Rroofl

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Crystal Clear action run.png
RepRap Out Of FabLab (RROOFL)

Release status: Development

Rroofl axes complete.jpg
Description A Mendel variant designed specifically to be made in a FabLab
License GPL
Author VikOlliver
Based-on Sells Mendel, Prusa Mendel, Community improvements
Categories Mendel Variations, LaserCut, RepStrap, XZ-head
CAD Models
External Link


"Don't like society? Print a new one." - Vik Olliver http://diamondage.co.nz


Contents

Overview

This RepRap/RepStrap variant is designed to be produced in a FabLab, and yet to be sufficiently modular to produce using a variety of local manufacturing processes - lasercutting is not necessary. It is rather unfriendly to the lone user in its present configuration, as it (a) will make use of all the available CNC-type devices in the workshop in parallel and (b) doesn't work yet. It sprang out of a 2-day session organised by User:VikOlliver and about a dozen hard-working volunteers at FabLab8 in Wellington, New Zealand. They are invited to add their names to the list when they find out about this page :)

Actual build volume currently 250mm x 310mm x 200mm in the lasercut version, about 190mm x 230mm x 160mm in the M8 frame printed version.


Build One

Not quite there with the full user-friendly documentation yet. Links to build instructions such as they are:

Design Objectives

  • Fabricate mechanical hardware in 1 person-day.
  • Absolutely no fiddly bits.
  • Completely Open Source
  • As many parts as possible to be able to use more than one fabrication technique.
  • All routing cuts at least 6mm wide.
  • No little extra bits to bolt on - minimize part count.
  • Widely available aluminium tube (we used 9.5mm) or steel wire can be used as Z guide rails.
  • If you do use bolts and threaded rod, either M3 (essential for the NEMA17 anyway) or M8 (or 5/16" and Sudo Mallet at a pinch) please.
  • If a zip tie or woodscrew does the job instead of 8 screws, 4 nuts and 16 washers, use one.
  • Common parts only.
  • Allow for alignment even with lots of variation in user-cut parts like the rods.
  • Modular design that can be mass-produced, and reused/recycled in other devices.
  • Control systems capable of being scaled to drive other workshop equipment.
  • Runs off 12-14V DC to be friendly to small, local, power generation systems.
  • There is but One True Bearing: the 608Z "skateboard" bearing. Rroofl and the extruder together need an astonishing 14 of them.
  • Hold oily bits in non-lasercut cavities as oil destroys MDF.

Current Status

Development of a lasercut version is in progress. The laser restricts the material thickness to basically 9mm MDF, which is not exactly a favoured building material.This requires reinforcement of some parts of the frame to damp vibrations. Also, neither M8 nor M3 fasteners are appropriate and specific M6 MDF fasteners are highly recommended.

(Are you recommending standard M6 nuts and bolts and washers, or are you recommending some other MDF-specific fastener that happens to be 6 mm ? What exactly are the disadvantages of 9 mm MDF ? What exactly are the advantages of 9 mm MDF -- i.e., why are you using it anyway in spite of those disadvantages ? Perhaps the MDF page or the Materials page would be a better place to discuss these questions and their answers.)

The Original Rroofl



Electronics

Prototype rroofl electronics.jpg
Electronics are assembled and working well. Stepper motors are Sparkfun NEMA17's and some beefier ones scrounged from Massey University, Wellington. Drivers are a mix of EasyDriver V4's and Makerbot V3.3's and connect to an Arduino 1280 Mega using mostly commercial jumper leads. Connectors and lead lengths are a nightmare, so we need to rationalise this into something that suits the inventory. It is important that we use screw terminals instead of proprietary plugs wherever we can, so pin spacing on stepper motor board through holes ideally needs to be 5.08mm (0.2") all-in-a-row.

There are no fixed or special electronics, though they must be designed to run of car batteries and donkey-powered generators etc. Not only does this make the printer capable of running on homebrew power, it ensures that they will continue to run in the event of natural disasters. Just put an automotive electrical lighter plug on the power lead and you can run it in the car. Do remember that the spring goes under the fuse in those things, not on top of it (otherwise the spring melts).

One option being explored here is the use of an inexpensive breadboarding panel as a universal parts interface and bodging board. No soldering required, it encourages tinkering, and simplifies things when you blow a pin on your Arduino - just move the connector and recompile. OTHO a cat can wreak havoc with it. The Du Pont jumper/connectors seem resistant to normal vibrations and movement.

Zero endstops are all implemented with microswitches. a 10K resistor pulls the relevant input low, closing the switch makes it go high. There are no max limit switches.

The stepper motor driver's STEP & DIR leads must not be longer than about 200mm. Otherwise they start to pick up weird signals from outer space and use your nozzle as a kind of Ouija board.

