Making a router table from some scraps of off-cuts

The other day Aldi had one of their "get tools for cheap" days and we snagged a 1250W router for less than £25. A bargain in anyone's eyes!

We did think about the router table, but it didn't look particularly study, with everything being made from moulded plastic. And from the photos on the website, it doesn't look like it is for particularly large pieces. Far better (although not exactly safer or inline with "elf-and-safety") to make one for our new router.

So this weekend, a few hours were needed at the BuildBrighton hackspace.

We cut some 18mm ply and marked it so that there was a minimum of 500mm from the cutting head of the where the router bit would be and the edge of the board. This should allow us to easily cut and rout sheet materials up to half a metre in size.

One of the great things about having wooden workbenches is that they're pretty easy to fix stuff to. As it turns out, someone had already drilled some M7 sized holes in the bench (it looks like a pillar drill or something had previously been mounted there). So it was no bother to find a few coach bolts that were long enough to fit through both the 18mm piece and the 40mm thick worktop and make some holes in our board.

After the centre hole was drilled and some holes placed 46mm apart (centre-to-centre) either side of the main, large hole, we were ready to mount the router.

It's actually far easier to mount the router to the board, and then fix the board to the workbench in this case. But it didn't take long to mount the router and leave the cutting head raised 6mm or so through the "tabletop".

Now at this point, it's fair to point out that this isn't exactly the safest way to go about using a router. There's no guard and no fence, and no feather boards or any of that stuff. But there is a cutting head and, placed 423mm from the centre of the router (so 420mm away from the cutting blade of a 6mm wide straight routing bit) there's a piece of wood, running parallel to the bench edge.

It took only seconds to pass the 3mm mdf sheet along the fence, cutting it with the exposed cutting head, then rotating through 90 degrees and repeating, to create two, perfectly square, pieces of 3mm mdf (420 x 420mm).

The edges left a little to be desired. We tried at fast speeds, slow speeds, feeding the wood quickly, feeding the wood slowly - none of it seemed to make much difference: the cut edge of the mdf had this feathered look no matter how it was presented to the router bit.

Luckily it's nothing that a quick wipe down with a piece of sand paper can't deal with.
Now we're probably not going to use the router table for actually cutting wood (it creates a lot of dust) but as a proof of concept, we're pretty happy with this so far.

Next we need to make a number of "offset" pieces to place along the fence, to allow us to quickly and easily cut channels into mdf sheets, at equal distances apart. After all, that's ultimately what the router table was set up to do!

BuildBrighton HPC laser cutter

For what seems like months now, the laser cutter at BuildBrighton has been out of action. First the tube went, then the new tube cracked. Then a replacement tube went in but it wouldn't cut. Now it does cut, but only in certain parts of the cutting bed.

So a few months ago, a few of us clubbed together to pay for a second hand LS3020 laser cutter that was going cheap. It's always a risk, buying stuff like this second hand. But we were already familiar with the LS3020 (we've got one at Nerd Towers which works like a dream) so were confident it should be a half-decent machine.

Today, I finally located a Windows XP machine down at the hackspace and got NewlyDraw installed on it (NarlyDraw does install on Windows7 and I've had my laser cutter working with my Win7 notebook, but it's a pain getting the drivers working properly, so Windows XP is much more favourable). I don't know where the PCs at BuildBrighton go to - one day there's a glut of XP machines, the next, some bugger has put Linux on, or replaced them with Raspberry Pi's or something! But with a WinXP machine finally located, and NewlyDraw installed on it, there was no need to delay trying the machine out.

Amazingly, it cut, first time!
Not perfectly, but it did scribe a circle onto some acrylic (a fairly wide, melted shape instead of a circle, but it was definitely a good start).

At some point, someone has changed the optics in this machine, and put a different lens in it. The lens focal guide is much smaller than the one that usually comes with the machine (or at least, the one that comes with later LS3020 machines - this one was definitely an earlier model than the one we're familiar with, albeit very similar). This means that the cutting bed is much higher up, and the cutting head is very close to the material being cut. It also makes it very difficult to see the little laser dot, for lining  up cutting on a sheet which may already have shapes cut out of it.

