3D PRINTING FOR DUMMIES

Getting into 3D printing looks intimidating & there’s a lot to learn.  There is a plethora of YouTube videos to help you learn techniques & to troubleshoot problems, but they can be frustrating due to the presenters not appreciating the depth of ignorance in their viewers & glossing over important steps.   I was fortunate to have mate already into it & just a phone call away to help to get me started.  Recently I began printing some figures after a few months break & found I’d forgotten some of the skills.  After re-learning them, I wrote out a detailed manual for future reference.  Then having done that, it occurred to me that turning it into a 3D printing guide for dummies might be of use for some of my blog followers. 

There are two elements to master, the hardware & the software.  Printers appear to be cantankerous beasts at first.  But with time they seem to get more obedient & easier to use, I suspect the problems are mainly with the user rather than the machine.  I found learning to use the software was often a bit frustrating, mainly due instructions assuming you understand nerd-speak.  But once you get the hang of them, the necessary Apps are easy enough to use.

 

There are two kinds of printer, differentiated by the feed material:

Plastic filament:   The feed is 1.75mm diameter plastic drawn off a roll & extruded onto the model through a heated nozzle. The extruder is moved mechanically in 3 dimensions.  

 

Resin:   This type of printer uses liquid resin as the feed material.  A plate is lowered into contact with shallow bath of resin & light is shone upwards to cause resin to adhere to the plate.  Then the plate is raised and another layer added.  The model is printed hanging off the top plate.  The finished model is then put into a curing chamber to complete the setting of the resin.  The only mechanical action is a screw drive to raise the plate vertically.

 

There are pros & cons for both types: 

Advantages in blue, disadvantages in red, comments in grey.

 

Resin:            Provides very high quality results.
Can print multiple models at once, so mass production can be faster.

Fewer moving parts.  (So less potential for mechanical problems).

                        Makes noxious fumes so requires a well ventilated workspace like a garage with a large door.

                        More expensive machine to buy & you also need to buy a separate curing machine.

Resin is more expensive than plastic filament & you also need to buy curing compound.

 

Filament:      The models have a slightly ribbed surface. (But the quality is perfectly adequate for wargames standard modelling).

The machine is cheaper to buy.
Filament is cheap to buy.
No noxious fumes & quiet operation allows it to be placed anywhere in the house.  (So it can be placed close to where you normally pass your time so easy to keep it working continously).

                        Mechanically complex, so more scope for mechanical problems. (But there are plenty of YouTube videos to help troubleshoot, & spare parts are readily available on-line).

                        If figures are printed grouped on a multi-figure stand to speed up production you get stringing between the figures as the machine lays plastic layer by layer & jumps between figures on each layer.  (This is usually only a problem with very small models, 15mm & up are usually easily cleaned up).

I chose to start with a bottom of the range Ender filament printer to see if 3D printing was worthwhile for me.  I had some frustrating problems learning to use the printer, but once I got the hang of it & upgraded a couple of parts, the cheap printer has worked well.  I subsequently bought a better quality Ender filament model, which is easier to use & less temperamental (though the quality of the results is much the same) & I think well worth the extra cost.  But I don’t regret having bought the cheapo model, it still works & having two printers is great as this doubles the production rate when mass producing wargames figures.  

I discounted getting a resin printer because I have a low tolerance for fumes, and the main advantage it would have over the filament type, quality of finish, is of little value to me given my moderate painting skills.

 

The comments below apply specifically to a filament printer, but the issues with file handling also apply to resin printers.

 

 

Sources of files

 

There are Apps available that allow you to make your own 3D models from scratch, but the learning curve for them is steep & high & unless you intend to do it consistently to keep your skill level up it’s unlikely to be worth the effort. 

 

There are many websites providing instant downloads of 3D model files.  Some are free.  Most have a price far less than the cost of a bought model, so a bargain if you are going to make a lot of them (there is no limit on how many times you can use a file).  These files usually come as either .obs or .stl format.  Often there will be a group of related files (eg: to provide various poses, hats or weapons) exported as a .zip file.  The files have to be converted to a format specific to your printer before being loaded onto a mini memory card to plug into the printer.

 

Thingiverse is a site with a lot of freebies.  Wargaming3D is a site with a large range of wargames figures for sale & some freebies.  There are others & more coming on-line all the time.  There are also kick-starters that can provide items such a whole WWI fleet at a good price.

 

 

Working with 3D files

The 3D files you download will need some modifications before you can use them.  There are some reasonably simple to use & free Apps that allow you to examine the files, to make simple models, to modify bought models to suit your specific needs, and to convert the file format to the one your printer needs.   

 

It’s essential to be very systematic with filing.  The downloads often come with multiple files & each one can generate more files as you process it.  It’s easy to lose track of which is which.  

 

Tasks you might need to do include:

 

Unzipping:             The individual files you want to use have to be copied from the zip file to a folder to be worked on.

