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Improvised tripod and light box

April 17, 2014

I am often taking photos of projects that I’ve made, be it projects on my CNC router, or hand made using other more every day tools. Mostly the purpose of the photos is to use here on this blog or other places where I share progress etc.
Something I’ve noticed more and more is that the quality of photos is pretty variable for me, and other makers do a really nice job of taking great photos of their projects.
Recently I was taking pictures of a little wooden watch stand I made for my bedside cabinet, and only noticed after posting that a couple of the images were a little blurry and generally the images are a bit meh.
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I feel like I’ve been at this blogging game long enough to feel I should have a better setup for taking photos/video of what I’m doing so I decided it was time to take action.

From doing a little reading the two basic tools I should have to take nicer photos of my creations are a tripod for my camera of choice and a light box to allow diffuse lighting of the subject.

Now it should be noted that the photo’s in this blog post mostly don’t benefit from either of these since I’m taking pictures of them, not with them.

The theory of the two items is pretty simple. a Tripod holds the camera steady, no more trying to brace my arms against something, in an attempt to keep things steady. A light box allows for good lighting of the subject but without hard direct light casting shadows all over the place.

The first thing I started with was a tri-pod. Now I could have made life easy for myself and bought one, or even just used my wife’s. However there is one point I’m being stubborn about. I take pictures with my phone. It is not the greatest camera in the world in terms of quality. However it is the camera that I always have with me, and always make sure is charged. It is also the camera that automatically backs up my photos to the cloud (in this case google+) and make it easy to share them. And even do some amount of editing on the phone.
This is important to me, since I don’t have to mess around with downloading pictures from a camera to my laptop, then uploading from my laptop to somewhere.
However this does make life awkward. a normal camera would just have a screw thread already in it for a tripod. But with my phone I had to devise a holder for it that would hold it firmly but also make it easy to get the phone in and out.

I *could* have just made a mount and have it attach to a standard tripod. However it turns out that standard tripods use an imperial thread, and its not so easy for me to pick up anything that isn’t a standard metric thread. So I decided that I’d just make the whole thing…

A tripod is a fairly simple thing. a collection of m6 bolts with wing nuts, a little time on the bandsaw and some holes drilled on the pillar drill and presto.
The only real measurements I made in the construction was to get the 120degree spacing for the 3 legs around the central circle.
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Everything else I just did by eye for what looked about right. Mostly I was just working inside the scrap of cherry wood that I pulled off the pile to work with.
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The tricky part was the ‘cage’ for the phone. I have a hard aluminium case for my nexus 4 which I stopped using because it degraded the signal and bluetooth performance. However it is perfect for this usage, I could build a structure that the case slides in and out of and then know I just need to drop the phone into the case and everything would fit nicely.

In this case I went with a ‘spine’ of wood that supports the buttom of the case, into which I cut a recess for the cases hinge to fit into. Then at either end I glued verticals that just hold the front and back of the case at each end. The spine piece was cut to the same width as the case, so everything just fits. The only tweaking required was to cut some recesses for the little dimpled feet of the case to fit into. This just made the whole fit more snug.
The only problem is that the contact area for the glue is not very large, I don’t think this would survive any real lateral stresses, however in normal usage it should not experience any real lateral force so hopefully it will be ok.

The spine of the phone cage just slots into the top part of the pivot mechanism and it holds pretty tight without any need for glue. With the phone in place it is easily able to hold it firmly in place and doesn’t suffer any wobble. To be on the safe side I have my phone camera configured on a 1 second delay, so if it does flex at all when I touch the phone to take a picture, it has time to settle before it actually takes an image.

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For the light box the idea was to use a cardboard box, drape some a3 paper from the back to provide my backdrop with smooth curve to avoid any sharp corners/shadows in the backdrop. Then to cut holes in the sides and the top, line with tissue paper to diffuse light, then just set lamps around the edges to illuminate.
I thought the trickiest part here would be sourcing some plain white tissue paper. I wasn’t really sure where I would find that supplied it, but as it turns out the answer is W.H.Smiths, which had white tissue paper in pretty much the first place I looked.
With a box, some regular white paper, some white tissue paper and some cellotape. I set to work and quickly constructed a little light box.

