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strongest possible prints (PLA)

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I'm printing a few components for an experimental snowboard binding and it would be nice if I didn't die during testing, so how to achieve the strongest possible print?

I am experimenting with combinations of infill and solid layers/borders.

S3D is telling me that 100% infill actually produces parts about 10% lighter than parts printed with enough solid bottom and/or top layers to fill the print, but maybe the infill patterns are stronger than the X by Y solid layers..

Anyone have any experience properly testing parts to destruction, or any other rigorous proof which is the best way to print the toughest parts?

So far I am trying:

Print slow (45mm/sec with a .4mm 3d Solex)

Print thin (well, .15mm layer height)

Print fat (extrusion multiplier 1.2 for added squashing)

Print hot (230 for PLA to get better layer bonding)

..anything else I could try?

C:)

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The orientation of the part in the printer matters. You can probably predict where forces will be in your part. Take care that these are not in Z-direction, as cross-layer direction is the weakest.

 

Weight matters. The heavier you can print an onbject, the better. The relation between weight and strength is non-linear:10% less material makes your part 30% less strong.

But most of all: choose the right material. PLA is stiff, but brittle. Abs is tougher, and maybe Nylon is a good choice. Ultimaker Nylon prints very well, and is really tough, but it might be too flexible for your application.

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If I would need a strong part I would try ppmax of polymaker. It can go up to 110C and has a matte color.

For infill strong part, use infill Infill overlap of at least 20-25, to make the infill and perimeters bond strong enough. Also use something like 60-80% infill using honeycomb infill. Also increase the perimeters to at least 6-8.

Nylon of ultimaker, at least the ones I tested, are way too flexible and they have a very low temperature resistance (bad if you plan to test the part vs friction), also is useless as a part to postprocess unless you just want to dye it.

I use platec/greentec, I don't know how strong actually is ppmax of polymaker, but all the info seems to show is very nice. I think @amedee tested it.

Platec/greentec also resists 110C, is very easy to sand and paint and is a bit more flexible than pla, but also is very hard to break. And has the advantage of being 100% biodegradable.

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I tested Polymaker PC-Max as I was looking for something that would resist higher temperature, together with good mechanical properties.

I have not done strength tests, but so far I am very happy with the results. When sanded you do not see any layer, it is just like a molded part.

PolyCarbonate has very good mechanical properties, the downside is that it needs to be printed hot (260-270°C) which is not possible with all hot ends (e.g. It is a no-no for UMO stock hot end)

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The orientation of the part in the printer matters. You can probably predict where forces will be in your part. Take care that these are not in Z-direction, as cross-layer direction is the weakest.

 

Weight matters. The heavier you can print an onbject, the better. The relation between weight and strength is non-linear:10% less material makes your part 30% less strong.

But most of all: choose the right material. PLA is stiff, but brittle. Abs is tougher, and maybe Nylon is a good choice. Ultimaker Nylon prints very well, and is really tough, but it might be too flexible for your application.

 

I hear you. Not much I can do about the orientation, and it's tensile strength which is critical, so to avoid delaminating I'm going for 100% solid layers (not 100% infill which still leaves a lot of air in the part, at least with S3D)

I'm not convinced by ABS- problematic printing for not enough added strength?

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I tested Polymaker PC-Max as I was looking for something that would resist higher temperature, together with good mechanical properties.

I have not done strength tests, but so far I am very happy with the results. When sanded you do not see any layer, it is just like a molded part.

PolyCarbonate has very good mechanical properties, the downside is that it needs to be printed hot (260-270°C) which is not possible with all hot ends (e.g. It is a no-no for UMO stock hot end)

 

Been looking at the Polymaker website and the material looks promising. Also some tests on Youtube, but mostly brilliantly non-scientific.

interesting figures for strength from the Polymaker website:

polymax.jpg.ab562a40d02f60f7854321d63eed22ec.jpg

Seems like PolyPlus is better..

Also, they recommend annealing.. ever tried?

I've got a 3D Solex nozzle on a UM2- you think that setup will handle the 270C required?

polymax.jpg.ab562a40d02f60f7854321d63eed22ec.jpg

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What do you mean with 100% solid layers, not 100% infill?

Do you want to share a picture of your design?

The experience from within UM is that esthetics and optimal mechanical properties don't go well together. you want to be nearly overextruding, to really fill the part, and leave as little air in the part as possible. But this often does not give very nice outer surfaces.

For your snowboard binding, I guess you must balance towards overextrusion.

Do you know which material is used for "real" bindings?

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Seems like PolyPlus is better..

 

Depending on what you are looking for. PC-Plus is a bit better on tensile/bending strength, PC-Max is more resistant to impact.

See also the data sheets PC-Plus / PC-Max

If temperature is not a factor for you (I don't think yo want to snowboard at high temp), you should consider fiber-reinforced filaments, like Nanovia PETG CF (Data sheet) -- @darkdvd uses it for the air intake on his car since quite some time (see the pictures at the bottom of the page)

 

I've got a 3D Solex nozzle on a UM2- you think that setup will handle the 270C required?

 

You probably need their I2K thing as well -- @neotko knows better...

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Yeah with the I2K you can go to 290C (changing firmware to tinkergnome) wit a TFM coupler the hotend won't suffer much with tha combo and you could use it for a really good amount of time. But IMO I2K isn't good for pla use since pla releases an oil.. blablabla. Long story short, it really works for high temps.