When cable paths are established, we need mounting holes for cable ties so we can tidy them up.

A stepper motor module capable of driving 2A and made from FabLab inventory is being designed. Hopefully with sane connectors!

Spiral cable tidy is one option for constraining the cabling, and it is at least reusable.

Files

Please link or add your files here, folks.

Guide to the filenames and intended arrangement of the Z-axis

Note that the Y axis brackets are replaced with zip ties in the prototype. If it works, why not? It looks likely that we will need to brace the frame across the top. In the prototype this is done with M8 threaded rod.

File:Rroofl Z-axis Assembly-Blender257.zip The archive included here contains the assembly model for checking gear meshes and interference. This model has been used to create the STLs listed on the image. Stand-in geometry for switches, motors, and gears have also been used to help in the design process. - updated 28th October 2012 by User:BouncyMonkey

File:Rroofl Z-axis STLs.zip The image above will guide you to the appropriate model contained within this archive. - updated 28th October 2012 by User:BouncyMonkey

Note that the tops of the M8 Z drive screws should not be overly constrained, so the bearings allowed for there will seldom be necessary.

Rroofl x idler end.jpg
The X Idler & Motor Assemblies. The slots in the sockets for the X rails allow for final tensioning and/or clamping, so the rails do not have to be cut with a precision of higher than 6-7mm. Ensure one end of each rail is pushed as far as it'll go into a socket. After assembly, take up the slack with one of these:

Proper Method: The outside of the socket is tapered. Using an approx 16mm M3 screw, 2 M3 washers and a nut, tighten immediately behind the end of the rail, right through the slot in the rail's socket.

Ghetto: Loop a zip tie round the front of the socket and through the aforementioned slot. Tighten zip tie so that it is snug behind the end of the rail.

Other Printed Parts

Rroofl y carriage complete.jpg
File:Y bed runners.scad The Y runners. It would be great if someone could vector this to cut on a laser. Print two of these and join with a couple of 140mm lengths of M8 studding, nuts and washers. Ease the frame into shape on the rails before fully tightening. Y Slider legs can be compressed with a bolt or zip ties if it is necessary to level the bed. The actual deposition bed is attached by using small double-sided foam adhesive pads. Clean the bed before sticking pads to it.


Rroofl y carriage belt.jpg
The Y belt is attached with zip ties; Make loops in the belt ends and secure with zip ties. Thread another zip tie through the small holes in one side of the leg of the Y carriage, pass it through the loop in the belt and then use to tension the belt to your requirements. Note that if you leave a large loop of zip tie this introduces unwanted springyness, so you'll have to cinch it with a zip tie or two.

Another good trick we've tried is to use a cable tie to hold one end loosely in place, but tension up the belt and clip it against one of the central supports with a medium bulldog clip from the stationery cupboard. Either way it pays to do that before you stick the bed in place with the foam tabs.
File:Rroofl.inc Common measurements. Based on Simpleton's include file so lots of crap in it.

File:X axis bits.scad OpenSCAD file for the x-axis parts. Needs File:Rroofl.inc. Contains the X Axis Idler and Motor Traveller Ends, which are also the Z axis sliders. Yes, we know the belt goes right over the top of the Z stop adjuster screw hole. We're moving it and the microswitch a bit. You can still make it work.

File:Printed rroofl stls.zip Contains historical printable STLs used in the prototype X, Y & Z axis.

Rroofl mendel prusa adaptor.jpg
File:Rroofl mendel adap.scad Printing 4 simple blocks (dark green parts in the accompanying image) with M8 holes at right angles allows the entire Z axis mechanism to be ported onto old Mendel and Prusa frames. The Y Sliders are also perforated in several places to make the attachment of a belt easier in such retrofits.


??? http://www.thingiverse.com/thing:85198 ??? How is this related to the above files?

Basic Rules of Engagement

Any rules or warnings that should be established before using the Rroofl can be included here. For example, a safety related tip would definitely make a good addition to this section (thanks for the reminder, OHM).

  • Do touch, but touch responsibly.
  • During assembly, look out for sharp bits of wire in the edge of the belt. They hurt.
  • Do not ever unplug/plug a stepper motor with the power on. It kills the driver.

Ongoing Development

Pronounced roofle, like rifle with an oo in it.

We need to sculpt the lower edges of the bottom of the sides slightly, to reduce contact with bench.

Rroofl is under active development at Diamond Age Solutions Ltd http://diamondage.co.nz with the first 3 Alpha kits being assembled, and the first client used the workshop to build it in. These have been popular and the run will be extended, pushing the Production of Beta kits out to February 2012. Supervised workshops are available on-site for advice and customisation, allowing the user to craft the design to their own requirements in the Fablab as long as they document the design under the GPL here.

See Also