Plans for Centre Finder Wobbler tool

[Jerry CashmanParticipant @jerrycashman49324]

HI guys, I've got to use a 4 jaw chuck for the first time soon so have been reading up on how to easily centre work… I found a reference to a simple looking tool called a Centre Finder Wobbler which has a mount you place in the tool holder, than a longish indicator bar which has a short end and long end with a ball mount in the middle – you carefully put the short end in the centre pop of the workpiece then as you rotate the chuck the long end wobbles about to indicate which way you need to tighten the 4 jaw – sounds much simpler than fiddling around with DTI's for irregular components….

Can anyone ether tell me with I can buy something like this or share 'how to' plans so I can have a go at making one myself please?

cheers. Jerry
Canberra – Australia

[Jerry CashmanParticipant @jerrycashman49324]

[SpringbokParticipant @springbok]

Hi Jerry
Could you tell us what the part is you wish to centre find as there are many ways of doing this. A piccy of item would be helpful
Bob

[Jerry CashmanParticipant @jerrycashman49324]

Hi Bob, it's a very simple part – I'm going to be building an Elmers #25 Wobbler and the cylinder is bored into a rectangular block, with the cylinder bore off-set a little from centre of the rectangular end – so I plan to mark up and pop the centre of the hole, then mount the block in the 4 jaw (a bit offset) and drill/bore.

cheers. Jerry

[Thor 🇳🇴Participant @thor]

Hi Jerry,

I don't know if this is what you were looking for? Here's another with plans in dxf format.

Thor

[Jerry CashmanParticipant @jerrycashman49324]

Thanks guys, the tool I'm looking for looks a bit like the following…

I'm sure I've seen plans for one somewhere, but can't find it now that I want it

[Clive HartlandParticipant @clivehartland94829]

Easiest way is put the block in the 4 jaw chuck with center pop towards tailstock. Bring up tailstock and place another MT center on the tailstock center and the point in the center pop. The MT center will wobble as you turn job and you can by eye bring it into center very easily, then using a DTI complete the centering accurately. No need to buy any expensive one off tooling.

Clive

[JasonBModerator @jasonb]

I have seen plans somewhere, give me a while to dig them out.

But my preference is a sprung centre they located into yout punched hole and the tailstock centre, this gives a round surface that you can then put a DTI against.

The spring keeps the tool in place as the work moves about unlike doing it with a solid pointed bit of bar, I'll dig out a drawing later unless someone else comes up with one.

J

[AndyfParticipant @andyf]

Jerry,

Like Thor, I favour the sort which is supported by a centre in the tailstock, and using an indicator on the end near the workpiece. I made one; picture here. The cannibalised dart is soft soldered to the brass tube, with a spring between it and the steel rod to hold the device in place.

In no way is it concentric, but as the friction between the rear end and the centre is far greater than the friction at the pointy end, it doesn't revolve and concentricity isn't an issue.

After taking the pic, a 1" slit was cut along the side of the tube, to take a pin into the rod, so the thing can't fall apart. All very crude, but works a treat.

If making one like your sketch, consider mounting the long rod in something springy, like through the hole in the end of a piece of old hacksaw blade sticking out from the toolpost. That would save the bother of a ball joint. It does strike me that the rod, which might be rather slender and prone to getting bent, must be dead straight to line up properly with the tailstock centre. But why bother lining up with a centre? Simply adjust the chuck until the far end stops waving around in little circles. Then, a bent rod wouldn't matter.

Andy

[JasonBModerator @jasonb]

Here is one, if you co to construction notes you can download drawings

[Eric CoxParticipant @ericcox50497]

Keep it simple. The accuracy is dependant on your abillity to place the center dot.

There is no point in having a fancy wobble bar and DTI if you can't place a center dot to within a thousanth of an inch.

[Harold Hall 1Participant @haroldhall1]

Here is another one to consider **LINK**

Harold

[AndyfParticipant @andyf]

Posted by Eric Cox on 29/07/2013 08:46:22:

Keep it simple. The accuracy is dependant on your abillity to place the center dot.

