.
The catcher also has some tricks up its sleeve. Use it with a GraviTrax bridge.
Use it with a GraviTrax scoop. Use it as an inkwell when signing the Declaration
of Independence. Oh wait. The ink would leak out. Scratch that idea.
Here’s my score card rating for the FALL AND CATCH:
For Quality I give 4 stars. These inserts work absolutely great. I would give 5 stars
if the design were updated to stack a GraviTrax base tile on top, allowing the funnel or a
vortex to be placed directly on the catcher. For Utility, I give 5 stars. In my opinion,
there is nothing in the GraviTrax universe that does as well combining the 3 functions
of dropping a freefall marble so precisely, catching it so reliably, and giving it a good
push down the track. For Fun, I give 5 stars. This is a versatile
add-on that you can use to add some wow factor to your marble runs.
For uniqueness I give 5 stars. I haven’t seen this add-on combo anywhere else.
That wraps up my review of GraviTrax add-ons from Etsy shop BackCorner3D. Tell me in the
comments which add-on is your favorite!
To see all the Etsy shops I’ve reviewed so far, click this playlist! Subscribe and
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add-ons.