One thing to note is that when the machine powers up, the cutting head goes to the top-right of the machine, not the top-left as one might expect. This is easily resolved using NarlyDraw - just move the head to -80,0 and when prompted, reply that you know this might make the head move out of the cutting area. The head should now move to the top left corner of the cutting bed:

We cut a few test circles, 20mm in size, in opposite corners of the cutting bed, to see if the alignment was good (if the alignment was out, we'd expect one corner to cut better than the other). The cutting was the same in both corners. We tried a few different settings - the power is controlled by a knob on the actual machine, the speed is controlled in software:

At 15mA and 12mm/sec, the laser almost cut through the entire sheet in one single pass:

The pieces could easily be pushed out, but a slight ragged edge remained in two points on the circumference of the circle. We needed either a slower speed or more power to get a perfect finish. In the end we settled on 20mA and 10mm/sec speed.

(pressing both laser buttons together fires a test beam which allows you to adjust the power setting and see the output on the dial above)

At 20mA and 10mm we got a perfectly circle (no ragged edges) which cut all the way through the 3mm acrylic in a single pass, and the circle fell away from the sheet when lifted out of the machine.

We repeated the cutting process in the opposite corner of the cutting bed, to check that the cutting action was the same (and thus confirm that the bed was straight and the mirror(s) correctly aligned). Both times, the circle cut exactly as we expected:

Placing one circle back into the hole it came from and rotating showed that the shape wasn't actually 100% circular. It started to bind in opposite corners of the hole (if the shape was totally circular, it show rotate freely with no binding at all)

The difference is in the regions of tens, if not hundreds of a millimetre - but it is possible to see. This suggests that either the mirrors are not exactly lined up, or one (or both) axis have a tiny little bit of backlash in them. It will take a bit of time of entering numbers, cutting and re-cutting shapes and measuring the results to reduce this entirely.

For now, we're happy that we've got a working laser cutter again down at the local hackspace. Someone else can take over now!

Magentic bearings

Last night's BuildBrighton Open Evening was a pretty busy affair, and there were some pretty cool projects being worked on. We particularly liked James's Magnetic Bearings idea - especially since he's coupled it with solar panels, to generate the electricity to make a motor spin:

The entire assembly magically "floats" above an array of magnets, as current causes the coils beneath the solar panels to attract, then repel, against the magnets placed around them.

It's not 100% friction free, because the lead of the pencil (which is being used as a shaft) is rubbing against a CD placed at one end of the assembly. But graphite itself is often used as a lubricant in bearings, so it's probably about as friction-free as we could hope to get!

As mentioned in the earlier idea, Jason had the suggestion of hanging the motor from a pivot using another magnet, to see if this could further reduce any friction in the entire system. The result is below:

Quite what he has in mind for the project, no-one really knows (and if James does, he's doing a very good job of making it look like he doesn't). But it's using electronics, motors, solar panels and magnets - so it's already up to 11 on the cool scale!

PCB routing at BuildBrighton

They say all the best things come in little packages. I'm not convinced, by yesterday a tiny little parcel arrived, and it was indeed pretty exciting. It was a range of v-shaped cutting bits for cnc routing:

They are made with a 3.2mm shank (ideal for Dremel type rotary tools) but the BuildBrighton router on the cnc machine has a 6mm shank. So we made sure we also ordered collet/adapter, which worked perfectly.

So last night, Mike, Stephen and a few other cool kids had a play about with the cnc routing software and actually got it cutting. Exciting stuff!

We used ExpressPCB and Inkscape to create an isolation path around the outside of the tracks we wanted on the board, using this earlier technique. The final board was pretty impressive. The tracks were drawn at 0.5mm wide. The cutting bit used was 0.2mm and had a 60 degree angle.

(hot off the cutting bed - quite literally, at 35,000 rpm, the cutting bit gets hot and some of this can transfer onto copper surfaced board)

Cutting was aborted after a few minutes. Not because it's slow and laborious (though cnc routing is!) but because the sparks and really bad smell coming out of an increasingly noisy router eventually told us that it was time to consider replacing it!

