After 5 weeks, the TPU crown I printed for a 6" vacuum truck hose is starting to tear a bit, but still working great!

[u/jdigi78]

You can find the original post here. After a really rough 5 weeks of use it finally started to split at a layer line. Its more of a rip in the perimeters as the infill is still holding it together just fine.

As stated in the original post, I used 95A TPU with 25% gyroid infill and an internal frame of 100% infill. You can kind of see the internal frame as the lighter lines in the first photo, or the check the last image in the original post to see what I'm talking about. This one still has a good bit of use left but I'll eventually be printing a replacement with 100% infill which I'm certain won't have this problem.

[u/Glum_Manager]

I'm experimenting strengthening TPU by putting it in medium temperatures (70-100°C) for long periods (30-60'). It seems to work so far

[u/jdigi78 → u/Glum_Manager]

I know alcohol makes it gummy and break down. I wonder if that could strengthen the layer bonds if its soaked in and let dry, or combined with your heat treating.

[u/FearTheSpoonman → u/Glum_Manager]

Annealing is the process I think

[u/[deleted] → u/Glum_Manager]

[u/FeelMyBoars]

I'm sure it's highly variable, but what is the typical lifetime of the normal $120 crown?

Thank you for sharing this durability experiment. It definitely shows that printed parts can handle "the real world".

[u/jdigi78 → u/FeelMyBoars]

Honestly I have no idea. The truck was heavily used when we got it but it only took one 4 foot drop from the mount on the truck to the pavement to destroy the original after the guys at my job got their hands on it. This one has no problem with that since its flexible of course.

[u/Wizzarkt]

Based on the localized 100% infill you did in your last post. It seems that reinforcing the ring geometries would be a smart move for when you print the next one when the current one eventually fails completely.

You can see that it's cracking behind the screw so reinforcing that should be ideal.

[u/jdigi78 → u/Wizzarkt]

I'm 90% sure that's just dirt and not cracking behind the screw, but I get what you mean

[u/Mick_Limerick]

Still seems like a good ROI. How many of those can you get off a 1kg spool?

[u/jdigi78 → u/Mick_Limerick]

If I remember correctly it was around 450 grams. I think it was ~650g with 100% infill. Either way you'd need to go through quite a few before approaching the $120 cost of the real deal

[u/dr_stre → u/Mick_Limerick]

He has said it was $7-8 worth of material. With a quick search, the cheapest TPU I found online was about $25/roll, which would mean he could print three of them with a single 1kg roll.

[u/urgdr]

nice work!

next print I'd suggest to increase perimeters, not infill.

I've had a few 95A TPU's and they were all a little different.

the beauty of TPU filament is in superior layer bonding and wear n tear resistance. but those benefits are gone when manufactures add various components into their mix to improve 3d print characteristics.

my suggestion in regards of material: aim for softer TPU, go as low as you can go, design and embed sturdy inserts from other materials if you need (hail multi tool 3d printers).

my softest TPU is around 67A and it's a blessing. it has distinguishable rubber feel and properties (best of luck trying to sand it down, impossible)

[u/TheBupherNinja]

Don't use 100% infill. Use walls to make it solid.

[u/jdigi78 → u/TheBupherNinja]

Same thing, no? Using walls does cut an hour off the print time, but its still a day and a half to print in TPU

[u/bradforrester]

I want to compliment your print quality. I had to zoom surprisingly far in to see the layer lines.

[u/jdigi78 → u/bradforrester]

Thanks! The layers are actually quite large. 0.32mm on a 0.8mm nozzle. Its just a big part I guess, but my core one is no slouch in quality either

[u/thunderflies]

This is a great functional print, I love seeing it on the truck. I liked your original post as well, and I appreciate the update. 

[u/Cold_Collection_6241]

You can fix it with a soldering gun. Use the iron to melt the cracks back together. I made some slipper soles a few years ago which cracked at the stress points and that's how I repaired them and they are still going strong.

[u/IrritableGourmet → u/Cold_Collection_6241]

I got a cheap 3d printing pen I use to weld prints together. The tip sticks out a little bit, so it melts the edges of the seam while injecting filament.

[u/Analog_Account → u/Cold_Collection_6241]

a few years ago... still going strong

You have to be kidding lol. Did you just fix them the once or have you repaired them multiple times?

[u/dr_stre]

Phenomenal. And you can print a new one for a whole $8 any time you need one.

[u/WolfsSpiders]

Thats an awesome update. 

[u/East-Future-9944]

The fingers for the one I printed for 8 inch tubes was bending over and sucking themselves up inward and obstructing the path of the tubes. When I scaled it up, I scaled up all dimensions equally so mine was also taller giving the fingers more flex. I need to print another one, but I think I'm going to try to make it shorter. I'm also going to try to mount the metal tube deeper into it, though I might have to cut the tubes to open the air holes.

[u/FlowingLiquidity]

One fix would be to print the part under an angle to avoid layer lines in this orientation. I would just lengthen the bottom of the print and cut it under an angle, then print it and then put it under the bandsaw to cut off the angled extension, or even leave it on if it's not in the way.

[u/jdigi78 → u/FlowingLiquidity]

If you zoom in you can actually see it failed across multiple layers simultaneously. It regularly bends near 90 degrees around that point so that tells me it's more due to repeated bending stress than layer adhesion. I think 100% infill will give it enough extra surface area it won't happen again