Here are the resulting images. I didn’t really have any good lamps to provide light sources, so I relied on a little post-editing on my phone to get the final result. But all in all when compared to the original set of pictures I took of the same item I am pleased with the results.

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Raspberry PI – adventures in case building

March 16, 2014

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Recently I was given a raspberry pi, it’s something I’ve thought about buying to play with a few times but hadn’t quite got around to what with other hobbies keeping me busy enough. However, I wasn’t about to turn down one as a gift. I won’t go into much about the device itself, there is plenty around about setting them up and what they’re capable of.

The important point is that they come as a bare circuit board, much like an arduino. This makes one of the first requirements to get a case to put it in. Now there are plenty around and mostly not too expensive, but anyone that has read even a few of my blog posts would realise I’m really not the kind of person that buys something like a case when I could just try to make one myself.

So I set off browsing through thingiverse looking to see what different designs existed. For the arduino I cut a case as 6 sides that interlocked to form the case, which is the kind of thing that you do when you have flat sheet materials and want to make a box. However, on this occasion I decided that I really wanted to try milling a case from a block of cherry.  The idea was to mill out the bottom and top halves that would then fit together. Most of the designs on thingiverse assume that you are going to use a 3d printer to create this kind of case, however the designs work just as well for milling out of a block.

The attempt was not without its failures…

The idea was to use a large 10mm bit to rough out the basic shape, then use a 3mm bit for finishing. Initially I setup the CAM to cut both the top and bottom pieces from a long thing block as part of the same job. The problem with this is that the job takes so long to run, and a mistake anywhere ruins the entire run.

Fail 1:- When setting up the model I made a few adjustments from the original on the basis that I would be using wood and cutting out rather than printing from plastic. I needed the wall thickness to be thicker. I made my modifications and generated some tool paths, but I kept getting errors about unsafe tool paths. I couldn’t figure out why or where the problem was, but I did figure out how to turn off the warning…ok stupid idea, but I’m still learning.
It turned out that at some point in the model it didn’t have a clean solid part for one wall of the top half, it was actually represented as two pieces stacked on top of each other. This was not easy to spot by eye, but the tool path generation had figured out it was being asked to move across the top of the lower wall piece which would take it through the upper wall piece. This became apparent to me when I watched as my cnc router, having carefully milled around the outside profile of the wall, carved straight through that section levelling it off much lower. stupid boy.

lesson 1: – don’t turn off the warnings, the computer is smart and you’re an idiot.

I went back and fixed the model, switched the warning back on, and regenerated. Good to go…

Fail 2:- After probably 4 hours of milling accross 2 days, I had failed to recheck the tightness on the chuck holding the router bit. During a cut the bit began to slip, as it bit into the wood and due to the increased friction get dragged further down and out of the chuck. To be fair to the spindle it kept on chewing throught the wood even as the cut depth went to something like 10-12mm, however the stresses on the machine by then were enough to pull the cutter off course, and into the area of the case. I hit the emergency stop, but I was too late, it was going to be difficult to reset the machine aligned properly with the workpiece again, and even if I could the top half was already ruined.

lesson 2:- Don’t try to mill multiple large complex parts in a single pass, break them into smaller units such that any failure impacts less work
lesson 3:- Always recheck the tightness of the chuck, particularly when its been a few days and temperature changes since the last run.

I split the model into a top half and a bottom half, and set about milling the bottom half.

Roughing it raspberry pi box bottom:

Fail 3:- I set the machine back to milling on a new block of cherry. In the interim I’d found some settings around exact stop versus constant velocity and was able to set the machine to actually run quite a bit faster than it previously was working. It made fairly short work of the 10mm roughing pass, and I got to switch to the 3mm cutter and watch it nicely refine the shape. It worked perfectly. though I did find that the roughing pass + the finishing pass left some places where the rough with 2mm clerance had left 2mm of material but which the finishing pass did not then go over. because the waterline finish doesn’t go over top surfaces. So I had to manually tweak a few things to make it do a proper final pass to clean up those few places. This to, worked perfectly.
I brought it in and set to fitting the raspberry pi into it, this required a little sanding, of the box and the corners of the raspberry pi. The model is a very tight fit and the radius of my cutters meant that corners weren’t as sharp as the pcb. However after a few tweaks I got a really nice, snug fit for the raspberry pi in its new bottom half case in cherry. It looks awesome.

