Centre finder?

[Howard LewisParticipant @howardlewis46836]

If you want to use the "two centres" method, look at the front cover of No.28 in the Workshop Practice Series, by Tubal Cain. A very useful method.

Lacking a centre with a centre drilling at the back end, made my own.

I used a piece of Silver Steel, about 5/8 – 3/4 diameter, about 3 inches long, (so long ago, can't remember exact sizes, and too idle to go and check ) , clocked in a four jaw and centre drilled , and then turned it around, recentred it before turning a 60 degree taper on that end.

Howard

[HopperParticipant @hopper]

I think this type of centering tool was popular back when dial indicators were expensive exotica beyond the reach of many home hobbyists. Fun to play with though.

[duncan webster 1Participant @duncanwebster1]

I just have a bit of 3/16" rod about 12" long with a point on one end. Grip it in the tailstock chuck and poke the point into the centre punch mark and run your DTI on the outside. The point doesn't need to be concentric as the rod isn't rotating. What I do to keep the point pushed against the pop mark is arrange for the handle on the tailstock handwheel to be off balance to push the rod along the bed. Saves taking the chuck out to put the centre in. If I were to improve it I'd loctite a 1/2" diameter collar up at the pointy end, then you could use the dti with more eccentricity. The fact that I haven't bothered in all these years means that either I'm bone idle, or it wouldn't make that much difference

[Bernard GreatrixParticipant @bernardgreatrix61453]

First apologies for appearing to ignore all your replies, I've been away on a long weekend.

I am greatly appreciative of all your comments and suggestions and went away inspired to make something.

I tried cooking a 1/2" Ball bearing (I don;t know what type of steel – it was 'rescued' from a dead ball race). I got it bright red hot and allowed it to cool slowly between the two firebricks that I'd cooked it in. Rather disappointed – the oxidation scale was rather heavy and it was still too hard to file a flat on.

I have – somewhere- a small double ended rose bearing, but have not been able to find it, so I'll put that on the back,burner for now.

So using materials that I had lying around I've a made a centre finder – al la Tubal Cain but found that until I get close to centre my dial indicator kept dropping off the side. I'll try again when I get some larger diameter material to add a collar, as suggested above.

I've made a gimbal model (see picture) which does work quite nicely. I just need to get some 3mm rod to complete the build. The photo shows just a piece of thin wire It's probably not as precise as I would have liked as I used odd pieces of material that I had and the smallest available screws are 6BA.

Again many thanks for all your replies

regards

Bernard

I've also ordered some 1/2" threaded balls off the net. They look too useful not to have any

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