Cement mortar rake for a patio, etc.

[brianr47]

The cement joints on my north-facing patio had suffered in the frosts of past winters and needed to be replaced.
Having tackled this job in the past, I didn't relish spending hours on my hands and knees with an angle grinder and diamond disc mortar rake, getting covered in dust and aching for days after.
YouTube kindly helped by showing demonstrations of 'finger' mortar rakes being used with angle grinders on brick walls and from that sprang the idea for a patio version.
As can be seen in the pictures, the angle grinder is mounted on a frame, with wheels donated from a child's roller skate. Direction is controlled by an old lawn trimmer handle.
For safety, I wired the power cable through the original trimmer switch and kept the angle grinder switch permanently on.
The rear wheels take the weight, while the front wheel controls the depth, which is adjustable.
The first attempt used an 8mm x 28mm diamond finger rake which did the job but was too slow. The Mk 2 version used a 3-sided tungsten-carbide rake of similar size which was more aggressive and so was quicker.
The concept works very well and allows me to stand up and easily guide the grinder along the gaps between the slabs, whilst not being covered in dust. I found that finger rakes produce much less dust than disc rakes as most of it stays in the joint.