Eccentric Turning

I've turned quite a bit of eccentric stuff over the years and have most, if not all, of the chucks on the market to do this sort of work. From my experinece, I think the answer to both of your questions is: It Depends! It depends on what you are trying to do. A lot of Escoulin's work is made up of many pieces. I really liked his small eccentric spoon that I saw him demonstrate a year or so ago at the Utah Woodturning Symposium. That is done from a single piece of wood.

It's been many years since I did much experimenting with between centers eccentric turning. I normally started at one end and worked toward the other and tried to always make the high points, I suppose you are calling those beads, to come together at a sharp edge and whenever possible turned at all points on the part. You never cut back into a previously turned area and you always do your sanding of a particular offset before going to the next offset point on your design.

Today, the only between centers eccentric things I do is oval hammer handles. I started doing these several years ago when a fellow ask me how to do it. He said a fellow in New Zealand had recommended he contact me. Well, I had never turned an oval hammer handle, but I told him what I would do if I was going to try to turn one. Then I decided to go into the shop to see if what I told him would work. I had just finished giving it a try when my wife walked into the shop carrying her hammer in her hand. The handle had just broken. That afternoon, I turned a new oval handle for her hammer.

It takes lots of practice to turn exactly what you want to create with multi-center turning. What you are doing is the right approach, lot's of practice pieces. I think everything can be worked out mathematically for a given offset and then all of those mathematical images combined to make up a complete plan of the shape you plan to create. It is easier to practice and try out techniques until you began to form a picture in your mind of what you will get if you do a certain thing.

I doubt that I've answered any of your questions so that you can easily proceed to creating superior eccentric pieces. Just start simple and build on those first simple trials.

Perhaps, in a few weeks, I can have more to report, since my wife purchased the new Escoulin chuck from Craft Supplies for my Christmas present. This thing has more adjustments than I have ideas.

Fred Holder

So, how do you turn Ovals? Thanks.

There may be a starting point here...

If it works... As long as you know the terms to search for...

For your entertainment...

============================ Charlie, I'm sure I can't answer your questions properly since I don't really understand all I know about using the Escoulen chuck. I've watched him do his magic, and much of this is due to the chuck he designed and uses. It is not a purely "multi axis centers" devise. It uses a ball and socket design that allows indexing as well as tilt adjustments. This permits you to have adjustments beyond what we would consider as multi axis. In multi axis, we can start at A center, then move the work piece to a different location on either end, or both ends. Any of these movements will give you a specific range of cuts. There must be a way to figure out how these different axis points will/can affect the final turning shape, but I haven't figured it out yet. My best advise is to experiment, and to take notes on what positions you use, and what the end results are. When I get time, that's what I want to do. Also, I've considered trying to buil a wooden version of the Escoulen chuck to experiment with. Good luck.

Ken Moon Webberville, TX.

From the December 2001 issue of More Woodturning:

"First you need to design the cross section at each end of the handle. You need to have a square blank of the proper size and a couple of inches longer than your handle. Without drawings, I?m not sure that I can explain how to determine where to put your multi-center holes. Take the drawing of one of the cross sections and locate a center that will be halfway between the top and bottom of the oval and between the two sides. Take a compass and draw a circle about this that passes over, or through, the center of the top and bottom of the oval. Draw a horizontal line through the center point and place the compass on the side of the oval and mark a line on the center line opposite this side. Do the same for the other side. I believe this will mark the offset needed for that end of the handle. Repeat this operation for the other end. Then making sure your square block is large enough to accomodate this offset, mark off the exact centers at each end and draw a horizontal line to layout your offset. Layout the center points and offset points on each end.

"Now, mount the block on the lathe and turn it round to the shape that you desire making sure that each end is of the diameter of the up and down dimension of your oval. Now. shift out to the offset points on one side and turn until you are almost halfway through at the top and bottom of the oval. Then, shift to the other set of offset points and do this again. You should have a near oval and a little sanding to blend it in should make it very presentable.

Like I said, I haven?t made one, but this would be my approach to doing so. I hope it is clear. Graphically, it seems logical.

This stirred my interest, so I had to find out if my instructions would really work. I went out to the shop and turned a handle out of dry Cherry. I turned on the offsets until the turning on each side joined on a nice little ridge. I used a skew to be able to get the smoothest cut. Then, I returned it to original center and sanded with a strip of 150 grit sandpaper. It became oval quickly. The process that I had described for Don did work."

I've never tried this say to make an oval bowl or platter, but it might work also. Incidentally, my book, "A Guide to Work-Holding on the Lathe", contains a description of how to do this and provides the layout drawings plus some photos as well.

Fred Holder

Even with no abbreviations, acronyms or insider jargon the terms used in eccentric turning can be confusing, at least for me. I think of eccentric turning as limited to either "multi axis between centers" or "single or multi axis on a single center not concentric with the spindle axis". To me, inside-out, pumping, oval chucks, rose engines, ornamental turning and voodoo are all separate entities distinct from eccentric turning. This may not be accurate nor a good way to consider eccentric turning.

