Limp Probe

[Grindstone CowboyParticipant @grindstonecowboy]

Working now, thanks Jason (just so you know in case Michael doesn't see this until later)

Rob

[Michael GilliganParticipant @michaelgilligan61133]

It is later, and all is good

Thanks

MichaelG.

[martyn nutlandParticipant @martynnutland79495]

Jason

If you remove what the literature calls the guard ring and pull down on what you call the 'vee shaped part' and the brochure the beam and me the crosspiece, everything works perfectly – there's tension, the hand on the dial spins and returns to rest when you release the beam or vee shaped part.

That's not the problem.

The problem is you can't tension the probe i.e. the part that holds the probe hangs limply down vertically however much you tighten the screw between the vee shaped part (beam) and what I call the arm (the bit I broke) and what you call the 'bit the probe fits into'.

Now – if you push the probe gently sideways in one direction, the wedge shaped pieces on the arm (I suppose strictly speaking we should call them cams) move the beam against the main spring and cause a reaction on the dial. If you push the probe in the opposite direction, in my case, there's no resistance at all after having tightened the screw between said arm and beam.

So, by my way of thinking there is no way you can take a reading with my particular instrument because, at the risk of being boringly repetitive, you need, in the case of an internal bore, to position the probe just outside the circumference – and for it to stop there – not flop back to vertical. If it did stop there – not flop back – you could gently ease the tip into the bore and would have an element of pre-load. Thus, when you started the mill, or turned it by hand, the probe would sweep round the internal circumference of the bore and give a reading on the dial that would enable you to manipulate the X and Y axes to centralise the spindle, which, is the point of the coaxial indicator is it not?

Am I missing something here?

 

Best Martyn

[JasonBModerator @jasonb]

Got it now, in that case I would

– Remove screw and dome nut from assembly and then screw them back together now offer up to beam and see if they are closing up enough to compress the split end, if not shorten screw slightly as it sounds like it is bottoming out in the dome nut rather than tightening the split in the beam.

– If it short enough but maybe not the strength to close up an overwide fork then add a shim washer into the fork

[martyn nutlandParticipant @martynnutland79495]

ABSOLUTELY BRILLIANT!

Of course, I've broken the arm!

But I did think that when I make the new one I could make it a smidgen wider in the slot on the beam, thus introducing a little bit of friction.

Again, of course, it would have been a much simpler ploy to shorten the retaining screw or introduce a tiny shim, had I not been so stupid as to think the person who put their undecipherable mark on the 'quality assurance chitty' had actually inspected the instrument and it was ready to go! You live and learn.

Thank you all and especially Jason.

Martyn

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