[Learning Series] – Making a widget case, from start to finish – part 1

Introduction

Hello! This will be a first, experimental post in a little series of blog posts detailing a complete workflow – hopefully useful to someone who might be wanting to use the laser cutter or work on a small project.
Recently, I’ve been playing with our space’s laser cutter with a couple of simple projects. My most recent was a branded flyer holder for Innovate Guildford, a recent event we attended – which came out great!

Fig 1: The finished stand – I really liked the aesthetic and simple assembly of this guy.

My first eyeballed design of the stand – done in Fusion 360, my CAD software of choice – would tip backwards with a light touch. It was also quite a tight fit, which required a visit from a persuader to assemble everything correctly. I quickly edited the design in F360 and made the side panels extend behind more to give a bit more support, and changed the kerf adjustment size from 0.3mm to 0.15mm (kerf is the size of the laser beam, and adjusts your design accordingly – a simple rule of thumb is a smaller kerf adjustment = looser fit).

This was the thing that really cemented the usefulness of the laser for me – a quick design change, set up the laser, make the cut, and replace the side panels took all of 5 minutes to do. Try that design change on a 3D printer, and you’ll be waiting a while.

The result was nice too – it fit together much more smoothly thanks to the kerf adjustment, the simple engraving on the front adds a touch of custom flair, and of course, it performed its job of holding our flyers very well.

Going from start to finish like this isn’t quite as hard as it seems. Neither is Fusion 360. In this little series of blog posts I’d like to approach something a little more complicated, which is to make a laser cut case for a small electronic widget – the Bus Pirate.

What’s a Bus Pirate?

Fig 2: Bus Pirates on a Pirate Bus – not what we are dealing with today.

No, not that. A Bus Pirate is a very handy little gizmo for electronics work – designed by Ian Lesnet and produced through Dangerous Prototypes. A simple look at the BP shows that its main purpose is for talking to electronics over a variety of protocols, such as I2C, SPI, 1-Wire, JTAG, MIDI etc. It can also act as a power supply, logic analyser, oscilloscope, ICSP programmer, and really, anything you might want to do with interfacing your computer to a component or circuit.

Fig 3: An actual Bus Pirate – v4 in this case.

 

I own one of these guys – specifically, the V4.0 version, and admittedly I have used it a handful of times – I’m simply not that good enough at electronics (yet!) to have needed it. However, when I do, I can reach for it with confidence that it will help me out.

Currently, the BP sits in a component box alongside it’s probe lead, a cheap Chinese logic analyzer clone, and some other bits and bobs. While I’m sure the PCB, with it’s mostly low profile SMD components, will be relatively safe from harm if I transported it separately, there is something reassuring and polished about having it in its own case – hence the start of this project.

Case features

As always, it’s good to start out with a few objectives, or specifications, before we even start designing. Let’s define what I want this case to provide and why:

  • Made from laser cut acrylic. Acrylic is nice, easy to cut, pretty cheap, and colourful. There’s a plethora of material options available, and I’ve used it already.
  • Cutouts for the business parts. There’s a mini-USB connector, the 12 pin shrouded connector for the probes, and an ICSP pin header. Access to these is the main function of the board, so it would be pretty daft to make them unusable. We need to bear in mind the sizes of the relevant connectors that will be plugged in to them.
  • Visibility of the 4 status LEDs on the top. The LEDs are coloured, and while easy to distinguish their function from their location, it might be nice to make them easily visible with uncoloured, clear acrylic.
  • Button pushes. There’s two buttons on the board, ‘Normal’ and ‘Reset’. Limiting access to these will always lead to frustration some day, so we could either add small holes for access for a pokey thing (technical term), or include some parts in our design to extend the buttons to the surface.
  • Labelling – engraved labels for the LEDs, buttons, and even pinouts would be very useful. The main connector takes a colour coded probe lead. If we can somehow add the colour codes for quick and easy identification, this would be very handy.
  • Sturdy – I’m not saying this will be subjected to abuse, but it’s reassuring to know that it can take a few hits.

