Monthly Archives: October 2017

salepredict3: automated test results

Based on a suggestion by Ché Lucero (LinkedIn), I wrote a test to see exactly how accurate this machine is.

I had 41 domains already entered into the engine and categorised as Sale or Fail, so the test was based on those.

For each of the domains, the test:

  1. changed the domain’s type from sale/fail to prospect
  2. retrained the neural net using the rest of the domains as its reference data
  3. calculated how much of a match the domain was to a sale using that neural net
  4. if the calculation indicated correctly a sale or a fail, then that counted as a correct test
  5. finally, clean up – reset the domain’s type back to sale/fail, ready for the next test

After 41 tests, it got 27 correct – an accuracy of 65.85%. That’s much more than chance (50%).

I’m going to get some more data now, but I expect it will only improve the value, not decrease it.

What does this mean for your own business?

Well, let’s say you have 100 companies you can potentially sell to, and you expect that 50% of them might end up being a waste of time, but you still need to spend about 2 hours on each in order to find that out.

Without using my engine, after 100 hours of selling, you will have made 25 sales. (100 hours is 50 companies. 50% success rate so 50/2 = 25).

With my engine, after 100 hours of selling, you will have made 33 sales, because it will have pre-ordered the companies and got it 66% correct, so in the first 50 companies, it will have correctly placed 66% of all successful sales.

salepredict2: we are live

I’ve finished the base engine of the Sale Predict project. If you go to SalePredict.com and fill in some of your sales and fails, then it will be able to predict the chance of success for any prospective jobs you have.

For example, let’s say you have successfully sold to 25 companies before, and 25 other companies have turned you down. Let’s say you also have a list of a further 25 companies that you want to approach, but because each of these takes a few hours of research and negotiation, you would prefer to work on them in order of which are most like companies that you have already sold to.

All you need to do is put in the 25 sales and fails, and a neural network will be automatically trained up based on that data, which will then be able to analyse the 25 prospects that you have.

The engine currently accepts logins via LinkedIn and Facebook. I will add more.

You are given 100 free credits as soon as you login. This lets you test it out to see if it works for you. I will add a payment method shortly for increasing the number of available credits. 100 should be enough for anyone to realise how effective this is.

I’m working on an automated test at the moment to figure out exactly how successful the engine actually is. The test works by taking a list of sales and fails, then doing a round of tests on each of those websites, temporarily changing the website to a “prospect” so the system does not know if it was a sale or a fail, then retraining the network on the other domains, and seeing if it accurately predicts the original value (sale or fail) for the test domain. This will take a while to run, so I’ll post the results in the next article.

salepredict1: the Sale Predict project

Around April of this year, I had an idea that I wanted to pursue. I felt it would make an important difference to our business (FieldMotion). The itch was so strong that one weekend, I set up a server and wrote a prototype of the idea in my own time. It worked perfectly. But, it solved a problem that we weren’t interested in anymore, so the work I did on it was mostly wasted. A by-product of it become some useful information, but not the main part of it.

Okay – let’s look at the problem.

Let’s say you’re a business that is trying to expand. You get your work by contacting other businesses that you think may need your product, and trying to get them to work with you. Cold-calling, or trying to arrange a meeting through mutual friends, etc.

The old way to do this would be to get a phone directory, find a list of companies in an industry that you think is right, and just start calling, working each number one by one until you find one that sticks.

But this is usually a waste of time. Either the prospects already have a solution, have no interest, or are too dissimilar to those you’ve sold to before so you can’t establish a common ground.

The problem, shortened, is this: How can you take a long list of potential clients, and order them so that those most likely to buy from you are first in the list?

A solution to this came to me earlier this year. You need to find companies that are similar to those that you have already signed with, but that are not similar to companies you failed to sign with. This is a top-level description, obviously. The technical details of how to measure similarity are beyond this article.

To do this, I wrote a program that takes three lists of domain names:

  1. domain names of companies that you have done business with.
  2. domain names of companies that you cannot do business with (either they’re too unsuitable for your work, or they just said No for any reason).
  3. a long list of domain names of companies that you want to figure out what order in which to call them.

The program reads the front page and all pages linked to the front page of all mentioned domain names, extracts words and “n-grams” (groups of words), and figures out using a neural network what kind of language is used by companies that you usually sell to.

After this, it can then come up with individual numerical scores of how suitable each prospective company is.

