23 October 2016
I’ve been struggling for free time this month for poking around with breadboards and other fun things. To work around this, and still (hopefully) get my RetroChallenge entry done, I decided to use a simulator so I could work on it with my laptop whenever and wherever there was time.
LogiSim Edge Detector
For an earlier RC2014 project I used LogiSim which is simple and easy to use, but I quickly hit some limitations. The built in sequential building blocks (shift registers, latches, etc) appear to support only a limited set of variants. There is no option for asynchronous resets, or transparent latches on the shift registers. It includes combinatorial building blocks (logic gates, etc) also, but these do not appear to work correctly for building sequential circuits, as feedback is not always handled correctly. Because of this I was not able to simulate the exact characteristics for most of the 74 series ICs I was using.
To solve this problem I switched to using Altera Quartus to build a model of the circuit and ModelSim Altera Edition to simulate it. I mainly chose this because I’ve used it previously for FPGA projects, and because if some functionality is missing I can implement it in Verilog.
When redesigning the autoshifter circuit (to shift out 8 bits of data after each IO write) I built it as a Block Diagram/Schematic File (.bdf) in Quartus. This allows the design to be entered as a schematic with various logic symbols supported by default. Additional components can be created with a hardware definition language such as Verilog, or by using Quartus’ “MegaWizard Plug In Manager” to configure and insert a variant of an IP core. I set my project up for the Cyclone II FPGA as I have used it for previous projects. To simulate the 74HCT165 shift register I configured a variant of the LPM_SHIFTREG IP core with 8 bits of data, parallel inputs and serial inputs, serial output, and a clock enable pin.
Unfortunately this still does not quite match the 74HCT165 exactly as it has D flip flops rather than transparent latches. I could build my own shift register in Verilog, but to save time I opted to stick with the LPM_SHIFTREG version and ensure that the timings seen in simulation were such that the transparent latches wouldn’t cause a problem.
In order to test the design I set Quartus up to launch ModelSim and run Gate Level Simulation after compilation. ModelSim can be driven manually through the GUI, but this is fairly fiddly and repetitive. Fortunately it supports scripting via ‘do files’ which contain lists of commands for ModelSim to interpret.
I set up four do files:
- init.do – Reset, add graphs for appropriate signals, set default values for inputs
- shift8.do – Drive the data bus to the appropriate values to set SHIFT8 and deassert /BITBANG, then assert and deassert /CONFIGWR
- write.do – Simulate a write to the device by driving the data bus and /DATAWR signals, zoom graph to fit
- sdtest.do – Run the previous three do files in sequence, zoom graph to fit
This allowed a fairly quick turnaround by hitting compile in Quartus, selecting the project once ModelSim launches, then typing ‘do sdtest.do’ to run the simulation.
For a different project I could have sped things up by keeping everything inside ModelSim, but this would have required me to design the circuit in a hardware definition language. Since my final target is a circuit built from discrete components and not an FPGA bitstream I decided to take advantage of the Block Diagram/Schematic feature in Quartus. This way everything could be easily translated back to a physical circuit once it was verified as working.
Now I have the autoshift circuit working, theoretically, I just need to find some time to build and test the physical version!
by moop at 23 October 2016 08:26 PM
This is my laser cut cryptex. It features 28 different characters and 9 rings, giving a total possible 10.5 Trillion different combinations. I took a bit of time developing the design so that I could add some nice features. This cryptex file is laid out so that you can have any number of rings in your own design. The best feature is that the codeword is changeable, each locking ring has an outer letter ring that can be placed in any one of the 28 different positions. Once the rings are back in place the ring locking bars can added and they prevent the rings from being modified until the box is open again. It's a bit hard to explain so I made a video showing how it all work (svg here
It took a long time to assemble this so I lived with my initial design choices but if I were to remake it I would adjust the file to make the ring locking bars out of 6mm ply and maybe put some blind holes onto the code rings to prevent the code being brute forced.
by email@example.com (Martin Raynsford) at 23 October 2016 01:20 PM
15 October 2016
In my previous post I promised to show the previous implementation of my Z80 SD interface, and to run through the problems which I intend to fix this month.
Original Z80 SD Interface Schematic (Click to Zoom)
The 74138 (U1) in the top left of the schematic is used to detect and decode IO reads and writes from the Z80. Three bits of the address bus (A7, A1, A0) are decoded along with the /RD line, M1 line and /IORQ line. With this configuration the device responds to any IO address between 0×80 and 0xff. Some more gates will be used to further decode the address later. The lower two bits (ie. the address modulo 4) select a register within the device. Address 0 selects the DATA shift register (U4) for reads or writes while address 1 selects the CONFIG register (U3) for writes only.
One NAND gate from the 7400 (U2A) quad NAND is used to invert the CONFIGWR signal, as the 74138 outputs are active low while the latch input on the 74374 is active high.
In the middle row of the schematic are the 74374 register (U3) that holds configuration information and the 74299 shift register (U4) that is used to transfer data to the SD card. To the right of these is a 74165 (U7) shift register that implements the automatic shifting mechanism for high speed mode along with some more NAND logic (U2B, U2C, U2D) to generate the appropriate signals depending on the operating mode.