Final pass raspberry pi box bottom:

however, we’re still in fail 3…

The block of cherry I used to mill the case from had been in my garage, for at least a year, and over one of the wettest winters the UK has seen for about a century. After a week in my centrally heated house, the very thin, very precise case, had shrunk around the raspberry pi, and seriously warped across the thin base.  I had forgotten the basics of working in wood. if it is not dry or even just not already acclimatised to teh environment you ultimately want it in, then the change of environment can easily be enough to shrink/grow and generally shift the material around. it is really not that suited to making accurate engineering type cases. At least not unless you started with really dry stable wood in the first place.

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Lesson 4: – Wood is a living material, don’t mill wood that has been in the garage for months and expect it to stay stable when put in a centrally heated house.

So, back to the drawing board. I need a case, cherry is probably not a great idea. This lead me to the pibow case, which has the designs available on thingiverse free for non-comercial use. The pibow case design is one of layers. Basically 8 layers, each 3mm thick and each with cut outs that fit around the parts of the raspberry pi at that point. This is back to the idea of cutting something from sheet stock to produce a case, rather than milling out of a block. This time I turned to some hdpe sheets that I had, which would also be stable and not warp when brought into the warm.

Milling pibow layers from hdpe:

Fail 4:- New plan, new material, the machine had been capable of a nice precise milling operation and the only previous problem had been material which I was now getting rid of by switching to HDPE. Let’s rock this thing! In my haste to get going again down this new path, I mounted a sheet of hdpe on top of a block of mdf with some clamps at 4 corners and I failed to notice that the block of mdf was substantially thinner at one side than the other. Having set my z=0 at the surface in one corner I didn’t notice that the rest of the sheet was substantially higher. The first cut that was supposed to be 1mm turns out to cut clean through the sheet in one go, wiping out any attempt at holding tabs and generally making a mess.

lesson 5:- Don’t get cocky kid, check the levels, make sure if you’re resting material on something that that something is consistent thickness across its surface.

Fail 5:- New setup, nice even thickness of mdf. Clamps caused the hdpe to bow up in the middle, but not too bad…I milled the base layer, and even engraved the little markings on it with some success. However I failed to notice that my two x-axis motors were nearly 9mm out of alignment from previous problems. So whilst it cut fine, the outside profile wasn’t square/parallel in its lines, essentialy the y axis was not cutting at 90 degrees to the xaxis

Lesson 6:- similar to lesson 3, – recheck the machine setup before you start. including that the x-axis motors are still in alignment.

Fail 6:- the hits keep coming…milling the exterior profile of the layer followed by milling out the interior spaces means that there is less support for the cutting than doing it the other way around. the thin walls of the quite delicate design bow under stress, break through the very small holding tabs you configured thinking you didn’t want to have to cut out too much by hand. the whole layer pulls free and is destroyed

Fail 7:- You think that milling out the interior spaces before the exterior cut out will solve your problems and don’t increase the holding tab sizes…but you are wrong, the thin walls and pressures of the cuts are still not suitable and the thin holding tabs easily snap away, destroying another layer

Lesson 7:- holding tabs are important, and you probably need more than you imagine. and they should be big enough to provide real support. Yes there is a trade off of too much time cutting out later, but err on the side of caution

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So I’ve had a lot of failures, and a lot of lessons learned. and I currently have about 4 layers I’m semi-happy with. And I think I no longer have enough 3mm hdpe sheet to finish the remaining layers ;-(
For all the failures I’m still pretty happy with how precise the machine is in terms of the path it follows. I think I have to chose a better cutter for this  material as the 2mm end mill I was using left a pretty rough surface. This has turned from ‘oh I’ll just cut out a box for the raspberry pi’ into a series of experiments to learn more about what it means to work with different materials and get reliable results.

Maybe the next one will be the ones that goes perfectly…

DIY CNC – handling EM inteference

February 16, 2014

So last time I wrote about my awesome new spindle. It is a serious piece of equipment and the rest of my machine now seems somewhat inadequate to deserve such a beauty of precision engineering.

