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3.0mm PLA vs 2.85mm PLA

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Usually 3mm PLA is actually smaller. Similar to when you buy a 2X4 piece of wood it is also smaller than 2X4 inches.

However some manufacturers actually do make it at 3mm and this is a problem for Ultimakers (more than most printers) because of the bowden tube. The Bowden tube on the ultimaker can usually take up to around 3.05 or 3.1mm before it jams. Every bowden tube is a little different so yours might be even 3.2mm but probably not.

So you would think 3.0mm PLA is fine. But it's not. For one thing, the feeder for the ultimaker squeezes the filament so hard that it is no longer round. The other problem is that filament diameter varies typically by .1mm over the course of a singe reel of filament. So it may be 3.00mm for the first 5 meters and then grow to 3.1mm for the next 5mm.

When it jams in your bowden you will get very frustrated and might have trouble getting it out again. After this happens 3 times you will throw it all away and wish you had spent more money.

There are many manufacturers of 2.8 to 2.9mm filament. What country do you live in? In USA I recommend printbl.com. Very good quality.

 

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BTW, I live in Hong Kong.

 

 

Oh. Then check out colorFabb maybe. They also make very high quality PLA.

 

Here is a partial list of filament providers:

http://reprap.org/wiki/Printing_Material_Suppliers

The only place listed that ships 3mm from Hong Kong implies that the filament really is *3mm* which would be a problem:

http://3dprinterczar.com/shop/filament/1kg-pla-filament/

You could ask them in an email.

 

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I got my UM2 a couple of weeks ago. Right now, I'm using the green 2.85mm dia PLA filament that came along with the machine. But pretty soon, I'll have to get other colors and maybe also ABS material. I'm based in Mumbai, India and don't have any local source/supplier for 2.85mm filaments. I could try importing, but the 42% Customs duty makes it pretty expensive. Standard 3mm filament is available from many sources locally.

So, I looked at the issues that prevent using a 3mm filament instead of 2.85mm and it seems to boil down to the 3mm filament getting stuck in the Bowden tube. Am I right ? If that is the only bottle neck, will 3mm filament work if I replace the Bowden tube with a slightly over-sized ID (maybe 3.2mm) ?

I also looked at the UM2 bowden tube in the Ultimaker shop, expecting it to be "Metric" sized with a 3mm ID (which would explain why it needs under-sized filament). But was surprised to see that they are using "Imperial" size with a ID of 1/8" (which works out to 3.175mm). So I must assume that the stock machine already comes with a bowden tube having an ID of 3.175mm. If that is the case, it shouldn't be a problem using standard 3mm filament.

Is my reasoning correct ?

Anool

 

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Welcome Anool to this forum!

I'm using 3mm filament as well as 2.85mm filament. For the 3mm filament it's necessary that the diameter does not vary. If the whole spool of material is keeping the 3mm you shouldn't see a problem with the standard UM2 bowden.

It might happen that feeding the 3mm filament to the nozzle needs some support by hand when entering the hot end, but that's the only 'problem' I saw until now with 3mm filament (in case the diameter is stable).

You have to change the material setting on UM2 (increase the diameter from 2.85mm to 3mm). It's also possible to reduce the material flow.

 

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I went ahead and bought a spool of regular 3mm ABS. The filament diameter was 2.90mm at 3 or 4 places that I measured. I'm hoping it's consistent through out the spool, but at the moment it looks good. Getting the ABS to stick was another story as it peeled off the first 2 times that I tried a print. I then rustled up the ABS-Acetone goop mixture, and applied a thin layer using a cotton bud (Q-Tip for you 'Mericans).

 

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I got my UM2 a couple of weeks ago. Right now, I'm using the green 2.85mm dia PLA filament that came along with the machine. But pretty soon, I'll have to get other colors and maybe also ABS material. I'm based in Mumbai, India and don't have any local source/supplier for 2.85mm filaments. I could try importing, but the 42% Customs duty makes it pretty expensive. Standard 3mm filament is available from many sources locally.

So, I looked at the issues that prevent using a 3mm filament instead of 2.85mm and it seems to boil down to the 3mm filament getting stuck in the Bowden tube. Am I right ? If that is the only bottle neck, will 3mm filament work if I replace the Bowden tube with a slightly over-sized ID (maybe 3.2mm) ?

I also looked at the UM2 bowden tube in the Ultimaker shop, expecting it to be "Metric" sized with a 3mm ID (which would explain why it needs under-sized filament). But was surprised to see that they are using "Imperial" size with a ID of 1/8" (which works out to 3.175mm). So I must assume that the stock machine already comes with a bowden tube having an ID of 3.175mm. If that is the case, it shouldn't be a problem using standard 3mm filament.

Is my reasoning correct ?

Anool

 

The bowden tube is bought as 1/8", however, in fabrication, everything has a tolerance. So the ID of the tube can vary, but is guaranteed to be at least 3mm.

Now, most filament sold as 3mm is actually 2.85. But named 3mm. Example, http://www.faberdashery.co.uk/ sells "3mm" but that is actually 2.85mm.

 

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When the PLA passes through the feeder it gets compressed into an ellipse such that the longer axis of the ellipse is longer than the average diameter before compression. So a 3.00mm filament might be 3.1mm wide after passing through the feeder. This is dangerously close to the 3.125 ID considering the 3.125 error is typically high (can be as low as 3.0 ID).

But typically if your filament stays below 3.01mm diameter you should be fine. In real life situations, if the diameter is nominally 3.00mm it *will* get stuck eventually and you will end up throwing it away.

Someone on the forums took a piece of sheet metal, drilled out a 3mm hole, then passed their entire reel of filament through the hole. Then they threw the whole thing away. You might want to just skip to the "throw it away" step as getting the filament out of the bowden means you might have to remove it from both ends and put it in hot water to pull out the stuck filament. The bowden is *not* symmetrical. The end at the feeder was drilled out to a wider ID. So if you remove it completely, mark which end is which.

It sound slike the filament you ordered in India is *not* 3mm but actually 2.85mm?

Don't forget to tell Cura the nominal/average filament diameter before you slice - or for UM2 you can do that on the UM2 instead under "materials" "customize" menu.

 

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We sell 2.85mm PLA (with a slight variation of 0.1mm I think) The machine excepts any PLA up to 3.1mm, but anything over 3.1 will cause jams. So 3.1000 works, 3.10001 will jam.

 

Do you work for Ultimaker @Daid ? I just thought you were some UltiNinja saving humanity one printer problem at a time!?

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