PETG parts and heated chamber

So I'm enclosing my smartrapcore alu machine on which I've begun to replace some parts with PETG. At what temperature will this deform under load? I intend for my chamber to be a maximum of 45 deg C?

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Simon Khoury

Co-founder of [www.precisionpiezo.co.uk] Accurate, repeatable, versatile Z-Probes
Published:Inventions

Google tells me a glass point of 75c, so you should be fine but keep an eye on motor mounts made with it as this area may exceed this. Refer to manufacturer to get a better number though, there is likely to be a lot of differences between manufacturers.

Thanks. I know none of my motors get hotter than 60 deg C as I bought some indicator labels which go black at 60,65,70 etc none have changed colour, also none of the motors are in the enclosure. I'm printing a new x carriage in petg as the abs one cracked.

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Simon Khoury

Co-founder of [www.precisionpiezo.co.uk] Accurate, repeatable, versatile Z-Probes
Published:Inventions

When you ask "At what temperature will this deform under load?", it depends on what load (or more to the point, what stress levels). For most plastics, the yield strength decreases steadily as the temperature rises (and then all hell breaks loose as you reach the glass transition temperature). So it is very easy to have a part that works fine at 30 deg.C fail at 50 deg.C. The other thing to keep in mind is creep. Most plastics will creep over time at stress levels well below the yield strength, and creep will be a much bigger problem as the temperature rises. Unfortunately, there's no easy formula to say if your parts will fail at any particular temp - you'll most likely just have to try it and beef up your parts if they start to droop.

I used ABS to make a motor mount and belt tensioner in the X axis of my printer. After about a year I noticed a slight tilt to the motor and took it off the mount. I found the screw holes distorted and the plastic scorched. I replaced the motor mount with one made of aluminum, and plan to replace the belt tensioner, too. The belt has slowly crept downward on the pulley as time has passed- I suspect the tension (and heat- I let the enclosure get to 45C when printing ABS) is distorting the printed parts.

Printed parts that are subjected to heat and mechanical force are just not a good idea. Use metal everywhere possible.

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Ultra MegaMax Dominator 3D printer: [drmrehorst.blogspot.com]