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John Stevenson
05-05-2003, 07:39 PM
I have 12 bearing blocks to do out of rectangular stock. These need to be identical and are offset in the bar stock.
I have marked them out with a vernier hight gauge and spotted them with an optical punch so these are spot on. The first one I setup with a sticky pin and dial gauge. Didn't take long but I wanted to speed it up a bit so I went into the shop tonight and made this centre finder up.

Not saying this is unique, not much is, but it's something I cobbled up in about 30 minutes.
Pic at:-
http://homepage.ntlworld.com/stevenson.engineers/lsteve/files/centre%20finder.jpg

The body is a bit of hex bar about 6" long in total. No reason for the hex, it could be round but I had three design changes between the saw and the lathe http://bbs.homeshopmachinist.net//biggrin.gif
About 1 1/4" is turned down one end to about 1/2 so it can fit in the tailstock chuck. This part is drilled and reamed 1/8" for 1 1/2"
It's then turned round and drilled to meet the 1/8" hole to about 1/2" diameter. This is only clearance so it doesn't matter about size.
Next a bit of 1/4" plate was welded on to form an ear for a clock to bolt to.
Last bit is a piece of 1/8" drill rod or silver steel with one pointed end and the opposite end held in the reamed hole with a small grub screw.

Method of operation:
Put atachment in chuck, offer up to the centre punched mark and rotate the lathe by hand. Any run out will be shown on the clock. Adjust the 4 jaw as per normal using only one pair of jaws at a time.
Got the second one setup in just less than 30 seconds.

I make no apologies for the state of the attachment. This was a rush job and needs play a greater part than shiny surfaces. It works and it's quick.
Feel free to make or modify as it suits.

John S.

Forrest Addy
05-05-2003, 08:38 PM
When I was an new apprentice and when I was sure my trade instructor was an ogre instead of a harsh talking softie, he put me in the school shop to make a dozen center finders similar to those you made.

He had me cut 8" pieces of 1/4 drill O-1 rod, hand forge the end flat 1/4 wide x 0.050 " x 1 1/4 long and make an upset bend 90 degrees to the side. Following McBride's sketch, I made a U-bend 180 degrees on a 3/16" radius so there was a springy tab in line with the drill rod axis.

Then I coned the opposite end 60 degrees and drilled a #3 center hole in the tab concentric with the ground diameter of the drill rod.

Set the cone in a center punched hole and nudge the tailstock center in the center holes of springy tab and you have a centering thingy with limited spring accomodation of axial movement.

It served the same function as the gadget you show. I still have one someplace. Wish I could post a picture.

Herb Helbig
05-05-2003, 09:05 PM
John -

Neat gadget! Neat picture. I guess if you have an alternative way to hold the clock, you could just put the drill rod directly in the tail stock chuck. Or am I missing something?

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ibewgypsie
05-05-2003, 09:32 PM
Pretty neat John.. My magnetic base would work too? We used to line up couplings with two dial indicators, check the weeble and wooble.

What I am still learning, all the set up can be ruined by one lil chip in under the morse taper or in the kwik switch tool holder.

Thanks for the post.

Thrud
05-05-2003, 09:50 PM
John Stevenson:
Looks quite usable to me - Bodging at its best!

BTW - you have nice flat stock, must be British Steel! http://bbs.homeshopmachinist.net//biggrin.gif We had a British Steel distributor here and their stuff was beautiful too - even the Cast bar 20" in diameter. http://bbs.homeshopmachinist.net//eek.gif

JCHannum
05-05-2003, 09:51 PM
Ideal made a similar item for their mechanical indicator years ago. It combined the spring loaded type wiggler with a holder for the indicator. Patent has long since expired.
I prefer the Starrett gimbal center finder for quick setup. Can get as close with that as with most indicators in no time at all.

John Stevenson
05-06-2003, 03:50 AM
Herb,
I just wanted something that was permanant.
This was an old clock off a redundant test rig so I can leave it setup and just pop it in as needed.

John S

Paul Gauthier
05-06-2003, 07:02 AM
Nice and quick I like that. Good job.

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Paul G.

John Stevenson
05-06-2003, 08:48 AM
Mark 2 released.
Ok quick mod this morning before I stared on the other blocks.
Took the dial gauge clamp off and just put a simple 2 holes link on to tilt the dial gauge so it can reach the end of the 1/8" rod.
Works a lot better this way.

http://homepage.ntlworld.com/stevenson.engineers/lsteve/files/centre%20finder%20mk2.jpg

John S

G.A. Ewen
05-06-2003, 09:02 AM
Very nice. There will be on in my tool box before long. http://bbs.homeshopmachinist.net//wink.gif