Evolution of a Blog

This blog has evolved as I have as a maker. It starts at the beginning of my journey where I began to re-tread my tires in the useful lore of micro electronics and the open-source software that can drive them. While building solutions around micro-electronics are still an occasional topic my more recent focus has been on the 3D Printing side of making.

Wednesday, June 21, 2017

Would I Recommend the Wanhao D7?

The price point of the Wanhao D7 has a lot of people wondering if they should buy one.  Some of these folks, a lot really, already have an FDM printer and want additional capability.  Some have no printing experience but want to start somewhere.

The first thing that a new buyer should understand is the process that printing using resin will entail.  I had described my workflow in an earlier post located here.  If you already knew all about resin, or you are ok with the process that I described, then we can talk about the D7

What do you want to do with a Wanhao D7?


So the first question that I would ask before making any recommendation would be to explore what they want to do with the Wanhao D7.   If they already have an FDM printer they can probably skip to the next question!

The D7 is a small printer.  It's build area is 120 x 70 x 200mm.  By comparison my Ultimaker 2+, an FDM printer, has a build area of 223 x 223 x 205mm.  On the other hand the best resolution that the Ultimaker can deliver is 20 microns (though I have never actually printed at anything lower than 60 microns) on the z-axis and 250 microns on the x/y axis.  Meanwhile the D7 can routinely print at 30 microns on the z-axis and it has an x/y resolution of 40 microns.

These two printers obviously satisfy different requirements.  The Ultimaker, an FDM printer, melts and extrudes plastic and prints large functional items in a variety of materials.  Its level of detail, however, is going to be a limiter.

The Wanhao D7 is a Direct UV Printer and uses UV light to harden a liquid resin into small detailed parts.  While they can be functional it is more likely that they will be ornamental, game pieces, or used to mold a functional part.  In general this process won't produce a particularly strong part though there are resins that will be stronger than the ones I am currently using.

So, if you are ok workflow associated with resin based printing, and you know that what you want to print are smallish but highly detailed parts, then you need to answer one last question!

Are you prepared for the adventure that a Wanhao D7 can entail?


You need to consider the results of a poll that I conducted recently in the Facebook Group devoted to folks that are have or are interested in the D7.  First I have to acknowledge that my construction of the questions was a bit flawed and the sample size of 32 is not large enough to bet your life on. That said I would also say that the results correlate with the posts we see here.



Slightly over half of the people responding like their printer and only one person (3%) hates it. That leaves 44% of you in between liking it and hating it.

My question about the build plate was badly flawed in construction and so I feel needs to be discarded. The (flawed?) results would indicate that over 70% of owners had to take corrective action on their V1/3 or V1..4 build plate. Based on the comments below, and on a daily basis in this group, I would still suggest that most users getting a new machine will indeed have issues with their build plate often requiring that it be sanded (or even sand blasted)! Maybe the survey question is not so flawed? Leaving build plate issues aside, I was surprised that nearly a third of owners had a problem other than with their build plate.

Finally, a little less than a third of owners printed straight out of the box. More alarming, almost 1 in 5 can still not print after more than a month.

If I were Wanhao I would want to understand these results in much more detail. I would do a more scientific poll drawing on the FB community but using something like SurveyGizmo or SurveyMonkey. I would try to understand numerically what problems are being experienced by new owners. I would then ask myself what my targets are for out of the box printing and ultimate customer satisfaction. Finally, I would wonder if I have tried to cut too much cost out of the printer and if there are areas where a little higher component quality might be justified. Like on the build plate!

If you are still interested in the D7 after reading the above, and you are patient enough to work through any initial problems that you might have, then you will end up with a printer that is capable of amazing quality.  You do, however, need to be prepared for the adventure that getting to that quality might entail!





Saturday, May 20, 2017

WIth a Good Hammer It All Looks Like a Nail

I have been down this road before.  I consider the Arduino microprocessor to be a nice hammer and I often find places to use it to solve problems that may or may not exist.  I have also been known to over engineer some of my solutions.  The  Wanhao D7 is giving me the chance to do both!

In a previous post, "Instrumenting a 3D Printer for Heat Testing", I introduced an Arduino based solution to monitor temperatures inside a printer.  I was able to demonstrate that the new 1.3 cooling solution is indeed effective at keeping operating temperatures within a healthy range for the UV LED array.

