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3 Weeks Of 3D Printing, What Did I Learn?

3/9/2020

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3 weeks with an Ender 3 Pro, printing model and miniature related content.  What did I learn?

Quality of the Prints
I tried the Ender with a .4 and a .2 nozzle.  The .2 nozzle and a small layer height will give the best quality. However even at the highest levels layer lines are still visible.  This basically means if you are making miniatures for display, it isn't good enough (in my opinion).  If you just want models for a game and don't care too much about quality then may be its OK.  Printing at high quality is very slow.

Another issue is glitches in the printer.  Obviously the Ender3 pro is very cheap and we are trying for very high quality prints, so any glitches or slips are a bad thing.  There are things you can do to minimize these like adding filters to the stepper motors, doing better calibration etc but there is a limit.  I had small amounts of slippage in x and z directions on most of my prints.  What this means is to get a perfect print you may have to print the model more than once. 
​
The conclusion I came to was the extra quality provided by the finer nozzle wasn't worth the extra time involved in printing and that the printer is too slow.  

PictureCura, the slicing program
Default Quality =  2 hours
High Quality = 6 hours

Slicing
Before I got the printer I had done quite a bit of 3D printing using services like ShapeWays but I'd never had direct exposure to slicing.  Cura is a free slicer and seems popular with the miniatures community. It generates the gcode (Tool path) for the 3d printer. I had assumed that the slicer would just "rasterize" each slice but actually the fill pattern is quite complex, aiming for best quality whilst having a hollow component.  Cura is also where you add stuff like supports which are required to enable overhanging regions in the model.  You can also orient a model so that the supports don't obscure details on the face or front of the model.  
The biggest thing I learned about slicing was to trust the slicer.  You can move up and down the layers and play the tool path in the preview option after slicing.  Carefully checking the model Cura before printing saves hours of frustration with failed prints. 
I used the fat dragon games profiles for the printer, they are popular and work well.  Their models are also very nice if a bit simple, however they print without the use of supports and so are ideal for use with an FDM printer.  Definitely worth checking out. 

Finishing
Pla is actually pretty nice to work with with sandpaper, knifes, file etc and takes paint well, but because of the limits of FDM you are going to need to do a lot of it. This means it's probably best not to add a lot of tiny surface detail in the 3d model.  Use the printer to generate the gross shapes and then add surface details and texture the usual way with putty, etched brass etc.  Similarly design the prints for ease of clean up.  It's much easier to sand individual parts than a complete model in many cases.

What did I think of the Ender 3 Pro?
It didn't start well.  Somebody told me they burn houses down.  So a slow printer than can't be left unattended.  Mine was completely unaligned out of the box and took significant rebuilding.  The instructions are pretty much useless.  There are no exploded diagrams anywhere that I could find.  I had a magnetic bed, the plastic z-limit switch mount was designed for a glass bed which is thicker. So the z limit switch is in the wrong place.  Based on info on reddit, I cut the locating tab off mine and mounted it myself in the right place.  Oh and my print bad isn't flat which made bed leveling a challenge.

So if someone tells you putting an Ender together is like Ikea, they are talking nonsense.  It took me 2 afternoons to get mine together.

Pretty much anytime you do anything with the printer you are going to have to level the bed.  This is kind of a misnomer, what you are actually doing is making sure the bed is perpendicular to the print nozzle and is a good distance away from it.  The bed leveling springs as supplied are crap (get some thicker ones) and "the thickness of a sheet of paper" isn't very helpful since that distance depends on the nozzle size in play among other things.  Anway, bed leveling is a pain and takes about half an hour.  It definitely helps if the printer is in a brightly lit location.  It's hard to work on if you can't see.

I've run my printer for about 25 hours and I've had to tighten the x-axis belt tensioner.  I've also discovered that my y-axis wheels are too tight and are eating themselves against the drive rail.  
Changing filament isn't too hard.  Changing nozzle takes about half and hour, plus you'll want to level the bed after.

What I'm saying is that you can expect to spend an hour fiddling with the printer for every 6 hours it spends printing...  which isn't great.  It isn't terrible, but it isn't great either.

Summary
I would say this printer is good for roughing out parts. It's not really up to doing wargame miniatures at commercial quality levels, but for models or terrain as long as you don't expect perfect surface texture quality and are prepared to put in some work on the finished article it's not bad if a little frustrating to use sometimes.  Also as a prototyping machine to test prints before sending them out to Shapeways for higher quality printing its probably pretty good.  

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3D Printed Character

3/8/2020

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I had 2 days left with the 3D printer.  I modeled up a little alien guy inspired by Babu Frik in the latest Star Wars, printed it on the Ender and then painted it.  The wet look on the eyes is 5 minute epoxy and his 'tash is golden retriever hair I found on the carpet. Thanks Abby. 
Still fighting with the fact that the printer is so slow and the quality isn't where it needs to be.  I tried filling the very obvious layer lines with a mix of acrylic filler and paint. It sort of works, but its a pain. 
Picture
Picture
Picture

Oh and before I forget...

I made a little RoJaws too. This was an experiment is parts breakdown.  It seems to me that smaller pieces are better than trying to print as a whole statue. 
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3D Printing for Casting

3/2/2020

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I decided to model and 3D print a small piece of architecture and then make duplicates using a silicone rubber mould and urethane resin. The main reason advantage of resin casting over 3D printing is speed of duplication. This part took 5 hours to print at medium quality settings.  Each cast part takes about 15 minutes. 
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I found a reference image of a holy well that looked ideal for a stand alone project.  I modeled the building in blender. I modeled the door and doorway using basic low poly techniques and then used 3D sculpting to add texture and bricks to the model. 
I then 3D printed the model on my Ender3 at medium quality. 

I did some clean up on the print with sandpaper, files and a craft knife. This would have been a great time to add some extra damage/depth with a dremel or to add texture using textured paints and sand.


I made a simple mould box from balsa wood and then poured in Oomoo 30 from Smooth On.  This is a soft silicone rubber moulding material. Because it has low viscosity, it’s easy for any trapped air to escape, thicker rubbers can result in trapped air bubbles which show up in the final cast.  Oomoo 30 takes about 7 hours to harden before it can be used.
Next day I popped the 3D print out of the mould and I was ready to begin making castings using Smooth-Cast 300.  This is a urethane resin that sets very quickly. Parts are ready to be pulled out of the mound in about 15 minutes.  I made 2 test castings and was very happy to see that both came out very nicely with no air bubbles on the detailed side.

I assembled and painted one of the pieces to see how it looks.  I’m quite pleased with how it came out.

SlideShow

Summary

If I did another project like this, I would make some of the gaps (for instance around the door frame) larger and I would bevel the edges. I think this would make them easier to print as well as making the mould stronger so it would last longer.  I would make the mortar gaps on the walls deeper but I probably wouldn’t add much surface texture to the parts before printing. I think it would work better to add those to the 3d printing before making the mould with a dremel and other tools

You can see the printer slipped halfway through the print.  I should have killed the print and done a fresh one with no errors.  

Obviously a simple open faced mould like this only creates single sided parts, in the future I want to try a glove mould that will allow for more complex shapes. 

The moulding and casting turned out to be very easy and none of the materials smelled bad which was a pleasant surprise.  

Seems like a modular approach could create some quite complex buildings from just a few quickly cast parts.  

​This was fun!


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    David Coombes

    Making stuff

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