Journal Fully 3d printed coral and stone cutting bandsaw - **Completed Project**

[Eric]

What is a coral cutting bandsaw?
Corals can be multiplied by propagation. Breaking or cutting corals into multiple pieces is part of their survival strategy for when storms come through and enormous waves break delicate coral structures. In aquaculture we use diamond coated bandsaws with water as lubricant to cut through their hard calcium carbonate skeletons. The bandsaw is ideal for making curved cuts in additional to straight cuts. While a spinning blade can do very clean straight cuts, it cannot do small curves like the nimble bandsaw can.

These bandsaws are commercial available for about $400-500, there are currently two major brands Gryphon and Inland who produce these saws. I was able to acquire two of the inland bandsaws some years ago and donated one to the HSU marine lab and kept the other for my personal coral lab.


This bandsaw does work well for it's purpose but it has certainly seen better days. When a friend expressed interest in designing their own I sent photos of the various components of the bandsaw so they had an idea of how they are currently done. I was shocked they had replied back with an entire assembly of parts modeled in solid works within about 3 days.

 

[Eric]

My friend sent this picture of their prototype, they said the colors were chosen because it was what filaments they had most of left over from other projects. I loved the pink and tan look though, while I wasn't going to use the same I knew I wanted to keep the pink body look.

 

[Eric]

Once my friend sent over the 3d models and excel sheet of the Bill of Materials I was able to start printing my own! I started with two high contrast pieces to confirm my vision of a Miami Heat style Pink and Turquoise 80s vaporware look.

One of the features of the 3d printed band saw is that the work surface is perforated to drain away water rather than letting it pool on the surface.

 

[Eric]

Most of the prints are done of the Prusa MK3s+ the only piece that needed to be printed on a larger printer is the case itself which my friend printed on a creality belt mill printer.

All the pink and turquoise main parts are printed in PETG which is really nice material for these kinds of projects.

Here is the base fresh off the printer with some prototype purple TPU feet. TPU is a flexible material of varying hardnesses depending on the brand so it can be useful for vibration dampening or gaskets in low-heat applications.


The base is joined the case using a dovetail style joint. Because they are printed on different machines and I didn't calibrate mine there was some "convincing" needed to get the parts to fit. This isn't usually a problem with assemblies all made on one printer. Once mechanically fitted I used the solvent Weld-on to weld the two pieces together. I then used a 3d printer pen fill any large gaps left.

 

[Eric]

For the parts with gear teeth I said, why not print it in resin? After all, it's my resin printer, why shouldn't I use it?!!


This is the 140 Tooth gear that drives the bandsaw wheels from the timing belt connected to the motor. I use SarayaTech Sculpt Resin which is a nice engineering grade resin with somewhat higher than typical heat capacity. I think this what they pulled the robots out of in the West World intro.

For the presser foot and handle I needed to use Hatchbox Teal resin to keep with the color scheme


In the end my resin prints didn't come out quiet a good as the PETG prints off the purse. They are beautiful but they are far too brittle for use. This may be overcome with tuning in the curing process, over curing can lead to brittle parts but that is an experiment for another time.




I broke the first PETG presser foot which was made on the prusa printer. the layer lines allow that particular section to be vulnerable to snapping off but this orientation doesn't require any support material which means a cleaner final part. The resin print is totally solid but I lost a lot of fidelity in the gear teeth. I think this could be remedied with another attempt but the PETG part is so good I no longer see the point for this part to be done in resin.

 

[Eric]

This is the door gasket believe it or not! Somehow my friend managed to measure it out and add all the kinks and turns needed to fit the door perfectly. Any deflection needed to return it to the full size of the door could be accommodated by the flexibility of this TPU material.


I loved how soft this pink TPU was so I reprinted all the TPU parts in it. The TPU parts include two wiper blades that keep the blades clear of material. It also includes some small bands that provide grip for the bandsaw wheel, several fastner covers that protect the screws from saltwater exposure, the small water reservoir on the presser foot and the 4 soft cup feet.