We’ll likely add more and take some out, and even iterate over the design, but before diving in it’s always worth taking our time to spec our design out and have some goals in mind.

Metrological!

Because we’re designing a case for an existing thing, it makes sense to get an accurate reference design of it as our first task. Sure, the flyer stand had this – we needed to know how big an A5 flyer was, to make sure it did its one main function properly – holding them! This wasn’t a hard task to accomplish, but our Bus Pirate is slightly more complex. We have the board size, mounting holes, LED positions and of course those connectors to deal with.

We have a few options of how to approach this. We could reach for our vernier calipers and measure everything up – or we can cheat, which is what I like the sound of. Being open source hardware, Dangerous Prototypes allow us access to all the design files. In this case, the board designs are in Eagle format – not my preferred choice (KiCad 4 lyf <3), but free and easy to install.

Now this next part took a lot longer than expected. There are a few options out there for taking an Eagle .brd file and getting some designs out of it – exporting to DXF, for example. There are promises of “easy” Eagle to Fusion 360 workflows, where the board and its components are sent over as a 3D model. Sadly this didn’t work – neither did exporting to KiCad, and some other things.

Fig 4: Flat board at first – adding heights in for each component is easy though.

What did work for me was a nifty website, ecad.io, which will happily take an Eagle .brd file and spit out a .STEP file. This wasn’t without problem, as all the components had no height thanks to (I think) it being an old version of Eagle. Thankfully the web interface made it easy to set the heights of the important components, and as it was late and I was feeling lazy this would do for my purposes. Looks like I will be using those calipers after all.

 

 

 

 

Fig 5: This only took a couple of minutes.

A few clicks later and editing the depths wasn’t nearly as hard as I thought it’d be. I measured the important components (connectors, switches, and LEDs) and guesstimated the rest. Thankfully the interface recognises all component shapes/packages of the same kind would have the same height, so you only have to enter the custom height in once for each package type.

For me, this is good enough for our design – all the important stuff is preserved and is more or less accurate.

A few more clicks, a bit of a wait for processing time, and I have a .STEP file of the Bus Pirate based off the actual board design.

 

Fusion 360 Beginnings

First off, let’s create a new project – a container that represents all of the files related to our case design. Even after using F360 for a few months, I’ve ended with reams of files and have found the cloud-based project approach refreshing.

After creating a project, I can click File > New Design From File and import our new .STEP file to create a component. Nothing exciting to say here – it took a few seconds to import while F360 thought about things, and it appeared. A slight mishap is that the mounting holes are filled in, I think because they were considered components in ecad. Not a problem though as the mounting hole is still there and selectable, and that’s all we need.

A quick test with the Inspect tool (shortcut ‘i’) confirms that the board is the same size as the one in my hand.

Fig 6: imported into F360 and looking good.

 

 

 

 

 

 

 

 

 

That’s it for part 1! In part 2, we’ll start designing the case from the imported board model, keeping in mind our design specs. Stay tuned for more 🙂

 

SHM 3D Printer Filament Store and Dispenser

This is a direct copy of a SHM forum post, which can be found here . If you’re interested in what we do or would like to share a project of your own with us, please take a look at the forum here

 

SHM Filament Store and Dispenser
Having finally got our 3D printer into a workable state it needed a permanent home, rather than just perching on a surface stealing valuable bench space. So we decided to put in into one of our large storage units. Great idea you say ! Of course you are right, but how on earth do we store and smoothly feed filament to the printer from the large 2 kilo reels of 3mm PLA that were kindly donated to us?

Our solution of choice was to put the reels outside of the cabinet, thereby minimising the loss of shelf space.

Being of a parsimonious mindset we looked around the SHM Makerspace to see what materials might be utilised for the build.

Filament Dispenser Brackets
These were made from some offcuts from our Reuleaux triangle stool build, which itself was made from laminated discarded ply. The ubiquitous all purpose offcuts of plastic plumbing pipe from the geodesic dome build were used as spindle holders. The pipe fits snugly into a 34mm hole drilled into the edge profile of the shelf support.

