3D Printing "Snap Off" Components


I'm putting together some Hull Pixelbot kits and one of the components that I need is a set of spacers to separate the circuit boards from the perspex base and top. You can of course buy these, but I'm too mean to do this, and I happen to have a 3D printer that I can play with. 

I wanted to print all the spacers as a single item, so that I don't have to count them into each kit. One way to group a bunch of components together is to print using a "brim". A brim extends around the base of a piece and helps it stick to the printer base. If components are placed close together the brim merges to form a single sheet which holds all the components together. This works well but it can be quite a pain to then peel the brim off the items once they are printed, particularly if the items are small, like the washers above. 

The solution I've come up with is to print a single layer which sticks all the elements together,  followed by another layer on top of that which stiffens the support layer. If you look at the picture above you'll see that the top layer doesn't go all the way up to side of each spacer, there's a tiny gap around each one. This lets you "snap" the spacer out of the base.

One other trick that I'm using with my spacers is to print the first layer of the spacer with a hole which is slightly smaller than the others. This means that the spacer will grip onto a bolt, so that they are a bit easier to fit onto the robot when you are building it. 

Network your 3D Printer with Windows 10 IoT Core. If only.


I've installed Windows 10 Creator's Edition Fall Update. It's very nice. It has a lot of extra support for 3D printers. And I got all excited when I found out that there's an application for the Windows 10 IoT Core running on Raspberry Pi that lets you install your printer on the network and then print to it straight from Windows 10.

It doesn't work. At least, not for me. I've spent all afternoon creating SD card images, configuring them and then finding out that I always get assigned the same (wrong) printer device and then the driver fails to load. 

Oh well. 

Design Iteration


One of the nice things about having a 3D printer is that it makes it really easy to iterate designs. I'm working on a new design for the configurable game controller. This version will have a socket for an input device and a bar-graph above each socket. I think I've found a design that sort of works, now to make up a panel. 

Oh, and one 3D printing top tip from Rob. Don't use oil on the sliding components. I thought this was a good plan, adding some "3 in 1" until the print head was moving really freely. What I'd forgotten though is that oil is sticky, and attracts dust. So when I fired up Una to print these prototypes she became very upset and pretty much locked up as all the sticky dust gummed everything up. Fortunately, after a good clean-up she's now working just fine. 

HullPixelbot Fridge Magnets

I've spent a chunk of the weekend printing Hull Pixelbot fridge magnets. I just took the logo and fed it into Cura (the slicing program that I use for Una, my 3D printer) and after a bit of fiddling I managed to get a 3D object that works quite well.

Once printed I just have to rub a black marker pen over the 3D text to make the letters stand out. Although I wasn't as careful as I should have been, which has made them a bit smudged. Perhaps I can print a little mask to put over the text when I ink it.

Anyhoo, the magnets will be going on sale soon in aid of Comic Relief. I'm doing a lecture in rhyme again this year all about robots, accompanied by a bunch of dancing Hull Pixelbots.

Oh, and if you are in the university on Wednesday I'm also doing a Hull Pixelbot seminar thee too.

Hull Pixelbot Version 2.0

I've just released a new set of design files for the HullPixelBot. I've made some improvements and also added holders for the pixel lights (always useful in a pixelbot) and the distance sensor. I was quite proud of the design for the distance sensor holder, until I tried to use it. 

I thought I'd been clever by providing mounting slots for the distance sensors so that the wires could come through the slots for the connections on the back. Turns out this was actually stupid. It turned out to be really hard to make the connections with the hole. 

The new design (which you can see above) has separate holes for the two sensor wires, and they are arranged vertically so you can just connect all the bottom wires together to a common ground (or reference voltage) and then take each of the top wires and connect them to their potential divider resistor and reference voltage (or ground). I'll be doing a detailed post about wiring things up a little later. 

HullPixelBot is going places

I spent a happy chunk of today designing and printing a front sensor assembly for the Hull PixelBot. The new part provides an ultrasonic distance measure and three light sensors. 

