A2 will likely be available at toolmaking suppliers or metal supermarket if there is one near you.

It will likely be at suppliers in bar form rather than sheet. I visualized making it out of a block rather than bending up a sheet.

Bosch likely made the original out of austempered AISI 1060 or 1080 steel, bent in the soft state then austempered. I designed and made many parts like it for the valve industry and for office equipment parts. Austempering requires a good proper heat treat chain belt furnace and careful heat and time controls, not simple in home shops but widely available at commercial spring makers and 4 slide shops.

Bending heavy sheet to tight shapes as part in your photos usually requires some bend/form tooling and significant press tonnage. If A2 could be found in sheet form it will require much more tonnage to bend than 1060 or 1080 in soft state. Can be done of course but likely much easier to carve your item from solid A2 and air harden. No bend/form tooling, no tonnage required, and heat treat usually dead simple. JD

like A2 tool steel?

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Yes … In deference to your expert advice, I was not discussing material; merely commenting on the obvious over-hardening of the original component, and suggesting that a tougher condition would be better.

MichaelG.

Looks like a simple blacksmithing job to me. I would think any half-decent agricultural engineer could soon make up a replacement, properly hardened . . . if they can't repair the original. If it's done 40 years it can't have been all that badly made!

If it was mine, I'd try cutting and hot bending one from any old bit of steel plate. It might not last another 40 years but I might not care by then.

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That is your prerogative, Ian … But it seems obvious, even at this distance, that it has suffered a brittle fracture, rather than a fatigue failure.

That said; I will stop interfering.

MichaelG.

Take a sheet of paper and wrap it around the two 'flaps'…mark outline and holes with fine pen being sure to prevent any slipage……..mark in the broken base parts as one outline (obviously) Transfer the 'drawing' to guage plate and mark out carefully using carbon paper or similar…or transfer to thin card and cut out an accurate template then draw around onto guage plate. Cut pieces or scrap sheet for 'sandwich' exactly 12mm thick and set aside. Drill and clean all holes THEN cut out part from guage plate. Heat with blow torch/bricks until bright red…..place against scrap sandwich, fit in vice and fold ONE of the flaps up only. Take second heat and place scrap against bottom of part,…fit into vice and fold other flap down…..

………Check of fit and accuracy on jigsaw.

Heat to red heat and drop into one pint engine oil (preferably non synthetic)……..remove part and clean with wire wool,………place on piece of sheet steel and heat from underneath the sheet with blow torch (or over forge) ….keep the part moving with pliers until it is uniformly 'straw' colour………drop back in oil…….clean and fit.

2 cents

You can heat up small pieces of steel with a cheap welding kit.

zap the piece while its over a jug of dirty engine oil and tip the red hot piece in

retrieve with a magnet, clean it up and grind away the welding part

Hi Ian

The part shown holds the wheel that forces the blade forwards on each stroke to improve the cutting action. It is subjected to repeated quite high speed cycling alternating load stresses. Maybe you can beef up the thickness of the section near the existing break without interfering with the operation of the tool if you are machining a new one from the solid.

The jig saws themselves are almost indestructible, We used to use them in a factory. I still have a couple, the only parts needed have been new brushes, this is after years of daily use. I would never part with mine. None of ours ever broke this part.

Regards
John