The Groupwork

The goal for this week's group work was to test the capacities of the 3d printers. We used the v3 test piece by ctrlV that we downloaded from thingiverse.

At this week we had 3 printers online for usage, with 4th one being down for maintenance. The printers in question were, Leapfrog Creatr, Formlabs Form 2, and my personal design I like to call Chrysion.

Of these three the formlabs performed the best, so it was the best choice for reference prints. As a general rule of thumb for the formlabs printer, you want to avoid very thin structures, as while the printer can produce them, they are too weak to survive. Another weakness of the formlabs is that using supports is mandatory, and this limits the number of good surfaces. As you can witness on its grey benchy at the bottom of the page.

Reference prints - Printed with Form2 resin printer

While I do enjoy dissing the Leapfrog, it generally does produce solid results. So the this weeks design assingments were printed out with the Leapfrog. As a design rule for leapfrog, one cannot make overhangs verywell without any support. Width of the nozzle is the limiting factor for small details. The printer doesn thave support material so either the designs need to be self supporting, with angles that never get too steep, or aligned on the printbed to compensate for that. IT can print supports out of the same material it prints with but these generally are hard to remove neatly.

Leapfrog

My personal machine does suffer from some theething problems, and my pride did demand me to take couple extra tests to finetune the results. It handles overhangs better because of the additional fans it has that cool the printed item fast enough. As with the leapfrog the nozzle width is the limiting factor, that the formlabs doesnt suffer from as its accuracy is based on the laser it has not physical extrusion.

chrysion

The thing with this test piece is, that it doesnt say anything to the common people who come around the lab to see if they could print a random thing. They see a fancy ring thing, but they have no mental basis of comparison for what is good and what is not. While the resin printed one is the perfect reference print, as it was reproduced so perfectly, still the holes, slits, slots, and such tell nothing to them. So I used the opportunity as an excuse to take out a benchy on each of the machines.

Benchy is one of the basic test pieces in the 3d printing community, if you need help with sorting out a problem with print quality, you print one out. Since pretty much everyone in the community has made one, they can just by looking at the pictures of it identify possible problems.

Also crucially, benchy is a basic ship. Even though one doesnt understand a thing about 3d printing, one usually has a mental image of a ship. So when they study the different versions of it, the differences and their value are more visible to them.

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Printing of the benchy was not that difficult. To get the reference one, since the resin printer reproduces the items so perfectly, I needed to use the preform software by formlabs.

To get the benchy printed, we first need to open it

Now that we have the benchy opened, we can start preparing it for printing. The Volume of the item is noteworthy, because unlike the normal extrusion based 3D printers the resin printer doesnt make hollow pieces by default. So the volume of the piece is the total amount of resin printing it will need, and with one canister being around a liter, its easy to quickly estimate the value of the print.

First the print needs to be oriented for the printer, while it is possible to skip this step it is advisable that you dont. The tilted orientation of the piece serves a purpose. It lets the resin drip back into the resin tank, the purpose of this is accuracy, if you dont tilt the piece and excessive amounts of resin hang around, the UV laser can cure it. Remember one layer can be 0.025mm thick, for one it wont have the stability to hold a lot of resin and can fail, but also layer this thin, the laser will shine through it. So you will have varying degrees of thickness instead of a exact thickness, not to mention the excess wont cure as completely as intented.

At this phase, if you click select base, you can choose the face you do not want support materials on, they can be tricky to clear so if you have a face with texts on it or details you dont want messed up, selec that face as the base.

Then we have the program generate the supports, and now you can see what I mean with them being tricky. It is like a forest holding the piece up. In fact the piece will be hanging down from them. It will take some careful work to get them removed perfectly. One idea is that you take an old electric toothbrush and cut a small piece of sandpaper and glue it to the brush. and now you have a small rotary sander you can use to deal with the remains of the supports.

If there are any red spots on the piece, they mean those spots are not being supported adequately, so you can either edit the supports or realign the piece.

Now we can handle the location of the piece in the printer, you can have multiple pieces in one print as long as they all can be fitted properly in here. It is a good idea to vary the location of the prints, the resin tank does wear out, so having prints in different locations gives you a some more use out of the tank. In general it is a good idea to start getting a new one after the tank you are using has gone through 2 liters of resin. It can develop a leak if used too long, and yes the leaking resin can go into the printer, and no you dont want to be the one cleaning that up.

Now we send the job to the printer, either over the network or over the USB, when it comes to printing thickness a good rule of thumb is, that 0.1mm is likely complete during the day, 0.05mm is good for overnight runs and the 0.025 is good for weekend long runs. Naturally it depends on the amount of layers, and it can be tempting to put pieces flat to speed things up. As I explained earlier it can reduce the quality.

Then we head off to the printer, and start the job. The latest successfully sent job is usually right on the display, and you can just push "print now" to start the job. After that has been pressed the printer reminds you to check that the cartridge vent is open so the printer can keep the resin tank filled, and that the build platform is in place so the print goes through properly. If the platform is not in place the laser will be curing the resin in the tank and potentially make the tank unusable because the resin cures right to it.

Once the print is done you use the supplied tools to pop the piece off the build platform and dip it into the alcohol for 10 minutes to rinse off the remaining resin. You need to dip the piece twice in separate basins, one bath alone wont get all the remaining resin off. You will want to use gloves while doing this, the resin is not something you want on your hands. Once the second bath is done I like to give the piece a final rinse under the faucet. Once freshly out of the printer the surface is still soft, you can simply leave the piece in the sun for an hour or two and it hardening completes. The manufacturer also has dedicated bathing and curing machines.

Then it is a good idea to use some paper to clean up the excess resin off the build plate, and then some alcohol in a microfiber cloth to scrub it clean. Then you can put it back in to its place in the printer, ready for next print. After this you can use the spatula to VERY carefully to clear the bottom of the tank. The bottom is covered in a thin layer of silicone, and every little dent in this silicone will be visible in every print you make. But it is necessary to do this, because during print there can be some minor specks of cured resin left behind, these can then stick to the next print causing flaws if they are left in place.

Occasionally it can be necessary to filter the resin to get every last little speck out of the resin. Some recommend using coffee filter, others are partial to paint filters.