One way in which the rest of my machine fell short was in its ability to cope with the Electro-Magnetic interference being thrown out by the variable frequency spindle. I noted last time that I had ordered some capacitors to try to resolve the issue.

So what have I learned about EM interference? Well, essentially every wire you run could pick up voltage blips from EMI. If these wires connect to digital signal lines, such as step and direction inputs to stepper drivers, then this gets picked up as random motion. If  those wires are connected to ground on your arduino… well that can cause it to crash. So… what do capacitors do to help?

I should pre-fix this by saying I have only what I would consider to be a pragmatic understanding of electronics, and I could be mistaken  in my understanding, however I have now fixed my problem so if nothing else there is that.

So the mental model I find most helpful is that an electronic circuit is a little like a closed system of water. In this model EMI basically causes ripples in the water that can be mistaken for the water flowing. A capacitor then is a little reservoir. they come in various sizes depending on how big of a reservoir you want. but even a very small one is enough to absorb a ripple without it making it to the outlet of the reservoir. Where a real signal is a more serious movement of the water, which easily fills and pushes through the reservoir. So capacitors act as filters for this ‘high frequency’ low but low power type ripple. They also act to ‘smooth’ power supply. essentially in our model the water in the system flows a little erratically around our desired rate, sometimes a littel fast, sometimes a little slow. for components that require a certain amount of flow in order to work, having a little local reservoir near their power input means that when the flow is a little fast the reservoir fills, and when it is slow the reservoir is depleted, but the component can keep drawing at a consistent rate so it looks like a nice smooth flow. Obviously depending on the peaks/troughs of flow, you may require a larger reservoir to have sufficient capacity to smooth out a larger variance.

Now with that model in mind. basically I put small 0.01uF capacitors between the step lines and ground, and also between the direction lines and ground. I then put slightly larger 0.1uF capacitors between the v+ and gnd of the stepper drivers. And lastly I put a big 10uF 25v capacitor between the v+ and gnd of the main 24v supply for all the steppers. In operation it is likely that there will be peaks of power usage across the stepper drivers, and the extra capacitor provides a chance to provide in these high use spikes without the power dropping lower than it should.
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In addition to all these capacitors, I also had a problem with spikes on the ground line to the arduinio causing it to crash. I wasn’t really sure how to solve this because I didn’t really know where I would introduce a capacitor. The issue here is that the arduino needs to share a common ground with the stepper drivers in order that the signals be correctly detected. However there is really 2 quite different voltage circuits here. the arduino and its signals are on 5V, but the rest of the circuit is 24v for the motors, from a different supply. The ideal thing here I have discovered would actually be to properly isolate these two circuits.

How? there is a component called an opto-isolator. essentially this is an led in a package with a light sensor. the led is powered by one circuit, and the sensor is powered by the other. basically the two isolated circuits are able to signal each other via light, and keep their electrical systems independent. This is an obvious next step for me, as this would allow a more robust setup and might pave the way for future enhancements with even higher voltage motors.
However those haven’t arrived yet. Thankfully there was one more change I made that fixed the last of my issues.
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It turns out there is a reason that computers come in metal cases, and those cases are earthed. This is what can also be described as a Faraday cage. These are used to essentially give any EM a path to ground.
When I originally set up my electronics I stuck it in an old cat food box. It just happened to be about the right size for my circuit board, and at the time I was only thinking of keeping components together and a little protected from dust.

But cardboard boxes do not screen EM. So I bought myself a cheap PC case, which even included a power supply and a fan. This was a bargain, I was able o use the pc supply to power fans in the case, and also cooling fans on the stepper motors. Whilst also neatly housing the electronics and running the cables neatly. It looks pretty good and the best part is that this seems to have completely eliminated the problems I had been having with interference in my circuit. yay!
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One last note of improvements. nothing to do with interference but certainly an issue I was having was the steppers getting hot. at 24v they were getting too hot to touch, and given two of them are mounted using 3d printed parts, they were getting hot enough to warp the plastic. So I bought 2 AMD cpu heatsinks with integrated fans. These things were fairly cheap, and they are super effective. I’ve really only lashed them in place, literally using string and gaffer tape to hold them in position. But even after hours of operation those steppers are still cool to the touch. I only did this on the Y and Z axis. the X axis has 2 steppers and they both seem to run cooler anyway, well around 50C, I balance a long steel ruler on each to act as a bit of a heat sink and that seems to be sufficient to keep them from getting alarmingly hot.

