3mm or 1.75mm feedstock

Hi all,

I am currently building my first Reprap Mendel and just about to sort out the parts for the hot end extruder. There are obviously two sizes of feedstock (and therefore extruder) available but I cannot find any information on which to choose. Are there any benefits to using one over the other or is it just as simple as which is most easily available to me for purchase?

Cheers

Andy

As long as it comes on a spool I'm happy.

I feel 3mm is more tolerant of imperfect compression of the pinch wheel. I do not use an extruder with a spring so I rely on a fixed gap to compress the filament into the hobbed bolt. being .5mm off on 3mm vs 1.75mm is a lot less in percentage. If you have a good extruder design it doesn't really matter. I've made excellent (and poor) pints with both sizes.

The 1.75mm stuff seems to have a few inherent advantages. Less force required to push the filament through the hot end. Smaller melt volume resulting in less stringy stuff. Others I may have overlooked. The major disadvantage is that the cost is far higher per pound/kg.

1.75mm can give you slightly better results, but 3mm is far cheaper. If you aren't worried too much about cost of plastic, then I would recommend 1.75mm. Otherwise 3mm will still give you good results.

I have got all the bits to make the new 1.75mm extruder and now I can't find anyone who has this size of filament in stock. It seems it has been discontinued at a lot of places. Is this obsolete or too new to be in general use?

Are you in the US? If so, you can get some from Ultimachine, Makerbot, or Makergear. Makerger doesn't have much, but Ultimaker and Makerbot have plenty in stock.

No I am in the UK.
I did manage to get some ABS from RoboSavvy but I wanted PLA.

Can someone tell me please what exactly "optimized for 1.75mm" means. Well it should be fairly obvious but how reliable can I print with 3mm filament? It's the Orca v0.2 Mendel variant.

Problem is: the 1.75mm filament is expensive, and really expensive in Europe. The only way to obtain is is via robotsavvy which charges way to much.

So are there any experiences with that?
Any tips on where to find available 1.75mm filament in Europe would be appreciated too!

3mm ABS is very reliable.

Quote

3mm ABS is very reliable.

How can Plastic be reliable?

My point is: if the extrusion mechanism, the metal part of the extruder is made for a smaller diameter I will get no grip, and if the hot end diameter is too narrow this would cause problems as well.
So I just want to know if this could be the case...

PS: Why do I get these 'weird' responses when buying a kit / not actually building a Mendel first?
Here, in the forum and the irc channel..
Is this supposed to be some sort of elitist attitude?

Quote

How can Plastic be reliable?

One of the most important properties is how consistent the diameter is. A lot of companies quote +-10%, but that is nowhere near acceptable for FFF. It needs to be 3.0 +=/- 0.1mm. All the "3mm" filament I have bought from USA has been about 2.8mm for some reason and this causes problems for an extruder designed for 3mm. If the diameter changes during the reel you can't get consistent quality unless you measure it before every build. If it changes during a build it is hopeless.

I haven't tried 1.75mm yet, but to be the same percentage accuracy it would need to be about += 0.06mm.

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[www.hydraraptor.blogspot.com]

ElectricMucus Wrote:
-------------------------------------------------------
>Well it should be fairly
> obvious but how reliable can I print with 3mm
> filament?

I did not realize this was directly tied to your previous statement. I interpreted this as "Can I print reliably with 3mm filament?"

I now see you meant "How reliably can I print 3mm filament in an extruder optimized for 1.75mm filament?"



As an aside, If in doubt, you should probably ask the vendor, as they will be the one profiting from your purchase.

ElectricMucus Wrote:
-------------------------------------------------------
> PS: Why do I get these 'weird' responses when
> buying a kit / not actually building a Mendel
> first?
> Here, in the forum and the irc channel..
> Is this supposed to be some sort of elitist
> attitude?