But before the router gave up, it cut some really fine traces onto our copper clad board.

If anything the traces are maybe a little too fine. This is because our tracks were drawn at 0.5mm wide. We used a 0.2mm wide cutting head and plunged it 0.15mm into the board. Obviously, the deeper the cut, the more of the blade that goes into the material and even with a relatively sharp 60 degree angle on the cutting tip, a deeper cut means a wider cut. We didn't get the software to draw on the outer edge of the tracks, the cutting head followed the line exactly.

So where we had a 0.5mm trace with cutting lines running parallel on either side, the first cut reduced the effective width of the track to about 0.35mm and when the cutting head passed along the other side of the track, it reduced it by about 0.15mm further - so our final trace was more like 0.2mm wide, instead of the 0.5mm we'd planned on.

But that aside, the pcb it produced looked very, very good. (It should be a simple fix, in the software we simple need to tell the cutter to follow the outer edge of the cutting line, rather than the following the dead centre of the cutting line)

BuildBrighton has a new CNC router

While there's not been much activity on the blog for the last few weeks, things have been pretty busy elsewhere. Firstly, we're looking at the feasibility of manufacturing locally and getting more people and businesses involved; so rather than sending designs away to the other side of the world to be made up, we're trying to encourage more people "back home" to try manufacturing themselves. Which has kept us busy these last few weeks - and hopefully we'll have more to report very soon.

In the meantime, locally-sourced manufacturing came one step closer to makers in Brighton with a new CNC router being installed at everyone's favourite local hackspace, BuildBrighton

Here it is, up and running - routing shapes out of scrap MDF today, but who knows.... PCBs next week?

Justin's LED flashing UFO birthday card

Ok, maybe the red LED is just a little brighter - or perhaps should have been put on one of the "wider" or closer-looking beams. Or maybe replaced with a green/yellow LED. Or maybe had a higher value inline resistor or something.

But the end result is pretty cool....

UFO birthday card with flashing LEDs - final pictures

Last night, at BuildBrighton, we helped Justin to get his flashing-LEDs-and-UFOs birthday card ready for this weekend. And, as ever, Steve made it not just look like a finished "product" but like the most awesome you wished you owned yourself. Where most of us would just slap a sticker on the top and call it done, Steve went the extra mile to make it really special!

The key to making this look so awesome was the thin layer of styrene immediately over the top of the LEDs - providing a single, flat surface for the image to sit on top of.

A photo-quality print is lined up and fixed over the entire board using Photo Mount spray...

... and the excess trimmed off. The print on the surface is pale enough that the LEDs shine through the relatively lightweight (90gsm?) photo paper meaning no nasty cutouts or holes required in the image surface.

Instead of just stopping there, Steve went to the trouble of making a striking green frame for the image, complete with sliding on-off switch to stop the battery from draining too quickly.

 With a 5v regulator onboard, the LEDs can be powered from a single PP3 9v battery.
Having mounted the image onto the uprights, a simple - but effective - acrylic border is placed around the outside of the photo and fixed in place with hot glue.

The final (amazing-looking) finished product. Hopefully we've done enough to help Justin earn a few brownie points for this one ;-)

Linear rails for possible CNC?

A few weeks ago, at one of our Thursday BuildBrighton meetings, Matt suggested another cnc machine idea.   We've already completed one - a pcb drilling machine - and while the mechanics and software side of things were pretty good (for a £30+ cnc) the quality of the stepper motors was always a little suspect!

These cheap little stepper motors are all over the internet (and despite being rated at 5v as this one is, we found running them at 7v-9v the minimum, else they stall really really easily, but they can handle being driven hard at up to 12v. Beyond that, we've no idea - we didn't want to intentionally burn one out!)

What's not immediately apparent from this photo is that the shaft is actually offset from the centre:

And that's because, inside, there's a load of internal gearing which gives these little motors a pretty decent amount of torque for such a small package. In fact, the motors we had were geared by 1:64 on a 1/64 stepper motor - meaning they required 4096 steps for one complete revolution. By the sounds of things, perfect for ultra-tiny movements, and therefore precision accuracy.

