3D printers

Preamble

After having purchased a number of parts made by 3D printers, and seeing that the DIY printers are controlled by Arduino Mega boards, with a RAMPS 1.4 shield, I thought that I would look into them.

There are any number of expensive 3D printers, with prices ranging from £400 up to the multiples of thousands. However, there is an Open Source community around the 3D printer movement, which has readily available designs which are free and relatively inexpensive.

The featured image above is from Review and build instructions for the Sintron Reprap Prusa i3.

Built from waste

Do you want to build a 3D printer for £40, have some old printers and CD/DVD drives hanging around and are willing to rip them apart?

Parameters

It is important to know what you want from your 3D printer, with respect to:

  • Build Volume – this can range from 200 mm3 to 200 mm x 300 mm x 200 mm, or higher.
  • Print Bed (Build Area) – in the case of the Prusa i3 this ranges from 20 x 20 cm (v 2.x) or 20 x 30 cm (v 4.x)
  • Rigidity – this is very important, but the more rigid, and better, the frame is, the more it will cost, as it will depend upon which materials are used. See Frames, below.
  • Dual extruders – do you want/need the capability of having dual extruders?
  • Materials – which materials do you want to print with: ABS (toxic vapours) or PLA (eco-friendly), or both?

Frames

The frames are commonly made from ACP (dibond), MDF, wood/plyboard, Acrylic, Aluminium (sheet or profile) and Steel. Acrylic frames are not very sturdy, and the stiffness/rigidity of the frame is very important. P3 steel is, arguably, the best material to use, see “Original” Prusa i3 kit VS REPRAP Mendel Prusa i3“Original” Prusa i3 kit VS REPRAP Mendel Prusa i3 and Disadvantages of acrylic frames.

RepRap

One of the most popular of these open source designs is the Prusa i3, wiki, which is based on the RepRap printer. However, there are many other variants of the RepRap design, as this is one of the most hackable and inexpensive 3D printers that there is.

See 3D Printer, which one is the best?

Variants of the RepRap

There are too many variations of the RepRap printers to give a complete list, but some of the variants are:

  • Wilson
    • Wilson II (Build area 20 x 30 cm)
    • Wilson RS (Build area 20 x 20 cm)
    • Wilson TS (Build area 20 x 20 cm)
  • LulzBot
    • Taz 6
    • Mini
  • Mendel
  • Prusa i3 –
    • There are many variations of this popular design, but considering only the P3Steel variants:
      • v. 2 (Build area 20 x 20 cm)
      • v. 2.5 (Build area 20 x 20 cm)
      • v. 4 (Build area 20 x 30 cm)
  • Prusa Mendel

Mendel Links

Info

From a contact, who has a 3D printer

As for my printer, I built myself a Wilson TS from self sourced parts, check out the following links:

http://reprap.org/wiki/Category:Wilson
https://github.com/mjrice/wilson

I would say it’s a variant of the Prusa I3, a design which looks to have become very popular with many kits being available. I would say they are both great printers but typically need a bit of tinkering to optimise them. A colleague of mine built a Geetech Prusa I3 kit and found it to work fairly well except for a few issues that produced artefacts in the prints similar to something called ‘z-wobble’. This happened to be due to the z-axis leadscrews being slightly bent which forced the linear rails to bend!

As for choosing or recommending a printer, it mostly comes down to budget, experience/confidence and ease of use/time available… Are you happy spending time learning and improving the machine? Or do you want an out of the box, ready to run experience? I found the learning, sourcing parts, building and calibrating to be a worth while project that helped me aid my colleague in improving his printer’s performance, but that’s the part that takes time.

From another eBay vendor

I use Ultimakers and Airwolf printers, expensive, but do a very good job….

From what I have seen and read lately, the Prusa V2 is a good printer,although it is still a big learning curve to get things right. Plus knowing what to do when something goes wrong, but it is all out there on the internet. Just a matter of going though it and sorting out what is bad advice and what is good…

Wilson

Looking at the Wilson, there are a number of versions:

  • Wilson II (Print bed: 20 x 30 cm);
  • Wilson RS (Print bed: 20 x 20 cm);
  • Wilson TS (Print bed: 20 x 20 cm)

Prusa i3

Looking at the Prusa i3, there are a number of versions:

  • v2 (Print bed: 20 x 20 cm);
  • v2.5 (Print bed: 20 x 20 cm) and;
  • v4 (Print bed: 20 x 30 cm)

This video, however, shows that they are not terribly reliable

Prusa i3 Kits

  1. Reprap Prusa I3 6mm Aluminium Frame Plus Full Rod Set, £81.99
  2. Reprap Prusa I3 Barebones Kit – 6mm Aluminium Frame, £143.50
  3. Reprap Electronics+Motors+Endstops+MK8+GT2 Belt/20T Pulleys/CNC Couplings, £112
  4. Reprap Electronics (RAMPS 1.4, MEGA 2560, A4988, 2004 LCD) + Stepper Motors, £71.99
  5. Reprap Electronics + Motors + Endstops + GT2 Belt/20T Pulleys/CNC Couplings, £89.99

Parts List for the Prusa i3

Taken from Reprap Electronics+Motors+Endstops+MK8+GT2 Belt/20T Pulleys/CNC Couplings. Note that these parts, are common to Prusa i3 derivates, such as the P3Steel and Wilson printers.

