Monday, 19 September 2022

Unconscious making! - Useful note board/ Index card holder!

 



Someone IRL made comment on this the other week as I pulled it out of my bag and it was noteworthy to me only because I hadn't considered that I'd made this object, even though I had! People may or may not know that I always, ALWAYS, have index cards on me! I've been a fan since the 43 folders Hipster PDA idea's were floating around but also, I used to pride myself as being able to create some kind of workshop activity at any moment, so long as I had some index cards and a pen. 

Aside from workshop materials, index cards are in constant use for note taking, but they are also cheap enough that they often are pressed into use as a place to dump some glue, or to cut and craft a quick card prototype. The problem they do suffer from though is they get pretty scruffy when a stack is just held in your pocket. So, I often have them binder clipped together and they often in turn get binder clipped to a board. I have a few boards knocking around and they often become focused on notes for one project. 

Anyway... this board that caught someones eye... well. I'm pretty sure it started off as a failed lasercut base for a little lollipop stick crane I made for a Hackspace magazine article and, as it was around the right size, it got pulled from the pile and some index cards added. It then started getting used for notes for a rocket related project and the rather overkill kevlar cord was added to hang the board up in the shed, the kevlar being an offcut from the rocket project. The decoration was an experiment I wanted to see how well my diode laser CNC rig would remove paint for an interesting engraving effect so I quickly slapped paint on the board as it was to hand near the laser rig! Laser cutters produce lots of bits and bobs of off cuts and I have absolutely no recollection of why I glued a small yellow piece of acrylic into one of the holes, I imagine it was just because I was fiddling around and realised it fit. The circular piece of wood is another laser off cut, I was working on *something* I can't remember but it had a lot of small screws, the bench I was using was scaffolding planks and there was a high chance a screw would disappear in a crack... so I glued a scrap ring onto this board and had a safe place to put small screws. Similarly I was working in the shed and was repeatedly using a small Allen key which I kept misplacing, the project also involved some tiny neodymium magnets and I had spares so I drilled a small hole in the board and glued one in. Later I ran a workshop on NFC stickers and how to get them to do stuff when scanned and a spare sticker ended up on there. I would love to tell you this links to the rocket projects files/repository but it probably doesn't, I should really add my phone number or an "if found return too" note on it.

So there we are. It's a thing that is definitely made, and probably made in my favourite way, in a responsive, tinkering, flaneurial spirit!

Friday, 19 August 2022

3D Printing Lightweight Nosecones - Vase Mode Approaches.


I've been looking at FAI style rocketry building a fair bit recently and doing some explorations. I'm not aiming to compete and my motivation is more that I want a cheap and light rocket with lots of internal volume for a weird deployable idea I have, more on that another time. The rocket above is a cardstock rocket which is bulkhead/centring ring free and pretty lightweight. When it came to the nosecone I wanted to keep it pretty short and stubby and in keeping with the FAI look. But I also wanted to keep it light. If you want to go really light with 3D printing then "vase mode", where you have a single perimeter printed in a continually raising Z axis coil (rather than a layer then a Z lift) is a great approach. However, a problem with vase mode is what happens when you get to flatter top areas that are over 45 degrees from vertical, essentially the vase approach fails as it can't print the geometry. Below is probably the best I could get it.


So the workaround, I redesigned the CAD model of the nosecone into 2 sections, one section that would vase print well but with the tip removed and printed separately in a standard print approach with a small amount of infill.  Below you can see the vase mode print complete with the tiny shoulder section (at the top) which steps in 0.3mm which is the thickness of the cardstock body tube. 

Below you can see the vase mode section and then the standard print mode tip. Printed in PETG  and ready for assembly with a spot of superglue. 


I'm pretty pleased with the approach, the rocket I'm building is slightly larger than the FAI style 40mm diameter body tube as I used some PVC pipe and a 3D printed section as a mandrel for the body tube and transition. Some research indicates that for 40mm FAI rockets the nosecone, without the shoulder, is around 1.5g. I could lighten the tip section of mine some more, I also could sand and polish the PETG print a lot and it already contains a working shoulder section so I actually think this approach is not far of being competitive with this first, larger sized one, at 3.26g. I'm pretty sure at 40mm diameter with some work I could get these under 2g similar to the vacuum formed styrene ones with paper shoulders that people seem to use. Of course a pointier geometry means you could entirely vase mode a very light nosecone as I did on my UK altitude record holding "Imp" rocket design.



Saturday, 4 June 2022

Creality Ender 2 Pro 3D printer review.

