We have a markforged mark one printer with our school for research. We were trying to print carbon but eiger only has the option for concentric fiber rings, but kevlar has options like isotropic and full fiber fill options. We were wondering if we could set up the printer with kevlar settings but load carbon fiber, and we tried it and behold if failed to print the fiber. But the print head temperatures are the same and the fiber diameters are the same, so what changes between the printer when you change fiber settings? would printer carbon fiber on the fiberglass setting work? Has anyone tried this too? We are trying to learn as much as we can for our research, so any advice will be welcome
3 Likes
CF is alot more stiffer and will not be able to make those sharp turns.
Artiz
3
Like you I really struggled with the MarkOne to get it to print the carbon where I actually wanted it. I then discovered it can only print the carbon in long lengths which made it a bit too specialised for my liking. This printers concept is to lay the carbon fiber down in lengths so as to add rigidity and strength to the nylon part. Basically when using the carbon it can only print nice big long things which donāt bend and Iām afraid thatās about it. I took it back within 14 days and got an Ultimaker 2 Extendedā¦ havenāt looked back sinceā¦
MarkTwo looks better but please donāt quote meā¦
idk melted carbon fiber shouldnāt have any stiffness at all to it, I have a hard time believing that is why the printer isnāt pushing out the carbon fiber when the kevlar settings are turned on. I just what to know what is different with the printer between when the carbon settings are turned on and the kevlar settings are turned on, or glass for that matter
ya i think the big myth with 3d printing is that you can click a few buttons and you are able to print anything you want regardless of design, but the 3d printing process with all printers has its limitations, whether it is accuracy, support material, strength of the part, etc. I am just trying to works with this printer that we have and am interested to find out what the printer does differently when using different fibers, cause to me it seems an awful lot like it does the same thing regardless of whether it is using kevlar, glass, and carbon fiber. however, kevlar comes out on the kevlar setting and carbon does not even though the print head is the same temperature.
Also I donāt really understand the difference between the mark one and the mark two, except they say the mark two can print faster of something. but it doesnāt seem like they changed the hardware a whole lot, I could be wrong
Artiz
6
Presumably its Eiger that will not allow you to do thatā¦ as I said above the software will only print the carbon in long lengthās and I assume that when kevlar or glass settings are selected the software by default will not allow the carbon to extrudeā¦ I only had mine for a week so Iām certainly no expertā¦ itās probably better to ask your vendor or better still the manufacturer.
Artiz
7
I think you are probably rightā¦ personally I think thereās a lot of āsmoke & mirrorsā surrounding this printer and I was very glad to have got rid of itā¦
Iāve not run this machine, but did look at buying one last year to compliment our other machines, so understand the fundamentals. When you load carbon fibre, (and use Kevlar settings) does it know which material is loaded?
Artiz
9
only if you havenāt surreptitiously switched the labels on the filament spools 
joking of courseā¦ I think itās more to do with your design and the Eiger (software) settingsā¦ if you are trying to print something smaller than the default length/parameter for carbon printing then the carbon will simply not printā¦ and it doesnāt tell you that it wonāt either so you just end up with a nylon model. Also no one actually tells you that when you buy it.
P.S. Also donāt forget that the filaments are proprietary and very expensiveā¦ Ā£200 for nylon and Ā£120 for carbonā¦
I think youāre right. There are some restrictions on where it can apply the carbon strands. Itās a fantastic concept, best suited to thicker geometries. Out of interest, how do those prices equate to Ā£/kg?
obviously i think that you are spot on: iāll probably have to call markforged and ask them myself, which shouldnāt be too difficult. However i still donāt think that is the issue either because my ātest partā that we have been working with (a super basic rectangular prism) certainly works with all different fibers in all different directions. Iāve already printed kevlar in the isotropic settings with this part and it works fine. however as soon as i unload the kevlar, load the carbon and change nothing else, all of a sudden it is not printing the fiber. It tried to load the fiber and extrude it (the fiber tube is transparent so you can see exactly what is going on with the fiber) but when the fiber reached the nozzle it stopped and no fiber was coming out of the nozzle. I donāt know why it would do this, but again it was working with the kevlar originally so the mystery continues
Artiz
12
āEach MarkForged Nylon filament spool contains approx. 1000cm3 of material.ā
"Each MarkForged Carbon Fibre spool contains approx. 50cm3 of material."