Parts Descriptions

  1. Mega 2560 R3 control board: the board is an ATmega2560 core microcontroller development board. The Arduino development IDE canbe downloaded to flash your choice of firmware to the board via USB.
  2. Mega Pololu Shield Compatible (RAMPS 1.4 Shield) is a MegaPololu Shield, or RAMPS for short, designed to fit the entire electronics needed for a RepRap in one small package for low cost.RAMPS interfaces an Arduino Mega.
  3. LCD 2004 with Controller: This full graphic Smart Controllercontains a SD-Card reader, an rotary encoder and a 128 x 64 dot matrix LCD display. You can easy connect it to your Ramps board using the “smart adapter” included. After connecting this panel to your Ramps you don’t need your PC any more, the Smart Controller supplies power for your SD card. Further more all actions like calibration, axes movements can be done by just using the rotary encoder on the Smart Controller. Print your 3D designs without PC, just with a g-code design stored on an SD card.
  4. A4988 driver module is a breakout board for Allegro A4988 DMOS Microstepping Driver with Translator and Overcurrent Protection;please read the A4988 datasheet carefully before using this product. Warning: Connecting or disconnecting a stepper motor while the driver is powered can destroy the driver. (More generally, rewiring anything while it is powered is asking for trouble.)
  5. MK2B Dual Power 12V / 24V PCB Heated Bed: High Quality 214 mm x 214 mm Heated Bed with wiring kit and 100k thermistor.
  6. 4 Powerful 4000 g·cm (4 kg·cm, 0.39 N·m, 39 N·cm, 56 oz·in) Nema 17 Stepper Motors. These are quality stepper motors capable of driving any axis of a REPRAP without missing steps or over heating. If you cut corners with your stepper motor specs you will likely degrade the quality of your prints through missed steps or struggle with overheating motor problems.These motors come with approx 30 cm of wiring by default with a motor wiring kit for adding Dupont connectors and extension where needed (5 x 4 pin Dupont Connectors with pins, 100 cm RBGB equipment wire, ferrules, heat shrink tubing). ===========================
  7. Mechanical Endstops with Cables. Caution: Incorrect orientation of connector to RAMPS will destroy your Electronics! The Red wire is for the Endstop LED power which can be safely removed if you want peace of mind in connecting/disconnecting these Endstop cables (i.e. Remove the red wire from the cables)
  8. 150 cm GT2 Timing Belt with two 20 Tooth GT2 Pulleys (X and Y Axis). Marlin Config for 20 Tooth GT2 pulleys can be found in the Firmware download from our website (Save hours of setup!)
  9. 2 x Flexible 5 mm x 5 mm CNC couplings (Z Axis). These are the best type of couplings to use on an I3 to minimise Z-Wobble.====================
  10. MK8 Extruder/Hot-End With 0.4 mm Nozzle for 1.75 mm Filament. A reliable, easy to maintain hot-end capable of outstanding print quality. A 0.4 mm Nozzle is a good choice for quality and print speed for most printing you will want to do in PLA or ABS. Note: We can also supply MK8 mount/X-Carriage/Build Plate Fans and spare Throats/Nozzles

Parts List

  • 1 x RAMPS 1.4
  • 1 x LCD controller
  • 1 x MEGA 2560 R3
  • 5 x A4988 driver
  • 1 x USB cable
  • 1 x MK2B Dual Power 12V / 24V PCB Heated Bed
  • 1 x Heated Bed Wiring Kit: 11 A thinwall power cables, 100k thermistor, 0.5 mm PTFE tubing, heat shrink tubing, bootlace ferrules, thermistor wire, 2 pin Dupont connector with pins
  • 4 x Nema 17 4000 g·cm Motors with wiring kit: 5 x 4 pin Dupont Connectors with pins,100 cm RBGB equipment wire,ferrules,heat shrinktubing
  • 3 x Mechanical Endstops with Cables
  • 150 cm GT2 Timing Belt + 2 20 Tooth GT2 Pulleys
  • 2 x Flexible 5 mm x 5 mm CNC couplings
  • 1 x MK8 Extruder/Hot-End With 0.4 mm Nozzle (1.75 mm Filament)

Assembly Manual

prusai3_f3d_buildmanual_1-1

Delta Printers

This video shows that the Geeetech Delta printer is much more reliable than the Prusa i3

Which printer? Prusa i3, Wilson 2 or P3Steel, or…

It has to be said that the Prusa i3 is a popular printer, however after owning one for a while, many people then upgrade to the Wilson TS, or Wilson II, for its improved rigidity. However, the P3Steel variant of the Prusa i3 is pretty sturdy in itself, so, which is best.

