PETG dishwasher parts

[AddMan 2]

Hey all,

 

Currently printing replacement broken clips for a dishwasher. Planning on using PETG as it should withstand the temps, but just wondering if there are potential food safe issues. Is PETG likely to leech anything, particularly at increased temps, or is this insignificant and not of any concern. Is there a better material option. I have an Ultimaker S5.

 

Thanks and happy printing!

[jirodriguez72 19]

I would go with poly carbonate or if you need the part to have a little bit of flex (so they don't crack) CFF-Nylon. Both would hold up to the harsh environment inside of the dishwasher and still provide good mechanical properties.

[AddMan 2]

Hey jirodriguez72, thanks for reply. I like your suggestion for PC. I have successfully made what I need in PETG, but it is a little too brittle and less forgiving like you said. 

 

I've got some PC here I can try, thanks for your help. 👍

[AddMan 2]

OK, an update to above.

 

Successfully used PETG for a few washes, no issues with breaking, however it has started stretching with each wash. Must be hitting the glass transition for PETG which surprised me a little, I didn't think it would get that hot.

 

Printed with Polymaker PC plus. Two have now shattered on the first try?? I was expecting the PC to be much more durable. This is my first attempt to print with PC; not sure if I'm doing something wrong. 🤷‍♀️

[DivingDuck 105]

This isn't surprising.

 

PC is not resistant to bases, aromatic and halogenated hydrocarbons as well as ketones and esters. Prolonged exposure to hot water can cause stress cracking (as you already experienced). In combination with dishwasher detergents whereas alkaline compounds (bases) are an essential part of, this isn't a really a good choice.

 

ABS is maybe the better choice for this DIY and you can gain the temperature range with annealing a bit further. As well doable at home.

Shrinking during the annealing process needs to be compensate in addition and is part related. You need to make some test parts for annealing.

[victorabreurodrigues 0]

Hello all,

 

I don´t have the plugin of the creality cloud in my marketplace, how can I do to have it disponible to install ?

Thanks

[AddMan 2]

Thanks DD,

 

I kind of based it on the glass transition of PC without considering the other factors at play. The inside of a dishwasher can be a pretty aggressive. 

 

I didn't anneal the PC, which is my bad, but I had issues with it being brittle even before I used in the DW.

 

ABS is going to be the next test; failing that I might give Nylon a go r some glass reinforced filament I have lying around.

 

Thanks for your feedback, much appreciated.

AddMan

[AddMan 2]

Thanks DD,

 

I kind of based it on the glass transition of PC without considering the other factors at play. The inside of a dishwasher can be a pretty aggressive. 

 

I didn't anneal the PC, which is my bad, but I had issues with it being brittle even before I used in the DW.

 

ABS is going to be the next test; failing that I might give Nylon a go, or some glass reinforced filament I have lying around.

 

Thanks for your feedback, much appreciated.

AddMan

[Torgeir 243]

Hi @AddMan,

 

Well, I've actually made some parts for our "old" dishwasher (the first mode here in Scandinavia using a microprocessor!). Sure it's still working strong and bought in 1983.

 

A few parts may be very easy to print and use. But inside the washing cabinet we'll need some tough filament.

I've been experimenting with a few types, but only one really stand the test -and this is Nylon!

I'm using Nylon from Taulman3D, that is Bridge Nylon 2.85 mm Natural.

 

You may find some special types, certified for medical or food usage so there is a lots to choose between.

So to the part I've printed for our dishwasher, this is the upper bearing for the water spreding "propeller". This dishwaser deal with 70 degrease Celsius water during the process. But worse is the drying sequence, about 15 minute and water damp up to 90 degrease Celsius(!) and this is the absolute worst periode for this bearing to survive.

 

The challance here is to design the part so it's strong in the direction needed to be and also dimensioned so it fit properly into the place it's used! You may install parts when they have a temperature thats softend the object a "little".

This will make it possible to install more easely like "to snap it on", I.E. you may not be able to removit after cooling down.

 

Printing with Taulman Bridge; printing temperature ca. 255 deg C. bed temperature 50 deg. C.

I'm using draft shield, see experimantal phane. The printer is closed in completly, no cooling fan for the printing object.

The very important here is to make sure all layers are completely glued and infill 100%!

 

Important thing is to find the temperatur making the best "gluing" and with less stringing. There may be a little stringing, but should be easy to remove. 

After printing the model/object, you should not be able to tear of any part from the object! If you do, you have to lo printing temperature and gluing is not as it should be.

Nylon is superstrong and you'll ned a real good cutter to part it up!

 

I have some picture of the project, if it's of interesst.

 

Thanks

 

Torgeir

 

 

 

 

[AddMan 2]

Hello Torgeir,

 

Thank you so much for your detailed response; I'm learning fast what a harsh environment it is inside my dishwasher!

 

I haven't printed with Nylon before so I really appreciate all your advice. I have a forgiving tolerance on the part I need, so dimensionally it is not an issue, it just needs the strength to survive the high temps. At the moment I've just replicated the original part, but I may redesign it to provide additional support in the direction of the greatest stress.

