HEXA Open Source Hexagonal Rocket

 

It's been a busy couple of weeks in the Concretedog lair! Numerous items have been restocked over on the Tindie store and a couple of new products have been released. The most notable though has been HEXA, my opensource hexagonal model rocket. 

A while ago I made some flat pack rockets for Hackspace magazine which had no tubes used in their construction. Whilst that was an interesting engineering experiment and produced some interesting rockets, it struck me that rocket kits without tubes are easier to mail!

HEXA is made from 3D printed parts and the hexagonal tubes are made up from 220gsm card stock using a cut and score technique which I have a small vinyl cutter machine doing so they turn out really crisp! 3D printing is obviously great for making parts but what's really useful here is you can print the nosecone with different amounts of infill to vary the weight to adjust the centre of gravity and stability of the rocket. At 20% infill the nosecone design prints to be around 10 grams in PLA and sets the CG perfectly, then, if you want to fly a payload in the upper section, like an altimeter you could print a second lighter nosecone to keep stability and weight optimised. Cool! 

Over on the project repository I've put together a 14 page PDF of documentation which covers building from the HEXA kit I am selling on Tindie, as well as tips and tricks for people creating their own HEXA from scratch. I've already seen some brilliant parts being printed where people are using a filament swap to make the nosecones look even more like pencils! The kits are complete with launch lugs and even a parachute kit for recovery, so, like many commercial model rocket kits, all you have to add is motors, wadding and launch gear. It flies really nicely on a B6-4 with plenty of altitude. 

Finally, I'm proud to say that I applied for and received OSHW certification for this project. In fact, it's the first OSHWA rocket ever to be certified! Hope to see more in the future.

My EDC Hand Sewing Kit

 

I've been doing a fair bit of machine sewing of late but whenever I sew, my little accumulated hand sewing kit is always at hand as I invariably need a needle at some point. The hand sewing kit is however more a kit for everyday carry for repairs which has certainly seen it's fair use. I thought it might be of interest to go through it and share how a few of the items are intended  for use.    

The case itself  is cobbled together from scraps. One half forms a pocket and the lid is lined with a piece of felt to hold a variety of needles and a small amount of tee pins. Not always sewing related, the tee pins are  regularly pulled from the kit pressed into service to unblock glue bottles and other fine poking! 

The pouch has a small piece of Paracord stitched onto it to which can be tied around the kit to keep it secure. I also have a smaller piece of cord stitched to the bag which has a loop tied and a quick link attached to which I attach a small classic Victorinox SD penknife.  I tie it to the kit as it's a nice little device that would be easily lost when repairing whilst camping in field or carrying out a parachute repair at a launch site. The penknife has a small blade, a file, a pair of fine scissors and tweezers and toothpick... more later on how I use it!

I also have a set of folding scissors that I bought in a sewing shop on the Isle of Arran a while back . They are super sharp and snippy and cut threads and fabric well. 

You'll notice I have some "wonder clips", these are fantastic little clips that have become a tool in all my    making.. they are so useful! I have a couple of hundred in my workroom but half a dozen or so is great for work holding for sewing repairs in the field. 

 I have a lighter, often the lighter is deployed to heat the end of Paracord or webbing to seal it and stop  it fraying, but I have another cunning use for the lighter. There is a bundle of white stuff, and a small roll of light green stuff. The white stuff is iron on stabiliser, I have loads of this for machine  sewing projects but carrying a little is really useful for repair . You can stop a small hole or tear from getting  larger by cutting a small patch of the stabiliser, then, without an iron, you can use the lighter to heat the file tool on the Swiss Army knife and use this to press fix a small patch in place. I can do similar with the green rolled material which is seam tape for Goretex garments, its super handy  to quickly  seal a small  hole  in  a garment (often after a barb wire fence crossing) but also could fix a small problem in a tent canopy etc. 

For thread I tend to wind amounts onto pieces of cardboard with slots snipped into them.  It makes the kit smaller than if you tried to carry actual bobbins of thread. As for the colours I tend  to either want muted and plain, or, really visible..    If I  am repairing something out and about I might use the day-glo stuff so it's easy to  find the repair again later when I might want to redo it in a more permanent  style. 

The  rest of the stuff is less critical, a few  buttons  a bit of cord. The small off-white pen like item is my quick unpick tool and of course, a safety pin or two are always useful  to hold  stuff or for reinserting a cord in a channel! Hope you enjoyed this little glimpse into one of my many bits and bobs kits I carry!       

EMF 2024 photo dump!

 

New Bike Project, the "Fauxtrino", a cheap Mini Velo.

I have a weird passion for small wheeled bikes. I own a couple of reasonable folding bikes (A Dahon and an older Brompton) and whilst the Brompton is semi retired for a big overhaul one day the Dahon sees some use (photo below). It's a great holiday bike when camping, running around campsites on errands, or for a run to a local shop. It's also not a bad machine for a longer ride out for pleasure. 

This love of small wheels has led me into ogling more expensive waters. In cities there's an interest in "Mini Velo's" which are non folding small wheeled bikes in reasonable sized frames. They get very hip and very expensive very quickly and there are a couple that I'd love but could never justify, the Orbeau Katu 20 (below) and the Velo Orange Neutrino (top image). 

