3D printed G clamps are easy to produce. The most important part about 3D printed G clamps is the strength. The ones I made are supposed to clamp down another 3D printed part that replaces a monitor stand.

How strong are 3D printed G clamps

That is the question and as always, there are a few ways to find out. I don’t have access to precise measurement equipment which would let me conduct various stress tests. One of the advantages of being a musician is the ability to improvise and improvising is how I plan to test. I’ve made four identical G clamps. One is printed solid and the remaining three have various degrees of infill ranging from 75 to 25%.

I have learned a lot about achieving the maximum strength for my models from watching YouTube videos. I can especially recommend CNC Kitchen because of the well-made videos

Cura slicer solid block features

I use FreeCAD to model my parts and Cura to slice them. After that is done, I can export the G code to a USB stick and start printing. But before that, I want to mention one of my favorite features of Cura. Most parts do not need to be solid. Printing a solid shape is time-consuming and uses much more filament. Both of those facts add to the cost. Although I don’t care about cost, I do care about achieving the best possible strength.

After all, I am planing to hang some very expensive 4K monitors on my prototype stands which are held down by one G clamp. Solid models (no infill) do not need solid blocks as they are already 100% solid. As soon as I specify an infill value, I have the option to add a solid block.

The most important part about adding a solid block is to size and move it to the exact area where the extra strength is needed. In my case, I want the cylinder to be solid. The bottom and top part of the clam should also be solid and the rest is a combination of wall thickness and infill density.

If you use Cura and have not yet discovered this somewhat hidden option then I encourage you to do a YouTube search for “Cura hidden features”. You will learn a lot. With the design portion out of the way, let’s get back to the strength test.

I have not used any other slicing software because Cura runs so well on my Linux workstations. If you are researching 3D printing and the needed software then I recommend that you check out the Cura website

Strength testing 3D printed G clamps

I don’t have access to digital measuring devices and don’t need to test frequently which means that it isn’t worth to build something practical. Instead, I found a well-built work bench which lets me attach the G clamp to the table surface. Then, I use a bought cast iron G clamp to attach weights. The reason why I use a cheap metal G clamp is simply to make sure that I have a flat and wide grip area available.

After that it’s just a simple matter of adding weights. My G clamps are each 10 millimeter thick. On top of that, I added a five millimeter thick brace to give the body a T profile. G clamps seem to be weak in the center and eventually, the back part cracks. I have looked at store-bought ones and noticed that all of them are thickest where the stress point is that highest.

How much weight can a 3D printed G clamp hold before it breaks

Amazingly, a lot. The solid one was not stronger than the others. All four broke between the 40 – 65 kilo range which is amazing. Because of those results, I will go ahead and print the computer monitor stands as planned. I know that I could just buy second-hand ones for cheap on craigslist but almost all of them require a lot of space between wall and desk which I don’t have. My design is simple. It is just a straight arm that has an up/down adjustment for the monitor. A G clamp clamps the arm to the desk.

Plan B

As always, I have a plan B (and C and D and ….)
If the 3D printed G clamps would have been too weak to hold the weight of the monitor, then I would have used cheap ones that Home Hardware sells for about five bucks a piece. Somehow, I trust the ones I made enough to use them first. I have seen many cast iron ones snap for no good reason. As they say “you get what you pay for”.

In closing I want to state that 3D printing is exciting beyond words. They have come a long way and no longer carry the steep price tag. Then again. Being able to make anything I want is priceless.

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