There is no point in having a fancy wobble bar and DTI if you can't place a center dot to within a thousanth of an inch.

True, if you want to put the dot dead centre in (e.g.) an existing finished diameter. But if you are leaving that until afterwards, a dot which is few thou out won't matter, will it? Surely the idea of these devices is to enable the chuck to be adjusted to get the dot centred..

Andy

[JasonBModerator @jasonb]

Andy say you wanted to machine an eccentric with a throw of 0.188" you would put the dot 0.188 from the center and pick that up so the placement/throw of the eccentric relies on the accuracy of the punch mark, thats when an optical punch comes in handy.

Or when there are more than one centre on the same item such as this its all down to the placement of the punch mark.

J

[MICHAEL WILLIAMSParticipant @michaelwilliams41215]

Far better to use toolmakers buttons for any job where accuracy of setting up really matters .

MikeW

[John CoatesParticipant @johncoates48577]

Posted by Jerry Cashman on 29/07/2013 06:28:10:

Thanks guys, the tool I'm looking for looks a bit like the following…

I'm sure I've seen plans for one somewhere, but can't find it now that I want it

Sure that has appeared in MEW Jerry. I remember the maker explaining what he used for the material to hold the "needle" in the main body. When I get home from work tonight I'll check my index and see if I can find it unless someone else posts on here first.

John

[peter ravenscroftParticipant @peterravenscroft57700]

try looking in one of kozo hiraoka's books (shays nad the likes

) he shows you how to make one

regards

peter

[dcostaParticipant @dcosta]

Hello Jerry, good after noon.

Using free MEW_Indexes **LINK** I found two ocurring artciles with the word wobbler in the title.
Year: 1997; Issue:46; Page:43; Month: November;Author:Johnson; Title:"Centre Locating Tool version of Wobbler".

Hope this helps
Dias Costa

[Danny M2ZParticipant @dannym2z]

G'day Jerry.

Workshop Practice Series #20 'Metalwork & Machining Hints & Tips' has detailed plans & manufacturing instructions for precisely what you described.

Cu Later * Danny M *

[dcostaParticipant @dcosta]

Hello Jerry, good after noon.

Sorry, forgot hte link.

Using free MEW_Indexes **LINK** I found two ocurring artciles with the word wobbler in the title.
Year: 1997; Issue:46; Page:43; Month: November;Author:Johnson; Title:"Centre Locating Tool version of Wobbler".

Hope this helps
Dias Costa

Edited By dcosta on 29/07/2013 19:30:54

[Jerry CashmanParticipant @jerrycashman49324]

Thansk very much everyone, really appreciate the advice and support!

cheers. Jerry

Jerry Cashman
Canberra – Australia

[HomeUseParticipant @homeuse]

Hi – Yes Kazo has details for Wiggler and other projects The Hobbyist Machine Shop – Kozo's Wliggler

I have made Wiggler and other stuff which works well

Mikeb

[Jerry CashmanParticipant @jerrycashman49324]

Thats the one! thanks Mike!

cheers. Jerry

[Duncan McHargParticipant @duncanmcharg91521]

G'day Jerry,

I knew I'd seen a simple wobler plan in a 1950's issue of Model Engineer. Second one I looked in (Yay). "The Model Engineer" Feb 26th 1953 (Vol. 108 No. 2701). Looks like it would work very well.

I've put it in 'Albums' and select Latest Images. Download the file as the original is larger than what pops up on the screen.

Cheers

Duncan

[Duncan McHargParticipant @duncanmcharg91521]

I was just looking over the article and Irvine is using some Rolls-Royce aero engine ball joints, but the iliustration looks amost identical to the ball joints in the gear change linkage on our '63 Hillman Minx, so we don't have to go to the 'top of the tree' for the parts.

Cheers

Duncan

[Author]

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