Since then I went a step further and tied two LED's to the Arduino, a green one, and a red one:
  • Solid green - Fans are on and temperature of the UV LED array is optimal
  • Flashing green - Temperature has risen above 50c
  • Flashing red - Temperature is approaching critical of 60c
  • Solid red - Temperature is above 60c
I have now taken my solution one more step and tied the Arduino to a relay that will power down the UV LED if the temperature rises above 65c immediately or after a solid minute above 60c.

Obviously this is pretty drastic but a) I do not see it happening unless something has gone badly wrong, b) RPis do occasionally burp and that burp could be after turning on the UV LED array and before turning it off again, and c) if something has gone badly wrong while a printer is running for a long period of time... I would rather lose a print than have expensive consumable items like my LCD and UV LED array burn out!

Naturally if I am going to these lengths then I am going to have a PCB fabbed!  Here is an image of version 1 which is being produced in China as this is being written:
Note that there are pins on the Arduino that are not being used and are easily accessible for jumpers. NanoDLP has some cool functionality that allows it to react to the state of pins on the RPi GPIO.  An example would be to insert a delay after a layer is cured to allow for cooling when temperatures exceed a certain threshold.  I don't see needing to do that but it is cool!

Thursday, May 18, 2017

Speedy Slicing with NanoDlp

UPDATE:

This was a crap idea.  The time to unzip files on the RPi is way longer than I anticipated!  I could probably transfer them faster uncompressed but have not gotten around to testing that theory!  Oh well.

END OF UPDATE

I really like the configuration that I have with two Raspberry Pi's running NanoDlp to drive my two printers.  It allows me to not have to dedicate my desktop (and laptop since I have two printers) from having to drive those printers.  One thing the Raspberry Pi's don't do, however, is slice fast!  But a Windows or Linux machine hosted on a much more powerful workstation can run NanoDlp and slice in a big hurry!  I looked around for a solution where someone else was already doing this and did not see one so decided to roll my own.

Overview

There are really only two directories to worry about.  There is the Db directory that contains all the various settings including resin profiles and the index to your plates.  Then there is the plates directory with a subdirectory for each plate you have created.


Enter a somewhat crude, but workable, Python script to synchronize my "master" with my "clients".   In this script I look at the contents of the Db directory on the master to see what the latest datetime stamp is on any of the configuration files.  Then I check the designated target client to see if the datetime stamp file we left there during the last update is older than what we just came up with on the master.

If an update is needed the contents of the Db directory are copied to the client.   Then the plates directories are compared and where needed a new one will be created and filled, or an existing one will be cleaned out and refilled.  The transfer is done after compressing the directory into a zip file.  A CRC check is done on the transferred file prior to decompression.


Obviously an assumption is made that ALL changes will be done on the master and propagated to the client(s).  In addition, the way that I currently have this configured precludes having the two printers setup differently.  This, however, can be accommodated by excluding some of the entries in the Db directory.  It may not be the height of coding excellence but it seems to work.

Command Line Options


Notes and Caveats

  • The script described above is still under development but is available here for brave souls.
  • The script is provided as-is and I will take no responsibility for its operation!
  • A knowledge of Python is required!
  • You may need to copy the directory on the RPi where NanoDlp is installed so that rights work with SFTP.
  • Once the above script is run the instance of NanoDlp needs to be restarted for changes to be visible
  • You need to make sure your RPi and your host computer are in the same time zone and running synchronized times!

Down to Fine Tuning

I am starting to see the potential of these little printers.  I still do not really have a use for them...but I can see the potential!  I am at the point where I get 100% adhesion to the build plate and I am comfortable that when I lift the lid I will find something printed!

That is...depending on the resin.  Fun To Do Snow White is incredible.  The sample that came with my second printer is pretty good.  The two liters of grey that I bought of Monocure is problematic!  Currently struggling to get a good print with this resin.  I am doing calibration prints measuring the expected size of an object against the cured size and am up to 35 seconds for a 60 micron layer,  At 20 seconds I was getting layer separation.

But the Fun to Do Snow White is amazing and the stuff that came with the printer is not bad at all.
Test and calibration pieces on the build plate (FTD SW).

Above off the build plate.

Collection of calibration and test prints.

