Mendel90

From RepRap
Revision as of 16:47, 5 March 2012 by AdrianKelly (talk | contribs)
Jump to: navigation, search
Crystal Clear action run.png
Mendel90

Release status: Experimental

Mendel90-front.JPG
Description
A Mendel with flat sheets at 90 degree angles
License
Author
Contributors
Based-on
Categories
CAD Models
External Link

Mendel90 is being designed by Nophead to replace many of the threaded rods and printed parts of the Prusa Mendel with flat sheets, either MDF or Acrylic.

Advantages

Compared to the Prusa Mendel, which it is based off of.

  • Fully parametric across build area, motor size, rod size, and sheet material. You can customize all the parts and increase the build area, and the OpenSCAD model will reflect it
  • Stiffer, especially in the X Direction, so it can go much faster without vibration
  • Much less calibration and jigging required; if your holes are in the right places, your rods will be parallel. If the buttresses are square, your printer will be square.
  • Can be drilled with a paper template to make sure all holes are perfect
  • Sheets are usually straighter and flatter than rods, as they are thicker and much wider
  • Everything is mounted on one of two planes, so it's all flat
  • Frame is held together throughout the machine, instead of just at the corners, so much less warping
  • Fewer vitamins
  • Open frame design, allowing it to be worked on easily and mostly disassembled without falling apart
  • Z axis motors are at the bottom, so that the couplings don't need to support the weight of the X axis
    • The Z couplings can be smaller, and therefore the Z smooth rods closer to the threaded rods, increasing stiffness
    • The center of balance is lower, making it more stable
  • Less printed parts, so it can be printed easier and faster
  • Parts are ribbed to maintain strength and decrease print time
  • Ribbon cables are used to prevent cable tangling and friction
  • Rectangular, so it can be shipped and put in Heated Build Chambers easier.
  • Uses LM8UU bearings
    • Uses 10 instead of 12, so only one package is needed
    • Fewer bearings make it less susceptible to problems with overconstraint
  • Heavier and stiffer construction makes it more resistant to decalibration due to transportation.
  • Less need for adjustment

Disadvantages

  • If you drill a hole wrong, it is much harder to fix than to adjust a nut on the Prusa Mendel
  • Less room for adjustment-only a few mm
  • MDF expands with heat, though less than steel, and also with moisture. Acrylic cracks. MDF could be sealed to slow response to changes in humidity.
  • OpenSCAD files have not been released as of March 5, 2012
  • More volume of vitamins-sheets are larger than rods
  • Probably heavier and harder to ship
  • More types of screws
  • Louder because sheets act as soundboards
  • Fewer bearings might make it less accurate
  • Ribbon cables cause electrical interference, false positives in the endstops and inaccurate thermistor readings.
    • Possible solution would be to tape a shielded cable with all the power wires in it to the ribbon cable

Development

The Mendel90 is being designed solely by Nophead, and he has shared his design through his blog and Thingiverse. He has made one prototype, out of 12mm MDF and 10mm rods. It has a build area slightly larger than the Mendel (214x214x150), and he is working on another prototype of 6 and 10mm acrylic and 8mm rods, with the same build area as a Mendel. This design is the one that all the files released on Thingiverse belong to. Before Nophead released the STL files through Thingiverse, Stevetronics worked on making his own version from the pictures on Nophead's blog, first in Solidworks and then in OpenSCAD. AdrianKelly is working on making a wooden Repstrap based on the Mendel90.

Nophead says he will put his OpenSCAD files on Github, but they are not up yet.

There are STLs linked below for a 8mm rod version with NEMA17 motors, T5 belts and an acrylic frame. They are copied directly from Thingiverse.


Bill of Materials

Printed Parts

STLs are links to Thingiverse, how do I upload them to the wiki instead?

Required

Quantity Description File Diagram
1 Bar Clamps stl Mendel90-bar clamps.jpg
10 Fixing Blocks stl Mendel90-Fixing block.jpg
2 Pulley stl Mendel90-pulley.jpg
1 X Motor Bracket stl Mendel90-x motor bracket.jpg
1 X Idler stl Mendel90-x idler.jpg
1 X Carriage stl Mendel90-x carriage.jpg
1 Y Motor Bracket stl Mendel90-y motor bracket.jpg
1 Y Idler stl Mendel90-y idler bracket.jpg
1 Y Bearing Mounts stl Mendel90-y bearing mounts.jpg
1 Y Belt Anchors stl Mendel90-y belt anchors.jpg
1 Z Motor Bracket stl Mendel90-z motor brackets.jpg
4 Z Coupling stl Mendel90-z coupling.jpg

Modified Wade's Geared Extruder

Quantity Description File Diagram
1 Extruder Body stl pic
1 Extruder Idler stl pic
1 Small Gear stl pic
1 Large Gear stl pic
1 Gear Spacer stl pic
1 Cable Mount stl pic

Optional

Quantity Description File Diagram
1 Fan Guard-If you have a fan stl Mendel90-fan guard.jpg
1 Cable Clips stl Mendel90-Cable clips.jpg
2 Z Pointer stl Mendel90-z screw pointer.jpg

Non-Printed Parts ("vitamins")

All measurements are in millimeters. Should this be a table instead?

 1 Sheet 468 x 432 x 10
 2 Sheet 170 x 324 x 6
 1 Sheet 224 x 224 x 6
 1 Sheet 468 x 324 x 6
 4 19mm bulldog clip
 3 624 Ball bearing 4 x 13 x 5, 1 for X idler, 2 for Y idler
 3 608 Ball bearing 8 x 22 x 7, for extruder
22 M3 cap screw x 10
22 M3 cap screw x 16
17 M3 cap screw x 20
 4 M3 cap screw x 25
 2 M3 cap screw x 30
 2 M3 cap screw x 45
 4 M4 cap screw x 20
 2 M4 cap screw x 40
 1 9 way D plug
 1 9 way D socket
 3 M3 grub screw x 6
 1 borosilicate (Pyrex) glass sheet 214 x 202 x 2
 5 M3 hex screw x 16
 2 M4 hex screw x 20
 2 M4 hex screw x 50
 1 M8 hex screw x 60
10 LM8UU
 5 NEMA17x47.5
 1 PCB bed
 1 polypropylene strip 373mm x 17mm x 0.5mm
 1 polypropylene strip 320mm x 27mm x 0.5mm
 1 polypropylene strip 275mm x 29mm x 0.5mm
38 M4 pan screw x 12
24 M4 pan screw x 16
 1 Smooth Rod 8 x 22, for extruder idler
 3 Smooth Rod 8 x 275, 2 for Z axis, 1 for Y
 2 Smooth Rod 8 x 382, for X axis
 1 Rod 8 x 428, for Y axis
 2 Threaded Rod 8 x 211
 2 Tubing OD 7 ID 5 x 16
12 No2 pan wood screw x 13
 6 ziptie 87
 1 belt T5x6x674
 1 belt T5x6x861
 4 hex pillar M3x20
 3 microswitch
 6 nut M3
 2 nut M4
 3 nut M8
45 nyloc nut M3
 6 nyloc nut M4
 2 rubber washer M3 x 9.7 x 1.5
 1 spring 12 x 0.75 x 10
 2 spring 7 x 1 x 10
18 star washer M3 x 7 x 0.5
53 star washer M4 x 9 x 0.9
12 washer M2.5 x 5 x 0.5
79 washer M3 x 7 x 0.5
78 washer M4 x 9 x 0.9
 4 washer M5 x 20 x 1.4
 1 washer M8 x 16 x 1.5
 2 wingnut M4

See Also

Category:Development