Unfortunately, the internal gearing comes with a price - backlash!
When you send up to 100 step pulses to these motors, they can either move a great distance (depending on the size of the cog the motor is turning of course!) or they may not move at all, as all the slack in the cogs is taken up. This can be compensated for, a little, in software, but it's not ideal. So a while back, when some cheap steppers came up on eBay, we got hold of three decent motors and waited for the opportunity to present itself...

As often happens, when eating pizza and talking rubbish at BuildBrighton, discussions soon got around to making another cnc machine - this time with a multiple head attachment, for doing solder paste spotting as well as pick and place for SMT components. We already had the stepper motors, we've got access to equipment for cutting frames, inside of messing about with cheap-and-ok, we thought if we're going to do it, we'll make a pretty decent spec machine this time. And that means linear rails....

This morning, Mr Postie dropped off another peculiar looking package at Nerd Towers, covered in hieroglyphics from the Far East and we tore into it:

Yay! 12mm linear rails. Perfect for any decent-sized cnc machine (up to about A3 cutting bed size we reckon, certainly more than enough for up to A4). They're actually quite chunky but in a reassuring way. The mounting holes are already tapped, ready to take an M5 bolt.

Check out those tiny little ball bearings! These rails (we've got six) are going to be perfect, at least for our X/Y axis on the next CNC machine (whatever that is, whenever it gets made). They're actually quite big for a z-axis, unless Matt has ideas about making a massive monster-sized machine.......

Rope making machine at BuildBrighton

With Xmas and New Year occupying so much of everyone's time, there's not really been much time for nerding about lately. Well, not for some of us. But thankfully Stephen Cropp from BuildBrighton hasn't been so pre-occupied, and set about 3D-printing this awesome rope-making machine.

It's really quite simple in design. At one end of the table is clamped a central cog, which drives three outer cogs (each spaced 60 degrees apart). By turning the central cog with a handle, all the outer cogs turn the same way and at the same rate.

Steve threads his twine through hooks on these outer cogs to a weighted clip at the other end of the table then cranks the handle...

Large format vinyl cutter at BuildBrighton Foison C24

Last night was BuildBrighton night (in fact, almost every night is a BuildBrighton night these days, but Thursdays are the "traditional" come-along-and-hang-out night) and as is usual, come the witching hour, cool things start to happen.

This video was taken at around ten past midnight, after we spent a couple of hours restoring the large format vinyl cutter that we donated a few months back. It's a Foison C24 and has been used about three times in it's lifetime. Hopefully, now it's in it's new home and working, and more people have access to it, it'll get used quite a bit more.

As you can see, it's quite a whizzy-fast machine. Because it's designed to use a drag knife, it takes corners quite slowly, but really flying down the straights!

For testing, we replaced the drag knife with a fat-tipped Sharpie and drew on some copper board. Of course, it's only a matter of time before we're drawing PCBs directly onto the copper board, by-passing the whole press-n-peel stage of etching ;-)

CNC milling machine

Following our success with our CNC drilling machine, we're now helping Justin from BuildBrighton hack our own device to create a CNC milling machine (that change in two little letters makes all the difference!)
Whereas our drilling machine had a simple peck-and-drill motion, and there were no lateral forces to contend with, Justin is looking to mill PCBs with a dremel or similar drilling head, which means the chassis needs to be able to resist some twisting forces on the uprights.

As a quick-and-dirty prototype, we put together an MDF-based frame and used drawer runners from an earlier prototype of our own drilling machine.

Justin is going for a moving gantry system, rather than a moving bed for the y-axis. We ran out of drawer slide rails to finish the x-axis but the frame so far looks very promising!

Inkjet printer teardown - get at those stepper motors!

At last night's BuildBrighton open evening, we set to work opening up an old HP Inkjet printer, using our favourite opening-tools - hammers and hacksaws!

We were after a few parts from inside the printer - namely the stepper motors and linear rods (that hold the print head carriage). Before setting to work with the hammer, we located which parts of the printer we wanted to avoid hitting (too hard)

There's a stepper motor, tucked away in the corner of the enclosure - best go easy down there!