This will mean that the robot will be able to find and move towards light sources and also detect obstacles in its path. 

You can find out more about HullPixelBot at the next C4DI hardware meetup on Thursday 18th August. Sign up here (it's free). Anyone can come along and get into building tiny cheap robots. I'll have some more chassis kits to give away. All you need to do is add around 10 pounds worth of parts and you have a wandering pixel bot. 

And if you want to see a bunch of HullPixelBots in action I'm taking a mini-swarm to the Amy Johnson Festival Makerfest in Hull on 27th of August. 

Who knows what they'll be doing by then....

Get Cura 2.1.2

Una, my four year old, hand built, 3D printer, just got a lot better. I've just downloaded the latest Cura slicing program and used it with the default print settings. And Una has produced some of the best looking prints I've seen for ages. Well up to the standard of the Ultimaker 2;s at work. The new Cura defaults are a lower temperature than I normally use, with a cooler heated bed too. But they work really well. There looks to be quite a few changes in the way that the slicer works and the user interface is now very slick.

The only thing I'm missing is a way to tell Cura that the print head on Una is a rather strange shape, and not the default. If I can't do this it means that its hard to print multiple objects on the platform because the fans will crash into parts already printed if I'm not careful. However, it's a small price to pay for such lovely print quality.

The great thing about Cura is that it is free and it works with a huge range of 3D printers. If you haven't got it, you should get it. If you have got it, you should go for the latest version. 

3D Printing at Cottingham WI

I've done talks at Cottingham WI before. Great fun. I was invited back again this year and, rather than talk computes I thought I'd take along the 3D printer and print some cheese.

The printer behaved herself impeccably. I love the way that I can throw my Ultimaker into a blue IKEA bag, take her somewhere and have her just work. Anyhoo, everyone was fascinated. Best question of the evening: "Why is it called a 3D printer?"I really don't know. You can't really call it a printer as it does't print as such. It makes things. I quite like the name "fabricator", but the world seems to have decided its a printer. So that's that. 

Thanks for inviting me and being a great audience folks. And I got to judge the chocolate brownie competition, which entailed sampling every one. Which was lovely.

Printing Green Cheese for 100% Students

I've been giving awards for the best performance in First Year labs and exams. Last week I gave awards to the top five or so exam scores. When it came to the practical work I had a bit of a problem, what with ten students getting 100% in the work - which is awesome by the way folks. 

Anyhoo, it means that Una the 3D printer has been busy for a large chunk of today dropping out perfectly formed pieces of green cheese for next Monday's lecture....

Print with a Brim

Three pigs and a crocodile. (sounds like the name of a musical). 

I'm keeping the 3D printer busy printing tiny 3D animals They are all going to fit into a puzzle design that I found on Thingiverse.  I'm going to use different colours, including a rather nice pink that I've got for the pig. 

One thing I'm doing to massively improve my prints is to print with a brim. This is printed as part of the base of the item you're printing. After the print you trim it off. This is known as a brim trim.

Anyhoo, brims make a big difference to quality. They are printed from the outside in, and give your printer plenty of time to sort itself out before the actual model is printed. They also provide a bigger sticking area, greatly reducing the amount of "curl" that you get on the corners of prints when they lift up from the print bed as they cool. 

I use Cura to do my printing and the Brim is one of the platform adhesion options. The other one is Raft, which I don't use much. You can set the size of the Brim too. 

This is what the Brim looks like in print preview. I suppose I'm using a tiny amount more filament than before, but I'm much, much happier with the prints I'm getting.

Adventures in 3D Printing #4: Pen Holder

I'm quite impressed by my Robot Drawing arm, but the pen mounting could be better. The problem is that the pen is held in place by a single bolt which doesn't stop it from wobbling when the arm changes direction. One of the great things about having a 3D printer is that I can solve these problems by designing and making a better one. You can see the design for mark 1 above. It has a thicker ring which will grip the pen over more of its length. I've got a plan to fit "rings" on the pens so that I can easily swap them in and out without having to worry about alignment.  I'm also going to experiment with tiny magnets to see if I can use them to hold things in place. Such fun.