The automatic shifting behaviour is implemented by latching the state of the SHIFT8 bit of the config register into all 8 bits of U7′s input register when /DATAWR is asserted (ie. the data register is written to). This fills the register with 1s. The serial in (Ds) pin of the register is connected to ground so with each clock pulse the train of 1s is shifted and the gap is filled with a 0. The serial output of the register (SHIFTING) is NANDed with the clock by U2B. The output from U2B is either a train of 8 inverted clock pulses or a constant logic 1 level, depending on the state of SHIFT8 at the time the DATA register was written to. NAND gate U2C will either invert this train of clock pulses if /BITBANG is high, or reflect the inverted state of the /BITBANG config bit if U2A is outputting a constant logic 1 at the time. Put together this allows either the SHIFT8 config bit or the /BITBANG config bit to control the clock depending on the desired operating mode (relying on the driver to avoid trying to do both simultaneously).
The final NAND gate of the 7400 (U2D) is used to invert the /DATAWR signal to drive U4′s S1 input to select the Parallel Load operation when /DATAWR is asserted or to Shift Left otherwise. S0 of U4 is tied to ground as the Shift Right and Hold operations are never used.
Finally, a 74107 dual JK flip flop was used to divide the RC2014′s clock signal (CLK) by four to produce (Q_CLK). This was initially intended to solve a timing issue, but has caused more trouble than it was worth.
The timing diagram below shows the behaviour of the device when the SHIFT8 bit is set and a write is issued to the DATA address.
Original SD Interface Timings (Click to Zoom)
A couple of issues are noticeable:
- SH_CLK is producing one partial pulse, followed by a gap, followed by 7 real clock pulses.
- /DATAWR (and therefore SH_LOAD) is asserted for several clock pulses.
- CLK (actually Q_CLK) behaves strangely.
Most of these issues were introduced by attempts to work around other problems.
Before the clock divider was introduced U7 was emitting a train of 11 clock pulses rather than the expected 8. This is because the 74165 has a transparent latch rather than an edge triggered latch. The Z80 asserts /IORQ for many clock cycles so the train of 1s from SHIFT8 was being reloaded, wiping out the 0 introduced through the Ds input, until /IORQ was deasserted. Introducing and resetting the clock divider was an attempt to prevent the shift registers from being clocked during this period by holding it in the reset state when /DATAWR is asserted.
Unfortunately because the Z80 instructions take a variable number of clock cycles to complete and aren’t necessarily a multiple of 4 cycles the state of the divided clock when /DATAWR is asserted is not predictable. This is likely the cause of the glitchy short pulse seen on CLK as /DATAWR is asserted.
Without this unexpected pulse U4 would not be loaded, as 74299′s the Parallel Load operation is synchronous with the clock, and shares a clock with the Shift operation. Extra logic would be required to create a seperate clock that is a superset of the shift clock.
Given these problems I’m going back to the drawing board slightly. I may try adding the extra logic to clock only the 74299 but if that fails I’m replacing the 74299 with a pair of shift registers – a 74165 for data moving from the Z80 to the SD card and a 74595 for data moving from the SD card to the Z80. This is probably wise anyway as the 74299 is a rare part which is many times the cost of a 74165 or 74595 and supplies are less plentiful.
I’ll also be removing the 74107 clock divider circuit and replacing it with a simple edge trigger circuit to limit the /DATAWR pulse to a single clock.
Hopefully I will have a write up of this new version soon.
by moop at 15 October 2016 01:51 PM
05 October 2016
I decided to join in with Retrochallenge 2016/10 this October. I’m also hoping this will provide some incentive to write more posts and updates about other projects once I’m back into the swing of things!
RC2014 Z80 computer
My goal for this Retrochallenge is to finish an SD card interface I started designing for Spencer Owen’s RC2014 Z80 based computer (which was spawned by a previous Retrochallenge, hence the name). This should work with most Z80 computers that don’t do anything crazy to the I/O interface, so I may also get it working on a ZX Spectrum if there is time.
I’m intending to build my SD interface from 74 series and similar discrete logic ICs. This is partly for fun and partly because the microcontroller in the SD card is likely already more powerful than the RC2014. Adding another microcontroller into the mix to interface with the one in the SD card is just a step too far.
I’ll be using the SPI-like mode of the SD card protocol, not least because information on the faster SD mode is not publicly available. The SPI-like interface should allow me to use shift registers for communication with the SD card.
I was initially planning to use a 74ALS299 universal shift register to reduce chip count. Unfortunately, in addition to being somewhat hard to get, the interface on this chip is troublesome as the shift, shift direction, and output enable are all synchronous and controlled via two pins that set the operation. The extra glue logic needed to deal with this completely nullifies the benefit of using a single universal shift register. Because of this I’m planning to redesign around a pair of shift registers: a 75HCT595 serial-in-parallel-out register and a 75HTC165 parallel-in-serial-out register.
The SD card requires a slow clock pulse for initialisation (around 100khz), but once initialised supports faster clock speeds. The design is complicated by the need to run at both speeds, but I have a scheme to cope with this.