 

Adding stands:     A stand can be added to the model if it doesn’t come with one. 

 

Grouping:              A row of figures can be printed simultaneously on a combined stand.

 

Supports:               If a figure has overhangs (eg: a horse’s nose) there needs to be a support under the low point for the first layer to be deposited on.  Some models come with these included, others require them to be added by you.  An App can be used to add either a web of weak honeycomb mesh under the overhangs or a set of stems from the base to low points.

 

Adhesion:               Unless the model has a good sized base included, it is necessary to add a removable base to enhance adhesion to the machine’s build plate.

 

Convert:                 The printer is loaded with files via a mini memory card.  The files need to converted to the correct format for the machine.

 

The free Apps I use are:

 

3D builder:            

This is a simple viewer that allows you to examine the 3D model in an .obs or .stl file from every angle to allow you to decide what, if any, modifications are required.

 

Tinkercad:            

Allows the building of simple models out of a library of simple shapes such as cylinders, cubes or letters.  It can also be used to modify bought figures by adding temporary supports to add stability during printing, adding bases, or assembling a row of figures on a group base.

There are good YouTube videos that show you how use this App, but the basics are: 

Click the Import tab at top right to import a file. 
You can zoom with the scroll wheel or change angle of view by right clicking the mouse.  
Shapes can be dragged into the workspace from the menu on the RHS.  The hatched items are negatives, they make holes in the model.
Clicking on an item brings up handles that allow you to manipulate it’s size and angle. 
When you are happy with the model, click the Export tab.

 

 

Meshmixer:          

Allows you to modify a bought model.  It can do a lot more than Tinkercad, but is not so easy to use.  I mainly use it to reduce file sizes, as Tinkercad has a limit on imported file size that is often exceeded with bought files.  You don’t notice any difference in quality.  The process isn’t intuitive & the YouTube instruction video sometimes obtuse.  This is the procedure to reduce a file:

Open Import & import the file.

Click Select on LHS bar.

Click Ctrl A on keyboard to select the whole model & bring up an Edit menu.

C lick Edit to bring up another menu of options

Click Reduce.  It will calculate a 50% reduction.

Click Accept.

Click Export on LHS bar.  This will allow saving in the folder as an STL with a chosen name.

 

UltimakerCura:    

Allows you to convert .stl files to the format your printer wants copied to a mini memory card.  It also allows you to scale the model, add supports & adhesion build plates.  

The model can be scaled up & down.  Click on the model & then the 2^nd icon on the menu on the LHS & you can scale the model up & down.  (28/15 = 187%.  15/28 = 54%).  When happy with the model, click it again de-select.

The menu on the RHS is brought up by clicking the Standard Quality-0.2mm tag at the top.
Clicking the General Support box will add a support mesh to overhangs.  There are options for type, but it’s not obvious what changing the settings from default does.
In the Build Plate Adhesion section select the Build Plate  Adhesion Type you want from Skirt, Brim, Raft or None.

Skirt:    Makes a ring on the machine’s build plate around the place where the model is to be printed.  All it does is give the extruder some time to settle down before starting on the model itself.

Brim:    Prints a thin layer to a specified distance out from each point of contact of the model with the build plate.  I usually use this one with 5mm Brim Width.

Raft:     Makes a raft about 2mm thick under the model. This provides a better base than Brim, but takes longer to print, so I only use it if Brim doesn’t work.

The rest of the options can be left on default. Once you have set the support & adhesion setting they will become the default for them until changed.

Click the Standard Quality-0.2mm tag again to get the menu out of the way.

 

When you are happy with the model, click the Slice box at the bottom RH corner.  The App will then convert the model into the form your printer requires. 

 

A Save box appears at the bottom RH corner that allows you to save the sliced file to your hard drive &/or the mini-memory card.

 

Clicking Preview on the top bar will give you a view of the model exactly as it will print with the Adhesion base.

 

 

Build plate adjustment & adhesion

 

Good adhesion of the base of the model to the printer bed is critical.  If the model doesn’t stick you get a birds nest. 

 

A range of plate base covers are available for printers at varying prices.  Buying a better quality one is worthwhile to minimizing frustrating adhesion issues.  Regardless of the type of plate, keeping it clean with an occasional metho wipe will help. 

 

Adding a Build Plate to the model with an App such as Cura is often necessary to improve adhesion.

 

The base plate has to be level & spaced the right distance below the extruder’s starting position.  There are 4 leveling screws under the plate to allow adjustment.  To prepare to print select the Prepare menu on the machine, then Auto home, then after the machine has stopped moving select Disable stopper.  Place a piece of paper on the plate & adjust the screws until the head is just touching the paper when placed at each corner of the plate.  The plate can go out of alignment, so it’s a good idea to check the alignment occasionally.

 

 

Filament

The 1.75mm plastic filament is supplied in 1Kg rolls & can be either type ABS or PLA.  They require different settings in the machine & it won’t work properly with the wrong feed.  I understand that most machines come preset for PLA.  Check this is so on your machine & if so, take care to always order PLA.

