Limp Probe Denouement

[martyn nutlandParticipant @martynnutland79495]

Solution

[martyn nutlandParticipant @martynnutland79495]

Hello Everyone

I thought those of you who so helpfully contributed to the thread on the dangly probe on my new coaxial indicator might be interested in the denouement.

Jason thought, and I had also come to the view, that the reason it didn't work was a lack of resistance between the slot in the beam and the arm that holds the probe. He suggested the simple expedient of devising a way of increasing the pressure on the clamping screw. But of course, by then I had broken the arm!

So I milled and drilled a thicker replacement arm to create more friction in the slot. I had difficulty machining the 48° wedge shape (cam?) on either side that bears on the slope of the beam and my version is a lot less elegant than the original. But it does work and is made from good steel instead of some kind of 'monkey metal'.

I tested it at 100 rpm on the inside diameter of an Austin Seven piston skirt and got the needle on the indicator dial to quiver around 0.01mm of zero. I don't think I can do much better than that other than send for a Blake!

Bonne Weekend Martyn

[Howard LewisParticipant @howardlewis46836]

Thanks form the feedback.

Hopefully, all will now be well!

Howard

[Clive FosterParticipant @clivefoster55965]

Martyn

Great to hear that its sorted and giving you good results.

That's about as good as I get on any normal object. Need something that has had serious efforts to produce a good finish and accurate roundness to get the twitch significantly less.

Never seen absolute rock steady zero twitch but I have seen barely visible movement.

They may not be a perfect device but they are darn good by any realistic standards. Most especially so considering the modest price.

Clive

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