The most interesting link is P3Steel or Wilson II?. It mentions an upgrade to the P3Steel, which originates in Spain, called the Toolson Edition Mk2 (P3sTE Mk2), which is, arguably, the best DIY printer available, according to one poster.

The thread looking at Prusa i3 printers, could use some help 🙂, is along the same lines as the others, regarding the suitability of the i3 as a starter printer, and again the Wilson is stated to be a superior printer:

I am not an I3 fan, but I built one called the OB1.4 from thingiverse that does a great job. If you are up to scratchbuilding, the best I have ever built is the WILSON II from github (Check out the build series on youtube). This is a very rigid and massive printer capable of very fine prints. I use a .3 nozzle when I want fine detail. I have scratchbuilt 5 3d printers in the last 2 years and use them all. I have a friend who bought a I3 all metal kit and it seems flimsy to me and he isn’t satisfied either. He is printing his own parts for the wilson II.

However, two excellent mods are suggested:

The two most important mods to make (and this is for ANY Prusa ) are:

The first mod addresses a basic design fault with any Prusa i3, in that they assume that all threaded rods will be perfectly straight. This is never true. Thus the design where the Z axis is “fixed”: to the X axis causes any, even the slightest deviation of the Z axis rods, to be transferred to the print. This is called Z banding and produces horizontal lines in your Z Axis print that will perfectly mimic the threads of your Z axis rods. This mod, removes this “fixing” and makes the Z axis “floating” free and gives almost perfect Z axis prints.

The second mod is to cool your prints, when using PLA, all round, to enhance the print result.

Wilson TS

Some good points are raised in this short guide, Building your own RepRap Wilson TS, such as stick with the Kysan motors, the RAMPS 1.4 board is better than boards with on board stepper drivers in case of burn out, not necessitating a whole new board, as well as some interesting video build guides.

Sourcing the parts separately

Stepper Motor Pitfalls

Torque

Pay attention to the force of the stepper motors, not all Nema 17 stepper motors are the same, they will vary in size and weight depending upon the force that they can exert. The example above uses 39 N.cm motors, but 44 N·cm (4400 g·cm, 0.44 N·m, 4.4 kg·cm, 62.3 oz·in) or over is recommended, see RepRap – Nema 17 Stepper Motor

However, from RepRap – Stepper Motor – Holding Torque 13.7 N·cm is deemed to be sufficient:

The Mendel officially requires approximately 13.7 N·cm torque (19.4 ozf·in) of holding torque (or more) for each of the X, Y and Z axis motors to avoid issues, although one stepper with less has been used successfully (see below). Recent designs for extruders (ExtruderController) almost exclusively require stepper motors as well, but no torque requirements have been given in those designs. If in doubt, higher is better.

For Wade’s Geared Extruder (most widely used one as of 2012) it is suggested to use motor that is capable of creating a holding torque of at least 40 N·cm.

To convert between to various units of torque, use Torque convertor.

See also How much torque do I need for a CNC machine?

Commonly used stepper motors are:

  • The Kysan 1124090/42BYGH4803 stepper motor has a holding torque of 5.5 kg·cm (54 N·cm, 76.4 oz·in)
  • The Rattm 17HS8401 has a holding torque of 5.3 kg·cm (55 (quoted 52) N·cm, 78 oz·in) (source: 1 and 2)
  • The Wantai 42BYGHW609 has a, relatively low, holding torque of 4 kg·cm (39 N·cm, 56 oz·in) (source)
  • The Wantai 42BYGHW811 has a higher torque of 4.8 kg·cm (47.1 N·cm, 66.6 oz·in) (source). This stepper is used in the P3Steel XXL printer.

Note:  Some people have complaints about the Wantai 42BYGHW609, see warning: don’t buy cheap motors for your reprap! However, the issues experienced in that thread seem to be related to the drivers, and controller configuration. The majority of users of the 42BYGHW609 are satisfied.

Note: The Wantai 42BYGHW809 has greater torque than the 42BYGHW609 which is useful for extruders.

Another very useful thread is on the RepRap forums – Motors. Among other topics, this is noted:

I recommend the smaller 35 oz-in (17HS3430) motors for the Z-axis and the extruder and the 74 oz-in(17hs8401) for the X and Y axes. This setup works perfectly on my main machine.
Never misses a beat.
I used to have a 74 oz-in on the extruder too but the motor is too long and you have to lose some build height to fit it in. The 35oz-in fits and works much better.
You should also wire the 2 z-axis motors in series. Most instructions show them wired in parallel. That is OK for high voltage/low current motors but series works better for the above motors.

