Evolution of a Blog

This blog has evolved as you can tell by comparing the title with most of my recent posts. The title should really be something like "The Physical Interface Side of Computing". Actually, more recently it would be "3D Printing and all of its Trials and Tribulations". Anyway, it will still feature Raspberry Pi and Arduino from time to time but my current hardware of choice are a Wanhao Duplicator 4S and an Ultimaker 2. Just before that it was a BeagleBone Black with JavaScript and Node.js providing the development environment!

Tuesday, July 21, 2015

After Market Cover for Ultimaker 2

The Ultimaker 2 is a partially open printer and as such is perfect for PLA which seems to be the preferred material for UM2 owners.   There are obviously a lot of people printing ABS, and other materials as well, but in my environment a closed build space is a requirement to ensure platform adhesion and limit warping (as the man cave can be drafty).

I wanted to be able to print in ABS so my first step was to jury-rig a cover (as shown below).  It worked but was just a little ugly!

I looked around for after market covers and was surprised at how few are out there.   I did finally find the one sold by the "3DPrinterstore24":



Obviously a German store with a website in German!  But I ordered it none the less as it looked pretty good and was of reasonable cost.   The door was separate and some contend is all that is really needed to print ABS.  I ordered both.

They arrived yesterday in a very securely packed box.   The instructions were all in German but the pictures made it pretty clear what needed to be done.   I would recommend that anyone building this cover insert all the nuts before the parts are assembled.   Some will be tight enough to stay in place but others might require a small piece of masking tape.   Once the sides start to be put in place I found it a lot harder to insert the securing nuts but this could just be me and my coordination!

The cover and the door look really good mounted on the machine.  They look like the were sold by Ultimaker though I suspect that Ultimaker would have used frosted plexi for the side panels!  I am very pleased with the cover though.



My only complaint, or suggestion for improvement, would be to either ship the door unassembled but still wrapped in the protective plastic.   Or strip the protective plastic before assembling the door.  I found it to be a real pain to get the plastic off cleanly and had to partially disassemble the door to do so.

Monday, July 13, 2015

Printing ABS on an Ultimaker 2

I was never really successful printing ABS on my Prusa I3 for a couple of reasons.   First, the build platform was heated by a 12v circuit and you really need more juice than that for ABS.  Second, the Prusa is a completely open machine and ABS simply does not like to be in the open as it cools.  So I printed PLA.  A lot of PLA.  Used either hairspray or ABS slurry for platform adhesion (yes, ABS slurry for PLA adhesion).

The Wanhao Duplicator 4S is a completely enclosed machine and has been an animal printing ABS.  I still have an occasional issue with build platform adherence but in general things stick pretty well.  I have experimented with a number of surfaces other than the glass, namely FR-4 and Klapton Tape.  I have also decided that some models do need to be printed on a raft.

Interestingly I have not had any real success printing PLA on the duplicator 4S!  I have not tried terribly hard but for some reason getting it to stick to the build platform has been a challenge!

Enter the Ultimaker 2.   I really does a nice job of printing PLA.   But it's semi-open nature still can make ABS a bit of a challenge particularly in my drafty man cave.   Enter my solution as shown to the right.  No this is not permanent but I needed to play with ABS on the Ultimaker 2 a little before I invested in the real thing.   What you see does work though.  It provides a nice, warm, breeze free, build environment.

I am still struggling a little with build platform adherence on the UM2.  I really like FR-4 but the sheet of it that I have is just too thin and it floated a little in the middle.   Maybe some double sided tape.

It is good to have another printer that can do ABS.  I guess I should work on the Wanhao and get  it to print PLA!

Sunday, July 12, 2015

Visual Impact of Resolution and Speed on a 3D Print

There are a lot, I mean a great many, parameters that impact the quality of a 3D print.  This is what makes calibrating a printer so much fun.  Two of the parameters that provide the most visible impact are layer height and printer speed.  These two parameters are also the ones that most dramatically impact print time.  The higher the resolution, the more layers, the longer the print.  Obviously the faster the printer goes, the shorter the print!

When I got the order for the truck I was in the process of setting my prices on 3D Hubs so I decided to do some tests using one of the tank models that I downloaded.   Obviously the time that a model takes to print has to be the largest factor in how much it is going to cost via my hub.  Equally obviously the customer should be able to expect a high quality print!

The printer that I used for this test was the Wanhao Duplicator 4S printing ABS.   I printed seven copies of the same model as follows:


Model Resolution      Speed Time
0 0.1
74
1 0.15 Fast 48
2 0.15 Slow 66
3 0.2 Fast 36
4 0.2 Slow 58
5 0.25 Fast 30
6 0.25 Slow 47

The "Fast" speed was 43mm/sec and the "Slow" speed was 25mm/sec.   I did not do two speeds for the 0.1 resolution print as I am not pricing that resolution on the Duplicator 4S.   The time is minutes.


Above is an image of all the test prints arranged with the fast prints in the front (0, 1, 3, 5) and the slow prints in the back (2, 4, 6).   The differences in quality that you get via the layer height are patently obvious!

Not so much the difference in quality from the speed.  This surprised me as I know there can be a huge difference but it obviously depends on the model.

One of the issues that I have seen that can be caused by speed are whiskers.  As I write this I am doing a print that I know is running faster than it should and there are whiskers! 