Adventures in 3D Printing #3: Panic Button

For reasons I can't quite explain, I fancied making a large, red, network-enabled "Panic Button". The idea is that if anything bad happens on the internets the button will flash red and I can then press the button to restore peace and harmony to cyberspace.  Or something. 

I'm going to pop a Photon device in there and then hook it up to If This Then That so that I can get it to signal simple messages. I've designed the box (curved corners and bevelled edges) and printed one out in yellow. I'm going to add some black tape to make it look properly panicky. 

Adventures in 3D Printing #2: Jack

Number one son reckoned I should have a go at printing the screw jack above, so I did. The intriguing thing about this design is that the entire object is printed as one, standing on its edge. There are some fairly prodigious unsupported elements in the design (you can see how the bar at the bottom left of the picture has some bowing at the bottom as it sagged during print) but to my amazement it printed mostly OK.

The only major problem was that I broke the knob off the screw thread in the middle when I was trying to "un-stick" it from the elements around it.  However, the designers have thought of this and provided the design file for just this component so you can re-print it.

The jack does work; you can raise and lower it using the screw. I've not got a use for the jack as such (although it makes a fine support for the robot printing arm when I'm not using that). If you've got a few hours to spare and fancy a challenge I'd advise you to have a go. Great fun and amazing to think that such a complicated device was made as one thing.

Adventures in 3D Printing #1: Tape Dispenser

I don't know what you think Christmas is the season for, but I reckon it is 3D printing. Plenty of time at home to keep an eye on the printer, and maybe even useful things to print. This is a tape dispenser that I thought might be useful for wrapping presents.

It works quite well, as long as you remember that the nut that holds on the roll of tape is screwed on with a left hand thread. If you forget this, as I did, you'll actually destroy your first print by trying really, really hard to "loosen" the nut. I got it to work but then I discovered this little gadget from Sellotape. 

You attach it to the knuckles of your left hand and you can just get tape as you wrap. It worked really well for me (I have slender and artistic hands - of course) although some of the reviews are less complimentary. Worth a look though I reckon.  

Printing in the Air

I've been doing a bit of 3D printing recently and I've had a need for some lens caps for, er, lenses that I seem to have bought recently. I found a design on Thingiverse that looked promising, downloaded it, sliced it and Una, my lovely if rather tempestuous 3D printer, refused to print it properly. 

To be honest, I've been expecting problems. I made the mistake of saying to Peter last week that I've reached the point where the printer "just prints" these days. At the time I said this I worried that I may have spoken too soon. And it looked like I was right. 

The print just refused to stick to the printing bed. The filament just went out into the air and all over the place. This is usually a symptom of poor alignment of the print head and so I spent a non-happy half an hour today getting the bed height precisely positioned. And it still didn't work. Very annoying. 

And then I noticed something odd about the print design. It seemed to be hovering in the air a millimetre or so above where it should be. Turns out that the printer was set up perfectly all along and the fault was with the design itself. I've found a different, less levitated, one and it prints out pretty much perfectly. Oh well, another good lesson hard learned....

Printing Tiny Robots

I've not done any 3D printing for a while. Then, earlier this week Peter showed me some things he'd been printing and they looked rather nice. And today on Twitter I saw a link to a tiny articulated bot that looked interesting. I like designs which print all as one. The legs, arms and head are intended to be separate items which stay fitted together because they are made that way. The original model had a print time of four hours, so I scaled it right down to speed things up and get a print time of an hour or so.

I was a bit worried that this would mean that the different pieces would fuse together into a single block but with a bit of careful twisting I managed to free of all the elements and I now have a tiny figure to help me with my breakfast cuppa. 

Robot Recovery

Last Wednesday my balancing robot kind of overbalanced, leapt off the desk and shattered on the floor. You can see the awful damage here. At the time I said that all I'd have to do is design some replacement parts, print them out,  and I'd have him back on his wheels again.

So I have.

