How to make one of these (hardened steel lever)

[Michael GilliganParticipant @michaelgilligan61133]

Ian P,

I have sent you a Personal Message

MichaelG.

[VicParticipant @vic]

As suggested, I'd mill a new part out of a solid block.

[duncan webster 1Participant @duncanwebster1]

The problem with Bob Stevenson's method (hot forming from gauge plate) is that by the time youve moved it from the hearth to the jig, and clamped it up, it wil have gone cold, or at least cooler. If you had oxy you colud heat it whilst clamped to the bending jig, but that's a non starter with propane.

If you want to try machining it out of solid gauge plate I've got some 1" * 1/2" that you're welcome to a slice of, send me a pm if you're interested. as others have said, leave radii in the corners, then heat treat as advised.

[Neil WyattModerator @neilwyatt]

Posted by Michael Gilligan on 03/08/2016 22:59:17:

Posted by Ian Phillips on 03/08/2016 22:40:44:

I disagree that the part was too hard when it was manufactured. It has survived millions of operating cycles over 40 years without failing. Because its tough (read hard and rigid) it would not have flexed very much, but millions of 'not very much' have eventually culminated in its fatigue.

.

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.

A clear example of planned obsolesence

Neil

[speelwerkParticipant @speelwerk]

OK, it is an old part but have you searched the German sites in German? Niko.

Edited By speelwerk on 04/08/2016 14:59:00

[KWILParticipant @kwil]

Just out of curiosity, what is the machine type number?

[Ian PParticipant @ianp]

Posted by speelwerk on 04/08/2016 14:58:36:

OK, it is an old part but have you searched the German sites in German? Niko.

Edited By speelwerk on 04/08/2016 14:59:00

Good idea but my lack of language skills is a berrier to me.

Ian P

[Ian PParticipant @ianp]

Posted by KWIL on 04/08/2016 15:56:32:

Just out of curiosity, what is the machine type number?

The jigsaw is a Bosch badged Scintilla with a type number of 0 601 580 042

Ian P

[Ian PParticipant @ianp]

Posted by duncan webster on 04/08/2016 12:04:16:

The problem with Bob Stevenson's method (hot forming from gauge plate) is that by the time youve moved it from the hearth to the jig, and clamped it up, it wil have gone cold, or at least cooler. If you had oxy you colud heat it whilst clamped to the bending jig, but that's a non starter with propane.

If you want to try machining it out of solid gauge plate I've got some 1" * 1/2" that you're welcome to a slice of, send me a pm if you're interested. as others have said, leave radii in the corners, then heat treat as advised.

Thanks for your kind offer Bob but if this part was to be made from solid it would need a block 35x17x23.

Ian P

[VicParticipant @vic]

I've looked at the picture several times now and I'm wondering if it has been bent and hardened or whether it's just been cast? If that's the case it may not even need to be particularly hard. It's certainly not a very well made looking component even though it has lasted a while.

I've carried out repairs and modifications to several of my machines and the replacement parts are invariably of better quality than the originals, particularly material wise.

[Ian PParticipant @ianp]

Posted by Vic on 04/08/2016 17:42:16:

I've looked at the picture several times now and I'm wondering if it has been bent and hardened or whether it's just been cast? If that's the case it may not even need to be particularly hard. It's certainly not a very well made looking component even though it has lasted a while.

I've carried out repairs and modifications to several of my machines and the replacement parts are invariably of better quality than the originals, particularly material wise.

Its definitely folded from sheet and has been hardened because it needs it.

Its lasted over 40 years so whilst it might not be a nice part to look at it was well made for the job it has to do.

Ian P

[speelwerkParticipant @speelwerk]

You will have to make it, searching German sites in German gives no result. Niko.

[Ian PParticipant @ianp]

Posted by speelwerk on 04/08/2016 23:57:35:

You will have to make it, searching German sites in German gives no result. Niko.

Niko

Thank you for doing a search, I did try myself also without success although I was tempted to bid on a complete working jigsaw identical to my broken one.

Ian P

[BazyleParticipant @bazyle]

There are two angles to this. 1) working out how to make a copy for the engineering challenge and 2) solving the actual problem of providing a functional blade support.

A quick google provided images of other roller supports that could probably be adapted.

[Howard LewisParticipant @howardlewis46836]

Does it need to be hard on the bend where it broke? Being hard probably made it brittle.