Speed Whiskers
There are several parameters in most slicers that deal with this kind of issue (oozing).   In Simplify3D you can adjust retraction, coasting, and wiping.   In the case above I have it set to to a retraction and to coast (at the end of a loop of plastic).  I did not have it set to wipe as I tend to see this as a negative more often than a positive.   I also know from experience with this print that slowing it down would result in a clean print.  I chose not to do that as the manual cleanup was worth the fast time to print.

In any case, no matter how hard I look I am not seeing a difference between the slow and fast prints when looking at my test cases. 

Left=Fast, Right=Slow
Left=Fast, Right=Slow

Above are images of the test prints.  You might be able to claim that the layers look more uniform but I am not seeing something jump out at me as to a big difference.

I am going to do another print at an even higher speed and see what evidence that produces.  My suspicion is that we will not see much of a difference.

Here are the test prints that more clearly show the differences in resolution (layer height).

0.1mm

0.15mm

0.2mm

0.25mm

I printed two more copies of the test model, this time with a larger speed difference of 25mm/sec and 50mm/sec.  There don't appear to be any fatal flaws showing up but the stitching of the filament loops is definitely tighter on the slower prints.

Faster - Slower
Slower - Faster
I don't think that this experiment yielded the result that I expected but I think that I know the reason why.   Namely that these models are simply too small.   I doubt that the extruder assembly is ever up to speed and there are no large distances for acceleration and deceleration to produce the kind of jerking that would cause an issue.

Given that this test did not give me a result my experience has been that bad things can start to happen above 50mm/sec and sometimes even a little below that threshold.   Based on my experience I decided to use the speeds of 33, 37, and 42 for the three levels of quality that I offer on my two printers on 3D Hubs.  Obviously I will adjust on the fly for individual prints!

Saturday, July 11, 2015

Tired of Tanks Yet?

Sorry.  Couple more to go!   Here are some examples from the 1:200 collection!

Luchs and Nashorn 1:200 in front of 1:100 Tank

Luchs as Printed

Luchs Cleaned Up

Two Luches Scaled to 1:100

Opposed Landing

T-34 with Coin for Size Comparison

If you want a tank but you don't have a printer you can, in effect, rent some time on one by winging your way to 3DHubs:

3D Hubs: Local 3D Printing
If you are in the UK you can visit my hub:

Wisar's Hub

You send me the order with the .STL file for the tank(s) that you want and I will be glad to print and ship them to you.

Removing Support from a Tank Print

This post shows the sequence of events as I strip the support structures generated by Simplify3D from on of the tank models.  The model is actually that of a combat carrier but they run with tanks!

I use Simplify3D as my slicer and it does really good work with support structures.  Still, I find that you need to examine the support built for each model and adjust as needed.   In the case of this carrier I needed to remove the support around the heads of the driver and gunner.



 I have also found that prints done in PLA can be cleaned up but expect a fight!   Finally notice how the support stuff hangs out from the side of the model.  This is a configurable option and really helps with cleanup.

1. Starting Point

2. Starting to Strip

3. Halfway Through the Bottom - You Need to Start Here!

4. Bottom all Stripped

5. Ready to Strip Right Side

6. Right Side Stripped

7. Ready to Strip the Left Side

8. Left Side Stripped

9. Ready to Strip the Front

10. All Stripped
I used one tool for the above with that being the small needle nose pliers that I dremel'ed down to have a very fine tip.   I could have gotten a lot of the support material off with a small screw driver and my fingers but am ok with the pliers!

3D Hubs

3D Hubs is a cloud based service that allows people with a 3D Printer to make that printer available to the wider community.   People without a 3D Printer, or even someone who has one but has a capacity issue, can find a local printer to which their models can be sent.

I have made my printers available to this service and while business is not brisk I have gotten two jobs that I have learned from having completed.

Below is a chart that illustrates the cost versus time to print pricing model that I have on 3D Hubs.  The model is based on the time and plastic that it takes to print a "Marvin".







Marvin

3D Hubs Resolution Layer Height Speed (mm/m) Startup Cost Cost per cm^3 Cost Time to Print
Ultimaker 2 Low 0.25 2500 7 0.5 7.99 24

Medium 0.15 2200 8 0.7 9.39 40

High 0.1 2000 10 0.85 11.79 60








Duplicator 4S Low 0.25 2500 5 0.4 5.89 32

Medium 0.2 2200 6 0.5 7.09 40

Medium 0.15 2000 7 0.6 8.29 54

There are two factors at work in the above model.   Resolution of the print is governed by the layer height.   The smaller the layer the higher the resolution, and of course, the longer it takes to print.  The speed that the printer moves while extruding plastic does not impact resolution, however, it has an impact on print quality though this can vary from print to print.  Obviously speed has an impact on the time to complete the print!

In either case, the longer a printer is tied up the more one needs to charge!

Friday, July 10, 2015

Some More Tanks

The prints that I am most impressed with were Shermans that were printed in PLA on an Ultimaker 2 with layer heights of 0.1mm and 0.15mm at 30-35/mmps.

0.15

0.10

0.15 and 0.10
Finally, since I live in England, how about a British tank? This is the Matilda Centaur IV. It is printed at 0.1mm resolution in PLA on my Ultimaker 2.


If you want a tank but you don't have a printer you can, in effect, rent some time on one by winging your way to 3DHubs:

3D Hubs: Local 3D Printing
If you are in the UK you can visit my hub:

Wisar's Hub

You send me the order with the .STL file for the tank(s) that you want and I will be glad to print and ship them to you.