Robot Plates.PNG

These are the FreeCad designs for the two plates that were broken. I did some careful measurement, wrote some Python to do the designs (it's a strange way to work, but I like it) and then printed them out and put everything back together. And it all works, which is nice. I think the new pieces are quite a bit stronger than the old ones. And if they break, I can just change one value in the program, run it again and print out some thicker ones..

3D Printing with iBox Nano

Update: Please read the comments section of this post for the latest on this device. 

Thanks to a combination of poor time management on my part and digging up an absolutely crucial road at rush our on the part of Hull Council I wasn't able to get to the MeetUp at C4DI tonight. But when I did get home I thought I'd fire up the iBox nano printer that arrived last week. 

The printer was a Kickstarter project. I've had pretty good success with Kickstarter. I've only had one Kickstarter project come seriously unstuck - I'm looking at you Agent watch. The iBox project promised a light powered high resolution printer for less than 300 dollars and was too tempting to pass up. So I backed it a while ago (I think it was November) and then waited.

The device was a bit late arriving, but I don't mind too much about that. Lots of people get very upset when these projects have delays, but I'm happy to give them time to get it right. As long as something turns up at the end. I'm still looking at you Agent watch....

The iBox is powered by a Raspberry Pi and uses a WiFi adapter to connect to your network. You set up prints on your PC via a web interface that works really well. There are a few buttons on the machine and some lights to tell you what it is doing. 

So I carefully filled the vat with resin, rubbed the build plate with some sandpaper to make it nice and rough so that the print would adhere to it, lowered the plate into the resin and set it off. 

My first print failed. All I got was a little lump of goo on the bottom of the vat. Oh well. I've got quite good at consistent printing with Una my Ultimaker, but I remember how much fiddling it took to get to where I am now. 

It turns out that, just as with Una, the key to successful printing is the print height. When Una squirts molten filament at the build plate it is crucial that the very first layer is just the right height for the filament to stick to the plate and provide the starting point for the print. With my iBox printer, which doesn't have a name yet by the way, the crucial thing is the distance of the build plate from the bottom of the glass dish, or vat, which holds the liquid resin.

The idea is that the build plate is a tiny distance from a sheet of teflon tape stuck on the bottom of the vat. The UV light makes some of the liquid resin in this gap turn solid. Then the printer pulls the build plate upwards, taking this layer of solid resin with it. Only on my first print the solid bit stuck to the bottom of the vat instead, hence the mis-shapen lump that was produced. So I re-adjusted the build plate and tried again. 

The printer does look great while it prints, like some kind of illuminated mini-tower block. It is completely silent and runs off a standard Raspberry Pi power supply. I'd be quite happy to leave it printing to itself, although you do need to come back and top up the vat with resin if you are printing something tall. 

This time it worked fine, and I got a tiny iBox logo stuck to the build plate. The output is pleasingly solid, although they say you should leave it in the sun or under a UV light to completely cure the resin. 

So I thought I'd go for broke and tried to print a tiny bunny. This was a disaster I'm afraid, with another lump of goo forming in the wrong place. However, I'm pleased to have made something. 

I'm not sure if I'm going to be OK with this liquid resin stuff. Everywhere you see dire warnings about the danger of the liquid touching your skin. I've got some disposable gloves on order but I spent big chunks of the evening fretting about the resin escaping and simultaneously burning a path to the centre of the earth (it's supposed to be corrosive) and poisoning me. 

I guess I might get used to it. It's totally different technology from printing with Una providing a new set of problems to deal with. I feel like a heart surgeon who is not very good at it and has switched to brain surgery in the hope that might be easier. I'm impressed with the iBox machine though. It really does work as advertised. I can now think about producing tiny components.  If I can get over the fear of the resin. 

If you are after a good, cheap 3D printer I think I'd still advise you to go for a conventional, filament powered, one like Una. There are some quite nice devices out there in kit form. Take a look at the nFire device on Kickstarter too. But if you fancy pushing the frontiers a bit and you want small, higher quality, prints then iBox is worth a look.