It didn't take long before the plastic casing was off...

And we had hold of a feast of salvaged goodies:

Of particular interest to us was the dc motor (used to make the print carriage travel left-to-right) the nice chunky steel rod with precision made carriage (actually just some moulded plastic with brass rings that slide along the rod - no fancy linear bearings here!), the rubber paper-pickup wheels (for our future lathe project) and of course, the stepper motors (complete with pulley heads and drive belts).

We started to get to work straight away on the stepper motors. They're five-wire connections so already we're considering uni-polar steppers. To find out exactly what we've got, we drew up a table of connections, put an ohm-meter across each of the pins in turn and noted down the respective resistances across each set of pins.

(Here Justin is testing the resistance between pins 1 and 5 - about 60 ohms)

We noticed that all connections to pin three were roughly half the resistance of the others (about thirty ohms). From this table of resistances we worked out that we had a unipolar stepper motor with a common "centre tap" - i,e the centres of both coils were connected together

To work out the wiring for the other coils, we had to do some trial-and-error investigating. We put power onto our centre tap (pin 3) then put a ground connection onto one of the other wires (pin5, we called this pin d). The motor energised, moved slightly and locked into place.

The idea now is to identify the other three pins, such that we can label them pin a, b, c and energise them in sequence a,b,c,d or d,c,b,a to get the motor to spin in either direction.

Here we can see our centre tap (pin3) connected to power, with pin5 grounded and pin1 at the same time.

With pin d still grounded, we then grounded the other three pins, one at a time. Where the stepper motor moved slightly anticlockwise, we'd found our pin c. When the motor moved slightly clockwise, we'd hit upon pin a. When there was no movement in the motor, we'd grounded the (remaining) pin b.
Using this rough-and-ready approach, we successfully labelled all four pins on our stepper motor.

With the pins sucessfully identified, we replaced our bit of wire that poked at the pins, connecting them to ground with some IRF640 power FETs. These are like big chunky transistors, with a flyback diode built into them. By putting them on the ground side of  the coil and activating them in the correct sequence, we managed to get the stepper motor to spin at quite a reasonable rate:

The driver chip is one of our old friends the PIC 18F2455, configured as a USB/HID device. Our custom software simply sends a "command byte" to tell the board which way to spin the motor.
252 = spin anti-clockwise
253 = spin clockwise
250 = stop spinning
249 = change the delay beween pulses.

We found with these steppers, that they ran quickly and quietly with a delay of 2ms between step pulses. We could increase this delay to slow the rate of rotation, but movement got more and more "jerky". A delay of just 1ms caused the stepper to hum without turning at all.

Define CLOCK_FREQUENCY = 20
Define CONFIG1L = 0x24
Define CONFIG1H = 0x0c
Define CONFIG2L = 0x38
Define CONFIG2H = 0x00
Define CONFIG3L = 0x00
Define CONFIG3H = 0x03
Define CONFIG4L = 0x80
Define CONFIG4H = 0x00
Define CONFIG5L = 0x0f
Define CONFIG5H = 0xc0
Define CONFIG6L = 0x0f
Define CONFIG6H = 0xe0
Define CONFIG7L = 0x0f
Define CONFIG7H = 0x40

UsbSetVendorId 0x1923
UsbSetProductId 0x1694
UsbSetVersionNumber 0x1001
UsbSetManufacturerString "Nerd Club"
UsbSetProductString "USB stepper driver"
UsbSetSerialNumberString "1111111111"
UsbOnIoInGosub input_report_before_sending
UsbOnIoOutGosub output_report_received
UsbOnFtInGosub feature_report_before_sending
UsbOnFtOutGosub feature_report_received

AllDigital
Dim i As Byte
Dim spindir As Byte
Dim state As Byte
Dim dly As Word
Config PORTB = Output
Config PORTA.0 = Input

UsbStart
spindir = 0
state = 0
dly = 10

loop:
      UsbService

      If PORTA.0 = 1 Then state = 0

      Select Case state

            Case 250
            Low PORTB.3
            Low PORTB.2
            Low PORTB.1
            Low PORTB.0