I ran this on a list of about 50,000 companies as a test back in April, to see what it would say about my own company’s chances with those prospects. In the top 10, it named a company that we had actually talked to a few years before and that had said they would go with us except we were too young at the time. In the bottom 10, it listed a charity shop, which is totally not our target audience. The thing worked!

But, we don’t work in that way anymore, so it turns out that the list generated by the machine was never used. Oh well.

This week, I’ve decided to revive it and make it generally available. So this weekend, I will work on a simple website to make it possible to generate your own domain lists. It will allow a list of, say, 50 domains free, but anything beyond that will cost. Hosting costs money, and this uses a lot of heavy computation.

dehumidifier 3: hot-plate hiccough

Yesterday, I was hoping to continue work on my dehumidifier project; using a desiccant wheel to adsorb water onto silica gel balls on one side of a machine, and hot air to evaporate water from the balls (regenerate them) on the other side.

The hot-plate arrived for the machine. I tested it, using an old 12V adaptor for power supply. It works well – heats up very quickly. I don’t know what its limits are, but I feel that 105°C is well within its capabilities.

But instead of then working on the machine itself, I spent a few hours making space on my son’s laptop and then installing the Unity development platform. I’ve been trying to get him away from Scratch and onto something more practical, because Scratch is nice, but it’s a dead end.

You won’t find people designing grown-up programs in Scratch, because it simply doesn’t have the capabilities. Database access, complex graphics, file manipulation.

But Unity does, because it binds naturally to some languages that you can then use elsewhere. In this case, C#. But, beggars can’t be choosers!

I bought him a book on how to start coding in C# by creating a game in Unity. With the book, you build a side-scroller game. I really hope he likes it. More than that, I hope the book is not obsolete already!

On the desiccant wheel project, I realised there is a really bad problem – in order to regenerate, the silica gel balls must be baked at more than 100°C in order to let the water evaporate.

PLA (the plastic I print in at the moment) melts at 180°C, but its glass-transition temperate (its Tg) is between 65°C and 70°C. That means that if I have a section of my machine which is around 105°C, then the plastic there may warp.

While this is a real problem, I don’t think it’s insurmountable. The first thing I will do is to just try it as if it will all just work out fine. You never know! And if it turns out there is a problem, I will come up with a solution. That’s what I do.

The biggest warping problem will be the grill on the inner-facing part of the desiccant wheel (green in the image), which keeps the silica gel ball bags from falling out. If that warps, then it will quickly jam the wheel from turning. A redesign of the wheel is major. It would involve changing how the wheel is turned, and probably changing the orientation of the entire machine.

The way I have it at the moment, the wheel rotates on-edge, with two big circles with small air-holes in them, to allow air into the silica gel balls contained inside. If I was to change the orientation so the wheel is held flat with the green grill facing upwards, then the grill would not be needed at all, and the hot air could be blown directly onto the bags themselves.

This is a major change to the design, though, because I would then need to change how to wheel is balanced (currently two ball-bearings on the edge) and how the wheel is rotated in the first place (currently a gearbox held against the grill).

A possible solution is to move the gearbox underneath the flat wheel. Hmm… Yeah, I think that’s actually a good solution. I have a plan now.

plantbox project 1: the train

I had an idea a year or two ago of a small train that travels along a track that leads along a wall of plants, each enclosed completely in a box so that water could not get in. This way the plants would not get overwatered. The train would then water the plants to their individually needs.

I had envisaged a sort of water-carrying trailer. The main carriage would couple onto some exposed wires in the track coming from a box it was passing, and use that to detect moisture in the soil of the box. Depending on that, the trailer might then tip its load into a hole in the side of the box, and the train would then return to its depot for a recharge and for a reload of water.

Yesterday I had an easier idea. A small aquaduct would travel along the top of the boxes, which would keep a container on each box topped-up with water. When the train detected dry soil, it would tip the containers over. The containers would be counterbalanced so that when empty, they go back up to the top of the box to refill, and in the top position, they would stay where they are unless physically pushed over-balance. This is a much simpler arrangement, I think, as the train is then just two motors and some electronics. One motor to drive the thing forwards/backwards, and the other motor to swing a hammer.

I’ve designed the basic shape of the thing to test out how the movement would work and to decide how to fit the electronics and battery. After 3D printing it with my Anet A8, the motors fit very snugly. The front wheels (with the square axle holes) fit perfectly over the motor axles, and the back wheels (round axles) are almost perfect – a little drilling needed to expand the axle holes slightly.