 

If you have pics of what you have done I would love to see them.

 

Thanks again,

AddMan 

[Torgeir 243]

Hi @AddMan,

 

I'll share some pictures of this project, but first something to explain. 

This was about how to get the object to stick to the bed, tryed just a clean bed (using the UM 2E+ for this).

The Taluman3D bridge nylon was not that easy to bond properly to the bed, after lots of test with glue sticks etc., I ended up using diluted PVA glue (the carpenters wood glue). Diluted 1 part glue into 12 part of water mixed well.

I've used a flat foam brush about 1.5 inc wide, this makes it easy to make a nice surface of deluted glue.

Before spreading the glue, i've use to heat the bed to about 40 deg. C. I'd use to cover up twice of the space I'll need on the bed.

After first layer is dried, it allmost disappear, but wait ultil all is glue are dried. Then redo this process until you have at least four layers of diluted glue. Then you should be ready for first print. 

The pictures here is from the first test with the object as it originally looked, however I realized this bearing needed some redesign. 

 

So this is the first picture of the two variants made:

 Here you see the warping as the model lifted off the bed. The left one is how the original was made, here with PLA.

 

 

Number two:

Same from another angle.

 

 

Number three:

 

There was a few more inbetween, but..

 

 

Number four:

 

After printer finished.

 

Number five:

 

Inserted into the "propeller".

 

 

This is just some general thing, but might help some.

 

Here's two liks to annealing nylon and PLA you may find interessting.

 

https://www.plasticsintl.com/media/wysiwyg/Nylon___Reinforced_Nylon_Annealing.pdf

 

https://www.fargo3dprinting.com/annealing-makes-3d-prints-better/

 

Good luck

 

Torgeir

 

Edited January 14, 2023 by Torgeir
One picture to much.

[AddMan 2]

Hello @Torgeir,

 

Thank you for all your help, Nylon looks like it needs some respect, so thanks for all your advice.

 

I have previously tried the PVA glue slurry, but only with PLA. It definitely stuck, I ruined one of my glass plates removing the print! Lesson learned.

 

How hard is it to remove nylon, and do you have any tips? Is it best to let it cool down first? I also need to print with support, which adds an additional layer of difficulty.

 

Thanks,

Add Man

[Torgeir 243]

Hi @AddMan,

 

Yes, for sure Nylon is the filament to use if you need something that do not just break off..
I'll think this is among the toughest filament there is.

 

Well for Taluman you'll need PVA "sluss" deluted.. I've reading in here that Ultimaker Nylon stick very hard to the bed and may be very hard to remove without loosing some chips from the bed. 

But in this case it is also good to use PVA to avoid this hard "stickness".

To loosen up PVA attached object, put the whole thing (with bed) into a water bath of approx 40 deg. C. and leave it there for some time. After 30-45 min use a tiny spatel to carefully split the object from the bed, just a little by time.

This have allways worked for me.

 

If your printer is to be used, -another bed is handy then.

 

It's not difficoult, but take's some time.

 

Thanks

Torgeir

 

 

[AddMan 2]

Great advice @Torgeir, I think it's important to be patient here 🙂. I get excited when my print is finished and want to get to it as soon as possible.

 

I think I will use my bed that is already chipped.

 

Thanks,

AddMan

[geert_2 557]

Polycarbonate is known for stress-cracking. Car headlights in PC also get dull from microcracks, so manufactureres tend to go back to plexiglass (PMMA) now.

 

If you can find PET or PETG that can handle 100°C, it might not be the worst choice. PET should be food-safe, as it is used in all sorts of bottles and other food packages. And it prints reasonable well with decent layer adhesion and not too much warping.

 

If the available space allows it, design the part way sturdier and fatter than the original part. Make it more "flintstone-like". And print slow, without cooling fan (if there are no overhangs), and in thin layers for best form fit, best layer-adhesion and minimal air-entrapment in the model.

 

I never tried annealing PET, so I don't know if that is possible. PLA can be annealed, but it deforms so much, and in different ways for different brands, that it is not worth trying in my eyes. It is probably not going to fit anyway, unless you do a lot of testruns.

 

Another solution could be: print the part as accurately as possible in PLA. Post-process for a perfect fit (but don't use it, just test-fit). Then make a silicone mould around that part. Spray the mould with silicone release-spray generously, so it is totally soaked in silicone oil, and let it dry well. And then cast some very strong filled epoxy into that silicone mould, e.g. sand-filled, metal filled or glassfiber-filled epoxy. That should give very strong parts. Chances are that your original part was glass-filled nylon or ABS too. Try to find a food-safe epoxy, or at least a not-too-smelly one, and let it cure well, preferably at somewhat elevated temperature, and clean thoroughly.

 

[AddMan 2]

Thanks @geert_2, I've started doing your "flintstone" idea 😁. I did my first prints as per the original design, but have now started to modify it with additional support where the main stresses are. This has been somewhat successful, but ended up clashing with other components so have had to refine design.

 

I've yet to try Nylon. I think I might try the stronger design combined with the strength of Nylon and see where it goes.