My intended interface uses a pair of registers mapped to the Z80′s I/O space.
- Writes to this address latch the byte from the Z80 data bus into the 74HTC165 which is used to send data to the SD card.
- Reads from this address enable the outputs on the 74HTC595 shift register which receives data from the SD card.
- Writes to this address update a 74HTC374 register holding a configuration byte. The following bits are currently used:
- autoshift – Automatically shift 8 bits from the shift registers to the SD card and back after a write to the DATA address. This is used for the SD card’s “normal” high speed mode and should allow fast enough I/O that the Z80 becomes the bottleneck.
- clock – OR’d with the automatic clock signal to the shift registers and SD card, allowing communication at a speed controlled directly by the Z80 to provide a ‘bitbang’ mode. This mode is not efficient, but allows the slower speed required for the SD card initialisation process without much extra logic.
Original version on breadboard
An initial version similar to this design has been built on a breadboard using a 74ALS299. In addition to the issues with the synchronous control signals needed to load this shift register, there were also compatibility issues with the timing of the Z80′s I/O control signals. This requires additional glue logic and a redesign of automatic shifting logic that enables the high speed mode to work.
Before I take the previous version apart to rebuild, I’ll take some logic analyser captures indicating the timing issues, and write up (and remind myself of) the problems.
by moop at 05 October 2016 08:04 PM
30 September 2016
The 1000th project for this blog very much took on a life of its own. I knew I wanted to make something big and impressive so the idea of making 1000 of something had a lot of appeal. The laser makes it very easy to churn out 1000 identical items so I also wanted to make something that needed assembly, something where I had specifically touched all 1000 things. So I built this little shark model, it had a few iterations and eventually ended up with five ribs and a flexible tail.
I managed to tessellate 60 onto a sheet of poplar ply and I set the machine to cutting out 18 sheets, each sheet taking just over an hour to complete. In between sheets I would pull the parts out of the laser and scoop them into boxes for later assembly. I spent many nights sat in front of the TV assembling parts and in full flow I was assembly one every 45 seconds, so it was roughly another 18 hours for shark assembly. This left me with two,80L crates full of sharks and lots of time to figure out what the next step should be
Arranging the sharks into some kind of sharknado
was appealing but it would need a sturdy framework. Suspending 1000 sharks inside a fish tank would be cool but there would be a lot of strings so I hit upon the idea of sticking the sharks together to form a larger shark. One big thing made from lots of smaller things
would look pretty good so I set about making one giant shark from all these pieces.
The first step was to create a former to make sure I got the right shark shape. Thankfully with a laser cutter you can change the scale of things pretty easily and in no time at all I had a full sized model form corrugate card. This allowed me to check it for size in the final tank and gave me something to work around. I just started gluing sharks into location on the side of the cardboard, putting them between the ribs and making sure that the shark picked up the right shapes in the right proportions. Because the card was flexible I was about to add a bit more shape into the design as it evolved.
Each shark was built in several stages and took about 40 hours each to complete. The first half of the shark was built against the cardboard former. All the sharks were packed as tightly as possible and hot glued together. Two more layers of sharks were added on top of that giving the body some shape. Next the fin was added to the top and sides and the tail made last. Because the tail was the thinnest part it was the first thing built on the other side when the cardboard was removed. The flexible corrugate spine allowed me to add some curves into the body shapes.
The first shark only used around 500 of the smaller sharks which left me a problem, I had to build a second shark to use up all 1000 sharks. The second shark was built in the same manor but it gave me a chance to put the shark in a different pose.
To make the shark tank I took the laser crate from a Greyfin laser cutter
and very carefully extracted the laser trying not to dismantle the box. I secured the lid back down and had full access through one of the side panels. In the walls of the tank I cut holes for the portholes
and screwed them in using Dome nuts
to give them an extra nautical feel. I used the large Just Add Sharks Stencil
to spray paint the company logo onto the side of the tank taking care to mask off the red and black areas as required.
The inside of the tank was painted white to hide the footprints and marks left from the laser cutter and the whole thing was illuminated with a water effect lamp
. The sharks were suspended from the ceiling using fishing wire and hooks screwed into the sturdy points of the roof.
by firstname.lastname@example.org (Martin Raynsford) at 30 September 2016 07:42 PM
This is my 1000th laser cut item. It's nearly my fifth blog anniversary and I wanted to make something epic so I built this shark tank and housed 2 large sharks inside it. Each shark is made from 500 smaller sharks so over the last few weeks I have cut and assembled 1000 of the smaller laser sharks
, 1000 things for my 1000th item. Portholes
into the tank allow you to see the sharks from all different angles.
by email@example.com (Martin Raynsford) at 30 September 2016 05:18 PM
29 September 2016
I set out this evening to make a cryptex
, it was fairly ambitious given that I also had to pack for New York. Instead all I managed to achieve was a single ring prototype but I figure that is most of the hard work done. This cryptex features a ratchet to make the ring rotate in a single direction. 27 digits, I view the blank character to be equally as important as the other 26, and as this cryptex will be infinitely extendable you could have multiple words in the code. The central section is square which means it doesn't have to be made from 100s of stacked layers.