White is under cured FTD SW, Clear to the right is the over cured Wanhao Sample and the Monocure Clear with a missing corner is on top.

Close up of the Eiffel Tower.  Note the result of what I assume was under extrusion in the middle of the photo.

The whole tower.

Monday, May 15, 2017

Major Surgery on a Build Plate

The good news is that Wanhao has made some great strides in reacting to feedback on the version 1.1 and 1.2 printers. Cooling and packaging in particular but a host of other things as well. The bad news is that they seem to be sending at least some customers build plates that are concave and painted with something slippery.

This is when I knew that I had a problem. Build plate should have had stuff on it! 100% casualty rate.


So I did a little bit of sanding. Clearly something is wrong here as only the corners and edges are being touched.

So I did a lot of sanding...by hand...with 80 grit paper. This is where I realized that getting rid of my 240 to 120 volt power supply and my yankee sander was going to be an issue. So I ordered a Black & Decker Mouse Sander.



See anything funny about this print? Since I had some down time I printed a build plate just to see if it would work. Extrusion lines!

Mine was printed using PET and it actually worked pretty well. Prints stayed on until I wanted to take them off.

Finally got the sander and a pack of papers from 60 grit to 800 grit and I walked through each one, a couple in come cases.

After hand sanding with wet emery paper from 1000 to 7000 we had 100% stickage. There is a problem on the left side but not a build plate issue.

Tuesday, May 9, 2017

Instrumenting a 3D Printer for Heat Testing

My DLP printer experiment is as much of tinkerers panacea as it is anything.  And I am ok with that as I expected as much.  I have version 1.2 of the printer and version 1.3 has just been released.  The difference between the two is all a matter of cooling.  Which is to say that version 1.2 ran hot!  With that knowledge in hand I designed a new case for the printer with cutouts for some new fans. But will both fans be needed and if so what way should airflow run?  These are the questions that I would like to answer!

To be able to answer these questions I needed a quick and dirty way to measure temperatures within the printer.  It would also be helpful to know when the UV array is lit and how much light it is producing.  I decided to use one of my many Arduino' for this task connected to three thermistors and a photo resistor.  Initially I will use a bluetooth adapter to talk back to my PC.  I also want to source power from the printer so I need to convert 12v to 5v to operate the Arduino.

Here is a picture of what I built followed by a brief description of the various components.

  1. Arduino Nano - Cheap as dirt on eBay but a capable little chip.
  2. Expansion board for the Arduino Nano. Breaks out every pin on the board adjacent to power for whatever you want to connect.
  3. Power converter to take the 12v from the printer supply down to 5v for these electronics.
  4. Bluetooth adapter for transmission of data back to my desktop.
  5. Thermistor (more below).
  6. Photo resistor (more below).
  7. Temporary 5v power supply.
The thermistors and photoresistor all operate in a similar manner.  Temperature or light change their resistance.  I create a voltage divider with the variable sensor as one of the two resistors.  By measuring the resultant voltage I calculate a heat reading for the thermistors.  The photo resistor reading is not translated but just used raw.  Here is the Arduino Sketch that runs on this device.

The output of the above sketch is a simple CSV stream of values that I capture on my Mac and then feed to a spreadsheet.  A sample of the CSV and a copy of the end chart are shown below.




Sunday, April 23, 2017

Mods for my New Wanhao Duplicator 7 (D7) 3D Printer

Update of 9/5/2017:  Two of the designs that I mention here have now been extended.  The base now has a variant that houses the RPi under the printer.  In addition, the "Feet" now include an option to adjust the printer angle.

I have some good resin coming for my new printer early this week and have been struggling a little with the sample that came with the unit.  Not to mind, however, as I have used the time to make the printer a little more tuned to me.

The last and best thing that I designed was a base that raises the printer giving the fan more air flow while providing a place to mount the RPi that hosts NanoDLP.

http://www.thingiverse.com/thing:2268534
The RPi is housed in a really nice design also available on Thingiverse.

I did some other designs as well:

Cover for the resin tank.
Spatula based on the one that comes with the printer.
Device to help me level the build plate.
Handles 'cause mine did not have one and the damn thing is slippery.
Feet to raise the printer for better airflow.

All of my designs are licensed under the Creative Commons - Attribution - Non-Commercial license.

Wednesday, April 19, 2017

Eeeh Gads. Another 3D Printer!

