DTI Elephants foot

[CharlesParticipant @charles]

I have seen several descriptions of setting up workpieces where the use of an `Elephants foot' attachment has been used on a dial gauge. Are these things commercially available and if so where do you get them? Or is it something that you make for yourself?

I have never seen one or an actual description or picture either. I can guess what it is like, but can someone give me some definite information on the subject?

Charlie

[CharlesParticipant @charles]

[Michael GilliganParticipant @michaelgilligan61133]

There is a brief description here, in a useful piece on marking-out.

Basically it's just a screw to replace the ball-point on the dti with a big flat.

To be useful, it needs to be accurately made. … I won't quantify that, but:

more accurate = more convenient = more useful

MichaelG.

.

Edit:

Long Island Indicator lists a wide range of "Contact Points"

… great site, with loads of info.

 

Edited By Michael Gilligan on 28/01/2013 09:07:39

[LambtonParticipant @lambton]

I made this elephant's foot to enable the accurate tracking of curved or circular items whilst being set-up to run parallel to the axis of the lathe or mill. It has a permanent flat mounting bar to fit a Dixon type tool holder. The diameter of the foot is approx.12mm. As Michael G says it need to be accurately made.

I turned mine in one setting on my Hobbymat lathe by reducing the end, threading it and finally parting off carefully. The Hobbymat is brilliant at parting off. The business end was then polished by rubbing it on fine wet & dry on a surface plate.

[CharlesParticipant @charles]

Thanks very much gentlemen, that is exactly what I wanted to know.

Charlie

[Sub MandrelParticipant @submandrel]

That looks a neat challenge for a 'coarse engineering' type like me!

Flatness I can test, but how can you check the 'foot' is at right angles to the axis or do you have to depend on the accuracy of machining?

Neil

[Clive HartlandParticipant @clivehartland94829]

Put the foot very close to the table and attempt to put a feeler gauge under it in different places and read any differences on the dial.

Clive

[Gordon AParticipant @gordona]

Greetings Charles,

You may find what you need in this set.

http://www.arceurotrade.co.uk/imagecache/8f22c40f-c9ed-495b-8fca-9ec400efcba4_300x234.jpg

Gordon.

[David LittlewoodParticipant @davidlittlewood51847]

I wonder just how important the accuracy of the elephant's foot really is. Its convenience arises AIUI from the fact that it is easier to make it sit on a round bar in the chuck, but once it is sitting there the part of the base in contact with the bar would not change much, if at all. Since the indicator is almost always being used as a zero checker (for runout), would it work any less effectively is it was slightly on the skew? I don't know the answer, I'm just suspicious of some of these frequently quoted "rules" – just like the one about the effect of tool centre height when cutting a taper.

David

[Gordon AParticipant @gordona]

Oops! Sorry Charles, got that one wrong. Try the Dial Gauge Contact Point Set on this page.

http://www.arceurotrade.co.uk/Catalogue/Measurement/Dial-Gauges

Gordon.

[Anonymous]

Posted by David Littlewood on 28/01/2013 22:27:00:

I wonder just how important the accuracy of the elephant's foot really is.

Dunno, and it's too late to start doing the maths, but likewise I suspect that it isn't critical. When I made an elephants foot for my DTI I turned the outer diameter, shoulder and spigot for the thread in one go. Thread (6BA) was put on with a die, aiming for a loose fit. Part off and then face off and tap a 6BA hole in a rod in the collet chuck. Without removing the rod, screw the elephant foot into place and face across the bottom. I reckon that should get the bottom face parallel to the top to reasonable accuracy along with a good finish. Worked for me anyway, the Morse taper that I ground using the elephants foot to confirm the taper with a sine bar was a pretty good fit in its socket.

Regards,

Andrew

[Ian S CParticipant @iansc]

I'v got a small, and old Starret dial gauge, the probe sticks out the back, at right angles to the normal gauge, it has at the moment a home made version of the normal ball ended fitting, but I think this one would be a good one to fit an elephant foot. Ian S C

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