            Case 1
            High PORTB.3
            Low PORTB.2
            Low PORTB.1
            Low PORTB.0
           

            Case 2
            High PORTB.3
            High PORTB.2
            Low PORTB.1
            Low PORTB.0

            Case 3
            Low PORTB.3
            High PORTB.2
            Low PORTB.1
            Low PORTB.0
           
            Case 4
            Low PORTB.3
            High PORTB.2
            High PORTB.1
            Low PORTB.0
                       
            Case 5
            Low PORTB.3
            Low PORTB.2
            High PORTB.1
            Low PORTB.0

            Case 6
            Low PORTB.3
            Low PORTB.2
            High PORTB.1
            High PORTB.0

            Case 7
            Low PORTB.3
            Low PORTB.2
            Low PORTB.1
            High PORTB.0

            Case 8
            High PORTB.3
            Low PORTB.2
            Low PORTB.1
            High PORTB.0

      EndSelect
      WaitMs dly

      Select Case spindir
            Case 1
            state = state - 1
            If state < 1 Then state = 8

            Case 2
            state = state + 1
            If state > 8 Then state = 1

      EndSelect
           
Goto loop

End

---

feature_report_received:
Return

---

feature_report_before_sending:
Return

---

output_report_received:
      'PC has sent us some data - use it here
      i = UsbIoBuffer(7)
      Select Case i

            Case 249
            dly.HB = UsbIoBuffer(1)
            dly.LB = UsbIoBuffer(0)

            Case 250
            state = 250
            spindir = 0

            Case 252
            spindir = 1

            Case 253
            spindir = 2

      EndSelect

Return

---

input_report_before_sending:
      'we're sending data back to the host
      UsbIoBuffer(0) = spindir
      UsbIoBuffer(1) = state

Return

BuildBrighton PCB making workshop

Yesterday (Saturday) was BuildBrighton's PCB making workshop, as part of the Brighton Digital Festival.
From a worryingly quiet start, we ended up with six people taking part in yet another successful practical workshop - 100% success rate!

Over six hours, we introduced the attendees to schematic drawing using ExpressPCB (it's much simpler and easier to get going with than Eagle for anyone new to electronics/PCB layout) and their PCB layout software. A few people had brought along projects that they were working on and we helped them create PCBs for their own creations, while everyone else set about recreating the famous BuildBrighton Drawdio  kit.

(all the tools needed for making your own PCBs, including ExpressPCB software, press-n-peel blue paper, ferric chloride, a sanding block and a heavy duty laminator!)i

Sadly, the workshop was such as success and everyone was having such a lovely time that we forgot to take any more photos! But, for reference, for anyone who attended and would like to know more:

The first step was to create/draw your schematic (the bit with the little squiggles and symbols for electronic components). The most important thing to remember here is to give every component on the drawing a unique Part ID (the name can be anything, it's that part id that's referenced in the PCB layout software)

Then we drew our actual PCB layout using ExpressPCB.
File -> Link schematic to import the list of part IDs used in our circuit. A lot of people found it easier to drop symbols for all components used onto the screen before starting the layout process (menu Component -> Component Manager). Make sure that all components are drawn on the top (red) layer!
The most important thing to remember here is no crossing the lines!
In a few instances, some people ended a trace with a round pad, allowed another trace to pass "through" and started the trace again the other side, with another pad

Where a trace is continued after allowing another to "pass through" we tend to draw a connecting line on the silkscreen (yellow) layer, to act as a reminder when assembling the final board.

Once the PCB layout was complete, it was time to get on with the toner transfer.
For our workshop, we used Press-n-Peel (blue)

Toner transfer paper tends to be quite expensive, so rather than just print straight onto the blue sheet, we printed our PCB layout onto plain paper first (using a laser printer - inkjet just won't work for this!). Then cut out a piece of p-n-p blue just a bit larger, stuck it over the printed image with regular tape (shiny side down, powdery side up) and re-printed the image. This gets the PCB image onto the smallest sized bit of press-n-peel, meaning you've got plenty more left for another go!