I have been thinking about getting an resin based printer for a while but have not pulled the trigger for a number of reasons.  First, I really do not need one!  Second, I have seen the post processing work needed to remove the support structures that are required for this kind of printer and am not keen on them.  Third, I am space constrained in the man cave.  Fourth, they cost a lot of money for something that I really dont need!

As with all things in the technology space the prices, particularly at the low end, are coming down.   There are FDM 3D Printers now available for just a couple hundred dollars.  Entry level but fully capable of doing good prints.  This trend is also impacting resin based printers though until recently the lowest price point has been around a thousand dollars.

Enter the Wanhao Duplicator 7 which is aimed at the bottom price point in the market at 400 dollars.  The printer is extremely capable for that price point though.  The build volume is decent (120, 68, 200), the speed is decent (15mm-35 mm per hour), and the resolution is more than decent given that it can do layers of 35 microns and an x-y resolution of around 500 dots per inch.

And it is cute!  Its small size makes it perfect for the man cave.  I think the printer is a great demonstration of how the Chinese can take a product and develop a low cost version.  The electronics are based on a RAMPS board which is the same thing that drove the 3D Printer that I built two and a half years ago.  Everyone knows what they are and what to do with them.  The motor is the same as a zillion other 3D printers.  The power supply is a standard brick.  The LCD display is repurposed from what had been designed for a tablet.  i'm not sure what the video interface is but I would bet that it was repurposed from a laptop or something of the kind.  It is eloquent in its simplicity.


Sunday, April 16, 2017

3D Printing and Scale Modeling - Recap of Selected Designs

This post is a "work in progress" summary of my favorite of the models that I have done over the past year or two.  Most of these models are available for download on Thingiverse and many have been discussed elsewhere on this blog or have an Instructable available.

One more note!  These are largely bespoke models crafted in Sketchup using its Pro features for solid modeling.  Those features don't make it the best 3D modeling tool out there but they help a lot ... and since I am an old dog that has been using Sketchup for a long time ... anyway ... the models are in Sketchup!


My Model
The Prototype
Curved Railroad Bridge and a Steel Pier
 
Retaining Wall


Concrete Railroad Bridge Pier
Ship - Cheated a little here as my prototype is a model from the Wrightsville Port N-Scale Layout!


Plate and Girder Railroad Bridge - Bridge No. 1276, Sideling Hill Creek Crossing
Bridge Fenders
xxx
xxx
Bascule Bridge

Windmill

Bailey Bridge [Thingiverse] [Blog] [Instructable]


Friday, March 10, 2017

Overnight 3D Printing - A Facebook Poll

I posted the following poll on Facebook and thought the responses interesting enough to summarize here.


Here is a summary of the results:

A strong majority of folks print overnight without concern. Another pretty large group prints overnight but with some concern. There are a fair number of folks that do not print overnight but the survey questions are flawed in that these folks could have reasons other than fire concern.

Some other observations. There are a number of people that have added fire detection and suppression with a variety of solutions mentioned from off the shelf, to external service provided, to self crafted. Finally there were even folks that admitted to having their spouse or boss tell them to pound sand on the printing all night thing. My other survey question asked if people had experienced a fire. A very large majority had not though a handful did. The fires described were all minor. Probably a bad survey question as someone that had a bad fire may not be doing the whole 3D Printing any longer! Finally, from comments on both polls, it seems like the concern is the highest with the cheap home built printers and diminishes as you go up market.

Cost and Appearance of Different 3D Print Resolutions

I had done a post some time ago comparing resolutions but thought that I would do another one using a model from a customer order.

600 micron nozzle with 300 micron layer height.  Time to print (each): 00:49.  Cost (for ten): 31.74
400 micron nozzle with 200 micron layer height.  Time to print (each): 01:10.  Cost (for ten): 41.17
400 micron nozzle with 150 micron layer height.  Time to print (each): 01:32.  Cost (for ten): 49.86
400 micron nozzle with 100 micron layer height.  Time to print (each): 03:07.  Cost (for ten): 62.90 

Looking at the costs by time it would appear that my costing for the 100 micron layer print might need some adjustment (up)!

Time (Minutes)CostCost per Minute
49£31.740.6
70£41.170.6
92£49.860.5
187£62.900.3