The Neutrino is gorgeous, rugged and nimble and quite capable of all but the most demanding performance riding. However it's a price. I think just the frameset in the UK would cost around £900 so it's a £1500 bike by the time you've put decent bits on it. 

Everyone knows I'm a packrat, so I knew there must be cheaper ways to explore none folding mini velo style builds. A few years ago I saw that Argos in the UK sold a kind of mini velo bike, the "Challenge Urban Camper". When I saw it I was blown away with how similar the frame geometry is, in particular to, the Orbeau Katu. It's pretty identical. It's angles are also really similar to the VO Neutrino, but it's £250 when new! 

I let the thoughts go as I (reasonably correctly) assumed that the Challenge Urban Camper would be a BSO (Bike Shaped Object) made from poor quality parts, but every now and again I kept thinking of it as a potential for a donor frame for a mini velo project. 

Cut to now, a couple of years later and I came across a couple of projects that have done exactly this. One is some skant comments in a reddit post and the other is a 3 part youtube video from Second Life Cycles. The realisation I am not the only nutter is powerful! I also might have a bit of work running some basic bike repair skills workshops and a small packable disc braked bike suddenly became a handy option there as well. At £250 I was considering purchasing a brand new Challenge Urban Camper, but then.. one appeared an hour and a half away on marketplace, for £60!

So I am NOT starting this project for a couple of weeks as I need to get EMF camp out of the way and a few bits and bobs of work. However let's look in this post at the state of the Challenge Urban Camper (CUC) and see whats what. 

Picking up the bike, it's clear it's not had masses of use. The lovely chap who sold it said it belonged to his late mother who only road it a few times. It's obviously come from the factory partly assembled as it still has evidence of plastic wrap under screws and bolts on components. It has a few small scratches, I'd imagine mostly from storage rather than dings and crashes. SO it's an aluminium frame, pretty rugged, with some pretty unrefined welds that look solid but with no artistry! The 20" wheelset look OK, disc brakes feature 160mm rotors and "clark" mechanical brakes. I haven't come across clarks before but they are functional and stop the thing. I'm probably going to do a few runouts on it with these brakes and replace em when they show they need it. I'm less concerned about 20" wheels as by definition, smaller wheels are stronger than their larger counterparts. I'd imagine the wheels on it are pretty tough, they run true and, apart from one little tweak, all the spokes seemed well tensioned etc. It has mudguards and I'd totally presumed these were plastic jobs.. I was shocked to find that these are pressed steel... they are rugged and shockingly well built.. they probably add a kilo to the weight, but they can stay for now!

It's got a 6 speed cassette on there and the godawful Shimano grip shift... I imagine that will be replaced with an equally cheap Shimano lever shifter, which will be a big improvement. The derailleur seems to shift and index OK so it again will stay until it shows itself not fit for purpose. I live in a very hilly region so gears are very useful. 

The bottom bracket is a pretty standard looking affair and again seems to work. The cranks are awful looking! Weird angular cast stuff that looks cheap and also is the rather odd 150mm length. They sort of offend me so even though they work I imagine they will be replaced sooner than other parts. 

Handlebars, there is a folding setup on here and it does make it very easy to slip into a car. I'm a little torn on this as I always feel on my folding bikes that the folding bar/stem/quill setup on folding bikes is the weaker link. The steel forks are 1" threaded and the quill is a standard clamp in device so there are a few options to replace it. Second Life Cycles went with a converter quill to break it out to a 1 1/8" and then added a BMX stem and bars which is a rugged solution. I probably have a better Dahon style folding set up in a shed, or I could go for a long vintage stem and bars... we'll see. 

The bike arrived with the most awful saddle I've ever seen on it and also a small (but quite good I guess) basket system. It also has some terrible russet brown grips that are horrid! I've actually already swapped out the saddle and chucked on one of my growing collection of Charge Spoons, which are an excellent saddle for not masses of money. The seat post is distinctly retro in 27.2mm steel with an oldschool seat clamp. I can imagine swapping this out for a Lofty Gussett at some point. 

Tyres on it are cheap and functional... after watching Second Life Cycles I have fallen in love with the gum walled billy bonkers tyres they put on their build, so I'm watching evilbay for if I can find a bargain set. 

There's always a weirdism with 2nd hand bikes. When loading this I glanced at the drive side pedal and realised it was a folding pedal. I have cheap folding flat pedals on my Dahon and they dramatically reduce the packed size of a bike and also really reduce the storage width of a bike when the bike is unfolded. I folded the pedal and the chap selling the bike was amazed as he hadn't noticed. Then... the non drive side... lol.. totally different non folding pedal?!? I can't quite believe it came like that from the factory? Dunno!

Finally, I could imagine getting to the point of stripping and painting the frame, but maybe not until I've got it set up in a way I like. I deffo want to make a frame bag for it so that's a DIY project in itself. 

Playing with ESP32 Camera and Designed a Case in FreeCAD.