I hope Fred, Ken, Charlie and others will post an outline and/or suggest terms that we can all use to describe turning that's not on a single axis that's coaxial. Unless, of course, I'm the only one who gets confused and fits another definition of eccentric.

Turn to Safety, Arch Fortiter

"Ken Moon" wrote: (clip) Also, I've considered trying to build a wooden version of the Escoulen chuck to experiment with. (clip) ^^^^^^^^^^^^^^^ I have built a coupl;e of vacuum chucks that simulate the action of the Escoulen chuck. Turn a wooden, faceplate-mounted piece of wood to a spherical shape, and feed your vacuum through the spindle. Turn a sort of flat bowl to stick to the spherical surface by vacuum. Attach your work piece to this. You will be able to slide this off axis and hold it in various positions, much as Escoulen does. To fully simulate Escoulen's chuck, the spherical surface should be convex.

However, I prefer to use a concave spherical surface, which results in having the work spin with the unsupported end on axis. This has some advantages:

1.) It is less hazardous. 2.) It permits you to use tailstock support. 3.) Cuts that are made on the end of the piece, where it is weakest, are made on axis--interrupted cutting (cutting air) is minimized, so there is much less danger of catching and breaking the piece.

"Fred Holder" wrote: (clip) I've never tried this say to make an oval bowl or platter, but it might work also. (clip) ^^^^^^^^^^^^^^^^^ It will work on the outside, but the best you can achieve on the inside will be a round cut. The minute you so offset, you'll see that the side that is not being cut will run into the tool. If you want uniform walls, you will have to do some hand carving.

Referring now to the outside, you are making an "oval" by blending two different radii. For larger work, the transition between the end radius and the side radius will not blend as well (you will see a sharp edge at the transition) and sanding to correct this will become more difficult.

Hello Arch,

I think of multi-center turning and eccentric turning as one and the same; however, in the manual that comes with the new Escoulen Reversed ball and socket chuck, which I received as a Christmas Present from my wife, they define the action of the chuck as being able to do three types of work:

1. Turn off center with the axis parallel to the spindle
2. Eccentric turning, in changing the angle of the axis
3. and combining both of the previous possibilities.

The chuck is currently mounted on my Nova DVR Lathe and ready to try out, as soon as I can decide what I want to try with it.

In essence, Number 1 above is the same as placing a piece of wood between centers and then offsetting it from center the same amount on each end. Number 2 above is the same as placing a piece of wood between centers and then offsetting the tailstock end off center, which is what happens with the ball and socket chuck. I don't know of a way to accomplish the third, which is a combination of both forms of offset.

Jean-Fancois Escoulen considers the work done by his ball and socket chuck to be eccentric. Robert Sorby considers the work done by their eccentric chuck to be eccentric although it basically performs the actions described in 1 above. It is all multi-center turning.

Fred Holder

I consider pretty much anything turned by myself as an eccentric turning. Others?

(Hanging head in shame) Just took me 20 minutes to find your book and about

15 seconds to find the diagram and instructions! As you can tell, I've only read what I thought were the 'good bits' in your very fine book. Guess I really need to do a cover to cover.

Thanks, Fred.

LD

Im not sure about the Product, but any time I am turning it fits the definition of Eccentric turning.

>

I was asking about between centers "eccentric" turning using different center points on each end of the blank. If you put the drive center on one corner of a square cross section blank and the tail stock live center on the diagonally opposite corner of the blank - you'll have a "null point" at the middle of the length of the blank - you'll have the maximum shadow at each end of the blank

Line drawing illustrations would make this easier but I'll see what I can do with ASCII "illustrations"

o \ /

Thanks to all you respondents to my query. Like rec.woodworking, this group has some very knowlegeable folks willing to share hard earned experience and insights.

I have "A Guide To Work-Holding On The Lathe" but hadn't connect Fred to it, though I realized this group's Fred had quite a bit of turning experience. To have the skills and experience to turn just about anything you can think of is wonderful. To be able to explain it well enough for someone else to do it is a more difficult task - especially when limited to "text only".

While Trial & Error is one way to get to being able to "see" the finished piece before actually turning it , I'd prefer a method that let's me "see" the piece via a less haphazard path.

What I'm looking for, and am working on a set of instructions - with illustrations, is a method to develop a "plan"/drawing for a

-"between centers"

- "vary the center points"

-"coves first, then the in between beads" or "beads first, then the coves connecting them" turned "spindle". Eccentric bowls I'll leave for someone else.

I've posted a first cut at a "beads first" method to alt.binaries.pictures.woodworking with the subject line

Eccentric Turning - Between Centers Eccentric Turning"Plan" Method

The attached file is a 48K GIF file that is about a page and a half of illustrations with accompanying text instructions. Feedback, comments. questions and constructive criticism will be appreciated.

If, with the help of this group, a set of simple, fairly easy to follow, instructions can be developed it can go into the Knowledge Pool and hopefully will a) get someone to try something they didn't think they could do because it seemed too confusing or too hard b) make it easier for folks who have already gotten into "eccentric turning" to work out an idea BEFORE turning a bunch of trial and error pieces.

Am now working on a set of instructions, usig the same basic approach, for a "coves first" method. Will post it to a.b.p.w when it's done.

charlie b