 

The filament goes brittle with prolonged exposure to air so an old roll can tend to break.  Fortunately this usually happens in the exposed bit between roll & feeder in periods between production runs, not during a print.  It helps to rig a guide to provide a smooth path for the filament from the roll to the inlet hole.

 

You have to feed the filament through the inlet hole, past the driver rollers & into the feeder tube.  Getting it to go into the feeder tube hole can be tricky.  It helps to straighten the end of the filament & to cut it in angle to make a point.  Even then getting it to go into the 2^nd hole may require holding the rollers apart & fiddling about.  Once it’s in, hold the rollers apart & push the filament in until it reaches the extruder.

 

The filament goes through a tube to the heated extruder.  The extruder can get clogged up & need cleaning or replacing occasionally.  You should buy some spare nozzles.

 

Supports

 

A critical thing to get right in order to get a good print is supports for overhangs – that is surfaces that face downwards.  If the surface is at an angle of over 45 degrees the plastic layers will usually cantilever out from the ones below & print ok.  But if the surface is near horizontal the bottom layer of that part has nothing to support it & you get bird’s nests. 

 

Cura provides the option of adding a honeycomb mesh under overhangs.  This works well for printing the model, but even though the mesh has a weak layer at the interface with model, the mesh can be very difficult to remove if in confined spaces or in between relatively fragile items like a horse’s legs.  In such cases it’s easy to break off fragile bits of the model. 

 

It is often better to manually add stem supports under the low points.  Some models come with these already included (or come with two options - with or without).  Tinkercad is good for adding custom stems for the purpose.  Stems of 2mm diameter are usually plenty strong enough & are easily cut out after printing.

In this pic, the Lance has mesh support added with Cura, the trooper has stem supports added with Tinkercad & the horse has stem supports & its base extended with Tinkercad.   All have 5mm brim adhesion plates added with Cura. (The horse probably has a big enough base not to need the brim, but I usually have brim set as default in Cura & extra adhesion can’t be bad).

Assembling figures

Some models are made in separate parts to minimize support issues (eg: horse, trooper & weapon).  For assembling model parts made with PLA filament I recommend Bostik Hard Plastics glue for plastic to plastic joints & Bostick All Purpose glue for plastic to metal joints.

 

 

Stringing

If you print a group of figures on a common base you get some stringing between the figures because the extruder lays down a layer on each figure zapping between them before stepping up to the next layer.  

This pic is of a strip of 15mm figures as printed.  The strings are easily snipped off if the figs are in a single rank of 15mm figs or bigger, but tricky for 6mm figs in two ranks.

 

 

Speed of production

 

A 3D printer isn’t fast, but it happily beavers away unattended once you get it going.  So as long as you are at home anyway & your printer is conveniently located, you can do other stuff (like painting what you printed yesterday while it’s printing what you will be painting tomorrow).  When you notice it’s stopped it only takes a moment to take off the finished model & restart.   

 

Examples of approximate times to print:

28mm horse:                                1 hour

28mm trooper:                            30 mins

28mm lance:                                 10mins

15mm AFV:                                   2 hours

28mm AFV:                                   5 hours

Strip of 6 15mm infantry:         1 hour

 

If you dovetail painting with printing, the rate of production isn’t much different to assembling & painting bought figures, & there are no delays in the post before getting started with a new project.

Most suitable subjects for 3D printing

I have had good results with the following:

 

Ships:                 The ease of mass-producing multiple models to any scale to suit your rules makes this very cost effective.  I figure my Napoleonic fleet alone more than paid for the printer.  I have also printed most of WWI fleets for both Britain & Germany.

 

AFVs:                  15mm are reasonably quick to print with quality as good as most castings.  28mm AFV’s are slow because of the shear size of them.

 

Trucks:               One resents paying as much for a mere truck as an AFV, but you can churn them out dirt cheap.

 

Guns:                  Anti-tank guns & artillery come up well in all periods & in both 15 & 28mm.  Getting the support mesh out from between spindly tails & under gun shields can be tricky.

 

15mm figs:        Best printed in multi-figure strips to speed up production.  Stringing is a bit of a pain, but worth putting up with for the speed gain.

 

28mm figs:       The detail is excellent & they are easy to paint.  It might get a bit tedious churning out whole armies, but perfect for gradual expansion & filling in gaps in your collection.  

 

Scenery:             Printing scenery items is a very popular use with many wargamers.  I have made a few scenery items, but I don’t feel a need to replace my existing stock of paper houses & plastic trees.  

 

Player aids:       Your imagination is the limit for making player aids.  Tinkercad is good enough to make items like dials, specialist dice, counters & rulers.                

Urgent reinforcements:   If you have a battle coming up & you belatedly realise that your list desperately needs say, another anti-tank gun, you can download a file & have a Pak or 88 printed, painted & ready for action in a few hours.