So, I printed several bars of length 60 mm, width 12 and 4 mm thickness. Each bar has 2 holes: one for fixing it on a table and another one for attaching a string for weights.
Bars were printed with 100% infill.
I have printed 2 PLA bars with filament from Innofil 3D and Reprapper. Temperature: 210 Celsius, heated bed at 65, no fans, speed 30 mm/s for loops and 75 for infills.
I also printed several PETG bar with the hotend raised to 235 C. Other parameters were identical to PLA parameters.
Here is a picture of the bar:
Then I have attached the bar to a profile:
Then I have attached a bucket for weights:
Then, I started to add weights in the bucket:
The PETG bar has started to bend:
If I remove the weight, the PETG bar returns to the original state.
I did not have a fine control of the weights … I had only 2.5 and 1.25 kg weights, so the results are a little raw.
The results are as follows:
Reprapper PLA bar broke when I put 7.5 kg in the bucket.
Innofil3D PLA bar broke when I put 10kg in the bucket.
PETG bar did NOT brake when I put 10 kg, but has been deformed significantly. I stopped my experiment there. After I removed the weight, the bar did not return to the original shape. Below is a picture of the PETG bar after I removed the weights.
PETG plastic claims to be a material strong like ABS and easy to print like PLA. I don’t print with ABS because it is toxic, so I’m very interested in other strong materials which can replace ABS.
I have ordered 2 rolls of PETG filament (from 2 different manufactures) and today I have received them.
I’m recording here my first experiments with this plastic on our 3D Printizer.
One roll is yellow and the other one is fully transparent. Both spools came in voided plastic bags (this could mean that PETG absorbs moisture (?) or maybe the manufacturers are just paying a lot of attention to details).
I have started with the transparent PETG filament one mainly because is more expensive (19USD instead of 12 for the yellow one). Lets hope that the transparent one is better.
The PETG filament is very clear, very transparent. It is soft like a flexible plastic.
I loaded it in the printer and I raised the nozzle head temperature to 200. When a reached that temperature I rotated the extruder gear manually … and the PETG plastic has started to come out very easy. This is a good sign … printing at lower temperatures is a good thing. I was also able to extrude at 195 C, but it was hard to push.
However, the manufacturer recommends a temperature of 220-250 C for the hotend … so I raised the temperature to 230. Other specifications for our hotend are: (custom) JHead with 0.4 mm nozzle for 1.75 mm filament. Layers have 0.25mm height and 0.45 mm thickness. These are the standard parameter that I use for PLA filament … for my first experiments with PETG I have not changed them.
I don’t know what temperature should I use for the print bead (the manufacturer has not mentioned that on their web-page) … so I started with no heated bed (with kapton tape on it) – room temperature (which is 20 C now). Verdict: PETG plastic does NOT stick to the cold bed (with kapton tape on it). Maybe it can stick on painter tape … I will test that later. EDIT: I have tested and PETG does NOT stick on blue painter tape (cold bed).
The strings of PETG plastic coming out from nozzle are flexible and very strong: even if I have stretched them several times … this flexibility is NOT possible with PLA.
Next step: I have raised the temperature of the bed to 65 degrees Celsius (this is the temperature that I use for PLA) and I hit Print again … this time the PETG plastic sticks to the bed. In the future I will investigate which is the minimal temperature that I can use for the heated bed so that the PETG will stick to it.
The first printed part was a very small one (a cylinder with 1 cm diameter with some wings inside). The part is not transparent (as I have expected from such a clean filament).
When done, I removed it from the heated bed. Very easily ! This means that (probably) it does not stick very well to the heated bed … so, maybe, if the parts warps, it will jump from the bed. More tests are required with larger pieces.
For PLA i cool the parts with 2 coolers … but I don’t know if they are required for PETG. For the second piece I have turned them off.
Now, the second part to print is my favorite one: the rocket glass … It has a larger base, so we can test if the material warps or not.
This time the speed is 30mm/s for loops and 75 mm/s for infill. The manufacture stated that one can use a similar speed with PLA. Infill was set to 25%
Here is a movie during print:
The part sticks very well to the heated bed … NO warping … and I was able to remove it easily from it even if the bed was still hot. With PLA I have to decrease the temperature of the bed below 50 C in order to remove pieces.
Below is another movie where I played with a calibration cube made from PETG.
Details about strengths will be given in the next post.
1. I have tested and PETG does NOT stick on blue painter tape (cold bed).
maybe it is a little too early to talk about history … but here is a short one…
While playing with my dogs my phone has slipped out of the pocket, and broke in contact with the concrete.
I have backup all the information inside … and I did discover some pictures from the beginnings of our 3d printer.
Here is a (not so nice) picture of myself handing the first (in January 2013) purchase of sigma profiles that we use for our printer:
Here is a picture with what was supposed to be the first version of the printer:
This version was built almost completely – only the extruder was yet to be constructed. In the mean time we have abandoned this version because we have realized that plastic connectors are not strong enough for our purpose. (Since then I avoid any printer whose main connection parts are made from plastic !)
On the left side you can see a dozen of t-nuts which was the first piece designed for our printer … and it is still used today in large quantities…
One of the problems with hobby printers is that the X and Y axes are not always perpendicular. Here is a simple procedure that can help you to ensure the perpendicularity of the axes.
1. Turn off your printer. All operations will be done manually!
2. On a cardboard draw 4 point (corners of a square whose edge is 100 mm). You can use a CAD program for that (like FreeCAD). I already did that, so here is the resulted pdf. Make sure that you print it on a solid cardboard. Regular (xerox) paper is not good because it can flex. Here is a picture of the result:
A magnified calibration point looks like this:
3. Take a needle or a drill. I used a 1mm drill.
4. Fix the needle to the hotend with adhesive tape.
5. Place the calibration cardboard on the bed, Make sure that the bed is not heated !
6. Assume that the points are labeled from 1 to 4, the first one being on the bottom-right of the screen, and the other one will follow anti clock-wisely.
Our purpose is to keep the Y axis fixed and to rotate (if necessarily) the X axis (to make them perpendicularly).
Ok, now place your (hotend) needle in the first point.
7. Move the Y axis only until you reach the second point. DO NOT touch the X axis at all.
8. If the needle is exactly above the second point … it’s perfect. If is not (like you can see in the above picture), it means that you have to rotate the paper a little bit so that the needle will be exactly over the second point. Make sure that you DO NOT translate the paper. Just rotate it. Rotate it so that the first point does not move. To ensure that, you can place a finger on the first point and rotate the paper around it.
Do this several times until you can move Y axis back and forth from exactly point 1 to point 2.
9. Ok, Now it is time to see if the axes are perpendicular. Move the needle in point 2 and start to move X axis toward point 3.
This time DO NOT touch the Y axis, just X. If you can put the needle exactly above the 3rd point … it is perfect, your axes are perpendicular. If not, you have to move one end of the shafts supporting X axis in order to have the needle exactly over the 3rd point.
That is all … enjoy now printing with perpendicular axes now !