1.75 mm vs 3.00 mm

How can you do both filament diameters in the same hot end? if I put even a slightly smaller diameter (2.75 vs 3) filament in my extruder the molten plastic will flow back up the relatively empty channel and create a block. It extrudes great for the first minute then stops completely. Whereas applying 3mm to a 1.75mm hot end would create way too much back pressure...

Yeah i have to change lining on the budaschnozzle from 3 to 1.75 or what ever I'm using, and should be possible to do on most hot ends

Edited 1 time(s). Last edit at 11/17/2013 07:16PM by nechaus.

I personally use 1.75. I like the look of 3mm better, but thats no good reason at all. Im about to build another printer and im going to use 1.75.

Professional FDM machines (Stratsys/3D systems) use 1.75, so i figure they probably have pretty good reasons for doing so...


-Nick

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N314
Professional FDM machines (Stratsys/3D systems) use 1.75, so i figure they probably have pretty good reasons for doing so...

Just for the record that is a terrible reason to do anything. Companies don't actively try to make their machine work better. Their only motivation is to design something so they can make more money. Maybe in some cases a better machine equals making more money, but usually not.

I would guess the reason they use 1.75 is so you have to buy their filament, since if they used 3mm then you could use plastic welding rod (which is 3mm in diameter and much, much cheaper than the stock stratasys filament). Of course I am talking about a time before reprap 1.75 mm filament existed.

From what I've read region plays a part. In some places 3mm filament is cheaper than 1.75mm filament. I think this is a combination of the fact that 3mm is easier to produce and in some areas it is more readily available so the supply side is pushing down the cost. I'm not seeing a large difference in price here in the United States. I've been using 1.75mm at work but I'm building my machine at home to use 3mm.

Here's my reasoning; if the filament is roughly twice the diameter the machine will have to pull half the length of filament for any given print. I'm cutting down the spool movement by half. I'm cutting the changes of the filament jamming on the spool in half. Less mechanical movement for the same job is always better.

From what I understand the only cost is that 3mm is stiffer. I imagine if I were printing in a detached building in a cold environment that would be a factor but I think printing in those conditions would be less than ideal in the first place.

A lot of commercial machines are using direct drive extruders that can only handle 1.75mm. Cost is a factor for the company producing the machine. Think about what goes into a wades extruder; 3 bearings, two gears, and a drive pulley (hobbed bolt). What goes into a direct drive extruder; one bearing and a drive pulley. When you produce a million units those bearings and gears add up.

If the trend continues eventually 1.75mm filament will win the day. Even if it isn't the practical choice commercial demand will increase the supply of 1.75mm and 3mm will be more expensive as suppliers re-tool.

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destroyer2012
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Just for the record that is a terrible reason to do anything. Companies don't actively try to make their machine work better.
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They do when they're competing. Still, it's not a good reason to make a choice when you can try to understand the design criteria yourself.

Linear filament required changes with the square of the diameter. All your doubling examples should have factors of 4.

Spool movement and tangles on the spool are a non-issue for my spool. I don't know what you've got going on. I don't think mine is remarkable in any way.

Dale,

I've got goin on whatever the producer gave me on the spool. Nothing more and nothing less. Is filament tangled on the spool? Sometimes. You betcha. The more I can reduce my margin of error the better.

Edited 1 time(s). Last edit at 11/19/2013 09:53PM by Dorian.

Yikes! Maybe I've been spoiled. All my spooled filament has come from Protoparadigm, and it's been great. The stuff I spooled myself from coils was another story.