I think the way I’ll attach the electronics is to add some catches on the back part of the fuselage (where the round axle wheels are) so that a little 3D printed box of electronics can be snapped into place over it. This way if I change the design in future, I don’t need to reprint everything.

The boxes that the plants go into will be completely enclosed in transparent plastic, protecting from the environment and acting as a mini greenhouse. The boxes will all have small water containers which are counterbalanced so that that can be tipped over to empty, and then when they right themselves, they start filling up again. I have not decided yet on the mechanism of refilling. Maybe a ballcock mechanism that is automatically lowered into the water container when it is in position?

new printer progress

What are 3D printers for? Printing new 3D printers! I’ve finished printing the CoreXY parts for my new printer. CoreXY is the method I’m using to control the X and Y axes (left/right, forward/backwards), using parts designed by Louis Zatak who put them on Thingiverse. He also provided parts for Z axis bed lift as well , using the same belt trick that the CoreXY uses.

The dimensions I’m printing are probably much too large – I went for 50cm cubed, which might end up with a print volume of about 44cm cubed, which is 8 times larger than my current printer (an Anet A8).

There will be problems, I’m sure – with 50cm rods, the x-carriage will probably droop near the middle. I have an idea how to solve that if it happens, but we’ll see if it’s necessary!

All that’s left to get for this new printer are some rods for the x-carriage, the y axis, and the z-axis, and a hot-bed. The hot-bed is not strictly necessary, but it will make it work much better. without a hot-bed, prints might curl upwards, and will probably have trouble sticking to the print bed.

After this is finished, I have a plan to build a brief-case sized foldable 3D printer.

The CoreXY design is compact and may be foldable, so I’m going to try find a way to have the z-axis fold upwards towards the CoreXY frame, and then fold the arms of the mechanism inwards. In my head, it works…

straight barrel door bolt

One of my students wanted a straight barrel door bolt printed for his door, because his dog kept on opening it. I designed one up in FreeCad in a few minutes and printed it out with an Anet A8 3D printer during today’s CoderDojo class.

The design is available now on Thingiverse.

The design was deceptively simple. Even though the shape of the thing looks difficult, it’s actually quite easy.

First, we make the base-plate, which I set as 4mm thick for strength. Instead of making three separate pieces, I opted to build it all as one long one. You’ll see what I mean.

Next, I put a cylinder right along it. This will be the outside of the barrel. Notice that I have it overlapping 2mm into the base. The walls of the barrel will be 2mm thick.

And to strengthen the barrel’s connection to the baseplate, I added a cuboid reaching down as a tangent from the cylinder.

I grouped those together using the Union tool.

Next, I worked on the bits that I needed to cut out of the barrel.

First, there’s the cylinder for the bolt. I made sure the leave 2mm in the near end so the bolt didn’t just come right out of the lock when opening it.

Then there’s the channel that the bolt handle slides along.

When locked the bolt handle needs somewhere to slide down into. It needs to be the same width as the channel from the previous step.

Finally, I separated the barrel into three pieces. First, by cutting a 1mm gap to cut off a chunk that connects to the door jamb.

And then a slice that has two uses – first, to let us put the bolt into the barrel in the first place (we’re not printing the bolt inside the barrel, so need a way to put it in). It also acts as a place for the bolt handle to rest when the lock is open. Its width is the same as the earlier two channel cuts.

Lastly, I needed to add 8 cones where the screws should go.

I grouped all of those together then did a cut of that group from the original group I made, which resulted in this:

The bolt itself was next.

First, create a cylinder that is .1mm in radius less than the gap in the barrel and long enough to reach the jamb end from the near end of the main body of the barrel.

Next, add a cylinder for a handle. Its radius should be .1mm smaller than half the width of the channels it slides in.

And then a sphere which serves no real purpose but it looks nice.

Finally group the bolt together into one object, and pull it back in the lock to make sure it fits. If it doesn’t, then adjust whatever you need to!

When we printed this out during class today, the print was difficult to remove from the glass on the hot-bed afterwards. I found it much easier to remove later on when I printed another of them for myself. The difference was that in the class, the hot-bed was still about 60°C, while at home, I was busy with other things and didn’t notice it had finished printing for a while, so it was more like 40°C. So, if you have difficulty removing a part from your 3D printer, maybe just let it cool.

missing layers in prints

I printed out a terrain piece for a friend to use in his Warhammer 40k game. His group was so happy with the print that they told me they would pay for more, so I went looking for more designs that would suit their purpose (technological debris on a sci-fi backdrop).

