Stepping Up From PLA to PETG

All of my early prints were made with PLA filament as it’s pretty much the go-to standard for basic 3D printing. However, when I was printing upgrades for my Ender 5 Pro the strong recommendation for the bed supports was that they were printed in PETG and not PLA. This was because PETG parts have a little more flexibility than the same parts printed in PLA. In this case flexibility was necessary to allow the support to have a tight stretch-fit onto the bed base.

Given the thoroughness of the testing the designer had documented on Thingiverse I was convinced it was time to make the move from PLA to PETG. I bought a reel of 3D Warhorse PETG filament and prepared to get printing.

Now, on the back of the box it says that this filament can be printed at a print head temperature of 200 to 220ºC, with a build platform temperature of 80 to 120ºC (optional). As a novice printer this sounded pretty reasonable to me. I sliced the small back part of the bracket with the head temperature set at 210ºC (the middle of the suggested range) and the bed temperature at 80ºC and set the print running.

Disaster – after about a fifth of the print the nozzle blocked. The printer carried on regardless, printing several layers of air before I noticed something had gone wrong. Undeterred I removed the nozzle, replaced it with the spare one that came with the printer, re-sliced with the head temperature raised to 220ºC and tried again. The result? The nozzle blocked after about the same amount of printing.

At this point I was out of nozzles, so I needed to unblock the ones I had before I could do any more printing. I unblocked them by holding a nozzle in a pair of vice grips and heating it up with a heat gun, then carefully removing the blockage with a needle. This is a slightly fiddly process and not without its perils. However, it did work and I managed to clear both nozzles without scorching myself.

So back to printing: after doing some more research online, it appeared that the 200 to 220ºC suggested on the filament box was pretty optomistic for PETG. I raised the print head temperature to 235ºC and re-sliced the part: this time it printed without any problems. The moral of the story being: don’t necessarily believe what’s written on the box!

After that initial hiccup – which did dent my confidence a bit – I’ve printed a load of parts with PETG. In fact it’s become my go-to filament for anything that needs to be stronger, more flexible or more durable than standard PLA.

I’ve never tried to print PETG at a head temperature below 235ºC since those early failures and haven’t (yet) had any further issues with blocked nozzles. Subsequently printing parts with clear PETG for my tubelight I bumped up the temperature to 245ºC and the results came out looking great. Now I generally use a print head temperature of 245ºC for all my PETG prints. So far this has caused no issues with any of the brands of filament I’ve been using.

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