Yes it is. It is pretty common in any techy group. We are all so much smarter than the average joe that sometimes it goes to our heads. (sarcasm intended) So you get a lot of "You bought what ??!?!? that bot is crap!!!" type of comments. Or "Just hack it together from spit and bailing wire, that's what I did, and I built a tripple extruder next gen mendel for $5 sort of comments. Don't let it get to you. If your time or comfort level dictate that a kit or even a prebuilt machine is your best value then stick to your guns. I bought a makerbot before I decided to build a Prusa and I will continue using it after the Prusa is built. The right answer to what "should I build" depends on how you value your time vs your money, and how you rate your own ability to learn the required skills.

Several People have reported that they have more stringing and ooze on 1.75mm than on 3mm filaments.
What is behind this?

For example there are some makerbot users having issues... [wiki.makerbot.com]
Is that more a issue due to unoptimzied software / the makerbot hardware or is there a principal disadvantage which leads to reversal not working as well?

I'd imagine that the smaller diameter leads to a smaller under-pressure being produced when reversing reducing it's effectiveness.

bryanandaimee Wrote:
> The right answer to what "should I build" depends
> on how you value your time vs your money, and how
> you rate your own ability to learn the required
> skills.

Thanks for that comment. Personally I've been building stuff out of basically scrap for many years, but at this point in my life a few hundred bucks is just a few hours of overtime at work, and even though I am perfectly confident that I could build a Mendel out of junk lying around, buy the electronics parts, heck, hand etch and drill the boards if necessary, it would be silly for me to do so, unless I'm trying to prove something.

I've been building both electronic stuff and mechanical stuff since I was a teenager back in the 80s, so I have nothing to prove to anyone, and if I can just get someone else to source all the parts for me and just send them to me in a box, I can get on to the fun bit of putting it together and starting to make stuff. Spending hours spelunking eBay and going through McMaster Carr catalogs isn't particularly thrilling to me.

I'm confident that I'll get my tinkering in when it comes time to make improvements, but I'd like to get up and running sooner.

I plan to order a complete kit sometime soon, through I am going to Maker Faire soon so I figure I might as well go poke at one in person first.

What does this have to do with the subject of this thread?

Derp advertising on forums...

I chose 3mm because that was the go to filament for Wade's. When starting out, I think it's easiest to choose the hardware with the most support though I honestly don't think it matters a whole lot because it's easy enough to switch.

I know Makerbot's new extruder (basically copied from up!) no longer supports 3 mm filament, but I haven't seen a similar switch from other groups.

---

Chris Sketch
Ann Arbor, MI
blog.chrissketch.com

We’re here to put a dent in the universe. Otherwise why else even be here?
—Steve Jobs

I have used bothe filaments, and have found no difference in the price where I buy it from, reprapworld.com
I used 3mm stuff for ages and found it very very hard to work with. Filament that thick wound on a spool just doesn't come off easily giving you feed problems. Sometimes with different colors the plastic can snap and break when coming off the roll because it is so tightly wound. I have many rolls of wasted 3mm plastic because the inner tightly wound part of the roll can't even be used as it makes a tight circle around the spool.

On the other hand I switched to 1.75mm filament and it is great, I would defiantly recommend it. It just works! Plain and simple easy to feed, a lot less pressure on the nozzle and no problems with tightly wound plastic!

Personally I would always sudjest 1.75 mm, I would really like to see more all metal hotends designed for this filament such as the prusa nozzle! The budashnozzle works great with 1.75mm

and your website is....

this is partly why i am starting to feel sorry for the forum moderators here, i think he is just someone looking for a quick buck.

dissidence Wrote:
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> this is partly why i am starting to feel sorry for
> the forum moderators here, i think he is just
> someone looking for a quick buck.


and if you contact them you find their MOQ start a 1000kg, which is tottally useless for 99.99% of the people on here anyway

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-=( blog )=- -=( thingiverse )=- -=( 3Dindustries )=- -=( Aluhotend - mostly metal hotend)=--=( Facebook )=-

nophead Wrote:
-------------------------------------------------------
> How can Plastic be reliable?
>
> One of the most important properties is how
> consistent the diameter is. A lot of companies
> quote +-10%, but that is nowhere near acceptable
> for FFF. It needs to be 3.0 +=/- 0.1mm. All the
> "3mm" filament I have bought from USA has been
> about 2.8mm for some reason and this causes
> problems for an extruder designed for 3mm. If the
> diameter changes during the reel you can't get
> consistent quality unless you measure it before
> every build. If it changes during a build it is
> hopeless.
>
> I haven't tried 1.75mm yet, but to be the same
> percentage accuracy it would need to be about +=
> 0.06mm.