With the image on the press-n-peel, we cleaned up some copper clad board (available from various online suppliers - eBay sometimes is a cheap source) using a fine-grit sanding block.
Sanding the board not only cleans it up (it needs to be bright and shiny and all traces of oxidation removed) it also provides a slight "key" for the toner image to stick to when transferred.

Tape the image (face down) onto the shiny copper board using paper-based masking tape, preferably cut to fit into a corner of your copper board (so it takes less cutting later). It's important not to use sellotape or similar plastic backed tape, as this will melt during the transfer process.

We used a heavy-duty laminator, but you could also use a regular household iron.
After three passes through the laminator, the image is transferred onto the copper board. Douse in cold water (carry the board by its edges, it gets very hot!) and carefully peel off the backing.

When done correctly, there should be no black traces left on the backing sheet. Check all traces carefully on the copper board. Where necessary, touch up any missing detail with a fine-tipped permanent (black) pen.
When happy with the transferred image, it's time to actually do some etching!

Ferric Chloride (FeCl) is messy stuff. Make sure you're wearing your old clothes and get ready to clean up any spillage immediately (it stains!). We made up a small batch using hot water and about a quarter of a pack of crystals. Etching in warm solution is quicker than in cold, although the end result(s) are the same.

The Ferric Chloride solution should be a dark brown in colour. If it's pale yellow, you need to add more crystals. If it's an orange-y colour, it will probably work but will take a long time. If you're re-using old solution (that's already had a few boards etched) and it's a dark green-y colour, it's getting a bit old and you should consider refreshing it. A dark brown (which is a golden yellow colour at the edges) is the perfect strength mix.

Submerge the board and either tip the container slightly to wash the mixture over the board (large boards in a small, shallow contianer) or dip the boards in and out of the mixture (smaller boards, suspended in a tall container on bits of wire). It will take 10-15 minutes for the board to etch completely.

The copper board etches in a couple of stages and if you keep checking it regularly, you'll see:
Firstly, the board goes a very vibrant pink.
Then the edges of the board (where the copper is exposed) start to look a little bit green.
Finally, the edges of the board turn a beige colour (the natural colour of the board the copper was stuck to) and the etching continues, usually from the edges, towards the centre of the board)

When no trace of copper remains (double-check for little bits of pink between the black traces on the board) your PCB is fully etched. Congratulations!

Some people prefer to drill then clean their boards - we did it the other way around.
You can use nail-varnish remover or similar acetone-based cleaner, or simply scrub with a fine-grit sanding block until all traces of the black toner are removed and you're left with a shiny new PCB.

During our workshop, everyone successfully made their PCB, etched and drilled to a finished standard! A few brave souls even populated their boards with the Drawdio components provided - and they worked!!

All  in all, another successful BuildBrighton workshop and a great day making stuff!

Brighton Mini Maker Faire

Yesterday (Saturday 8th September) saw the second Brighton Mini Maker Faire. It was utterly awesome. Or so I'm told. In fact, we didn't get to see much of the rest of the 'faire since we were inundated with questions and queries about our CNC drilling machine - not least of all how we'd managed to make it so cheaply (cost to date is about £30 for all parts, motors and electronics - less than the cost of a single stepper motor driver board, or a single - really good quality - stepper motor).

The day started with us trying to resolve some of the issues we'd encountered the previous Thursday - namely reducing the servo z-axis speed, measuring the backlash accurately and improving the software.
Of course, no sooner had we written two lines of code than the doors opened and we were swamped all day!

This year, the Maker Faire took over the whole of the Brighton Dome Foyer AND the Corn Exchange next door. It was a massive venue, and was rammed busy from the moment the doors opened at 10am until the final whistle blew some time after 5pm!

So we managed to un-hack a few changes made to the CNC machine to get it working again and demonstrate the drilling action - complete with software control of the drilling head (when we tried the machine last Thursday, we had to control the drilling spindle separately and leave the head spinning all the time).




We didn't have time to implement (and test) all the changes we'd proposed, but had a great day, meeting people, sharing ideas and generally talking nerd. Maybe next year we'll need to attend not as "makers" (as in these last two MakerFaires) but as visitors, to see what everyone else is up to!