Dr Vax
a request (unless you have already done this) for a video on how to strengthen parts of a design by selectively changing the fill?
Chuck (CHEP) did one in the past and I could refer back to it when i needed a refresher… but the menus all look different now I have the later Cura version 4.7.1… I now get lost in it easily.
Pretty please?
Adding an additional wall has usually more effect than the infill. Also printing the part in a proper orientation is helping a lot. Printing it in an orientation, so the layer lines have the same orientation as the forces applied. Infill itself is not that important. Make sure it is dense enough, so the layers can be placed properly and you´re done.
3D gyro infill provides an additional orientation to the mix, as the usual infill only works max when forces come from an 90° angle sideways to the layer lines. Gyro infill provides an easy way to create a unified force distribution in all directions, while the layer lines and their direction will be stronger than the rest anyway.
Having to much infill will make your object brittle as the infill cannot compensate forces by bending. I never used more than 42% infill and normally only use a simple line wall grid infill and 3 or 4 walls.
You can reinstall the old cura panel. It is available via PlugIn. The new version is basically not much different, It just pops up when you click on the right top side of the main window, where supports, infill and bed adhesion are shown.
Thanks for the reply Geit
Yes I have tried that (thicker walls and mostly agree, it IS usually better than a higher density infill… I have found thought that in cases of my last quick and dirty print (for demo only) which was a tool with just two pegs sticking up out of a handle the pegs would just shear off without having a substantial connection internally to the handle. CHEP showed how to selectively make underlying surface a lot denser selectively… I’d just like an updated YT from Dr Vax if he has enough support for it… He explains so well…
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Thanks again
Oh, thats a nice example. I had a similar with a hinge that always failed. The solution was easy. I angled the print by 35°. In your case the handle side up and then slice it. You need supports, but you can reduce that to a minimum. The goal is to get the layer lines from the base into the little pegs, so that the pegs get printed as overhang.
Optimal would be a 90° angle, but thee the handle would be easy to break. For this model there seem to be no perfect way. It will break one way or another.
I personally would replace the pegs by holes and print the pegs separately in a flat orientation. Afterwards I would insert them with some glue. That way the handle and the peg have the optimal strength required for their individual tasks.
I’m all for learning and will look that up:)
I’d like to just print it flat in one go with these areas in green as 50-60 infill including the pegs…
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I just don’t know how to do it with selective infill as CHEP demoed on the older Cura… It must be possible with the current version and same plugins? It just looks different now.
I’ll try and experiment with it.
Thanks
The infill does not matter at all in this case. The little pegs are only connected by their own layer lines. Imaging the handle without holes and two pegs glued onto. The glue is all which is keeping the pegs in position and since you want to apply a rotational force the surface with the glue is all that keeps it together.
When 3D printed, these pegs footprint is all that keeps it from breaking. Specific Infill will increase the strength of the pegs itself. Even if they can handle 20Kg in the end, they break loose from the handle way earlier. In 3D printing the layer line orientation is the most important value, when it comes to the strength of a part.
If you would print the handle standing up, the pegs would be printed together in one line with the handle. The printer would drive into the handle and back out. The price however is that the handle will break quite easy.
Rule #1 for FDM printing is to print the orientation of the print that needs the most force horizontal., because the printer is laying lines of plastic in the horizontal direction. Everything vertical is weaker. The thinner the part the weaker it is. That is why your pegs will break of the base handle when printing the part flat on the ground. Even if you add a chamfer on the bottom, the peg itself is just a glued stick made from circles. It will break above the chamfer.
The only solution to print this part cheap and without support is printing it on a belt printer. On the belt printer you always print in a 45° angle do to its construction.
With FDM on a normal printer the only way is to print the pegs laying to give them stength and print the handle flat as well, to give it strength. Combined they both have the max strength in the orientation they need. Or you simulate a belt printer and use a 45° angle and support to print it. But this will only be 50% as strong as separate pieces.
I thought CHEP’s YT article was about strengthening via selective infill
seems to be a pointless function now then…
pointless me asking Dr Vax to do his own YT on this subject after all
I will add it to the list. Strength testing videos take a long time to make because you have to print a lot of models and build a testing rig. I did one comparing filament types about a year ago so it is probably time to revisit.
Thanks for considering it
I thought I was imagining the function of it for what other had used it for…
I have done my own YT videos and it is time consuming both filming and editing… so thank you for considering it… You always do good stuff!
