[chbot] 3D printer kit recommendations, and quick start help

Peter Ellens ellensp at gmail.com
Mon Sep 22 08:47:50 BST 2014

This is a very big subject....

> 1) Get or create a design.

Yes, most 3d printers use STL files to define the 3d object.  Lots of 
cad program can export to STL, and even if they dont meshlab can import 
a lot of 3d format files and can save as STL
> 1a) Assume that the starting point is to print a simple object from 
> http://www.thingiverse.com/ - learning to design items can be left as 
> a later activity.
Correct, but quickly you find you want to tweak the file a little.
Most simple things are designed in opencad. but can be any CAD program 
that exports STL
I would recommend anyone with a 3d printer to learn basic openscad

> 2) Convert to some kind of motion vectors
Commonly called slicing

> 2a) What is the most common intermediate format, is it G code - if 
> not, then what ?
gcode is the final format, its is what is passed to the controller to 
implement all machine functions. From heating up the hot end to 
movements of and axis.

> 2b) What are the recommendations for the best free/open source 
> solutions to convert from design to printing motion activities ?

Many people swear by slic3r and may other at slic3r.... http://slic3r.org/
The main contender in my view is cura http://software.ultimaker.com/
There are others...
> 3) Convert the output of 2) into a format that can be carried to the 
> hardware controller.

3d printers such a reprap have intelligent controllers, they interpret 
the gcode on the micro controller.
> 3a) Presumably there is a name for the physical link, and payload, 
> again, name please.

not really. Its just gcode.
> 3b) What are the recommendations for the best free/open source 
> solution, or does 2) also drive the interface ?

pronterface is a popular minimalist GUI. It allows you to load the STL 
file, call up slic3r and then spool the generated gcode to the printer.
Cura is also a GUI, looks fancier but is limited when it comes to 
tweaking settings.

> 3c) What is the currently most popular physical interface (USB, LPT, 
> etc.)

USB, really its serial over USB.
> 4) Controller interface to hardware
> 4a) Plugs into 3c).. What are the names of popular, low cost, readily 
> available controllers, and suppliers ?
There are two types... arduino based and the newer arm based board..  
all arm board should be considered experimental.

RAMP's is the most popular, its is modular, being a PCB stack. Is 
available all over the internet. But I would not go for a cheap board. 
'They' do nasty things like inferior MOSFETs and thin pcb tracks and 
connector plugs that are not up the currents required.

There are many boards that are basically a ramps but all on one board 
solutions.  These are good in some ways, except if you have to repair 
it...  http://reprap.org/wiki/Comparison_of_Electronics
NB this is editable, and unscrupulous sellers add in their proprietary 

The cheapest board is the Sanguinololu (but get 1284p chip not the 
smaller 644p)
These work well, but are the minimal solution..  no extras.

Gen7 is also good, if you want to make your electronics from scratch.

I personaly like reprapdiscount.com   they are really good, and their 
representative is available on the #reprap irc channel. They are also 
good at returns etc if there should be an issue.

> 4b) I think older interfaces used a pretty dumb motor controller using 
> an LPT port. Are smarter controllers now used ?
3d printers require real time movements. Operating systems where found 
to be dreadful at this, so all timings are on the smart controller. A 
delay in movement == a blob in the 3d printing world
> 4c) What not to buy, and suppliers to avoid ?

Avoid most cheap reprap stuff from china, especially controllers and 
> 5) Hardware interface
> 5a) A collection of stepper motors are attach to 4a). Which stepper 
> motor type is more popular, bipolar of unipolar ?

> 5b) recommendations for typical stepper motor size, NMEA type etc.
Most printers are designed around nema17

> 5c) Any special features for the stepper motors (voltage, dual shafts 
> etc)

	ideal stepper is ideal stepper is NEMA17 size, rated 1.5A to 1.8A or 
less, 1-4 volts, 3 to 8 mH, 62oz.in (0.44Nm, 4.5kg.cm) or more of 
torque, 1.8 or 0.9 degrees per step (200/400 steps/rev respectively), 
for example the kysan 1124090/42BYGH4803 or the rattm 17HS8401 or Wantai 

Single shaft, 5mm diameter.

> 6) Mechanical frame
> 6a) From first hand experience, recommendations and warnings about 
> current designs.

Most currently recommend the I3, there are two models, the plate and the 
box. The original plate is cut from 6mm aluminium, but has no support in 
the Y direction. It wobbles and needs bracing.
Modern laser cut wood frames are good as long as they have the braces.
Box is also fine. (but looks primitive)
Stay away from acrylic printers, looks pretty but it fractures at all 
stress points

the mendel 90 is also a good printer.

Delta type machine look cool and will print faster, but are 
exponentially hard to get working properly. If you go delta get a laser 
cut kit, you need the accuracy.

> 7) Omissions, corrections
> 7a) Anything I have forgotten

This is a big subject... One that comes to mind is what materials do you 
want to print.
Main contenders are ABS and PLA, but there are others, and some that 
require higher temperatures which dictate what type of hot ends you need.

Hot ends, very important you do not get a jhead clone from china
Jheads and aluhotends are good for PLA and ABS (hotends.com and 
If your wanting hotter things such as nylon, you need a all metal 
hotend. but these do not like PLA

Nozzle sizes

0.5 0.4 0.35 0.3 are all commonly available. The smaller the nozzle the 
finer the detail you can print. But the smaller the nozzle the longer 
prints take to print.   I would recommend .4 for most new printers.. you 
can change it out later if you want.

> 7b) Things I have got wrong ?
> 7c) Pointers to a web site, quick start guide document, or book that 
> may cover these questions in more detail ?
Everything in on http://reprap.org and discussions and question on the 
forums. http://forums.reprap.org/index.php   live chat on 

Documentation. All documentation is just a rough guide. Since its 
maintained by the community its is always one step behind the latest gear

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