 

I feel pretty lucky, I work hard and have to hustle but I get to work and write about stuff that I really enjoy and sometimes wonderful things happen! A couple of weeks ago I was discussing the new Creality Ender 2 Pro with @Woodpunk who had been a great advocate for the original Ender 2 as a cheap small from factor printer for farming. Particularly towards the end of their commercial life the Ender 2 was often to be found for under £100. Mr Woodpunk was considering getting the new ender 2 pro out of curiosity but in a fit of unbridled wonderfulness he decided instead to send me one to outsource the research to me!

So I see the Ender 2 Pro retailing in the UK at between £140 and £170 (the lower price being from technology outlet who I have bought off previously and had good service) and it arrives extremely well packaged with all tools and decent instructions for the pretty straight forward assembly. 


It went together in about 20 minutes and only really needed 7 bolts inserting and tightening up and a few well labelled cables connecting up. It's a smart looking unit with a carry handle on the top of the Z axis tower for portability and the rather nice filament spool holder rotates in and out for a stowed and deployed position. It does make it pretty small if you want to put it away and not have it permanently taking up desk space or if you need to carry it elsewhere. 

On this unit I found all the belts to be at a decent tension and all the vee wheels running smoothly with no play and it didn't need any tweaks mechanically apart from setting up and levelling the heated bed. I'm spoilt these days by my Prusa Mini + (which I reviewed in Hackspace Magazine Issue 53 ) which has the automatic bed probing and compensation but in a way setting up and levelling a print bed is a better solution as you aren't forcing a compensation in the build rather getting it right from the start! The bed has large turn wheels fitted and it's pretty straightforward to level using a piece of paper for a feeler gauge. Better than my first printer, the Wanhao I3 V2 you can see in the background which had no wheels fitted and where the first item I had to print! Whilst I could add a probe in the future, I only had to level the bed twice on setup after thermally cycling it and haven't had to tweak it so I doubt I would add one. 

I've LOVED the removable print surface on my Prusa, and it's great to see that budget end machines are starting to include this. The print surface on the Ender 2 Pro is very good in terms of print adhesion and release and it works very well. A minor gripe is that it's incredibly flexible and the magnetic bed grabs it a little well making it hard to line up before the bed grabs it, but really that's a tiny tiny concern. 


The LCD display clips on and is easy to read with a familiar Marlin firmware. Whilst again after using a prusa mini + with it's snazzy 32bit controller and hi res display this feels a little low tech it's absolutely fit for purpose, responsive and easy to read. 


The included micro SD card has some documentation, some windows software and the obligatory example file gcode for printing. Loading up the sample creality PLA and setting it off it produced a very nice bunny model albeit with a noticable Z seam on the reverse side. Print quality was amazing though apart from that and it felt like a very good start. 

I haven't used the Cura profile provided for slicing as I am a fan of PrusaSlicer now and I was pleased to see that there is a beta configuration for the Ender 2 Pro included in the latest version. I tinkered with a few prints using the default settings of the PrusaSlicer ender 2 pro profile and initially had reasonable result but with constant blobbing/zits at new layer start points. The ender 2 pro is a bowden set up and it's quite a short bowden tube which means that there is quite a lot of pressure in the hot end. I knew I needed to up the retraction amount and speed but initially this seemed to make little difference. I was puzzled but began to suspect that the included SD card wasn't particularly quick and that the machine seemed to be making some longer pauses at layer change than I expected. I grabbed a better brand micro SD and tried again, this, combined with what seem astronomically high retraction distances (6-8mm) and near light speed retraction rates.. (200mm/s plus!) the blobbing and oozing was cured. So far it's had trials with a variety of PLA and some nice Prusament PETG as well as some cheap generic PETG. It's handled it all very well. 



In conclusion I'd say this is a great printer for the price, although there are a lot of great printers around the £140 to £200 mark these days. It is certainly capable of producing good prints straight out of the box and it has some nice support and user communities building around it already. I can only imagine making 2 changes to this machine. The first is, this is an incredibly quiet printer.. ruined by one fan in the power supply... honestly this is such a shame as the fans on the hotend and the steppers are incredibly quiet for a budget printer but the cheap fan in the integrated power supply is really loud, Creality really missed a trick there as an extra dollar or two on that fan component and people would be amazed how quiet this thing can print. Secondly, I don't like the fact that the top of the Z axis lead screw is floating... it seems like with all the handle assembly up there they could have popped a bearing in that could support the end of the screw. I can't say I've had any problems though with taller prints so it's only really an issue in my own mind! 

So there we go. It's an excellent printer. It's definitely going to get used and it's probably going to get abused with weird filaments and experiments as, at the price point, it's a great printer to not be too precious about. 



Monday, 16 May 2022

Things You Never Thought You'd Make - Flags!

