Thursday, 9 September 2021

Hot box

It is often convenient to be able to put tools away while they are still hot. To make this safe, I keep my soldering irons and hot air guns in metal cases but it is necessary to keep the hot ends away from anything else, including their own leads.

Having added a rework station to my collection, I needed a different box. For this, I have used a large army style ammo crate.

I've added divisions inside to separate the hot ends from the other items in the box.

I got carried away. I've sprayed it a gun metal colour...

and stencilled some lettering.


Tuesday, 31 August 2021

Home made twisted pair audio cable

I'm not sure if many people would appreciate my reasoning but I decided that I could make a slightly tidier job if I used a twisted pair cable to connect up the sub-woofer in Shelley's car, rather than a long RCA (phono) cable and an adapter.

I could buy twisted pair cable but for a one off job I decided I might as well make my own. To that end, I rigged up a tool out of short lengths of timber and some spring clamps.

I use the spring clamps and timber, rather than the vice, so that the cables do not get crushed. I use the same thing when holding wires to be soldered

I spun one end by hand, doing about 40 full turns per metre of cable length. When I stopped to add more length, I put a bit of tape round, just to keep the cables together. Cable gauge and twists are all guesswork but I'm confident it is better than I need.

It took less than an hour to make over 5m, including cutting the timber and threading the outer sleeve.


Sunday, 15 August 2021

Defenders update

A lot has gone on with Shelley's Land Rover Defenders over the last few months. It all started back in May, after someone drove in to Fender and wrote it off. Shortly after, we purchased another Defender and we have been bringing that back to the same configuration as the previous one.

The new one has been named, Thunder Truck. It is 11 years newer than Fender but is still over 11 years old. It has a 2.4 TDCi engine, usually called a Defender Puma after the Ford name for the engine.

Fender had done over 250,000 miles. This one is a mere youngster with less than 100,000 on the clock.

Most of the jobs we are doing to Thunder, are jobs that we had previously done to Fender.

Convert it from a van to a pickup.

Swap over the rack from the remains.

Fit more appropriate wheels and tyres.

Fit a double DIN size stereo and replace the speakers.

There are a couple of new things. One odd thing is a hand made dip stick for the coolant because the tank is too close to the bonnet and not easy to see through. A new feature is a lock box in the back, to free up space in the cab.

The rear rack has a cover.

Another convenience is a glove box which very neatly fits on the passenger side of the dash. It was so obvious, I have no idea why Land Rover did not fit one themselves.

The jobs are getting more time consuming. I've started to thread the cables to eventually fit central door locking.

There are plenty more jobs left on the list.


Sunday, 11 July 2021

FreeCAD tips and gotchas

I've been using FreeCAD more often recently and I know enough to create the sorts of models I usually want. From time to time I find something in FreeCAD that is either useful or confusing.

Don't Mix Part Workbench with Part Design

FreeCAD 0.19

I was surprised that the shapes in the Part workbench do not fit in to the same structure as the Part Design workbench. This means that if you try to mix the two, the result does not fit in to the Part Design tree structure. That ends up making further edits very awkward.

It is possible to use them together with the aid of shapebinder but that is a concept I also find very confusing.

As the primitives from Part workbench can also be created in the Part Design workbench, there is no need to make life complicated by trying to mix the two.

Boolean Fuse on Moved Parts Clone

FreeCAD 0.19

I spent ages trying to fuse two parts where one clone had to have its position transformed to be in the right relation to the other.

The gotcha is that the Part Transform function is ignored when doing a Boolean on a clone. It is necessary to manually adjust the position of the clone component item, not the whole part.

Once I knew where to edit, the fuse was fairly easy. That said, you do have to know how the Add Part button works for the Boolean method, its a toggle. Once on you can just click any other object and the bool happens.

Can't Export STL if Boolean is Last

FreeCAD 0.19

If the last action, in Part Design, is to use a boolean, the STL or OBJ file exported will be empty.

I just did a superfluous operation after the boolean and the model exported perfectly!


Sunday, 23 May 2021

Giant Trance X 29er 2013 components

Whilst helping my brother replace the pivot bearings in his two mountain bikes, I made a note of the components and produced these diagrams.


Download the diagrams as a PDF.


Monday, 19 April 2021

Bike tyre air nozzle

When fitting tubeless bike tyres it is usually necessary to have a fast blast of air to get the beads to seal enough to hold air then more to seat the beads in the rim. This is easiest done with a compressor.

Most tyre inflators, for compressors, use a rubber hose with a Schrader, car, valve end. In to which a small Presta valve adapter has to be fitted. That combination can be difficult to hold in place on a Presta valve while also trying to hold the wheel when it is not on the bike. 

I have designed an adapter that fits an air blower tool, which can be easily held on a Presta valve with or without the valve core installed.

An early version

It took a few attempts to get it right. The first version only fitted when the valve core was removed. It worked and didn't need a washer but it is more convenient to be able to use the same tool to complete the inflation, so I designed some more.

Disappointing adapter

Another attempt used a standard Presta valve adapter. This was disappointing. It was hard to hold in place and, as is typical with these adapters, the rubber O-ring kept being pulled off when removing the tool.

The latest design uses a rubber O-ring that fits tightly in a deep groove.

The metric O-ring has a 5mm internal diameter with a 2mm cross section, making it a 9mm outside diameter. It is a snug fit and needs something like a blunt needle or small nail to help get it in.

It is designed to 3D prints without any supports. I used 2mm thick walls and a 30% fill. My preferred filament is ColorFabb nGen.


Download 3D models:
Tyre Air Nozzle, STEP and STL (Zip)
Licence attribution - small business exception

My models in the GrabCAD library.