Most significantly there is an outer ring containing all the letters. The letters are glued into place using a jig
to ensure they are all square on the wheel but the wheel can be rotated in relation to the keyed slots, this means the code word is actually going to be changeable once the cryptex is assembled.
by firstname.lastname@example.org (Martin Raynsford) at 29 September 2016 11:01 PM
28 September 2016
I made some bowls before
but I lost some of them at the Newcastle Maker Faire this year, as I'm bringing my 'A' game to New York, I thought it was quite sensible to make another one for display. I chose to make another wavy bowl from a single concentric stack. This time the layers had guides to show you where to glue the next layer (svg here
by email@example.com (Martin Raynsford) at 28 September 2016 11:31 PM
27 September 2016
I finished the counter mechanism
, I doubled the size of the wheels to make them easier to run and I added a detent mechanism to ensure that the smallest wheel falls into place and it also stops it spinning wildly. (svg here
The geneva mechanism was rebuilt using a layer of 2mm ply, this allowed the two different gears to sit half a step out of sync with each other and eliminates any clashing as the gears rotate.
The detent mechanism gave me a few headaches, typically these mechanisms usually look like a rounded ratchet. The rounded end allows the lever to slide in either direction. The trouble with laser cutting and wood is that the edges are a little bit rough and I really struggled to make this design work in the reverse direction.
To solve the problem I got thinking laterally, I put some 0.8mm ply in side ways to press against the sides of the decagon. I put in 2 bars to create even pressure on both sides of the wheel. As the decagon rotates it flexes the two bars outwards and that helps it bump over into the next detent. The rough side of the decagon rubs against the smooth surface of the 0.8mm ply and there is no sticking.
by firstname.lastname@example.org (Martin Raynsford) at 27 September 2016 11:25 PM
I made a church window
a long time ago and I was never very happy with the way some of the layers were offset. The perfectionist in me always knew the glass layer was a bit awry from the rest of the framework. Given that it is well received at most events I figured now was the time to redo it and make a 'perfect' one this time around. It's a pretty straight forward layered design, the only real tricks are engraving on the pillars to add some depth and make it appear like there are bands around them and the perspex layer is a dodecagon, rather than a circle, to prevent it from rotating within it's hole.
by email@example.com (Martin Raynsford) at 27 September 2016 08:45 PM
25 September 2016
I'll be attending the New York Maker Faire
this weekend coming. I'm taking as many items and kits as I can possibly manage but I also wanted something smaller that I could gift or sell as appropriate. I ended up cutting 200 of the mini shark kits, if you would like one simply come and find me at the maker faire and tell me you read my blog.
I actually cut a whole lot more sharks last month but that's a project due to be completed in the next few days so keep an eye out for that.
by firstname.lastname@example.org (Martin Raynsford) at 25 September 2016 07:53 PM
Over the last 5 years I've made a lot of stuff for a lot of people. As I approach 1000 laser cut items here is just a small selection of things that people have sent back to me recently. It's always great getting follow up photos, it lets you know these things are appreciated.
by email@example.com (Martin Raynsford) at 25 September 2016 03:14 PM
24 September 2016
I was inspired by some end grain chopping boards I saw on you tube to try and recreate some of the techniques with the laser cutter. This coaster was made by cutting the basic outline with the laser and then cutting across it with the ribbon pattern. The cut was made in two lines removing a chunk 0.8mm wide, a single layer of veneer was inserted into the gap and then the coaster was glue shut again. The second set of ribbons (overlapping the first) were cut once the glue had dried. The second line of veneer was inserted and the whole thing sanded up to a nice finish. (svg here
by firstname.lastname@example.org (Martin Raynsford) at 24 September 2016 07:18 PM
I've had this chopping board in my garage for at least a year and I figured now was the time to finally put something on it. I found a nice illustration I liked online and converted it into a line drawing for the laser. I think the style works well even if the subject and item is a little dated. I'll be sure to use it next time I'm doing fondue
though. (svg here
by email@example.com (Martin Raynsford) at 24 September 2016 10:07 AM
22 September 2016
We're doing a bit of decorating which means we shuffled rooms round too and Kim is now studying in a room without a lampshade. It's never been a high priority until today so instead of traipsing into town just to settle on a lampshade we don't really like I made one instead. It's made from 0.8mm white polypropylene and I'm a bit peeved because I over cooked it and you can see the burn marks through the plastic. I'll clean it up eventually but it has gone into service today and it seems to be doing an acceptable job.
by firstname.lastname@example.org (Martin Raynsford) at 22 September 2016 01:41 PM
20 September 2016
I should have known that the master of woodwork Matthias Wandel
would have also built a counter and he did it
much better than I did. This counter has a Geneva drive
between the digits so the upper digit only moves 1/10th of a rotation each time the lower digit passes zero. My counter is a bit flawed, the tolerances weren't tight enough so it gets a bit sticky as it increments. I can rebuild it so that the parts overlap in a better way and avoid snagging.
