The Making of a Maker

Wednesday, September 6, 2017

Generation of a NanoDLP Mask for the Wanhao D7

Update as of 17/9/2017: This is a very flawed article as I confess in a later post here. Flawed, yet because the D7 UV light is distributed so heavily to the center, it still worked well! Sorry for any confusion and that I did not post this confession sooner (though I did make a note on the 14th)!

I finally decided to invest the effort in creating masks so that my build plate is evenly exposed to radiation from the UV LED Array of the Wanhao D7 3D Printer. The annotation on the following images explains the process. Links are at the bottom.

Note that as of 14:53 on 7/9/2017 I am chasing a little bit of under cure on the edges even with the measurements. Things are much, much better than without the mask, just not perfect!

Note that as of as of 16:24 on 14/9/2017 I need to 'fess up that my understanding of how mask generation works in NanoDLP was pretty flawed below. Stay tuned.

Created a printable grid that matches the default grid on the NanoDLP mask generator (e.g. 10 columns by 5 rows). The tabs can be used to secure the grid. Theoretically the one without tabs could be printed on the D7. The camera adapter was my first plan but the iPhone light meter app I tried could not detect the UV well enough. The little square thing is a mount for the photoresistor that I ended up using.

Ultra simple Arduino circuit. Photoresistor to ground and to A5 with a 10k resistor to +5v. Read A5 averaging 2 seconds of inputs 100ms delayed from each other (20 in other words) and display the result.

Printed matrix secured to the printer with the photoresistor in a cell.

Top right is the output from the Arduino. Bottom right is the monitor built into the printer. Left is the spreadsheet that I used to calculate the mask values.

View of the completed spreadsheet. Layer cure time will need to be increased by the stated percentage.

The above spreadsheet also has tables for subsets of the build platform. This one only uses two fifths of the build plate and as such only increases cure time by 11%. The white area of the first table is the printable area to model. On the second table the yellowish cells represent unprintable but the light grey ones are adjustable to be useable.

Mask as generated. Located in ~/printer/public/plates on the NanoDLP instance.

Proof is in the pudding.

Grid on Thingiverse
Arduino Sketch
NanoDlp Mask Calculator
Link to Mask - Use at your own risk!

Parts needed for your own measuring device:

Photoresistor - Search for "5516 Photoresistor Sensor Detection Light Dependent Resistor". Interestingly I did not buy this for UV sensitivity but it works fine and I wonder if other photoresistors might as well. If you are reading a difference of more than 30-40% from the middle to the edges of your display it might be the photoresistor.
10K Resistor - Used for the other leg of a classic voltage divider.
Arduino Uno - Search for them on eBay. You can get clones from China for a couple of quid if you are patient with shipping times.

Comparison of masks for my two printers.

Interestingly the printer on the left has a glass plate behind the LCD and the one on the right does not.

Here is the test piece from my second printer. Same issue with measuring the little pointy things...there is a slight under cure at the edges.

Calibration pieces from printer #1. First time anything has stuck to that corner!

Closeup of the above calibration pieces. Can you tell which one was center, versus side, versus corner?

Monday, September 4, 2017

Resin Mixing Pump

I have noticed that FTD Snow White, a heavily pigmented resin, tend to separate over a long print. Someone on the D7 Facebook Group had used a dosing pump to keep resin mixed so I decided to do the same.

Here is the pump that I used (from Amazon UK). The tubing that I used was from eBay and was described black silicon tubing with an inner size of 2mm and an outer of 4mm.

The pump vibrates when it operates so it should probably be turned off when the printer is curing a layer. This means putting it on the 2nd fan output on the power supply so you can control it with "M106 P1 S255" for on and "M106 P1 S0" for off. I guess the alternative would be to have it off the printer and running constantly?

The mount that I designed for the pump is pretty simple and is available on Thingiverse for download. Ideally I would have liked the hoses to feed around the back of the vat but there just was not enough clearance for the build plate to travel. As you look at the picture of the printer the left is suction and the right is output. I route the suction tube to the near right corner and the output to the far left corner. The tip of the input tube is cut at an angle so it does not attach itself to the FEP.