So, do I now have a perfect machine?

Not yet…I still ahven’t managed to make a complex 3d carved object successfully. I got very close this week with a raspberry pi case that I was milling. But I’ve been plagued by human error in various forms. First attempt I messed up the model and the setup of wood. this meant the milling process first wiped out a wall of the box that it should not have, then it cut all the way through the stock when it was supposed to leave some material to hold things in place.
Then in my second attempt after about 4 hours of machining the bit slipped in the collets grip, causing it to cut far to deep and pull off course into the piece and ruining it. Frustration abounds, but I am trying to learn from these mistakes. I feel like I am close to making a really nice precision part. I just need the time!

Today – I am going to upgrade GRBL to the development branch to see if I notice any improvements in speed, and I’m going to push the speed of the machine higher. This is a real tradeoff, the faster I push it the more forces at work, and the higher the chance of a failure. However too slow and everything takes far too long, and I consume days and days of time, and still risk a failure screwing up. So I will at least try to go faster, but also to try machining parts one at a time, to reduce risk of failing half way through a pass on multiple bits. Wish me luck!

DIY CNC router – new 2.2kW water cooled spindle

February 1, 2014

For Christmas I was lucky enough to be given a new spindle for my DIY cnc machine. Until this point I had been using a combination of a small rotary tool, essentially a knock-off Dremel, and a bosh palm router.
the small rotary tool was good for small bits, however it was not really designed for continuous operation over hours of cnc time, and inevitably it burned out.
knowing full well that the bosh palm router was similarly not really intended for continuous operation I was keen to avoid the same problem. So I looked around and found the wonder that is a 2.2kW water cooled spindle. Then I dropped some heavy hints, and since I have the best wife in the world, she bought me one for Christmas.

Here it is:
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It is epic.

the spindle weighs about 5.5kg, It comes with a separate box of electronics (VFD) for managing the 3 phase voltage frequency. essentially you dial up a frequency on the control box, and it sends that to the spindle which maps to a particular rpm.
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This is a serious piece of industrial equipment, I needed to buy the appropriate power cabling, and wire it up. I did a lot of research and I have a pretty decent familiarity with doing this sort of thing, I would advise against doing this unless you are very confident. high voltage wiring is not something to take a chance on. I bought a crimping tool especially to make a nice job of the wiring, and be triple sure there were no stray wires making odd connections.

I was initially worried that the z-axis might not be able to lift the additional weight, it is significantly heavier than the bosh router. However it seems to cope just fine.

I also mounted the VFD onto a big metal plate, itself mounted off of a hardwood back piece. this ensures proper air clearance around the box, for cooling etc. the metal plate came from an old tv table I had. At this point that table has been cut up and used into all sorts of different things ;-)The hard wood back came from a hi-fi cabinet my dad made probably 20 years ago. I have a feeling the wood originally came from an x-ray machine room decommissioning (they used to have hard wood tool racks or something), since that is where he wound up with a bunch of such materials during his career as an engineer.
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In any case I got everything wired up, and started up the spindle and was delighted by just how quiet this thing is. At full speed (24,000rpm) i can still easily hear myself talk. No more need for ear defenders!
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Now this is water cooled, and whilst it will probably be a long time before I really push it hard enough to require the cooling. I set that part up also. I got a huge bucket (intended for wine making) and put in  70:30 mix of de-ionised water and anti-freeze coolant. submerged the pump in it and plumbed everything together. based on my research this much fluid should be able to passively cool around 400watts of heat. That number was an estimate assuming the worst case of a 2.2kW spindle, 80% efficient and thus putting out around 400W of that as heat. If it ever becomes a problem that it is not sufficient I can either add a load more fluid to the reservoir for passive cooling, or I could put a radiator inline. But I’m guessing it will not be an issue.

