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Plans for Centre Finder Wobbler tool

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Jerry Cashman29/07/2013 03:39:05
21 forum posts
1 photos

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

Springbok29/07/2013 04:37:37
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879 forum posts
34 photos

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 Cashman29/07/2013 04:49:33
21 forum posts
1 photos

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 🇳🇴29/07/2013 05:55:09
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1598 forum posts
45 photos

Hi Jerry,

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

Thor

Jerry Cashman29/07/2013 06:28:10
21 forum posts
1 photos

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

wobbler.jpg

Clive Hartland29/07/2013 07:26:01
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2810 forum posts
40 photos

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

JasonB29/07/2013 07:31:52
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22560 forum posts
2634 photos
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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.

Firefly3

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

Andyf29/07/2013 07:33:55
392 forum posts

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

JasonB29/07/2013 07:37:04
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22560 forum posts
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Here is one, if you co to construction notes you can download drawings

Eric Cox29/07/2013 08:46:22
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541 forum posts
37 photos

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 129/07/2013 08:53:38
418 forum posts
4 photos

Here is another one to consider **LINK**

Harold

Andyf29/07/2013 10:32:10
392 forum posts
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

JasonB29/07/2013 11:44:44
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22560 forum posts
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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

John Coates29/07/2013 12:49:46
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558 forum posts
28 photos
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 ravenscroft29/07/2013 13:21:26
97 forum posts
3 photos

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

) he shows you how to make one

regards

peter

dcosta29/07/2013 16:35:50
496 forum posts
207 photos

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 M2Z29/07/2013 18:52:47
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962 forum posts
1 photos

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 *

dcosta29/07/2013 19:29:31
496 forum posts
207 photos

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 Cashman30/07/2013 03:27:10
21 forum posts
1 photos

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

cheers. Jerry

Jerry Cashman
Canberra - Australia

HomeUse30/07/2013 11:37:08
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168 forum posts
12 photos

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

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