I've recently started measuring a lot of 1.75mm filament, and although most is "in spec" it's tolerance for most of it varies within that tolerance a lot even locally I.e. you'll see the extremes of the quoted tolerance within 1M of filament, the one exception to this I've seen is Ultimachine which on the material I've measured is MUCH better than the quoted tolerances.
Also worth noting that for whatever reason PLA is generally worse than ABS in this respect.

---

___________________________________________________________________________

My blog [3dprinterhell.blogspot.com]

Polygonhell Wrote:
-------------------------------------------------------
> nophead Wrote:
> --------------------------------------------------
> -----
> > How can Plastic be reliable?
> >
> > One of the most important properties is how
> > consistent the diameter is. A lot of companies
> > quote +-10%, but that is nowhere near
> acceptable
> > for FFF. It needs to be 3.0 +=/- 0.1mm. All the
> > "3mm" filament I have bought from USA has been
> > about 2.8mm for some reason and this causes
> > problems for an extruder designed for 3mm. If
> the
> > diameter changes during the reel you can't get
> > consistent quality unless you measure it before
> > every build. If it changes during a build it is
> > hopeless.
> >
> > I haven't tried 1.75mm yet, but to be the same
> > percentage accuracy it would need to be about
> +=
> > 0.06mm.
>
> I've recently started measuring a lot of 1.75mm
> filament, and although most is "in spec" it's
> tolerance for most of it varies within that
> tolerance a lot even locally I.e. you'll see the
> extremes of the quoted tolerance within 1M of
> filament, the one exception to this I've seen is
> Ultimachine which on the material I've measured is
> MUCH better than the quoted tolerances.
> Also worth noting that for whatever reason PLA is
> generally worse than ABS in this respect.

it's really dependant on where are you get it from 90% percent of the filament we get is repraper.com stuff, if i get it from a reseller it's pretty good stuff, and maintains a pretty tight 1.72 to 1.78ish where as if i order it directly from repraper.com i simply don't get the same stuff and the tollerance becomes a joke in the forms of lumps,and broken spools

---

-=( blog )=- -=( thingiverse )=- -=( 3Dindustries )=- -=( Aluhotend - mostly metal hotend)=--=( Facebook )=-

3mm with a 0.5mm Nozzle is great.
But when you get down to 0.35mm Nozzle, people seem to get a lot more jamming problems when using 3mm.

Understandable, as you are trying to force a wider diameter filament through a smaller hole.

But in order to push out the same volume of plastic, the 1.75mm extruder needs to turn a lot faster, depending on whether your extruder is geared or not, and the limitations of the speed of the stepper/electronics could be an issue.

So I don't think it's an issue of if 3mm or 1.75mm is better.

It's an issue, of what's best for your Nozzle Size and extruder you have selected to use.

From a standard material availability standpoint, 1.75mm vs 3mm seems to pretty much be approaching equality. Some shops offer more colors in one size while others have more stock of the other size.
However, 3mm still has a broader selection of materials by means of plastic welding rod.
My current machine has got a 1.75mm extruder, but because I want to experiment with e.g. HDPE, the next one will accept 3mm.

And soft materials will probably need to be 3mm to avoid buckling in the extruder. On the other hand very brittle materials like acrylic need to be ~1.75mm or less in order to be able to spool them in a reasonable diameter.

---

[www.hydraraptor.blogspot.com]

I am overthinking my next Reprap, I am leaning towards nopheads Mendel90, but I would like to put in a bowden extruder.. 3mm or 1.75 better?..

3mm is also fine by me, but I was thinking maybe the Bowden would work better with 1.75?