Materials

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Here is a list of parts and the materials used (or not used) on a RepRap Mendel. The goal here is to brainstorm new materials that are better for making (some part of) a RepRap -- cheaper, easier to work, easier to acquire, or "better" in some other way -- as well as to explain why particular materials succeed or fail. This page can also be used to judge the most successful materials used by the community. eventually maybe we can add some code so that we can vote for particular materials. In the meantime, just edit this page to add info or examples for both failures and successes.

Contents

Goals for this page

  • a) List all materials used and the reason for use
  • b) List failed materials with reason/theory of failure
  • c) List untested but promising materials and explain their potential.

Metals

Steel

Used to form the frame of Mendel and Eiffel, as well as for Bearings and Fasteners (bolts/nuts/washers)

  • Galvanized cheaper than stainless
  • Stainless No corrosion, low thermal conductivity 16.2 W/m*K
  • Carbon Steel cheapest, but rapidly corrodes unless painted or kept coated with oil. Thermal conductivity is 43 W/M*K

Copper

The second-most-electrically-conductive metal (after silver)[1], and so used in practically all category:electronics PCBs and wires. Coefficient of Thermal conduction of 204 to 223 W/m*K.

Aluminum

Advantages: lighter than steel and much stronger than plastic. Does not corrode very much. Conducts electricity fairly well, 61% as well as copper[2]. Easily machined. Disadvantages: heavier than plastic and weaker than steel. Has a thermal conductivity even higher (167 W/m*K) than Brass (115 W/mK). Often used in Hot End Heater Blocks.

Brass

Often used for the nozzle, or "Hot End" of extruders. Thermal conductivity is high, at 115 W/mK. Quote from Team Open Air[3]:

The reason that people started off with copper and brass is because they are EXCELLENT conductors of heat, and we want the heat from the nichrome wire wrapped around the nozzle to be conducted inside to the plastic to melt it. However, with a thin, long cylinder it is very easy for the heat to move inward, even with an insulating material for the nozzle. But the copper and brass also carry it sideways a LONG ways, requiring a long rod of PTFE or other high temp plastic to isolate the heat of the nozzle from the Stepper Motor and any electronics.

Solder

Often used for electrical connections. Lead-free solder melts around 215°C, well within the RepRap hotend temperatures. Hard solder melts at higher temperatures 230-350+°C, depending on the alloy.

Plastics

Thermoset

PEEK

High temperature plastic (143C glass transition, 343C melting), easily machined, less thermal creep than PTFE. CTC: 0.25 W/m*K

Note: The PEEK, used in Extruder Hot Ends, softens at 248C.

PTFE

PTFE, also known as Teflon, is used in Extruder Hot Ends (Nozzles) and Bowden Extruders for its low friction and self lubrication.

Caution PTFE gives of very toxic fumes when over heated.

BakeLite

High temperature plastic found in most kitchen saucepan, frying pan handles. First tried by Grogyan on his JunkStruder, material suggested by friend. Machineable, low thermal creep. Available everywhere.

Disadvantages: Prone to crack when machining scavenged material. Hot end design may have to modified to work with pre-existing shapes. BakeLite is a phenol of formaldehyde and may present a health hazard when machining.

Thermoplastics

Thermoplastics are extrudeable. (Unlike Thermoset plastics.)

ABS

A very common extruding material, most RepRaps are made of it because it melts at a higher point than PLA.

User:Nophead had some problems [4] with his Mendel X-axis carriage degrading from the heat coming off his extruder nozzle. This suggests that low temp exposure over a long time will shorten the lifetime of extruded parts. A reflective heat shield, fan, or better hot end insulator would help prevent this. The X carriage could also be made of plywood, like [5].

PET

PET

PLA

PLA

Nylon

Possible extrusion material, different types melt between 190 and 350C. Could also be used instead of PEEK and PTFE in hot ends. Often used in screw spacers, and M3 screw spacers[6] have an inside diameter of 3.2mm, perfect for a hot end barrel. Easily machined and self lubricating.

other melty materials

  • water ice (IceRap) (it's technically not a plastic, but it melts when you heat it like all thermoplastics ...)

Wood

For all pages tagged "wood", see category:wood

lumber

Fiberboard

  • LDF (low-density fiberboard) also called particle board, or fiberboard
  • MDF (medium-density fiberboard)
  • HDF (high-density fiberboard) also called hardboard or Masonite

Plywood

PlywoodRepRaps:

Glass

When used as a bed parts come off very flat, but a Heated Bed might be required. User:Mike Bushroe has successfully made Glass Nozzles. [7].