These are the TPU grips that the blade will hug while rolling around the wheels. They are inset of the edges of the wheels to keep the blade from rolling off. In this photo I am comparing the purple TPU I replaced with the pink TPU. In addition to the purple not fitting my color scheme goals it was much more rigid and less capable of doing what those TPU parts were designed to do.

 

[Eric]

Testing the electronics and mechanism of the assembly. The motor is from the RC hobby and the motor controller is as well. I couldn't tell you much about them as my friend was able to source and pick them out. The motor is small but packs a real punch. You can see the motor mounts feature slotted fixture points so you can adjust the belt tension before tightening it down. The wires are secured temporarily with Wago connectors which are reusable and do not twist up the conductors like wire nuts. Final wiring will be soldered with marine heat shrink to protect connections. a large cover protects the electronics enclosure from splash damage.

 

[Eric]

I thought I liked that second pink TPU but I eventually found an even softer TPU called Ninjaflex. I used their color Flamingo which is darker than I would have liked but I am willing to use it still for how much softer it is. After using a slicing profile from printables.com it printed much cleaner than the others. Almost no clean up was needed.



After the electronics were soldered I found I was not happy with the black rubber used for the DC jack cover. A few minutes with the calipers and Fusion 360 and it was on the printer being made in Flamingo.




The flexibility is very close to the original black rubber version, I was very pleased it's replacement was so simple.

The saw is now complete! The only thing left is to compare it to the commercially sold version and run it through it's paces on some corals.




Time to begin cutting corals! On the left are some flat encrusting corals that will be an easy test for the saw. We have a chalice coral which is rather thin and could be also cut with pliers or bone cutters. We also have the much denser War coral that should only be cut on a bandsaw. On the right are some ceramic coral fragment "plugs" where they be superglued and allowed to re-encrust onto the plug. The use of the plugs is standard in the coral growing hobby as they make it easier to handle the coral without damaging them.



There was a decaying patch in the middle of the coral was easy to cut out and remove. The corals are capable of great healing and regeneration but the dead spot would take a long time to be re-encrusted over and it will be much better to allow the small fragments to be separated. The perimeter is the only area that can grow on encrusting corals so dividing this one coral up will greatly accelerate the overall growth.


Gross water is being drained away successfully!


Coral fragments made are then super glued to their plugs. They are returned to the aquarium to heal and begin growing again.

 

[TassieMarine]

I thought I liked that second pink TPU but I eventually found an even softer TPU called Ninjaflex. I used their color Flamingo which is darker than I would have liked but I am willing to use it still for how much softer it is. After using a slicing profile from printables.com it printed much cleaner than the others. Almost no clean up was needed.
View attachment 25


After the electronics were soldered I found I was not happy with the black rubber used for the DC jack cover. A few minutes with the calipers and Fusion 360 and it was on the printer being made in Flamingo.
View attachment 24

View attachment 26

The flexibility is very close to the original black rubber version, I was very pleased it's replacement was so simple.

The saw is now complete! The only thing left is to compare it to the commercially sold version and run it through it's paces on some corals.
View attachment 27
View attachment 28
View attachment 30

Time to begin cutting corals! On the left are some flat encrusting corals that will be an easy test for the saw. We have a chalice coral which is rather thin and could be also cut with pliers or bone cutters. We also have the much denser War coral that should only be cut on a bandsaw. On the right are some ceramic coral fragment "plugs" where they be superglued and allowed to re-encrust onto the plug. The use of the plugs is standard in the coral growing hobby as they make it easier to handle the coral without damaging them.

View attachment 29

There was a decaying patch in the middle of the coral was easy to cut out and remove. The corals are capable of great healing and regeneration but the dead spot would take a long time to be re-encrusted over and it will be much better to allow the small fragments to be separated. The perimeter is the only area that can grow on encrusting corals so dividing this one coral up will greatly accelerate the overall growth.
View attachment 31

Gross water is being drained away successfully!
View attachment 32

Coral fragments made are then super glued to their plugs. They are returned to the aquarium to heal and begin growing again.

Amazing! re you going to make this publicly available to download? Would love to give this a go!