I do still think it has its unique uses thoughā¦ its moreover that they are trying to sell it as a consumer multi-use type printer which from my experience it is notā¦ as part of a 3D print farm it may well be invaluable but it is still pretty much model/design specificā¦ looks absolutely amazing in your front room/office if youāre looking to impress of courseā¦
Artiz
13
That is interestingā¦ maybe it does actually have some kind of sensor fitted because they knew we would try to do exactly what you are attempting to doā¦ would definitely be interesting to find out the response from MarkForgedā¦ keep us updated.
Perhaps you really should try surreptitiously switching the labels on the filament spools 
Carbon Fiber is too stiff to make the sharp turns that the machine can make with either fiber glass or Kevlar. Hence the reduced options in the Carbon Fiber menu.
I was a bit disappointed by this as well with my Mark One. Pretty sure the limitation is due to the brittle nature of carbon fiber. Dig into you composites text books. You will find that there is a minimum radius of curvature that you can bend a brittle fiber around before it breaks. It is a function of the individual fiber diameter, modulus, and strain capability of the fiber. Markforged does not really tell you what the exact fiber they use. So exact fiber modulus, fiber diameter, strain capability are hard to come by. Isotropic Fiber mode has to bend the fiber around a very sharp radii after each pass. The fibers would likely break at every pass and jam up the extruder. Looks like the Mark Two can run in Isotropic Fiber mode to put down discrete fiber orientations. I think the Mark Two keeps the chamber hotter which might help keep the tow bundle from breaking. They also put the fiber cutter much closer to the extruder so the minimum cut area is 15x smaller per their literature. The cutter location distance to the extruder on the Mark One dictates the minimum filament length that has to be put down. The Mark Two might be able to cut the fiber at each pass before it changes direction eliminating the need to bend the filament. Havenāt seen the Mark Two in action yet, so I am only hypothesizing.
Well said, this is by far the best comment on the thread. I would only add an extra tidbit. The Mark one has a distance of just over 600mm between the cutter and the extruder. I believe the distance is 45mm on the Mark two.
That 3DXMax stuff is basically Nylon loaded with carbon fiber dust. It wonāt even come close to the structural performance (stiffness and strength) that the Mark One or Two can deliver with continuous fiber. There is actually a fiber cutter in the Mark One and Two to cut the fibers.
Artiz
18
But if that was the case regarding the carbon nano-fibers breaking then all other carbon filaments would also have had the same issue regarding minimum radius of curvature?
I do however think we are all being slightly āhoodwinkedā with so called ācarbon fibreā 3D printingā¦ it does give nice results regarding print accuracy, warping and rigidity but strength doesnāt seem to be particularly elevated in any of my prints. Possibly even more brittle than some materials I have used.
One thing I did very much like about the MarkOne was that it could produce some epic nylon printsā¦ very strong and very beautiful but for Ā£5000 far too expensive to say the least.
Artiz
19
you sound slightly irritatedā¦ I did add/say no offence intended and I did actually mean itā¦ the MarkOne was a marketing triumph for MarkForged because it clearly funded MarkTwo with all of its absolutely critical upgrades. When I got that beauty home I was totally in love with itā¦ after a week of trying to print with it I felt totally ripped offā¦ Iād be disappointed with myself if I was not frank and honest here now that I have entered into a discussion about this printer.
Expensive marketing strategies can clearly go a long way.
Have to disagree with you on the weaving giving the strength to carbon fiber part. The weaving process actually degrades the basic structure performance of CFRP. Precisely because you are bending fibers when you weave it. A laminate of the same fiber and reinforcing plastic made from individual unidirectional layers will always be stronger and stiffer than a woven material. Looks pretty for car hoods though.
These machines are not putting down fabric.
http://www.seattletimes.com/business/boeing-aerospace/massive-speedy-robots-ready-to-build-composite-wings-for-boeing-777x/
1 Like