Phase Inductance/Current

Be careful to note the phase inductance, and phase current, of your stepper. I nearly purchased a set of Astrosyn MY17HD6N-4 stepper motors on eBay for $45 + $19.40.

However, unfortunately, the phase inductance (21 mH) is too high for a reprap motor, I think, which needs to be around 3 – 8 mH. Likewise the phase current is only 0.8 A, which is a bit too low, as 1.5 – 1.8 A is recommended. As such this stepper is, evidently, incapable of any speed and is unusable for a printer, as are most very low current steppers.

Stepper Motor driver pitfalls

If you are using 24V then some care is required when choosing the Stepper Driver. From RepRap – Using 24V with DRV8825 Drivers, it is better to choose the A4988 over the DRV8825:

With a 24V power supply, the current increases much more quickly than with 12V (this is the reason for using the higher voltage – it allows faster speeds) and on the DRV8825 the minimum on-time is too long and the current will overshoot the target, making the stepper miss microsteps, overheat, and making hissing/squealing noises. So drivers based upon DRV8825 should be avoided for any voltage over 12V and are generally not good drivers for 3D printers.

The traditional A4988 chip used in a lot of controllers does not suffer from that problem and is a good solution for printer if properly cooled by its bottom, the heat being dissipated by the bottom of the printed circuit board, which is where a heat-sink is most efficient.

RAMPS 1.4 parts

If you are purchasing the LCD 12864 smart control panel,

then you do not need to purchase the SD card reader add-on, nor the smart controller adaptor, as both of these parts come with the LCD panel – the panel has a built in SD card reader and the smart connector adaptor comes as a separate, but included part of the LCD panel package.

RAMPS 1.4 SD card reader
RAMPS 1.4 SD card reader

and

RAMPS 1.4 Smart Controller connector
RAMPS 1.4 Smart Controller connector

Stepper Motor dampers

Astrosyn dampers are interesting as they use two diagonal bolts for the motor and two opposing diagonal bolts for the chassis mount:

Should I enclose my 3D Printer?
Astrosyn damper

See Stepper motor dampers, which mentions that the surface upon which the printer is sat can amplify noise and vibrations. If the Z axis/arm is suspended then this can drastically reduce noise.

Another article, vibration insulators, mentions that cork dampers are rather ineffective as the 4 screws transmit the vibrations. A solution is to use only two screws to secure the Nema17 whilst it is under tension, and to allow the motor to “articulate” around these two screws.

Cover/Case for printer

Stack Exchange, 3D Printing: Should I enclose my 3D Printer? states some good reasons for encasing the printer. In particular the smooth bars should be protected from dust. Another advantage is heat distribution within the case. A simple perspex 5 sided cube case would be sufficient.

Double the extruders – double the fun

The Prusa i3 and RAMPS 1.4 supports dual extruders. See upgrading from single to dual extruder

Dodgy Extruders

Beware Chinese knock-offs [links] Built Wilson TS, having some issues!!!

Recommended:

  • Bowden
  • MK8
  • MK7

Dodgy Hotends

As with the extruders, so likewise with the hotends – avoid Chinese sub standard fittings. Recommended:

  • E3d v6 ($60)
  • E3d Lite6

Threaded Rods or Lead screws

The Wilson II makes much fanfare over its use of lead screws, whereas the Prusa i3 uses threaded rods. What is the difference and is it all just hype? No, there really is improved accuracy and precision when employing lead screws, see Accuracy vs Precision and Threaded Rod vs Leadscrews in 3D Printers.

Also worth a read is Need to decide 5mm, 8mm or proper leadscrews, with respect to a P3Steel RepRap. The OP plans on welding the P3Steel frame for extra rigidity.

An in-depth analysis can be found in Backlash, Hysteresis and Wobble.

It is worth noting that some leadscrews, whilst having a pitch of 2mm, actually have a lead of 8 mm, because they have four leads. An example of this is the reasonably priced 550mm 3D Printer 8mm Lead Screw Rod + Nut Z Axis Linear Rail Bar Shaft PK, £6.11. However, even though it is considerably more expensive, it is preferrable to get the 8 mm leadscrew with 1.5mm pitch/lead , TR8x1.5Dx500mm 1.5mm Pitch Trapezoidal Acme Ballscrew Leadscrew – Fine Pitch, £16.30, or the 5 mm lead screw with 2 mm lead (1 mm pitch, 2 leads) T5 /5mm Trapezoidal Screw Rod pitch 1mm, Lead 2mm,100-500mm cut – CNC/3D Printer, £15.50

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