How to print a good 3D print out ...

Let me share with everyone how to get a good print out.
First since 3D printer is a precision equipment, if your components are not precise, you will never get a good printout for a reasonable time. eg, use of  threaded rod may not be ideal for a long time.


Let's assume, you have a structurally stable and good print head or extruder.

First in order to print well, look at the first layer. If it print well, you will more likely to get a good printout. If it does not, the structure will move and you will a pile of rubbish.. what do I mean by a good first layer. Assume that you had calibrated the flow rate and you do not get something like this....

1) Print bed slanted - You will see one side is crushed and the other side does not stick well.
Remedy : make the bed flat or it could be your print head  is slanted.

2) Print head too high - the print out just does not stick to surface .
Remedy : I prefer to adjust the Z offset in my slicer program. it is easier because your are talking about probably 0.1 to 0.4 mm. Adjust your stop switch will be tough.

3) print head too low - will cause excessive adhesion to surface. Filament will get compressed on the surface and if you see carefully, you will see that it is very flat and enjoy your hard time getting the pieces out of the heated bed.  I prefer to adjust this by the Z-offset also. It is easier.

This print out is good. A little more will crush and compressed the print out.


Next let's talk about the various type of surface to print on.
1) kapton tape:  My experience is, it is not very sticky and in the surface is too little , the printout will dropout. So I will definitely put a raft layer as a interface layer.  I use it on the Felix printer.

2) Uhu Glue on glass - The prusa I have is using UHu glue on glass. It sticks really well. even when the base is small. Usually I apply 1 time, I can use it for many print.

3) Blue painter tape: the adhesion is pretty strong also, but sometime, it just come out with the printout. So I find it quite a trouble to reapply the blue tape.

I will edit with more pictures when I gather them ...

The 3D printers that I used

I am very fortunate that I used many of the 3D printers due to my work. Lets just talk about reasonable one. And forget about those that cannot make it.

Felix - The program, print is very good at the price of the printer. But I find that it does not stick to surface of the heated bed well. often need to add additional perimeters to stablelize it. Sometimes, half way through, the object just lift up and drop ...dead...  Other than that it is fine, especially when I print honey comb structure.


Next , I used Uprint. This is a more professional machine than the conventional Reprap family. It used propietry filament and support material. They sell in a carton of 7 sets. Costing about USD 1 K per box. The filament is ABS. The support material is soluble in acid. Print out is very hard, professional. But cost wise, it is higher.  The support material is actually not so hard to take out,  even if you are using simple tools like penknife and screw driver. Unless REPRAP machine, the support material is the same and hence hard to take out. Even if u can, it take a long time to clean up.

 

Also with this machine, I can tilt or adjust my printing to suit the force exerted on the layers. As we know, one of the weakness of  3D printing is due to the layers. If you exert a force parallel the layers, it might give way. So for Uprint, we can tilt the angles of the print  out till the forces are  not parallel to layering. Of course at the expense of the support material.

 

Next, we have OBjet.  

 OBjet is very expensive.The material is also very expensive. I would have though that this machine can print out molding quality. But I discover I was wrong. Conventional 3D printer including Uprint uses material that is quite brittle and not soft like injection molded  plastic. So under pressure, the printout might crack or give up. With OBjet, I thought it will be much better. Later I realised that  this is not the case. It still crack. Although the material is better the PLA or  ABS.

The printout is super smooth. It actually flatten every layers and make a smooth surface.

Another problem with OBjet is, you need to go through washing to clean the parts, as the parts is still wet after printing. Cleaning  will take a you while to do it. You can see it is very well protected, the material could be a bit toxic. The material is VERY expensive.

Comparing J-head hotends

I had bought quite a few hotends. I bought
1) J-head , Aluminium nozzle , Plastic body
2) J-head with aluminium heat sink and brass nozzle.
3) Mk7Direct extruder
4) E3D Hotends.

Also , I had many sizes of nozzles. 0.2 to 0.5  And in the end, I prefer to use 0.4.

Let's talk about this type of J head hot end. Plastic high temperature body and aluminium nozzle. The nozzle is relatively expensive to replace. I use it when I first started my Prusa I3. What happen is even with this body, YOU NEED A COOLING FAN. If not, your PLA might melt and solidify in it.

 

This nozzle clot easily. residue stick to Aluminium and hence you will find that the flow gets smaller and smaller. Then after I cleared it, one might accidentally enlarge it. Because Aluminium is soft. How I clear the choke. Basically I heat it using bare flame of my cooking hob. Then I have to get a stiff wire or the right size drill bit to clear it. After clearing afew times, I got fedup with it. I changed to brass nozzle.  And stop using J head. Now I have 2 sets of J head with 3 nozzles.

 

Next I bought a all metal J-head. I bought it cheap. probably less than  5 USD. I bought the heat sink , stem and nozzle separately. It works very well. Only thing is , YOU MUST HAVE A COOLING FAN. If you do not put a fan, the PLA filament will melt in the heat sink portion and solidify. then it will be hard to extrude.  I machined My own heater block. Just for fun. Now I am still using this extruder/ hotend.  The Brass nozzle is very important . It just don't choke. Ever since using this, I had never need to resort to barbeque my nozzle. I used a  0.4 mm nozzle.

 

 

 

 

 

 

 

 

 

 

 

 

Also I tried using direct extruder. Mk7 direct extruder with non contact heat sink but  with fan.