I took a short video of the two different counters in action but for some reason my camera was only letting me take 4 seconds of video at any one time.
I improved the counter wheels, each number has a tab which fits into the end wheel, this ensures even spacing around the wheel and that the numbers are all square.
by email@example.com (Martin Raynsford) at 20 September 2016 10:13 PM
I have combined all my tips and tricks for making a good kit into this one new design now available for sale in my store
. You've seen this shark pop up
a few times
recently but I've now turned it into kit form. It varies from the original shark after Sam from Shiny Shiny
wisely suggested that I put a flex section in the tail.
The kit itself numbers each part on both sides of the slots so part 1 fits into slot 1 etc, but when they are slotted together both numbers are hidden from view. Each part is held into the framework by very small 0.8mm wide tab which can be easily broken (so no need for a knife) and each tab is pointed at by an arrow so you know where to snap. I have redrawn the Just Add Sharks logo to be a Hershey text font
which makes it much faster to cut and I have also included a little illustration of an assembled shark which will also aid building. Buy one from the store
or cut one for yourself. (svg here
by firstname.lastname@example.org (Martin Raynsford) at 20 September 2016 12:05 AM
18 September 2016
I want to keep track of how many times I've performed a task with a little mechanical counter so I built this prototype. This was intended to prove the gear ratios work and demonstrate how bad the numbers go onto the wheel. The next iteration will have a ratchet to click round one number at a time, the numbers will be done differently too, finally I'll add a third wheel so I can count to 999.
by email@example.com (Martin Raynsford) at 18 September 2016 02:57 PM
15 September 2016
One of the stranger request I've ever had. Gradwell came round to see me this evening to test if it would be possible to engrave onto these crucifixes. The first cross is made of oak reclaimed from old pews which is pretty cool. I let the laser cut a hole in the right place and we used that to align the text. The second cross we gauged by eye which is why the text is slightly to the left.
by firstname.lastname@example.org (Martin Raynsford) at 15 September 2016 10:18 PM
14 September 2016
I have a lot of corrugated card floating around from my materials orders and I needed a large shark model for the basis of a new project so I quickly scaled up the small shark model
and cut myself a new one over 1m long (there is a join around the fin). It quickly enabled me to check that the scale is right and I can carry on building.
The blue foam is a different project again and came rolled up so this is the easiest way to get is flat for cutting again.
by email@example.com (Martin Raynsford) at 14 September 2016 07:14 PM
12 September 2016
With the Glowforge laser cutter currently experiencing at least 12 months of delay
in expected shipping dates, several wannabe owners have started practising their drawing skills in preparation. Jules drew this rather cute Sheep Trivet and shared the files with everyone else on the forum
. She used the pattern from one of my flexible sheets
for the wool on the its back and I couldn't resist cutting it for her. One little sheep is now winging it's way over to the US in a parcel for her.
by firstname.lastname@example.org (Martin Raynsford) at 12 September 2016 11:30 PM
I engraved some glasses for a friend with images of block dice. This was actually the reason why I had artwork to put on the sides of the die
I previously engraved, I just had to wait for a moment to put in the rotary attachment. Whenever I use the rotary I find I end up having to cut a jig to hold the glasses in the right place this is partly because no two glasses appear to be the same and also because I always feel like I'm going to smash the glass in the jaws of the chuck. It's a simple jig that can be cut from scrap wood and it makes things a lot easier.
While I had the attachment in and some spare glasses I thought it would be cool to do some for myself. I chose to use the image from the top of my treasure box
and I made a left and a right pair.
by email@example.com (Martin Raynsford) at 12 September 2016 10:56 PM
10 September 2016
I used the patterns from these celtic knot dice
to create myself a piece of knotwork. The knot was then split into lots of pieces, alternating between cuts and lines on the knots so that even pieces with multiple sections look like they overlap each other. No two pieces are the same so I'm hoping this only goes together one way. (svg here
by firstname.lastname@example.org (Martin Raynsford) at 10 September 2016 05:37 PM
09 September 2016
The ritual magic system in Vale
has different colours of magic to represent different things. This little dohicky shows what each kind is for, and also shows the rotation of magic around the great wheel. It's made of Birch and the grain from each section is aligned to point towards the centre. 0.8mm ply holds each of the mana crystals into place and because they're translucent you get a really nice shiny effect when you hold it up to the lights (It also helps to differentiate between the Pink/Red and Blue/Light Blue gems)
by email@example.com (Martin Raynsford) at 09 September 2016 08:00 PM
Jigsaw puzzles are such a simple thing to laser cut I'm surprised I hadn't done one before. I took the vector artwork from Wikimedia and a nice picture of a rose to make this puzzle. I made this to add content to my puzzle instructable
, it's part of a competition so if you wanted to go over there and vote for me it would be appreciated. (svg here
by firstname.lastname@example.org (Martin Raynsford) at 09 September 2016 07:48 AM
08 September 2016
The sliding block puzzle
was invented in the 1880s with the fifteen puzzle which simply had the numbers 1-15 on the blocks. My homage to this form of puzzle is the eight puzzle which is remarkably similar in concept but only uses 8 blocks which is a much more sensible prototype. You could also put any kind of picture you want on the top of the blocks.
