3d Print Welding and Fibreglass

New little video I've edited today chatting about some 3d printing techniques, welding parts with a 3d printing pen and also embedding fibreglass into prints to make very stiff components.

FreeCAD video part 2

I've really enjoyed making these videos for the Ffiws project from Arloesi Gwynedd Wledig and its been a welcome opportunity during lockdown! Building on Part 1 we move to the part design workbench and build a part using the "body" concept, mapping sketches to faces and using tools like the pocket tool and hole tool to create a nice model. The model is a part of the larger MTV robot project I built and wrote about in Hackspace Magazine.

Printing Pinion Gears for the mini lathe.

I managed to strip one of the pinion gears on the mini lathe a while ago and I was surprised that I couldn't find a 3D model of them to print, particularly as I'd seen a lot of gear wheel sets for the mini lathe on thingiverse and elsewhere (I think this is an indicator that perhaps other people aren't as idiotic as me and don't strip their pinion gears)!

 Today I set about sorting it with some 3d printed replacements. I used the involute gear tools in the "Part Design" workbench of FreeCAD which I am using more and more as my go to CAD environment. It's a pretty easy tool to use so long as you know the "module" of your gear which can be worked out as it is the pitch circle diameter divided by the number of teeth. Counting up the teeth on the old stripped gears showed they were a 25 tooth and a 20 tooth and the overall diameter was close enough to make me feel that the pitch diameter was going to be the number of teeth in mm giving a module of 1. I'd read online that the mini lathe gears all ran at 20 degree pressure angle. A quick bit of calliper work on the hole diameter and we were ready to CAD!

The results are great, printed in PLA at 35% infill I've been running the gearbox for a couple of hours and all seems well. I've printed up a few spares and chucked them in the box of gears. As I couldn't find this set of gears online anywhere I've put it up on thingiverse as a project so hopefully it's of use to others. You can find the files and the print settings here. 

10 minute make, Filament reel stand!

So whenever I swap to use a big reel of filament (2.3kg ones) I always end up concocting an elaborate balancing of stuff to hold it on! I've been known to have 2 piles of books with a piece of threaded bar balanced across them before now. The other day I was about to scrap some small stands I'd made that could hold a 25mm dowel between them I'd originally made as a jig to help fibreglass onto a tube. I quickly realised with a larger base and a shorter piece of dowel it would fulfill my filament holding needs. I just use a slightly undersize "o" ring on the dowel to stop the reel from drifting along and off the stand. Perfect!

Hackspace Magazine Issue 32, Opensource MTV robot!

Normally when each months Hackspace Magazine comes out I update this "keeping track of my articles" post, do a few tweets and move on. This months magazine has a project I put together that feels worthy of a little blog post all of its own though! I was asked to write a tutorial using a cheap tracked robot chassis kit (just the wheels, chassis, motors and tracks around £20-25 online) on how to build a budget robot. I decided to go a bit further than just cutting a couple of boards to mount stuff to and came up with an entire modular system built up on the cheap chassis from 3d printed parts. Whilst this particular robot is referred to in our house as "red one" the whole modular robot project is called "MTV" short for Modular Tracked Vehicle. All the modules feature M4 holes on 10mm centres so that modules can be mounted in lots of places and it can all be reconfigurable perfect for adding experiments and other doohickies too! I did all the 3d work in FreeCAD so that it is made with opensource and free tools and also all the files are published in a project repo on gitlab. I'm not going to give you the link though, you have to go download the (excellent imho) magazine, read the articles and find the link there! Check out hackspace issue 32 here.  I'd love to see others tinkering on this so do feel free to join in, merge requests are open on the repository and do get in touch if you build one!

Follow Up - Thermal Insert Tool Rig MKII

A few weeks ago I posted about converting a Dremel workstation and adding a 3d printed part and a hacked soldering iron to make a thermal insert tool. It was great and through a combination of some spacers and some copper tape as insulation it would resist the heat for a short session of inserting. However, I wasn't satisfied with it for longer sessions of use and so I decided to remake the mount out of a block of EN1A steel I had in the scrap pile. Rather nicely Hackaday picked up on that original post here.

I used the 3d printed part as a quick drill guide as it didn't need masses of accuracy and it sped up the conversion a lot. I also decided to do away with the soldering iron handle as it didn't really need it.  The last job I did was to modify one of the soldering iron tips by cutting a few mm off the end of the point. This meant that when fitting smaller thermal inserts the tip would fit inside the insert and self centre and could apply pressure without either poking through the underside of the insert or marking the plastic outside of the insert. It works very well and I may well may some different tips for different sizes.
Whilst the Dremel workstation inherently are a bit wonky and flexible (I'm thinking of a new experiment to try and make it a little better and some other mods, I'll post at some point) it's been great to use and the height adjustments it offers are great and it can accommodate a good range of work pieces such as this "MTV" robot... which I need to do a blogpost relating to in its own right!



Finally, below is a picture of an insert, It's great to be able to get these in well without marking the surrounding plastic and they work incredibly well and if put into the correct size/tolerance hole they are much much tougher than tapping into a 3d print.

£12 HDMI-USB Video capture card on Ubuntu (cheap portable Rpi Monitor!)

A while back I was ardently reading @biglesp post on a HDMI-USB capture card that he had been tinkering with and using as a way to have a super minimal setup for a raspberry pi without needing a monitor for it. At the time I think the Mirabox cpature cards he was looking at were over £100 and it was to rich for my tastes!

Then last week my fellow flame trench buddy @Ascii211 posted about a $10 usb capture card he had been playing with. Having tracked one down on Ebay in the UK for £12 I thought it was worth the punt to see if it would play nice with Ubuntu.

I rigged it up today with a raspberry pi4 (4gb) as an input and plugged it into the trusty (badly in need of a reinstall) Thinkpad x220 running Ubuntu 18.04. A quick check of dmesg seemed to indicate that it had been recognised etc.

I noticed in the terrible instructions with it it mentioned VLC as a potential bit of software for capturing, after tinkering around in VLC for a few minutes I couldn't get it to work at all. However... I'd used "gucview" as a camera capture application before so opened that to see if it played nice. Short answer... yep it does. Video preview and capture at 1080p at 30fps was pretty happy, theres a slight lag in the video feed but nothing that isn't workable. I'm keen to checkout how it does with camera input and I keep meaning to play with OBS (open broadcaster software) so I'll update after tinkering a bit more.