This is a very simple but good extruder. Once I realised that  maybe I do not need geared extruder, I put this into use. with indirect heat sink and fan. It works quite well but I still prefer the all metal j-head. I do get jam once in a while. But I think probably I did not set it well. I think this is simple and good. and importantly, nozzle must be brass.

 

lastly, I bought a E3D hotend. this is just a smaller version of all metal J-Head. so the result is comparable,  but the size is smaller.

 

Additional cooling fan for the printed parts. I had a chance to use Felix 3D printer. I am very impressed by the printout. It is so simply built and printout is so good. I realised from Felix that you need another cooling fan for the printout. This is to make sure that the previous layer harden and make the structure more rigid. especially at slope. previous layer need to solidify or else some times, you see a big lump on the curve or slope at the side of it.  

 

 

 

 

 

 

Extruder - Greg Wade Geared extruder with J-head Hotend 0.35mm

From the Prusa I3 orginal documentation, I downloaded the STL file and assembled the extruder. Assembled as they taught and mounted it on. The only problem is I used J head. I was not sure whether J head can be mounted onto it.
Let's talk about  the gear head. It works well. For so long, the gear did not fail at all. still hard and steady. And I use PLA to print it.

To confess, the PLA printout from Cube 3D sucks. I am not sure how long it will last. but I know, as long as I get it to work, I will duplicate all the printed parts again....

THIS IS AWEFUL

YUCKS.....

But In the end, I managed to get it working ..... 

First Few Prints....

After completed building it, it is time for my first few prints....

There are afew basic print to determine whether your printer is doing a fine job. A hollow box like this....This shows that the printer did follow the path, but the hot end did not do a good job.....

After that I tried to print a solid box 20mm X 20mm. It look like a sponge. This shows that I did not calibrate properly. A better one look like this,.... 

You can see the cross line being clearly laid out.....The print was much better...

You can see that the line are pretty much aligned... also... that is good. But not the end.

My thought on Prusa i3 (3) : Building the XYZ structure ......

Building that was easy.... Simply cut the M10 threaded rod , re-thread the rod ends. Bolt and nut it.
Had alot of cable tie on hand. It is needed to tie many things...
 That is all. But I found a problem. I do not know what size( height of the NEMA 17) the motor used in the drawing given, so after I built it , the Nema 17 DID NOT TOUCH THE FLOOR......

So I added a piece of supported printed from the 3D printer , after I fully make it work... but the print was bad... You can see the wave print . But not bad consider that I had not fully optimize it....

My thoughts on Prusa I3 (2) : Machining the Vertical Plate and the heated bed support.

The Heated Bed support and the vertical plate is machined from 1 piece of 8mm acrylic that I salvage from somewhere. So it is considered free . If you do not have a milling machine, you can consider buying it. For your info, you need not machine it until like this. I simply had a rectangular plate. It is not that heavy. I was lazy and the milling machine was not that good, So I did not reduce the size too much... But I managed to cut some slots for the linear bearings...

For Heated Bed I used Mk2. Now Mk3 is produced. It will be good as you can possibly lift the bed rather than lowering the extruder. MK2 must be mounted with a flat surface glass. I salvaged a a scanner glass and cut to size...

 Mk 2B.

The New Mk3 is availlable and it has a aluminium layer on it. So not more glass panel. This is good. I will use Mk3 when I have a chance.  But becareful when you buy MK3, Make sure it is MK3. Some supplier make MK2a/2b BLACK.......

My Prusa I3 .............

I built a prusa I3 some 1 years ( or 2 years ago)....     And till now it work better than I had expected.  But of course, I improved it through out these many months,

My Prusa I3 

My built Plan was from http://reprap.org/wiki/RepRap_Options  here.  There are many plans here but do bear in mind, not all work well. 

My reason for choosing Prusa I3. 

I find that Prusa I3 is probably the most easy to built 3D printer that I can find and it is very well documeted . I had a 8 mm acrylic  which I salvage somewhere. I reused it , mill into 2 parts. 1 for the heated bed and the other for the vertical stand,  I used milling machine to cut a center hole. This center square hole become my base for the headed bed., The vertical  stand 

It is very well documented here. http://reprap.org/wiki/Prusa_i3. But beware, it may not be the best....

Thinking back, if you want to built one , but might want to consider other models like Wilson etc. I will blog the reasons why Prusa i3 may not be a good model to follow. 

Where do I get/buy the components from ?

The Frame can be found there.https://grabcad.com/library/prusa-i3-frame-catia-catpart-stp-stl-igs-model-dxf-dwg .  

I bought the threaded rod, screws  from local hardware shop. I bought the other components like RAMPS 1.4, Heated bed, linear bearing, 5 Nema 17 Stepper motors , J-head extruder from a shop call  RobotDigg. http://www.robotdigg.com/ .  I paid about USD 230 including DHL. 

The quality is GOOD, compare to other parts that I bought later at ebay, especially the linear bearing.

 The motor was good, the hotend was good.  I receive the items few days later. Really fast...  Well packed....

The green PLA 3 d printed parts are printed from Cube 3d. I am sure it is the worst 3D printer I had used. Expensive and poor results.  The STL file can be found in the wiki page that I referred to above. But since this is the only 3D printer I can access to, I used it to printer out all the parts that I need. Hopefully it will work till I can reproduce another set. I let you see what happen to cubify 3D printout . 

Ok ....Soon I will upgrade this set to a Aluminium profile structure with Mk3 heat bed. Also I am building my first CNC machine . I had some ball screw rods and I managed to test the arduino CNC V3 and IT WORKS...