Controlling the pump entails putting the following gCode into the printer setup:

Below is a ten hour print. There is no sign of pigment leaching which I would have expected towards the end of the ten hours.

Monday, August 28, 2017

Terraforming Mars Game Tiles and Markers

This post describes the sets of tiles and games markers that I print for the board game Terraforming Mars. The tiles themselves were designed by Frank Strauss. There are a set of articles on this blog that talk to them here, here, here, and here. All of my proceeds for printing these models will go to support my wife's entry in the 2018 London Marathon where she will be running in support of the MS Society.

The cost for the game tiles and markers is 70 GBP with a case available for another 30 GBP. Tracked and signed for shipping will be included if you live in the UK. The tiles consist of 16 City Tiles, 24 Green Tiles, 9 Ocean Tiles, and the 11 Special Tiles. The markers consist of one each of Generation, Oxygen, and Temperature printed in a material called Steelfill and then polished. They have a weight and look to them that is much like steel.

The default set of tiles can be printed in all grey if you are planning on painting them. Alternatively they can be printed in the following colours:

City Tiles - Grey
Green Tiles - Green or Matte Green
Ocean Tiles - Blue
Special Tiles - Tan (other than Nuke Explosion which will be orange)

Cases can be printed in red, black, gold, green, or light grey. Top and bottom can be different colours.

Note that there are three designs for City Tiles that I believe Frank means to represent different eras in construction:

Requires Gumball Top - Not Provided!

You can mix and match these tiles within the standard 16 city tiles or you can purchase additional tiles for 1.35 GBP each. My default mix would be eight of each of the first two styles shown above.

There are two ways to order and pay for these items. Both start with an inquiry through 3DHubs. In the first case I will create an order there for you once we agree on the composition of your set of tiles. This gives you some buyer protection but the MS Society will get less money. The second method is different only in that once we agree on the details I will provide you the price and you make a direct donation to my wifes page on Just Giving. The MS Society will get more money but you will not have 3DHubs as your agent if I turn out to be a scallywag.

Ocean - Blue - X9

Green Area - Green or Matt Green - x24

The tiles below are the "Special Tiles"

The case

The markers

Picture of a final product

Thursday, August 17, 2017

Pigmenting Resins

Given that I really don't need one, much less, two resin based printers one could question all the time that I am spending calibrating, mod'ing, and generally learning about them. But it is fun so I do it. If it felt like work, why would I do it?

I have a collection of resins that I am working with to better understand their characteristics. I have another article that will review a number of these resins but here I am going to briefly talk about pigmenting.

My thought process was that I could offer my 3DHubs customers a wide range of colour choices without having to stock a wide range of expensive resin. Enter two of my resins, both from Fun To Do.

Enter also the Fun to Do Pigments.

Finally, from stage left, enter a collection of dyes meant for fabric painting!

An easy first test was to pigment the IB resin so I chose red. The result is pretty good!

I can stock IB unpigmented and offer black, red, yellow, and blue. Or mixes thereof!

A second test was a little more odd ball as it involves using some pigments that are 'def not designed for the task. My first attempt showed an obvious need for better mixing and filtration!

A subsequent test, however, was a dramatic improvement.

I think some better filtration and it would be perfect. This opens up the FTD SW to being able to be a lot of different colours! I have not done any strength testing on the final product but I would note that it seemed as though it might be a little more brittle than the nature resin. I would also say that the addition of this non-standard pigment has "softened" the look of the model. Slightly less surface detail.

Finally, I wanted to see if the FTD pigments would work on a non-FTD resin. The only thing that I had to test with was the Wanhao sample so I added some black to it. My intent was only to add enough to change the resins printing characteristics. The print on the right is pigmented (slightly I will admit) and the one to the left is not. Note that on the red I used 15 drops of pigment for 225ml of resin. On the Wanhao resin the ratio was more like eight drops to 100ml. It seems like it should be much darker!

When I had tried to calibrate for maximum sharpness I had so many issues that I gave up. The slightly pigmented resin, however, printed much better. I am still giving up as I do not intend on using Wanhao resin but I thought the impact of the pigment was interesting.