I have done a couple of test runs, and I’m super happy with how much power this thing has, I actually had an incident with the gcode generated by F-engrave, it was supposed to be metric, but for some reason grbl didn’t like a couple of  the commands and wound up ignoring the call to set metric mode. So rather than attempt to plunge 1mm into the surface, it tried to plunge 1 *inch* into the surface. luckily it was doing this along a path and slowly getting to depth so I was able to hit the brakes before it got too far, but by then it was already probably 10mm down and going strong. the spindle didn’t have any trouble at all maintaining 12000 rpm as it plunged on in. But I am not quite ready to stress test it…

The other great thing is that the spindle takes er20 collets which range from 1mm to about 13mm, this means I can use all my router bits, and all my Dremel bits, plus other specialist cnc bits that I bought. It’s a quick change to swap out the collet so no more having to remount different machines to do detail versus heavy work.

However, all this awesome is tempered by one issue which I can no longer ignore. As I have discovered over the course of this project, every time I fix an issue, it reveals another which was previously not significant enough to be noticeable. This time the issue was how poorly my electronics setup handles interference. Previously this had not been terribly evident, however now there is a big 240v variable frequency motor right there, and even with shielding it is obviously putting out some EM. In this case it is getting picked up on the step/dir pins of my easydrivers, and causing the axis motors to twitch (very evident when you start or stop the spindle) and this causes lost steps etc.

So for the moment I am still not able to achieve the accuracy I want, I have on order a bunch of capacitors and the plan is to essentially sprinkle them around the circuit board in an attempt to prevent the EM interference from causing a problem. If that doesn’t work, then I will likely return to the drawing board on the driver electronics, but I’m hoping it won’t come to that. Unfortunately despite having ordered my capacitors last weekend, I’m still waiting for delivery, and Maplin has failed me in that they hold essentially no stock, and 1 cap is not going to do it.

Making Christmas presents – personal gifts

January 1, 2014

Every year in the run up to Christmas, I go quiet on the blog, and other places where I would normally share the projects I’m working on. Because the projects I’m spending my time on are gift for Christmas, and I don’t want the recepients seeing details before they get the present.

This year I worked on two things, one for my wife, and one for a secret Santa that was going to one of my brothers.

Project 1: A personalised book press

My wife made a number of notebooks to give as gifts for Christmas, and has done so before. They are really nice hand made notebooks, and a key part of the process is to squash the pages nice and flat. Normally she does this with a pile of heavy books. However it gave me the idea to make her something more designed for pressing things. 

The idea was fairly simple, 2 blocks of wood, with holes drilled in each corner, and through hole a long bolt with a wing nut to allow the blocks  to be tightened together.
The personalisation touch here was to engrave the words ‘Kat’s Book Press’ on the top surface of the top block. This was of course somewhat inspired by the fact that I’ve spent much of the year building a CNC router, without which this would have been an extremely time consuming and difficult carving exercise.
To make the model I setup openSCAD to be able to render fonts, then rendered the words and set them into a a recess in a block. It was a fairly simple piece of cad in the end, though only because there were good instruction on setting up openSCAD to render text.

For the machining I had it run in two passes, one with a 1mm material allowance, then a second tighter pass. This worked pretty well despite being limited to quite a large 6mm bit.

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Project 2 : Custom painted Nerf Gun
During this year I have customised a couple of Nerf guns for myself, at one point it became a bit of an addiction…
So when thinking of what secret Santa present to come up with for one of my brothers, a Nerf gun seemed the obvious choice. I picked the strongarm as it is very popular among the guys at work.
I didn’t do any of the normal firing mods, like removing air restrictors etc. I just focused on the paint job. In this case I decided to go predominantly white, with some details picked out in blue and red.
It was the same basic process as the others I’d done. Disassemble, sand off the logos/warning labels, lightly sand everything, spray with a vinyl undercoat, then a few coats of chosen colours using masking tape to block off different areas. Then a pass with the detail colours, and some dry brushed silver for a slightly worn and aged effect. Lastly a clear crystal coat  to protect the paint and make it something that can be used.

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I think both presents where appreciated by their respective recipients, and I hope they get some enjoyment from their use. I didn’t actually intend to make any gifts this year since it takes so much time. However once I’d had the ideas, I couldn’t help myself. In the end I enjoy making something a little more unique, if I had the time I’d try to do more gifts this way.