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Regardless of the material, try to print it as hot as reasonably possible, but without burning the material in the nozzle. Also try to minimise cooling as much as possible, but without the model sagging and deforming. And try to print rather slow, so the new layer has enough time to melt well with the previous layer. This will give the best layer bonding.

This in addition to (depending on your printer) increasing the flow a little bit, so you have a little bit of overextrusion, as said above by the others. So that all tiny holes in the print are filled well. When I print in Cura and use 100% infill, my models are always quite solid, without visible gaps in the surface. Only in the corners of the extruded sausages (I don't know how to describe it correctly), there are very small gaps, the so-called "weld lines".

Concerning material, how about PET? This is tougher than PLA, but not as flexible as nylon. And it prints reasonably well.

If I were in your place, and my life would depend on it, I would add some steel wire somewhere as backup. Maybe keep the steel wire loose enough, so it does not influence the normal function of the part, but still good enough to keep things together if the part would fail. As a sort of safety belt. Obviously, first thoroughly test it on a bench, and hammer on it (simulate hitting a rock), before going downhill at 100km/h. :)

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Yep, your points seem to represent the consensus here.

I am going to do some testing of various materials and settings, if I can get my hands on some lab equipment. I'll certainly post up the results.

One big unknown is how very cold temperatures will affect things. I would expect some increase in brittleness for most materials..

"If I were in your place, and my life would depend on it..."

Ha, I have broken three parts so far in testing. Was quite 'exciting' to say the least...(and thinking back, always happened on very cold days)

Ah well, they call this learning by messing up :)

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What do you mean with 100% solid layers, not 100% infill?

Do you want to share a picture of your design?

The experience from within UM is that esthetics and optimal mechanical properties don't go well together. you want to be nearly overextruding, to really fill the part, and leave as little air in the part as possible. But this often does not give very nice outer surfaces.

For your snowboard binding, I guess you must balance towards overextrusion.

Do you know which material is used for "real" bindings?

 

So far I've printed my parts twice, once with 100% infill and once with enough solid top/bottom layers to completely fill the part (in z-axis). I'm using S3D, which predicts about 10% heavier parts with all solid top/bottom layers, so there must be less air in these parts. I tested them both with my rigorously scientific "put in vise and whack with hammer until it breaks" test: 100% infill lasted 2 whacks, all solid layers lasted 5 whacks. Both brittle fractures..

Esthetics are secondary at this stage of prototyping, so yeah I'm thinking heavy overextrusion to guarantee as much filling as possible. I'll take an ugly but strong part any day.. :)

Final production parts would be injection-molded in some super-strong glass-filled resin, so my proto-parts look quite different.

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Another method that just crosses my mind: you could 3D-print the model, make a silicon mould of it, and then fill the mould with a fiber reinforced composite. Whatever fibers you like. Then you might get something that has the correct shape, but with physical properties closer to the real thing. Or first stuff the mould with fibers, and then pour a very thin liquid composite or polyurethane in it. These methods overcome the layer- and infill-problems of 3D-printing.

(Note: concerning my idea of "steel wire" above: if you ever do that, make sure it can not cause amputations if some body part gets stuck in it...)

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Another method that just crosses my mind: you could 3D-print the model, make a silicon mould of it, and then fill the mould with a fiber reinforced composite.

Yeah, I've done a lot of this over the years. One of the reasons for buying into 3d printing was to avoid all those toxic chemicals.. :)

Does make strong parts tho..

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Don't overlook layer thickness as a factor. Thicker layers are stronger because each extruded trace is stronger and there are fewer layers to bond. Also, rotate the piece so the printed "grain" - the layers - align with the max stresses.

IMHO, thicker is also stronger because each layer won't cool quite as much before the next layer is printed on it, giving a better bond.

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Don't overlook layer thickness as a factor. Thicker layers are stronger because each extruded trace is stronger and there are fewer layers to bond. Also, rotate the piece so the printed "grain" - the layers - align with the max stresses.

IMHO, thicker is also stronger because each layer won't cool quite as much before the next layer is printed on it, giving a better bond.

 

I agree. Also, I am goinbg to swap to a wider nozzle for the same reasons..

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Well, no one asked what components are you printing. As a designer I think the part design is of foremost importance. Sometimes you can design something to be printed in a weaker material, but with such a structure that makes it stronger than the original item printed with a stronger material.

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The real question is: what are you really wanting to test? a design concept ? the endurance of a part? the resistance of a printed part? or evaluating how a final injection molded part will behave?

 

read the opening post: it is an experimental snowboard binding.

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The real question is: what are you really wanting to test? a design concept ? the endurance of a part? the resistance of a printed part? or evaluating how a final injection molded part will behave?

The parts would end up being injection-molded, which can yield very strong parts. I've been milling test parts from solid Delrin, but this is expensive. Would be great to achieve similar strength with printed parts, but I'm coming to the conclusion it ain't possible..

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If tensile is the deal... what about nylon Taulman Alloy 910? I don't know how it perform with impact but it should be good! Just take a look of the specifications:

http://taulman3d.com/alloy-910-spec.html

I will also follow this topic cause I'm planning to make some parts for a mountainboard brand (a snowboard from tropic/ off-road skate with big wheels) and I'm interested for a kick ass material for crash tests (base of bindings, top of trucks and hubs). If possible I don't wanna go to hot, more than 255°C, but maybe I will upgrade to reach it :D

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