 

Lately I've been playing a little with ESP32 camera's. In case you don't know they are super affordable little wireless modules with a camera and SD card attachment that can be programmed via the Arduino IDE. There are heaps of guides out there to get going with them and they have a range of interesting uses. It's pretty trivial to set them up so that the configurable camera feed is available on your network, or I've also tinkered successfully using them in station mode so you connect directly to them as a wireless device with no network needed. 

Use cases are many, I like to slap them down in front of machines or running experiments that can be left unattended but you might want to periodically take a look at. You could use them as a little simple CCTV camera or for wildlife monitoring. Indeed there are lots of examples out there which add PIR motion sensors etc so that you can increase their versatility. 

Often these days they are sold with a little sub PCB module that acts as a serial programmer with a CH34X IC on board and these then allow you to power the ESP32 camera via a USB micro socket. The ESP32 camera and programming board are really affordable so I've found them cheap enough that you can leave the programmer board attached for ease of use. As such I wanted a simple case. 

After  a bit of calliper work I designed a couple of variants of a snug fitting case for this device in FreeCAD. I'm pleased that, once 3D printed, the PCB's slot in with no rattle and no play at all. The lid side of the case is designed to receive some M2 3.5mm diameter and length thermal inserts which can be pressed in with a soldering iron. Then I've used 20mm M2 bolts to close the case. Both versions of the case have a large USB access slot and there are versions with or without space to have an SD card inserted. 

 Of course the FreeCAD files are also up on the printables listing so you can redesign it to your needs. 

How High Did my Rocket Fly? DIY Inclinometer

If you fly a model rocket, or a kite how high up does it go? It’s a tough question to answer and you might think you’d need to add some expensive electronic sensors in the form of an altimeter to work it out. Whilst that might make a great electronics project in itself it’s quite complex and it might be easier to start with an excellent and accurate DIY tool for gauging heights.

The tool we are going to build is an “Inclinometer” so you might guess from the name that it measures inclines or angles. It’s basically a protractor but we will add a component or two to make it easier to take a measurement. We’ll also do some simple mathematics, or rather some trigonometry, which is a branch of mathematics that deals with angles. Don’t worry if this sounds hard, it’s not and we’ll step through what you need to do.

The DIY Inclinometer can be used to measure the height of anything you can see, the only other thing you will need to know is how far away you are from the base (or the point directly underneath) of the object.

So let’s get started. If you print out this linked design onto a piece of paper you can then stick it to a piece of cardboard to make it a little tougher and more handleable. You can get fancy and trim the card to exactly match the printed protractor design or you can simply mount it on a larger piece of card of any shape. Make sure though if you mount it to a larger piece of card that the top edge of the card is parallel to the top edge of the protractor.

Next you need to make a hole through the little hole design in the protractor. A good tip to do this safely is to use a big blob of adhesive tac or modeling clay behind the protractor and then use a pointed object like a ball point pen or a knitting needle to poke a hole through. With your hole ready we now need to tie a piece of string to the hole that is long enough for it to hang over the protractor with a bit left over. Onto the other end of the string we need to attach something that can act as a small weight to keep the string straight. This can be a small metal nut or washer, or it could be a blob of the modeling clay you used earlier, anything will work.

Now that we have made our inclinometer we can use it to measure angles. If you hold up the protractor and look along the top edge of it you can aim it at the top of a building or other object. The weighted string will remain straight downwards and you can either have a friend read off the angle it reaches or you can trap the string once it’s lined up using your hand and then hold it in place whilst you move the inclinometer and take the reading.

So imagining we have just measured the angle of the inclinometer compared to a tree we could then walk from where we have taken the reading up to the tree and count our paces. If we know how long our pace roughly is, say 75cm, we can then work out the distance in meters. Of course you could do this more accurately, you could have a long string marked in meters to work out your distance, or, a modern approach is you could use the map application on your mobile telephone placing pins and reading the precise distance between them.

However you get your data, once you have your distance from the object or launch site, and the inclinometer angle reading you can work out the height of the object. To do so, maybe grab a pencil and some paper and make a little sketch.

You can see in the image we have the tree and we’ve added the details of what we know and measured to the sketch. To find out the height we need to use a calculator, either a hand calculator or an app on your phone or computer. We’ll calculate the following.

ground distance * Tan(angle)

So if the distance to our tree base was 12 meters and the angle was 64 degrees then we can see that the height of the tree according to this calculation is 24.6 meters. However, can you spot a bit of an error? The calculation presumes that the angle reading is taken at ground level, whereas we actually take this reading at eye level. Adding distance from the ground to our eye level is needed to make this calculation a little more accurate. If I add my eye level height to this it makes this tree 26.4 meters tall.

It’s good to practice with stationary objects like trees and buildings, but you can also use this with moving or rising objects. If you are launching a kite for example you can ask your launch helper to hold the kite and then walk away spooling out a known amount of kite string to set the distance you are from the launch point. Then when you, or a friend, takes a reading of the kite later in flight you have all the data you need. If you are launching a model rocket, you can do something similar by measuring the distance between your inclinometer observation point and the launch pad of the model. With rockets it’s harder as you need to follow the rocket upwards as it moves very quickly and stop the inclinometer and trap the string at the point where it reaches its highest altitude. A good challenge!