Running – beyond 5k

December 1, 2013

Back in August I wrote about completing an NHS podcast series ‘from couch to 5k’,I found it to be a useful structure for getting myself into running, and up toa reasonable standard.
Since then I have carried on running. This morning I completed 16km, the second time I’ve run this distance and i beat my first time by a few minutes.

So I thought I’d write a little about the stupid mental tricks I’ve been using to stick at it.
When I did the original programme it was summer, the weather was pretty amazing, and I did a lot of running on bright, hot, summer evenings. Since then we have plunged into UK autumn and now heading into winter. It is dark before I leave work and it is frequently only 2-3 degrees C when I get home in the evening.

Believe it or not, I am not imbued with a non-stop high energy feeling, bursting to get out and get running. I am frequently tired, and looking for excuses to not run. I suspect this is the case for all runners ever. So the question becomes, how do I overcome this natural instinct to curl up on the sofa for the entire winter.

Mostly the parts of me that know I should keep up the running, lie to the parts of me that really don’t want to. Its definitely a psychological battle within yourself.

There are the traditional elements of trying to remove barriers. Making sure that your kit is clean, dry and ideally warm and ready to go is essential. During week day evenings I start trying to get myself prepared for the idea that I will get in, get changed, and get on the road. absolutely no stopping to relax or sit down. No distractions. I know if I allow myself to think “i’ll just get that done first before I go” that its the top of the slippery slope to the sofa.

If I’m not in the mood, I tell myself to make it a short one, just get a few km out and turn around if you want.
my route has lots of obvious places I could bail out early, turn back and go home. Mostly though I find this just helps me pretend I’ll turn  back long enough to get warmed up. Then of course its a matter of “well you’ve come this far…it would be a waste of all that will power if you just give up so soon”

I often tell myself I’ll have a nice treat when I’m done, want pizza? sure we can have that when you get back, Wine? absolutely, whatever you want… when we get back. The thing is that after a good run, I’m always out of that mood, not that hungry any more, don’t feel the desire to follow through on whatever treats I promised myself.

At the weekend I have certainly found that if I drink the night before, I’m in for a hard time. It makes running a hard slog. So I try to flip it around and choose to go easy or not drink of an evening, with the idea that I’ll run in the morning but reward with wine the following evening. Another super important part of prep is that I have a box of alpen bars next to the bed. In the morning I can sit in bed, catching up with the internet and eat an alpen bar before getting up. The bar kicks my metabolism into gear, and gives me the start I need to go for a run. I tried running without this, again it was a horrible hard slog. Also it is relatively easy to sit in bed and eat the bar, but once I’ve done that its like I’ve committed to the run. can’t back out now.

I often leave the house without really deciding how far I’m going to go. I generally try to go further at the weekend and during the weekday evenings, but that is mostly because I have more time to do so. It is easier to decide to do 10k when you’re already 5k in and still feeling pretty good.
Though when I do decide to go for a longer distance than I’ve managed before, I do tend to explicitly take it much easier, not trying to get near my normal pace, just settle into the long haul. This is good because I make it easy for myself to hit my goal, and I also set myself for the second attempt to easily beat the time of the first run.

I’ve not spent too much time explicitly chasing personal bests. I’ve tended to try to run further rather than faster. The faster happens on its own as what was once a challenging 5k becomes just how far it takes to feel you’ve warmed up.

So far I’ve run through a gorgeous summer which was easy, through dark nights which was easier than I thought, and pouring rain which can actually be quite nice as long as it starts after you’ve started (once you’re soaked, rain stops having much impact). But the worst thing is cold. Rain and darkness is fine if its mild. But cold is very hard, it takes at least 2km to start to feel warm. I’m hoping there are enough mild days to the winter to avoid me having to deal with any seriously cold days. But I’ve also bought some longer running trousers, and will get a warmer jacket to try to mitigate against the cold.

So far I’ve racked up about 450km of running since I started. The fact that I know this is one of the main long term motivators. I’ve been tracking my running with a gps tracking app since I started. Every so often I approach a big marker, like 400km, and that run becomes pretty easy to go for, its the run that will take me over the next big step. as I head towards 500km, I have my eye on that, but also the longer term idea of one day making it 1000km. All of which seemed like complete crazy talk back when I was starting out with 1 minute runs. But through studious mind games, and some reasonable prep I’ve somehow become someone that runs 10 miles before breakfast at the weekend.

