Dividers.

[Adam Petersen]

I recently got a nice pair of old Pexto dividers. I understand their use in dovetail layout but am curious what else people use them for? Does anyone have any good references to study the use of dividers? I did some googling and searched this site, but it's mostly all dovetail or look what I got threads. Just curious.

Thanks,

Adam

[Edward Mitton]

Hi, Adam,
I've used dividers in a number of applications:
Marking repetitive dimension on workpieces. This is the one you've commonly seen for dovetail layout. This method can also be used for marking such things as evenly spaced holes to be drilled along a line.
Transferring dimensions from an existing piece to a piece of stock for making a copy.
Laying out geometric shapes such as octogon or star patterns.
Scribing circles and radii.
Finding the center of a rectangular worpiece.

I'm sure there are many other uses I haven't touched on here.
In a pinch I've even grabbed a pair of dividers to use as a marking awl for hole centers when I couldn't find my regular awl.

[Mel Fulks]

The old architecture books showed detail size expressed as how many divided ,(by dividers) parts of the whole it should occupy. I've used them like that for high grade work,little call for it since the hodge podge style took over .Also used to space louver slats ,etc.when the rails must all be in a predetermined position.Used on maps and charts to determine distance by different routes.

[Mike Henderson]

I use dividers often in my shop. Of the top of my head, I can't think of other applications than the ones Edward mentioned, but I find myself often reaching for a divider. Every shop should have one or more dividers (different sizes).

Mike

[James Conrad]

You might want to take a look at the book By Hand & Eye by George Walker and Jim Tolpin. It provides a very good historical look at the use of dividers and proportional design, along with practical exercises.

[John Sanford]

You will find your answer here:

By Hand & Eye (http://www.lostartpress.com/product_p/bk-bhae.htm)

The answer is very, very good. Eye opening and mind expanding, in the best sense.

[Jim Ritter]

I use dividers (with a pencil) to scribe parts of a boat to fit.
Jim

[jason thigpen]

+1 on By Hand and Eye. Amazing resource.

[Jim Koepke]

Another source for information might be old drafting (draughting) texts. There may be some available through your local library system. The uses on paper can also be used on wood.

There are also various types of dividers (compass, caliper, oddleg). With care, a compass can be used like a scribing gauge for marking a pencil line a controlled distance from an edge. This is often done with one end of a compass on a surface and the pencil end marking a leg or other piece.

I often use dividers to check and compare pieces for thickness.

273987

On the top left is a bow compass. At least my memory thinks that is what this type with a center wheel adjustment is called. The lead holder can be changed for a point or an inking pen. Some use the inking pen by removing the adjustable blade and sharpening the static blade to use like a marking knife.

Center left is divider 9". Center bottom is a caliper/divider for measuring and comparing inside measurments.

Top right is an outside caliper/divider for measuring outside.

Second and third from the top are two small dividers/compass. The one on the right can be changed to pin point, pencil point or pen point.

Next is a inside/outside caliper.

Second from the bottom is another multi-tip friction divider/compass. This one allows the legs to be moved independently. It is more like what is known as an oddleg divider used for marking distances from an edge.

Finally bottom right is a simple friction divider. The legs move together.

When ever a size has to be compared they can be handy if the actual measurement isn't needed. If a measurement is needed in a difficult to reach place they can also be handy.

Finding centers has already been mentioned.

Both Chris Schwarz and Roy Underhill have recently shown how to layout an ogee using a compass.

There are more of them in my accumulation. There are a couple of drafting sets that are still packed from our last move. There is also a drafting set that sits on a shelf.

Old drafting sets can often be bought for $20 or less. Often at yard sales one can find individual compass/dividers for cheap. The inside/outside calipers might not be cheap if it is an old machinist selling them.

jtk

[Chuck Nickerson]

"By Hand and Eye" is great.

For a deeper dive there's a reprint of a 1773 "Treatise on Scientific Instruments".
It was not easy for me to read and work the exercises but it's a matter of timing.
While sitting with my MIL during her final week working through parts of that book kept me sane.

[Bob Glenn]

Used with a sector, they have lots of uses. Proportioning, dividing distances in halves, thirds, sevenths, what have you.

[Jim Koepke]

Three of mine were used yesterday to lay out mortises on legs for a small table.

Guess some pictures would be in order.

Maybe when it is all done a write up chronicling the build will be posted.

jtk

[Adam Petersen]

Thanks guys, I ordered by hand and eye today. It'll by my Christmas present from my mom. I'll probably read it before I wrap it though. lol.

[Cory Newman]

I use them alot on the lathe for transfering measurements.

[Adam Petersen]

Shameless Tools for Working Wood plug to follow:

Ordered By Hand and Eye from them on early Thursday morning. Showed up at my door Saturday well packaged and in immaculate condition. That's awesome shipping response. Cheapest shipping of the places I checked too. Started to read it and my wife took it and put it in the Christmas present pile. Damn.

[Jessica Pierce-LaRose]

I've linked these on forum posts, but I don't know if I've done it here before or not, but looking up "compass and straightedge constructions" finds you lots of neat things you can do with dividers. There's plenty of historical texts on these things, of course, but here's a couple of modern versions. The animations help a lot for some folks.

http://www.mathopenref.com/constructions.html

http://www.mathsisfun.com/geometry/constructions.html

I keep meaning to pick up By Hand and Eye. I remember seeing a video they linked showing Violin layout with dividers that blew my mind:

http://kigiri.free.fr/tdl/eng/page3/files/page3_5.swf

(You need flash enabled for that last link, and probably some of the earlier two)

[Jessica Pierce-LaRose]

From my previous post, this is actually one of my favorite divider tricks that I've used quite a bit:

http://www.mathopenref.com/constdividesegment.html

Using dividers, I just make small pricks along the lines rather than drawing arcs with a compass. Often I do it right on the piece, other times I just mark stuff on my bench - (My bench is often covered in calculations and drawings and such, and if I mark the divisions on the bench, I can slide the piece up and transfer the lines to end of the workpiece.)

[Adam Petersen]

Thanks for those links Joshua. I watched a bunch of them and played with the even division of a sector. I did use my dividers to walk off some exact shelf pin locations. It worked a charm for that purpose. I always used a ruler and did inexact measurements for those. This was so much easier and quicker. Can't wait to see what else I can do in my future projects. Thanks everyone!

[James Conrad]

Here are some more animations you can download: http://lostartpress.files.wordpress.com/2013/05/by-hand-eye-animations.zip