 


I'm really lucky these days that I get to make lots of projects and even luckier that I've hustled and grafted to get myself in a position where I often get paid to do so. Occasionally I catch myself pondering and giggling about something I could never have imagined I'd end up making. Often these are small side projects that somehow relate or help another project along the way.  

A recent example is I've ended up making a flag and a slot together flagpole! "Why" I hear you cry. Well, I've been continuing to develop and test fly the EXOS swing wing rocket glider and I've been using a local site as a launch area. It's a swampy moorland known locally to our ragtag bunch of RC/Freeflight plane and rocket group as "The Swamp" and it's perfect, but quite featureless. I discovered the first time I set up a rocket launch rail there that as soon as you walk more than 10 meters from your launch spot, well, it disappears! A flag was needed, so I created a pole using 2 x 1m lengths of aluminium tubing and glued a 4mm brass tube into one end which means they can then slip into each other. The flag is simply a bit of rip stop nylon left over from a parachute project which I've sewn a small sleeve into which slides over the flagpole. Finished off with a heat transfer vinyl concretedog logo it's working well to get me back to my launch equipment after a long walk to recover a rocket! 

Tuesday, 15 February 2022

EXO-S The EXperimental Opensource Swingwing Rocket Glider.

 


I uploaded this video about the EXO-S Swingwing Rocket glider I've been designing and making. I need to get some decent weather to try and fly this! I'm hoping for a first flight test with the aim to get a transition from vertical mode to horizontal and expecting it to not be the best glide phase! The CG and wing load are pretty good so it should glide a little but it probably needs to shed a little weight and also needs the wings carving into a better aerofoil. Once tested and refined I'll put up some more video and post some build instructions. If you are curious the balsa parts and the 3d print CAD are published on this repo. https://github.com/concretedog/EXO-S-mk1

Sunday, 26 December 2021

Recycling 18650 cells into Useful Battery Packs


This has been on my todo list ever since I reviewed the Sunnko 709A spot welder machine in Hackspace Magazine issue number 48 and I finally got a bit of time to play this morning. Making battery packs from recycled 18650 cells, the cells commonly found in older end of life laptops and other devices, is nothing new and there are plenty of technical blog posts and youtube guides out there to explain the process. It appeals to me on a few levels, I like the recycling part but also it's handy to make some battery packs up that can be used to power FPVground equipment or even for use with my Pinecil soldering setup in the field. Of course it's also great practice perhaps for making 18650 packs with brand new cells which I may be tempted to do for long range drone or fixed wing projects as you can pack a lot more capacity into a smaller and lighter battery than a LiPo.   


I recovered these three cells from an old Sony laptop battery someone gave me and whilst I recovered 5 cells, I only wanted to build a 3 cell battery. I spent some time charging the cells to find that they were all serviceable and then made sure to charge these three cells so that their voltages matched pretty closely. This is useful when making a battery which you wish to balance charge as then it doesn't take an age in the first instance getting the pack to balance. The cells as recovered retained the little paper disks on the positive end which afford protection from shorts, It is good practice also to add extra insulation between the 18650 cells to protect from accidents and you can see in the above image I arranged the cells with some barley gasket paper between them. Whilst many people use a jig to hold the cells and then the pack covering to reinforce them, I decided a few spots of hot glue make for a robust structure.  


Next up I cut some nickel strips to make the connections and then spot welded them using the Sunnko machine. For the strips that connect the cells I simply made straight cuts but for the positive and negative terminals I wanted to make tabs with smoothed edges to solder to to avoid them snagging or cutting any insulation or wiring. The spot welder can create really nice joints and it's great to be able to avoid soldering directly to the cells as it puts a heap of heat into them and isn't massively safe.


All that remained was to solder up an XT60  battery connector and also a balance connector and associated wiring.  I made up my own balance connector using a JST XH connector and it's relatively straightforward to wire up, soldering to the new spot welded tags in between the adjoined cells, again, with some decent flux and a hot iron it's much easier to avoid putting too much heat into the pack. Finally a good dose of sanity checking and triple checking with the multimeter that everything is connected correctly and it's happily charging correctly. I've just used some Kapton tape to insulate the pack and hold the wiring in place, a more common approach is to find some large heatshrink which is on the list to pick up at some point. As I'm not too worried about the weight or the ascetics I am tempted to just give it a good wrap of PVC tape. 

Tuesday, 14 December 2021

Tool Tuesday - Wire Brush

This is a tool that perhaps shows my predilection for rusty projects! The wire brush is an excellent tool for loosening and removing rust or loose surfaces. It's a tool that gets a lot of use on my collection of scruffy vehicles but also has been used to remove flaky masonry paint and more. It's not a refined tool and I tend to go for the budget end if possible as they are almost by definition destined to be abused.