Finding the centre

[splott]

I am new to the world of wood turning and was wondering what the best way of finding the centre of a log, is it best to use the pith. Any good advice will be appreciated

[wheelinround]

Welcome Splott
you can buy one of these http://www.woodcraftsupplies.com.au/showitem.php?cat=AC01&item=9656

or make one

I measure usually find it more accurate as many logs are not round

[TTIT]

One of those gadgets Wheelin' suggested does the trick but on your average not-quite-round, all over the place type log, just judge centre by eye or a few quick measurements and completely ignore the pith - you will get better visual effects from the growth layers by being away from the heart with your centre anyway.:U

........and welcome to the forum :;

[artme]

G'day Splott. Welcome to the madhouse.:):D
Can Make your own centre finder.
Get a square of ply, run diagonal line with pencil.
Run lines parallel to two adjacent sides from one of the corners of the diagonal line ( about ruler width is good as you can use rule to make lines parallel).
Cut along diagonal line to point where it crosses the two intersecting lines you drew. ( The ones parallel to the two adjacent sides)
Make another cut parallel to this cut, again a ruler width away and stop where it intersects the line.
Two more cuts along each of the side lines so that the triangles fall out.
You have a centre finder.:o

Otherwise do as TTIT does.:q:q:q

[orraloon]

G'day Splott and welcome,
On a log just eyeball it. The center finder works on a circle but most logs are
not perfectly round. As TTIT says pick a spot to take advantage of the grain pattern. Large heavy stock you want to close to the center for balance and use a slow speed to start with. It gets the blood pumping when the lathe is jumping around the place.
On square stock cross the diagonals. I get by with a steel rule and compasses and have not had the urge to get a center finder.


Regards
John

[Calm]

A trick from (Grand Master & legend) using a "square" to find the centre of a circle, So with a log it would work as well as any other centre finder.

Place the corner of the square on the edge of the circle and mark where the straight edges meet the ouside of the circle. measure 1/2 way between these points and that is the centre.

If i could do sketches i would add one but i havent worked that out yet.

[Skew ChiDAMN!!]

I made up a fairly simple gauge, similar to the one wheelin' showed but much cheaper. :-
65149

I've found that in practice it's pretty good for determining centres, even on heavily ovalled pieces. I'll use it to make four or more marks, at least one from every quadrant, and even though they rarely all intersect in one spot they define a much smaller area.

It's a helluva lot easier to accurately eyeball the centre of this small area than the entire end of a log. :;

[robutacion]

Hi splott.

I have made this tool, and works very well for me.
This is a link to my site, where the information is.
http://timberssoul.webs.com/centrefindercircular.htm

Hope this helps

Cheers
RBTCO

[scooter]

I have a Vicmarc centre finder similar to the one wheelin linked to above, it is made of cast alloy or similar & has other handy stuff like angles for gouge edges, etc around the outside. Link here (http://images.google.com.au/imgres?imgurl=http://www.jacquescoulombe.com/dscn1333.jpg&imgrefurl=http://www.jacquescoulombe.com/vicmarc.htm&h=478&w=567&sz=14&hl=en&start=4&tbnid=ls6MvDYbAeIsiM:&tbnh=113&tbnw=134&prev=/images%3Fq%3Dvicmarc%2Bcentre%2Bfinder%26gbv%3D2%26svnum%3D10%26hl%3Den%26safe%3Doff%26sa%3DG).http://images.google.com.au/imgres?imgurl=http://www.jacquescoulombe.com/dscn1333.jpg&imgrefurl=http://www.jacquescoulombe.com/vicmarc.htm&h=478&w=567&sz=14&hl=en&start=4&tbnid=ls6MvDYbAeIsiM:&tbnh=113&tbnw=134&prev=/images%3Fq%3Dvicmarc%2Bcentre%2Bfinder%26gbv%3D2%26svnum%3D10%26hl%3Den%26safe%3Doff%26sa%3DGhttp://images.google.com.au/imgres?imgurl=http://www.jacquescoulombe.com/dscn1333.jpg&imgrefurl=http://www.jacquescoulombe.com/vicmarc.htm&h=478&w=567&sz=14&hl=en&start=4&tbnid=ls6MvDYbAeIsiM:&tbnh=113&tbnw=134&prev=/images%3Fq%3Dvicmarc%2Bcentre%2Bfinder%26gbv%3D2%26svnum%3D10%26hl%3Den%26safe%3Doff%26sa%3DG

I read an idea somewhere & made a perspex one that I probably use more than the vicmarc one. I got a square of clear perspex about 6" on edge, found the centre using the diagonals & drilled a small hole, then with one leg of a sharp set of dividers on centre scored a series of concentric circles about 10mm or so apart as big as the square would allow. Then drilled out the centre a little bigger so as to fit an awl (sheoak handled scratch awl that dai sensei made - v nice. :) ). Drill another hole in the corner for hanging, and flame all edges to smooth.

Used by placing on the end of the log & moved around to determine the centre you want, then sticking the awl through the middle to mark the centre for turning.

[splott]

Thank you all very much big help much appreciated. Can make a start on turning these big logs i have.

[Calm]

Under instruction from the kids i made the sketch in Paint, saved it and now hopefully will attach it. Gee i'm getting cleverer all the time - next i will try to set the VCR or even watch a DVD if i can start it.

This is 's trick and works quite well. If the log is not perfectly round i do it in a couple of different places then choose a common point.

[scooter]

Good drawing David :2tsup:

[Black Ned]

I have been making and using this as a centre finder.

Use a drawing or paint program to draw concentric circles on a cross hair grid.

Substitute Transparency film for paper and print.

I have done this both using Laser and Inkjet Printers and have had good results.

Make a few and discard when damaged.

If you are careful they will last for years.

Pierce the centre so you can use a pencil or compass point.

[robutacion]

Hi splott,

Another day I gave you the link to my wed site, for you to have a look of what I made and use to get my centres. In the 4 pics that I had there, it did show the tool but didn't say much about how to use it, etc. I took some pictures yesterday, when using it on a job, this way you can see how and why is so effective, so have another look!


Cheers
RBTCO

[Sawdust Maker]

Another idea
I'd put aside a number of the kids cereal packets (growing boys eat a lot of cereal so we buy larger sizes)
One wet rainy day (like today) I grabbed some and a compass and cut out a number of circles from the biggest I could make then decreasing them by about 10cm for each successive one. The biggest is about 250mm the smallest 80mm.
I use these, both for marking out a cutting line for the bandsaw and using an awl to mark the centre. When doing a cutting line on a half log or similar I sight from above, sort of like using a shadow line.

[splott]

Cheers robutaction that is a great help just created one yesterday