Filament Feed Through
We designed a parametric feed through tube1 and mounting in openSCAD to allow the filament to pass through the cabinet wall, the tube angle was set at 30 degrees to the mounting axis. Two of them were produced on the SHM Makerspace printer and bolted together through the cabinet side.

Mounting
Each bracket was mounted on the side of the storage unit with a pair of screws.

Spindle
The spindle to hold the filament was an old piece of pine curtain rail, complete with a fine finial, reclaimed from the original space conversion.

Shelf feed and installation
The final step is to feed the filament through the shelf to the printer. For the moment we’ve just drilled a hole in the storage shelf above the printer until we work on a design for a 30 degree overhang feeder tube.

 

Space 3D printer commisioning / repair

We were kindly donated a 3D printer which was 50%~ built by a hobbyist who had decided he had too many hobbies already and couldn’t take on 3D printing. Take a look at the restoration/commissioning our member Matt has completed. We now have a fully operational, well tuned 3D printer in the space!

 

Extruder Spring Tension Increased
The spring tension on the extruder was adjusted to be quite firm to reduce potential slippage of filament.

Faulty X-Y Driver Board
On occasions the extruder on the x-axis would stutter and miss steps, even to the extent that it sometimes reversed direction. Switching the x and y axis stepper motor connections on the board demonstrated that the problem followed the interface and not the motor. @Folknology was very kind and offered a replacement dual motor driver module from his own printer. The replacement driver module rectified the problem Open source driver board details here.

Y-Axis Linear Bearing Issues
After the electronics were mounted and a few trial prints were executed some anomalies in the movement of the heated bed ( y-axis ) were observed, it was definitely sticking in a few places.

Removing the linear rods and three bearings from the y-axis and testing them standalone revealed that they were definitely not moving freely. This was most likely due to one of two causes: the printer had been in storage for a number of years and may have been subject to some corrosion or that it had attracted dirt and dust, some of which may have come from the space rebuild.

All three of the bearings were replaced and that they ran smoothly checked, the linear rods were reinstalled and trued.

Belt tensions
Both belts were removed and the tension and alignment on the X and Y axes were adjusted to be tight and running true.

Grub screws
A number of good prints were then achieved but at some point there reappeared some inconsistencies in the geometry on a number of items. After a lot of head scratching the problem was tracked down to loose grub screws in the drive gears. These were tightened. During this investigation one of the bearings for the y-axis carriage was observed again to be exhibiting some degree of sticking, this was replaced.

X Axis Drive Gear Failure
At this point the printer was able to produce prints of several hours to a reasonable standard and good accuracy.
A problem occurred during a 6 hour print in which, 10 minutes before the end, a catastrophic slippage on the x-axis occurred. Investigation revealed that the x-axis drive gear had failed, breaking into several parts. This failure was probably attributable in some proportion to three factors: increased belt tension; tightening of the drive gear grub screw and degradation in the structure of the PLA printed gear after 4 years of ageing.

Truing
Replacement gears had already been printed and were installed and the belts retensioned. Despite several hours of experiments of shimming the x-axis stepper motor, it wasn’t possible to get the printer to operate with shedding the x-axis belt. Eventually, thanks to an idea from @Jagmills, a large diameter washer and spacer were added to the x-axis idler bearing to prevent the belt coming off.

Recalibration
The replacement drive gears for the x and y axes mate more securely with the T5 belts but are a slightly larger diameter than the original gears so recalibration of the x and y steps was required to ensure accurate print sizes.

 

For more pictures and a more detailed log check out the forum topic here

 

The space in pictures – Feb 2017

It’s been a while since we had an update on the space. Thanks to the hard work of several members we’re now pretty well set up and open to making… A picture speaks a thousand words so please join me in a quick tour of the space in pictures:

Our main work benches and shelving. Note the LED shelving, each LED is individually addressable (you can control the colour and brightness), they’re waiting to join the IOT “Cloud” with the use of a Wemos (https://www.wemos.cc/) Maybe you can be the one to help progress this project?