As a hammer and chisel type injuneer, it seems to me that you have little to lose if you get someone to TiG weld it, promptly followed by quenching in oil.

You never know, 1) it may work, and 2) the weld may thicken, and strengthen the section that failed.

Howard

[John McNamaraParticipant @johnmcnamara74883]

Hi Ian

Using Google images I located this site, is your model included in the list of compatible saws?

**LINK**

One site at random from the image sites listed there are others.
**LINK**

Regards
John

[ken king, King DesignParticipant @kenkingkingdesign]

Fold one up from M.S. plate, drill and tap, check fit, then case harden either just the four holes in tne vertical limbs, or the whole thing for a bit of extra stiffness. Make two while you're at it (won't take twice as long) and you're covered for life.

[Ian PParticipant @ianp]

Posted by John McNamara on 08/08/2016 23:47:25:

Hi Ian

Using Google images I located this site, is your model included in the list of compatible saws?

**LINK**

One site at random from the image sites listed there are others.
**LINK**

Regards
John

John

I have found numerous exploded diagrams of Bosch jigsaws and seen lots of very similar looking parts but not seen any that are identical. One of the Bosch dealers assures me that none of the available spares are exactly equivalent and although there are one or two parts that look is if they 'might' fit I would have to order them specially to find out, so it could get expensive.

Ian P

[Ian PParticipant @ianp]

Posted by Howard Lewis on 08/08/2016 23:08:59:

Does it need to be hard on the bend where it broke? Being hard probably made it brittle.

As a hammer and chisel type injuneer, it seems to me that you have little to lose if you get someone to TiG weld it, promptly followed by quenching in oil.

You never know, 1) it may work, and 2) the weld may thicken, and strengthen the section that failed.

Howard

Howard

I think you are right, welding might work and little to lose.

I have looked closely at the space surrounding the part when its installed and can see room for any weld build up. Done skilfully/quickly by TIG welding the loss of hardness immediately adjacent to the weld should not be a problem.

Finding an a skilled and amenable welder is another matter! I seem to live in a black-hole area with very few local engineering companies. Its no use reminiscing but years ago one could always get little jobs done for beer tokens, nowadays with ISO 9000 or whatever, no one wants to bother.

Ian P

Ian P

[Ian PParticipant @ianp]

Update…

I have made a new lever from solid out of EN24T (it was the only bit of decent steel I had) and having assembled and tested the Jigsaw it works!

I spent less than two hours to hacksaw the rough shape and then mill, drill and ream as required. I thickened up in some places compared to the original and also did not drill a couple of holes as they did not seem to serve any purpose, in fact the original part broke across on of the holes.

This part serves to push the blade forward on the cutting stroke, the so called pendulum action. I assumed that this lever was highly stressed and that was why Bosch had mad it very hard and tough. What I did not think about at the time was how the operating force was applied or transferred to the lever.

On examining the Jigsaw innards when I reassembled it I can see the oscillating arm that presses on the tail of the lever but I now realise that it must apply only a very small force as the witness mark on the lever is no more than a witness, its removed the blacking on the surface at the contact point but there is no detectable wear.. Its the tiny bright spot to the right of the hole (bottom right corner of the picture). The other bright area of the part is where the lever passes through a felt seal out of the gearbox casing.

Thanks for all the useful advice, comments and encouragements. I now have a fully functional machine again. I've not heat treated the part, I'm going to inspect it after a few hours of use but I suspect it will be OK as it is.

Ian P

[Michael GilliganParticipant @michaelgilligan61133]

Well done, Ian

Hewn from the solid …

It looks much better than the original part.

MichaelG.

[AjohnwParticipant @ajohnw51620]

A bit late but I wondered if the part was cast. It reminds me of a part used in some Leitz Orthoplan microscope model's binocular head. Grain structure awful. That particular part seems to be cast steel or maybe iron. It too is rather hard.

John

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[Grizzly bearParticipant @grizzlybear]

Ian, That is a brilliant job.

Bear..

[Ian PParticipant @ianp]

Bear/Michael

Thanks for the compliments, it was pretty straightforward to make greatly helped by Bosch keeping to preferred sizes, ie, 4mm holes, 12mm centres, 12mm wide tab, 12mm between forks etc. There was only one dimension not in round numbers which was bottom hole centre 3.5mm from bottom edge.

Chopped out some disks of 12mm thick Delrin with the repaired jigsaw today, cuts beautifully.

Ian P

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