I found this really nice design of a crashed “killabot” (pictured above) – a robot driven by a race of aliens called Orks.

I priced it at €5.65 – €0.65 for the cost of the filament, and €5 for the time to setup and print it. This is actually quite a ridiculously low number compared to other people that print things professionally (see 3dhubs.com for your local supplier!).

It was going to take about 8 hours to print, according to the slicer program (Cura). I set it to print about 10:30pm.

This morning, I went to check on my 3D printer (an Anet A8), and noticed it was doing something strange at around the 80% mark – some missing layers in a part of the print were leaving obvious bands in the model.

After checking the Layers view of Cura, I saw that what appeared to be a solid model in the default view turns out to have some errors in it that cause Cura to print out some empty layers (pictured below). This is bad, as it can cause later layers to blob.

Cura has a number of built-in mesh fixing algorithms that can be used. It is not always obvious which one (or combination) will fix the problem so you may need to play with it.

In this case, I managed to fix the missing layers by using “Keep disconnected faces”, which is a last resort option. Here’s the fixed view:

I’ve left the faulty print to continue on, because I think the missing layers were few enough that the thing as a whole will still bond together well, but in future, I’ll take a close look of the layers view of a print before I start an 8 hour print…

printing a new printer

I promised myself that the first major thing I would complete with my Anet A8 3D printer was to print another printer.


After calibrating the A8, I found a design online that I liked (the MyCore CoreXY design on Thingiverse (pictured)) and printed out all of the parts needed for both the CoreXY part and for the bed.

I’ve encountered two problems so far:
1. the Y axis rail sliders are designed for LM6UU bearings, but I have LM8UU, so they don’t fit.
2. the MDF I have, which will be used for the walls and floor of the printer, is too thin for the design I printed out

These are easy enough to fix, though.

I can simply adjust the radius of the holes on the Y axis sliders and print them out, fixing the bearing radius issue.

The MDF is slightly harder. I could go out and buy new wood, but I don’t like spending money when there is a free solution in front of me. So, I’m going to thicken up the parts of the MDF box that the plastic parts need to interact with.

If I glue two extra strips of MDF over the existing sheet, that should bring it up to thickness, and should also strengthen the MDF against warping under pressure.


To do this, I needed some G-Clamps for gluing the MDF. I found a wonderful print on Thingiverse which turns out to be very strong when printed at 35% infill. The Anet A8 even did a great job on the knurling detail on the end of the screw (pictured).

I will also need to print out some corner clamps, but there are designs available for that as well.

I love 3D printing! Everything you need, someone has already designed and shared, or you can design for yourself.

After I’ve finished fixing the thickness problems and bearing holes, I need to make a bed for the printer to actually work on. For the first few weeks, it will be an unheated bed, as I haven’t yet ordered a heated bed online. Maybe I could design and build one myself? Or an alternative is to totally enclose the printer and heat the air itself in there to 60 deg – make the thing into a small oven.

Actually, that’s something I’ve been considering anyway – totally enclosing the printer, but having tubes feeding cold air to the fans.

dehumidifier 2: Rolling the drum

I tried setting this up so that the drum could be rolled from an elastic band or cog against the edge of the drum, but it turned out there was a simpler way – the little air-holes in the drum are an equal distance apart, so I designed and printed a gearbox that could turn the drum using those holes.

It sacrifices a little bit of surface area for the cold side of the drum, but I don’t think it will make a huge difference.

I made a few 1mm errors in the gear box prototypes, but when I corrected them, it worked as soon as I applied power to the motor. The motor I’m using in this case is one of the standard yellow geared motors (like this).

I’m still waiting for the heating element to arrive, but have a few fans I can use to get started on the airflow. I don’t even know what size the heating element I ordered is, so can’t design that side yet, but I can design the cold side while I wait. I’ll get started on that tonight.

The 3D printer I’m using is an Anet A8, and I have to say that it’s a dream to work with compared to my old Makibox 3D printer. I was amazed when I printed out the drum and enclosure for this project and they fit perfectly. With the Makibox, the circles would have been flattened and I’d have to sand away any bits that rub, but this one is just perfect.

Even the gearbox would have been impossible to print on the Makibox. The Anet A8 is so good that when some of my students were asking me for a bill of materials to make a 3D printer, I told them that even though it would be possible to spend €120 or so and make a 3D printer from scratch, they’re better off spending $150 and buying one of these ones instead.