Each block is made up of 3 different layers, the middle layer is shifted right and up slightly to form an overlapping section with the block next to it. Where the tiles overlap the surfaces have been engraved, this reduces the thickness of the material and makes it slide easily in the gaps. The edge of the puzzle also have 3 layers which is staggered in a similar fashion. The edge is backed like the other tray puzzles and this stops the pieces from falling out of the middle. The edge is a single solid piece, because of this the last row of blocks has to be glued into place inside the puzzle so be careful not to spread the glue outside the block or it won't slide correctly.
Because this puzzle is just a series of blocks it could be expanded to any dimension and size you requires. I made this from 3mm poplar ply wood which makes it very easy to have a deep engrave. (svg here
by email@example.com (Martin Raynsford) at 08 September 2016 10:58 PM
07 September 2016
The aim of this final puzzle is to remove the ring from the column. (svg here
While I was making puzzles I took the opportunity to remake some of these very old puzzles
from 2012 in 6mm ply. I also got some better photos of them.
by firstname.lastname@example.org (Martin Raynsford) at 07 September 2016 07:31 PM
In this puzzle you have to get the ring from one side of the puzzle to the other. I probably should have marked the arms differently to make it more obvious that the puzzle wasn't just flipped. (svg here
by email@example.com (Martin Raynsford) at 07 September 2016 03:30 PM
I made this simple little entanglement puzzle, they seem to appear around Christmas time and with some craft fairs coming up I was wondering if I should add some toys to my selection. It could ideally do with thicker string but it's functional and sturdy. The aim of the game is to separate the two parts. (svg here
by firstname.lastname@example.org (Martin Raynsford) at 07 September 2016 10:23 AM
06 September 2016
Anyone of a nervous disposition should look away now. I moved our Lego storage coffee table
from the lounge to the sun room and I tried to wedge it into the corner there. Unfortunately the bottom drawer wouldn't open because of the foam matting and I really didn't want to cut away the matting so I added some feet to lift the table above it. Annoyingly if I lift the front above the foam the back wedges under the window sill and the front overlaps the matts slightly so I had to get creative. The front feet ended up being taller than the back feet and they're not the same size as the table leg so it can overlap. I told you it was ugly but it is at least functional.
by email@example.com (Martin Raynsford) at 06 September 2016 10:13 PM
Scaling up for production is rarely as easy as just making 20x the same thing. In this case I was asked to make 20 of the moving BB8 cake heads
. I changed the design in several places to make assembly easier, switched out the controller for a different arduino (and then changed it back again) and finally rewrote the control code to make it more obvious that all the functions were working correctly. It's been a bit of a long slog this weekend but seeing them all lined up on bench this morning was pretty rewarding and I can't wait to see them all when they're done in cake.
by firstname.lastname@example.org (Martin Raynsford) at 06 September 2016 04:02 PM
04 September 2016
I wanted 3 different sizes of porthole for my project and multiple holes too so I changed the scale on a few things and tweaked the designs to come up with these two different sizes. Here are the 3 modified porthole drawings 100mm window, 220mm window and 290mm window (svg1
by email@example.com (Martin Raynsford) at 04 September 2016 03:45 PM
02 September 2016
I guess I'm a runner now, it didn't really happen overnight, I completed the NHS couch to 5K
program and just didn't stop. I do recommend it if you want to increase your fitness. Anyhow my headphone cable is too long and it bugs me while I run so I made a winder. There are two sets of loops, one to shorten the cable and hold it there and one to wrap around the outside for storage. It's made from polypropylene so it's lightweight and won't slow me down. It might be a little big but I can just scale it down on the laser in the future. (svg here
by firstname.lastname@example.org (Martin Raynsford) at 02 September 2016 07:30 AM
01 September 2016
I had a request to make a chess set, the pieces had to be stack into a column so they can be wrapped into the middle of a flexible chess board. With the challenge accepted Doug gave me dimensions and artwork for the tops of the tiles. Each piece has a 1.5mm birch disk, engraved with the relevant symbol attached to the top and a corresponding ring on the bottom, this allows the pieces to stack together without falling over.
by email@example.com (Martin Raynsford) at 01 September 2016 08:49 AM
31 August 2016
Here is a prototype for a porthole I'm currently making. It does have a functional hinge made with a 6mm dowel but the catches aren't functional yet. The window is made from 3mm perspex and the rest from 6mm poplar although I'll be moving over to birch shortly to get a more woody effect from it.
by firstname.lastname@example.org (Martin Raynsford) at 31 August 2016 10:35 PM
30 August 2016
At first glance this might look like a turkey temperature gauge and you'd be forgiven for thinking that because that's basically what it is. It's actually a laser power meter which is essentially a thermometer for laser beams.
The large black block on the end of the thermometer is a thermal mass to hold the heat and it is placed in the path of the laser beam (usually before mirror 1). The beam is fired for a specific length of time and the laser heats the metal. The temperature change of the metal block is directly proportional to the amount of power being output by the laser. The whole gauge is calibrated to the dial by the length of time to fire the beam, in our case 15.3 seconds.