Our laser cutter, several members are now fully trained and have been starting to making various projects developing laser cutting and etching skills , they’re raring to pass these new skills on to other members.

Our 3D printer has been tuned and fettled by a dedicated member. He has been printing parts for other members and it is pretty much ready to be opened up for general use by all members.

Our soldering station has been put to good use so far. We’re looking forward to the magnification, heat pencil and hot plate being used for SMD assembly. Our oscilloscope and meters are out of shot.

Our engineering area where all manner of turning and drilling has taken place.

Member’s storage is starting to fill up with all kind of interesting projects and equipment.

 Our in house designed and manufactured (laser cut) cable storage rack.

It you’re not a member come along on a Friday night to see the place for real!

 

February Update

It’s been a busy few months for SHM!

We’ve more or less completed our renovation works at the Boileroom and our members have started coming along regularly, working on their many projects. Our fancy laser cutter is installed, working and has already been producing a variety of projects. The laser cutter is a very nice addition, as (for those who don’t know) it is much faster at creating a variety of items – and from cheap materials, too.

a case for an EMF TILDA badge

Milling Machine

We’re looking to expand the machinery available to our members – one new potential addition is a milling machine, for creating all sorts of shapes out of materials like aluminium and steel. This is open to pledges, so if that’s something you’re interested in using or you’d like to know more, please visit the forum thread for more information.

 

Slack

We now have a Slack channel! This is a chat room where a lot of our members gather to discuss projects and generally be social. There’s quite a few of us there in the daytime and evenings – coming to say hello is quite easy 🙂

AGM

Next week will be our AGM, currently limited to our members. If you’re a member and want to come voice your opinions and help shape the Makerspace, do feel free to pop along – details are on the member’s area of our forum.

If you’re not a member though, do please feel free to pop along to one of our Open Sessions! These run every Tuesday and Friday from around 18:00 onwards. We often have all sorts going on, so if it’s a flying visit for a chat, you want to come see what a Makerspace is all about, or you have a project idea – feel free to pop along. We advertise our open sessions on our Forum, which is also bustling with lots more information on the ‘space.

Hope to see you soon!

 

 

Plans for Friday session 18/11

I don’t think there are any grand plans today, but we will be open for all comers.

I’ll be checking the new laser setup and hopefully doing some test jobs, and no doubt playing with some OpenTRV stuff along the way.

Keep an eye on the comments to see what others are up to!

I’ll be there from about 6pm to open up for those without an access-card.

 

Space Update

We’ve made fantastic progress with building our space over the last couple of weeks. The benches are now in, shelving is going up, and everything is really taking place.

There are only a few items left for us to do, but it hasn’t stopped some of our members making already – we’ve had various personal projects turn up, as well as work being done to get our 3D printer and laser cutter up and running.

We also have a space webcam (featuring motion detection too!) for a bit of added security, and I hope to write a script that will allow us to create timelapse videos of our open sessions – which don’t forget, are every Tuesday and Friday. Do check the forum if you’re planning to pop in, as we update the ‘Open Sessions’ category when a keyholder is in the space.

 

spacecam

 

Plans for Friday session 07/10

We’re still in the process of refurbishing our new space, so for now we’re sticking to just Friday for our open nights. However, due to the somewhat chaotic state of the space at the moment (still some construction going on), we’re limiting it to members only for now.…

I’ll be there to open up at about 18:00.

 

Plans for Friday session 30/09

Just a little update for this week’s session. We’re still in the process of refurbishing our new space, so for now we’re sticking to just Friday for our open nights. However, due to the somewhat chaotic state of the space at the moment (more hammers’n’saws than arduinos’n’laptops), we’re limiting it to members only for now. Obviously if you’re in the area you’re welcome to pop by and have a look, but I wouldn’t expect any fancy makerspacey stuff going on just yet.

Watch this space…