I’m reliably told by more experienced runners that a half-marathon is really just a 5k with a 10mile warm up…So I guess that is the next obvious milestone.

Do you have tricks to keep yourself running? let me know!

Custom Nexus 4 Dock

November 10, 2013

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I have a nexus 4, which I think is a great phone. I have it in a fairly reasonable hard aluminium case to protect it. Using a case is normally a good idea, however the thing about most cases is that they are incompatible with and dock.

Since there are so many case options, and they’re all slightly different, no one that makes a dock can do anything but make it for the bare phone. However, that is a real hassle, it means constantly removing the phone from its case every time you want to put it in a dock.

Enter – a job for a CNC router!

This seemed like the perfect job for my CNC router, so I fired up openSCAD and set to designing my own dock, specific to the exact dimensions of my nexus 4 in my chosen case.

Originally I wanted to make it out of some clear acrylic sheet I had, but that turned out to be somewhat over ambitious, my CNC setup just wasn’t able to cut the acrylic without melting it.  Sadly in my attempt, the melted plastic wrapped around my cutter and under the stress is snapped. This was not a good day.

So I switched to trusty mdf, not the sexiest material, but has the advantage that it cuts easily, and you can always sand/paint it to a nice finish.
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The design is parametric, at least kind of, which just means there are a bunch of variables in the file to try to adjust for things like material thickness, so that if you need to switch from 4mm acrylic to 3mm mdf, then there isn’t too much work to do in the model.

This version came out ok, however I decided I’d like to try making one from plastic, so I ordered new router bits, and some HDPE (dense plastic) in the hopes that I might get away with machining it without it melting.

I also made some tweaks to the design, the hole I had left for the usb port was not quite big enough, I wanted the legs to be a little longer at the back to give a bit more stability, and I needed somewhere to mount the electronics that I pulled out of an old htc desire z dock.

New design

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I did a few test cuts on the new hdpe, and it went well from a cutting perspective, however it revealed real levelling problems, the base was a couple of mm out from one side to the other causing problems for cutting way deeper than intended. I spent a while faffing around trying to get things more level which improved things a lot, but I think I was still a little out, as some parts ultimately got cut completely out and others had a small layer of plastic left.
This is something I need to work on more in the future, I think I need to design something that lets me adjust the level of the bed, whilst still allowing me to clamp things to it and keep everything firm.

cutting out

The actual cutting went well, I used a new control program the GRBL Controller, where previously I’ve been using the universal client. The big advantage of the grbl controller is the ability to set different limits on the speed of z movement to that of x/y. I didn’t take advantage of it this time, but will certainly try it out as I know the z axis stalls out on me much slower than either the x or the y do.

The assembled mark II dock

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The final assembled thing needs a lot of work, sanding to clean up the sides, and I had to hot glue things to hold them together. I think this method of tabs just doesn’t work so well unless you have crazy precision, and possibly a laser cutter. Maybe at a larger scale, with a thick material and chunky tabs the inaccuracy would be negligible, but I think at this scale I’ll need an alternative technique.

The engraving of the nexus 4 label on the front panel went perfectly in one sense, and not so good in others. It was a great precise cut at shallow depth with a bit that spun exactly central (the finer the point the more obvious any vibration in the point becomes) However the cut path revealed a clear 1mm backlash in the x-axis, particularly on the middle bar of the S which is cut approached from both directions. It actually looks ok, with a double bar in the middle because the cut was so fine, but clearly there is still work to be done on the x-axis. To that end I have ordered some delrin anti-backlash nuts, which hopefully will arrive soon.

Things that went well:
Building the model in openscad, helped visualise and adjust precisely for certain clearances etc,
Repeatabilityy – everything cut in a nice repeatable way, it was a long job and nothing went wrong whilst it was running
Cutting HDPE – this worked, no melting just clean chipping. so it adds a new material to the arsenal of options

Things that went badly:
Cleanness of cut – I got lots of frilling along the top edge, I now understand why I need to make 2 passes, the last with a downcut bit! will need to buy one
Levelness of cut- my bed is out of level, possibly due to temperature variation since I levelled it
Holding tabs – not very happy with how these look in the end result, not a clean finish, and don’t hold tightly without glue

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