You have to let the gauge cool down between measurements, although you can hurry that along by dunking it in cold water. There is also an adjustment knob on the back which allows you rotate the scale so that zero lines up with the needles current position.
This also qualifies as a laser cut item, Dominic dropped it the other day and smashed the glass. I bought it home and 30 seconds later we had a new perspex screen to go into the gap :)
by email@example.com (Martin Raynsford) at 30 August 2016 08:04 PM
29 August 2016
This simple burr puzzle is cut from 9mm poplar (mostly because I couldn't find my 10mm perspex. It is made from 12 identical pieces but the parts need cuts in 2 axis. This is achieved by cutting the first side and then flipping the piece within the hole.(svg here
This picture shows the various steps number from top to bottom, normally I would cut 6 pieces at once and this picture is for illustration only.
- Cut the outline and the cut outs for the first piece.
- Remove the piece, being careful not to bump the outline
- Remove the shrapnel from the hole
- Insert the puzzle piece back into the hole but rotated through 90 degrees.
- Cut the next set of cut outs
- Remove the finished piece from the outline.
by firstname.lastname@example.org (Martin Raynsford) at 29 August 2016 02:29 PM
28 August 2016
Another A2 sized stencil cut from Mylar material. You'll be seeing where this one actually gets used in the near future but for now it'll allow us to mark up some of the things around the unit.
by email@example.com (Martin Raynsford) at 28 August 2016 09:00 PM
Here is a set of block dice for the game bloodbowl
, They're cut from 16mm Beech cubes.
by firstname.lastname@example.org (Martin Raynsford) at 28 August 2016 07:41 PM
27 August 2016
A quick commission request, this is the front plate for a Lithium Polymer battery charging briefcase. It's 5mm black perspex and explains why I had black Pokemon for the silhouettes in the tray puzzle
by email@example.com (Martin Raynsford) at 27 August 2016 01:23 PM
Pokemon evolve into other Pokemon and I thought it would be quite cool to convey that in a tray puzzle with the names on it as well. To convey better silhouettes and make the shapes stand out from the tray I made them with 5mm black perspex. The tray is 2 layers of standard poplar ply and all the text is hershey text done with marking for a fast cut.
by firstname.lastname@example.org (Martin Raynsford) at 27 August 2016 09:09 AM
26 August 2016
I simply can't understand how you can buy a laser pointer
and have it delivered to your house for less than £1 but I'm not going to complain about it. Instead I'm just going to strap one to my little shark model
and use it to bug the cat (and children), yay lasers!
by email@example.com (Martin Raynsford) at 26 August 2016 07:18 PM
I wanna be the very best, like no one ever was. To draw them was my real test, to cut them is my cause. Anyway, so that's Pokemon set 103-150
all original 150 Generation 1 Pokemon
drawn and cut, they make a fairly epic collection and with that many to stack there are infinite combinations. The actually Pokemon collection was done by Jadael over on Imgur
but a fair few of the silhouettes needed modding before they were cuttable. Like most things they should probably go up in my shop
but for now... (svg here
by firstname.lastname@example.org (Martin Raynsford) at 26 August 2016 11:03 AM
Here are some tips for making items like these, this set is Pokemon 52 through to 102
. I cut the 9mm ply on a fairly high power, this ensures that the cut goes all the way through regardless of blemishes in the material and then you know each piece can be easily removed. This causes quite a lot of burning on the underside of the material due to reflections from the honeycomb bed. Once a set has been cut I often secure all the pieces back into the framework using masking tape across the top side of the material. This allows me to lift all the pieces out of the machine at once. I can then flip the whole sheet and sand the reverse down while they are still in the framework. It's much easier than juggling individual tiny pieces.
I guess for something like this you could also mask the reverse so that most of the burning would be on the masking tape instead of the work piece.
by email@example.com (Martin Raynsford) at 26 August 2016 09:58 AM
25 August 2016
There was a fairly positive response to the small selection of stacking Pokemon
I made so I thought I would extend the range. These are the first 51 Pokemon
, all cut in 9mm poplar ply and slightly smaller than the previous set. This makes them more stable and better for stacking. As you can see I get all the fun of stacking them into a sensible sheet for optimised cutting.
