Printing With Glass Fiber Filament

[ModBot] has been trying different engineering plastics for 3D printing. He recently looked at carbon fiber mixed with PET, but this time, he shows us his results with PET with glass fiber, or PET-GF. You can see how it all turned out in the video below.

The first part of the video compares the specifications, and, as you might expect, some factors are better for carbon fiber, and others are better for glass fibers. Once he gets to the printing, he covers the high temperatures needed (280-320C). He also talks about how either fiber will chew up nozzles and extruders.

If you haven’t printed at high temperatures before, there are a few gotchas. For one thing, even if you don’t have PTFE in your hot end, you must be sure your thermistor will read the higher temperature accurately. Many people use thermocouples instead of thermistors in this application.

The prints looked good, although we hoped to see more testing of the parts under stress. Comparing them with the carbon fiber prints would have been especially interesting. Need help boosting your print temperature? We look at exotic filament every so often, and every time we do, there are a few more choices.

12 thoughts on “Printing With Glass Fiber Filament

  1. As nice as he makes GF sound I honestly have to say after printing for over 3 years now and having almost 100lb of different filament laying around I haven’t used GF but still am not sold. I have used numerous CF blends and the strength to weight ratio should be suffice for anyone that the video is seen by. Also not to mention that GF does have more downsides not mentioned in the video, premature wear on bowden tube, premature wear on heatbreak, premature wear on inlet of extruder (if it rubs) and obviously the nozzle. CF to me is less damaging to all those components and more manageable with hotend temps. I personally like CF-PETG CF-NYLON from 3dxtech because it’s made in the USA and super easy to print.

    1. One reason one might use GF over CF is electrical resistance. Carbon is a poor electrical insulator, so if I need some extra strength and stiffness as well as electrical resistance, GF is a good choice.

    2. So you’ve never used it yet claim it wears all those components out more than carbon fibre filled filament? Carbon fibre wears all those components relatively quickly as well. As for hotend temps, it all depends on the base material, as stated the range is 280 – 320 C, that is about the range that would be expected for a high temperature nylon or PET and all metal hotends are generally capable of 300 C.

      There are use cases for GF filament that aren’t suitable for CF filament, for example anything to do with electronics since CF can be conductive. There are very good reasons that GF is used in injection molding rather than CF.

      “I have used numerous CF blends and the strength to weight ratio should be suffice for anyone that the video is seen by.”, people who watch his video will generally be interested in 3D printing, that includes engineers or people with projects where GF filament may have the properties they require. To say that CF is enough for anyone who watches videos about 3D printing on YouTube is just untrue and you have no way to back it up. Who are you to dictate what mechanical properties people need anyway?

        1. How does that sentence end?

          “..I haven’t used GF but still am not sold”

          You can’t judge a material until you use it and test it. I work in an R&D lab for a fortune 100 company and our additive manufacturing team, full of PhDs in engineering and chemistry, with decades of experience in 3d printing (several have patents on printer mechanisms and filaments) and they still rigorously test and analyze every filament they make/purchase. Appealing to authority does not justify dismissing a material out of hand.

    3. That’s nonsense. I’ve printed over 100kg of pa6gf10 and the extra wear is effectively identical to carbon. If you’re using steel, you’ll never notice. Brass parts will wear quickly. I have a Bowden tube with 2000 hours on it, still fine using almost exclusively filled filaments.

  2. My boy ModBot made it on HackADay!!! Super dope. Ya GF is superior to CF for a bunch of applications and only when you get into some of the specifics do you need to sort out what’s best. CF PET or CF PETG can be printed at 215-220 depending on nozzle size and extruder strength and you can do that with a standard ender3 with a Bowden, doing so will result in a very flexable and strong print even when you get to small stuff like window screen clips and fasteners, as opposed to the GF PET where you do need a bit closer to the 230-245 temps and your part is far more rigid and heat resistant. Both have a very unique application.

    1. I much prefer this type of marketing to paid product placement, or ads.

      To me it shows confidence in the product. Putting your product in someone’s hands who both has a platform and no particular allegiance to you or the company could go wrong in a lot of different ways if the product isn’t up to snuff.

  3. I would admit this is not directly about printing it- I used to machine glass filled plastics, mostly nylon. Maybe this will help someone when they go to do a 3D printed part. The stuff machines just fine- but even carbide tools will start to wear out quicker. Fortunately though since it’s plastic you won’t see it for quite some time but I did notice.

    If you have to machine glass filled plastics, they machine very similarly to their normal counterparts. Holding tolerance on them is actually a little easier because they are more reinforced, less squishy.

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