filament question

hello all, i wanted to ask about plastic filament. my first question is if there is a difference between ABS and PLA and different sizes. do some machines only accept one kind of plastic filament? and also, how fast is filament used? how many prints would a get out of 1 pound of filament?
thanks!

pla is non toxic melts at lower temperatures and is stiff.

abs is durable, more heat resistant, warps more without a heated bed, and has fume you shouldnt breathe

if you're just starting out i suggest 1.75. I use 3mm and am happy with it, but 1.75 is the direction everything is going and it makes sense.

1 pound of filament is about how much i8t takes me to print all of the prusa mendel parts with a few screw ups. I buy 5 pound spools and print pretty regulkarly it lasts a couple of months but I have prints running over night and almost all weekend at times. This can vary based on your infill and perimeter settings of course.

I would say the opposite, hardly anyone I know uses 1.75 as it breaks way to easily

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Experimenting in 3D in New Zealand

PLA has a sweet smell, ABS smell depends on the color. Some stinks, and some smells fruity.

PLA has a melting point around 185'C, ABS has a melting point arround 230'C.

PLA takes longer to solidify, so a fan is needed to help cool the layers, otherwise, smaller parts tend to sag.

PLA has a brittle finish. ABS is smoother. This makes PLA parts feel rough to the touch sometimes.

PLA has a lower frition coefficient, which makes it useful when making parts that need to rub against stuff.

ABS is softer, which makes it good for tight fits. One reason they are used in making LEGO.

1.75mm extruders tend to be less forgiving about diameter variations. I like 3mm, but I have not tried 1.75, so have no other oppinion on it.

NelsonRap Wrote:
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> I would say the opposite, hardly anyone I know
> uses 1.75 as it breaks way to easily

I've never broken 1.75mm ABS. It's all I've ever used, so far. I have heard that some grades of PLA are a bit on the brittle side.

The reason people have been moving to 1.75 is that it takes less torque to extrude, allowing for simpler extruder designs without step down gears. Makerbot's latest extruder uses a regular stepper motor with no gearing, because its designed just for 1.75. That said, if you already have an extruder with gears like most of the standard reprap extruders, 3mm will work just as well as 1.75. For now it still seems like 1.75 filament is more expensive, but with makerbot going to it exclusively that might not stay the case.

I'll give you a "new guy" perspective.

I agree with most of the above, but I only have experience with 3mm filament, so I can't comment on 1.75mm.

PLA seems to provide stiffness that ABS does not.

ABS provides flexability/durability that PLA does not.

For instance, my machine (bought it used-ebay) had opto-endstop clamps made of PLA and they were all cracked and in need of replacement. My machine came that way. I've since done a lot of upgrades (lm8uu bearings and more) and used ABS for everything.

I personally believe that all printable printer parts should be made using ABS for durability and temperature stability. And here's why:

My x-carriage, also made from PLA, was badly warped. Even with an ABS insulator plate between it and the budaschnozzle (my particular hot-end). If you never see yourself having to use additional heat (hot-box, radiant heat, so-on), then you might consider PLA for some parts. But you have to be careful with which parts you choose, because in addition to the extruder and bed, the stepper motors can become quite hot as well and PLA has a low service temp.

Now on the flip-side, when I'm producing proto-type parts for my company, I've really come to like printing with PLA. It may be less suited for structural testing (not really sure about that), but most often, I just need a close representation of my model and PLA gives me that. It doesn't seam to lift and warp on larger parts and it looks really nice when it's running well.

Even with a hot bed at 110c, my ABS parts lift on larger models. Most of my prints are right on the edge of my Prusa's cube. I'm currently building a larger machine because of that.

I started my reprapping adventure using strictly ABS, and I'm glad I did, because it just printed well right from the start and I didn't see any quality fluctuations (aside from warping on big prints). No mysteries. You really need to have a heated bed tho.

I just started using PLA a few days ago, but I've been running it around the clock since. I've gone through nearly 5lbs and most of that has been trouble free, until today. Suddenly, I'm dealing with diminishing print quality with PLA.

So while PLA really prints beautifully when running well, it may be more sensitive than ABS to operating conditions. I'm still trying to figure my problem out, but since settings haven't changed I'm suspecting moisture.

That's most of what I have to offer, and it's all based on my own limited observation, so don't take it as a matter of fact.