Limp Probe Denouement

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

Thanks form the feedback.

Hopefully, all will now be well!

Howard

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