by firstname.lastname@example.org (Martin Raynsford) at 25 August 2016 11:51 PM
24 August 2016
Everyone is raving about Pokemon since the release of Pokemon Go
. It was suggested that I should make some stacking Pokemon shapes much like the stacking cats
so here are the first 9 Pokemon in the series. (svg here
by email@example.com (Martin Raynsford) at 24 August 2016 03:00 PM
23 August 2016
The ravens on these tablets
came out really well so I thought I would draw up the other animals in the set so I could use them for future decoration (svg here
by firstname.lastname@example.org (Martin Raynsford) at 23 August 2016 12:58 PM
22 August 2016
Apparently I never got round to posting the files for the three fractal puzzles on my blog, they got posted to other places but never here so tonight, in lieu of an actual laser cut item, here's one I missed earlier. (svg here
by email@example.com (Martin Raynsford) at 22 August 2016 12:06 AM
20 August 2016
Ye olde tablet weaving
is a way of making decorative bands that have a million uses. Like many old crafts it uses simple tools which can be easily recreated with modern means. The basic weaving set requires 8 tablets with holes in the corners and 1 or 2 shuttles to wind thread onto. Plain tablets are a little bit dull so we added these celtic ravens as decoration. I chose to do them as line art instead of engraving to make them really stand out. (svg here
by firstname.lastname@example.org (Martin Raynsford) at 20 August 2016 05:45 PM
These large stencils are cut from 350 micron mylar. A friend asked if I could cut some stencils and I just happened to be visiting Bee Crafty
on Monday who gave me some really useful advice about what I needed and how fast to cut it. The mylar cuts really well and if you keep the power sufficiently low you can avoid the burn reflections on the reverse.
by email@example.com (Martin Raynsford) at 20 August 2016 08:39 AM
16 August 2016
I've been through some iterations on a little shark model recently. Figured it would be nice to have a little giveaway at some point. This one is almost ready but I did a bit of playing with scale. The largest here is 150mm long and is the 'right' size, the teeny one is made from 0.8mm ply and is just 44mm from nose to tail, a bit too small really but still cute.
by firstname.lastname@example.org (Martin Raynsford) at 16 August 2016 10:41 PM
15 August 2016
I made some of these
way back in the day, I noted they had issues then and I didn't post the files. I actually corrected them about 6 months later but don't appear to have blogged that at all. I do keep getting asked about them though so I thought I'd post up the files. This time round as I was looking at them, the lengths and curves all seemed wrong so this is basically a redraw of the whole damn thing just so I can share the files. (svg here
by email@example.com (Martin Raynsford) at 15 August 2016 11:01 PM
These little gaming counters are very useful if you need to track something like hit points or scores for a whole wide range of games. The clever thing here is the use of the magnets in the middle which allow the wheels to hold together and rotate but doesn't add any thickness to the counter. (svg here
by firstname.lastname@example.org (Martin Raynsford) at 15 August 2016 08:25 PM
14 August 2016
I make a lot of things and from time to time I need to clear some space so I've put my arcade cabinet up on ebay. You can see the original info about the build here
and if you feel like you would like to own it for yourself you can bid on it here
by email@example.com (Martin Raynsford) at 14 August 2016 05:22 PM
Continuing my quest for noise makers I made one of these air horns
. A membrane is stretched over the back of the horn, air goes in through the mouthpiece and escapes from the outer ring to the inner hole, as it does so it vibrates the membrane which produces a loud sound. The benefit of this design is that you can add a cone to amplify the sound coming out. I was a little disappointed by the volume when I made this before EMF camp, but at EMF camp I discovered that if I stretch the membrane tighter (with my thumbs in the hole) the noise became rather deafening. It certainly made people jump in our tent and was probably heard halfway across the field. I definitely need to remake one of these with a tighter membrane.
by firstname.lastname@example.org (Martin Raynsford) at 14 August 2016 11:16 AM
13 August 2016
I also cut some rings for Sam
at the same time as the perspex. These were cut from oak veneered mdf
, like all mdf it creates a lot of smoke when it cuts and that can stain the surface. Masking it is still one possible solution but at least with veneers you can sand them smooth and clean again.
Sam also needed some claps for necklaces so we squeezed those into the material too, it's a very clever laser cut solution and we all know everything should be lasered if at all possible.
by email@example.com (Martin Raynsford) at 13 August 2016 11:01 PM
wanted me to cut some acrylic parts for her but she wanted them with a really deep engrave. The trouble with deep engraving on plastic is that it throws up a lot of dust which stains the work and fills the etch. I tried to reduce this staining by masking the area with tape first. I think it certainly reduced the amount of staining but I could have increased the power to get a much deeper etch.
by firstname.lastname@example.org (Martin Raynsford) at 13 August 2016 10:20 PM
One of the weapons I missed from the last batch for eldritch. This ying yang blade was made from several different thicknesses of foam to get some height effects on the handle. The actual symbol was just a simple line on the detailing.
by email@example.com (Martin Raynsford) at 13 August 2016 08:21 PM
12 August 2016
Hebecon is a tournament of terrible improvised robot fighting, Jim McArthur
was looking to make a terrible improvised trophy when he wondered into our tent so he could use the pillar drill to attach a stainless steel mug to a camera tripod. In the spirit of improvisation I realised we didn't have the right thing
to laser engrave onto the mug but we did have black sharpie which can be used to similar effect
. The tournament looked great and I expect it will be even bigger at the next emf camp.
by firstname.lastname@example.org (Martin Raynsford) at 12 August 2016 07:34 PM
had an idea to make some bike shedding
dice, an amusing way to generate your next project full of buzzwords. Each dice was cut one side at a time using hershey text for the font, the die was then flipped and the next side cut. Amusement was had by all :)
by email@example.com (Martin Raynsford) at 12 August 2016 01:15 PM