Kapton Tape

High temp tape used mainly to attach heater element to the extruder. perhaps could be replaced with PTFE heat shrink wire rap?

Caution Kapton gives off noxious fumes from the adhesive, adhesive does drip onto barrel and nozzle, making it very icky. Available from specialty vendors (and from pretty much all companies which sell 3D printer parts and kits).

Nichrome

Primary source for the heating mechanism of the extruder. Comes in two varieties, uninsulated (available mostly everywhere), insulated (fiberglass coated, difficult to acquire, if not impossible, locally).

Carbon Fiber

Carbon fiber rods and tubes in ~8mm diamater are available at mcmaster carr. They would be much lighter than steel and can be machined to similar tolerances. Steel will last longer, we must assume, but would CF Rods last long enough i.e. the life of the machine? They are cheaper as well. if true 8mm can be found in high tollernace, it would be a good experiment to try replacing the non-threaded rods with CF rod or tubing.

McMaster Carr also has Hith temp CF, which might be useful in an extruder. presumably would not transmit heat like metals, but be easier to work than glass or ceramic, yet sturdier than PTFE.

-4/6/2012- Also, carbon fiber is said to be much stiffer than metal rod. If so, it could be an improvement to the smooth rod, especially for the purpose of a wider Y axis. I'll try this out ASAP.

Material Capability Expansion Devices

State College RUG Universal Paste Exturder [8]: The State College RUG has a page with detailed information on how to build a universal paste extruder. Current materials supported by this design are:

-Ceramic -Dough -Cake -Icing -Chocolate -Sugar

There is also a new product compatible with RepRaps that allows it to use a wide variety of pastes. Discov3ry Paste Extruder [9] (currently a Kickstarter) allows printers to use a variety of pastes including:

- Nutella - Icing - Silicone - Latex - polyurethane - drywall - clay - ceramics - wood

The project is currently over 400% funded.

Materials by Part

Frame Materials

Main page: frame material

Frame Issues

Any? Not Printable?

Extruder Materials

Main page: Category:Extruders

Extruder Issues

The design ethos of the extruder should be focused on using the fewest materials and skills to construct a extruder that works consistently with multiple materials. The extruder, being the heart of the machine, can end up being a complex part. However, it seems that the part is becoming more complex in order to solve an issue with the X carriage, not the extruder.

PEEK and PTFE are being used in order to protect the extruded carriage parts from the hot end. Would it be easier to construct an X carriage that doesn't melt? For example, perhaps an all metal or plaster cast carriage, or using wood to mount the extruder but having thermoplastic parts for the x-rail bearing mounts.

The standard X carriage, with the extruder hot end directly underneath, puts the carriage directly in the hot plume of the extruder. Mounting the hot end to the side of the carriage is better but can reduce build area slightly, but could be minimized by mounting the x axis rails one-above-the-other instead of side-by-side.

To block the heat from the hot end from melting the rest of the RepRap, we require some material that can withstand that heat, but has low Thermal Conductivity. "Hot End Insulation" Early prototypes used PEEK, but there has been some discussion of alternatives ("Why is PEEK needed?").


Some people have been discussing how to make the hot end of the extruder -- or at least the insulator -- out of something that can be "printed". ("Printable ceramic hot end") Currently the most promising approach seems to be printing something out of clay, and then firing that clay to a high-temperature-resistant ceramic in kiln in a separate step.


bed materials

Main page: bed material

bearings

main page: bearing

The vast majority of RepRap and RepStrap printers (as of 2012) use surprisingly low-cost off-the-shelf ball bearings "skate bearings", to reduce friction on most mechanical motion, and PTFE (Teflon) to reduce filament friction.

Mendel Bearing Kits have 48 Bearings 624ZZ (4mm x 13mm x 5mm) and 2 Bearings 608ZZ (8mm x 22mm x 7mm). (Is there some reason a Mendel-like printer can't use all the same kind of bearings, either all 624 bearings or all 608 bearings?)

Some alternatives people have experimented with: printed PLA bushings (Prusa Mendel), LM8UU linear bearings (ABSPrusa and LongboatPrusa), printable linear bearing, Bearing clip 01, etc.

Bearing-related discussion on the RepRap forums: "skate bearings vs linear bearings", "Open sourced linear bearing", "Skate Bearings?", etc.

Bearings typically require lubrication.

materials used in other parts of a RepRap

Other materials that a RepRap is or could be made from: motors, fasteners, materials for electronics, etc.

materials a RepRap can be adapted to print out


External Links

More on Glass, Ceramics, and Carbon from McMaster-Carr. Mechanical and Physical Properties of various materials. VERY USEFUL(PDF is copyrighted, so just a link).