2 * 2.1 SD

[Dieselman]

I carried on de-rusting the boot strengthening bracket and all was going well until rain stopped play...both physically and metaphorically, when my mini engraver tool burned out.

The way these work is they are a solenoid with a plunger hammering a tungsten pin. The frequency is simply the mains A.C. frequency, so at 50Hz, the plunger vibrates forwards and backwards 50 times per second, or 3,000 percussions per minute, 6,000 times per minute for both stokes as rated by the manufacturer.

I had noticed it becomes very hot after a only a short time operating, as it's not really meant to be used continuously.
I only need slight depth of percussion so had been using it on settings 1, 1.5 and occasionally 2, out of 5.
Only when I looked inside did I realise why running on low settings makes no significant difference to the power consumption and heat generated The solenoid core is a split core and the control is a mechanical one, which varies the distance the split part of the core is from the main part.
This does reduce the magnetic flux, but the coil is still being fed by unlimited current.

This one was rated at 24Wh and the only replacement I can obtain immediately is 35Wh, so possibly worse, so I have ordered two more rated at 13Wh as well.

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As far as rust removal goes using a percussion engraver (not rotary grinder) is very slow, but the single point really is the best method as it shatters and vibrates the crystalline rust particles.
I find the best method is to flood the area with clean acid at which point any rust particles are very visible, then dig into the rust with either the engraver tip, or a pin attached to the engraver tip (I have a safety pin bent to shape to wrap around the tip). The rust is soon seen to be dissolving into the acid.
Once the acid pool is saturated with rust wipe clean and then dab clean with a acid wetted paper towel and start again. Do not re-apply fresh acid unless the area has been cleaned, otherwise the supply of acid becomes contaminated and causes flash rust.
For final cleaning I use a paper towel soaked in acid squeezed against the area, thus using hydraulic action to flush out any ferric corrosion particles, then a good dab and scrub with a fresh towel to dry it before any flash rust can form.

I have the left boot floor to wheel-house bracket nearly rust free. There are a few spots on the very left edge and the section on the raised section to the right of the large hole.

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I moved onto the right side and found a patch creeping under the seam sealer, so dug out the sealer and wire brushed that section and the other small areas.

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As you can see, wire brushing is not anywhere near as effective as the engraver, due to skipping over the pits.

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I do have a bottle of Bilt Hamber Hydrate 80, rust converter, but believe that rust removal is better than simply converting the upper surface. I suspect it is Phosphoric acid, which can cause issues due to the outer surface being electrically charged, so doesn't create strong paint adhesion, without physical removal...which rather negates the point of the product.