Wednesday, February 27, 2008

work in progress: burl on the lathe 2

The work on the burl continues after a day or so hiatus. I had a funeral and that takes precedence over everything, even turning. Nice fellow, but sixty years of heavy smoking catches up with you. Lung cancer. Take care of yourselves and use those dust masks when sanding.
Anyway I got the piece roughed and attached a faceplate and glueblock to be able to use all the burl. I have used epoxy which is likely overkill, but I like overkill especially when I take the chance of throwing something at my face. You can see the work as it continues if you would like to take a look.

Sunday, February 24, 2008

Spam warning

I just checked my blog here and found a comment by Tojagal. Clicking on it immediately led me to one of those obnoxious registry scanner programs designed to scare the crap out of anyone who does not know better. Total spam. The comment has been deleted. Do not click on comments by Tojagal. Spam, spam, spam. Now back to wood turning.

Friday, February 22, 2008

work in progress: burl on the lathe

I managed at last to get a chance to get a couple of pictures and thoughts up about the first spruce burl. It is about 10" x 10" but will likely produce an 8" hollow form given the vagaries of burls. So far I have been able to make some design decisions and find out some of the difficulties it will throw at me. I expect to use the regular hollowing tools for this one, but it has introduced some interesting problems in mounting. The wood is soft and displays some of the common punky and spalted woods that are often found in spruce burl. On the other hand, it also has some of those bark inclusions, sap pockets and incurves that make these so much fun. Challenges are only design opportunities after all.
starting the burl

Sunday, February 17, 2008

New Work in Progress

I have been having some difficulty with uploading to YouTube so the next installment on the natural edged bowl will be a while, but at least I am trying. Meanwhile I have started another work in progress. This time it is deciphering a pile of wood that is mostly burls.

One of them, the large spruce burl has to made into a fruit bowl, I think with the natural edge obvious. The folks who own the big burl, I think maple, want a piece made with the burl surface obvious or emphasized. Other than that, it will be whatever the wood and I want. To start with I am going to do something with one of the smaller spruce burls.

This should be fun.

Wednesday, February 13, 2008

Sharpening Wood Turning Tools (3)

One thing a wood turner must do is rid oneself of the notion that the tool in the shop is a grinder, at least most of the time. For sharpening things like plane irons and chisels we have all sorts of things like sandpaper of various grits, oil or water stones, strops and who knows what all. To each his or her own.

For wood turning tools, we generally go straight from the grinder to the lathe. However, in this case the grinder is the sharpener. It is set up differently from that of a general shop worker or metal worker. Instead, it is set up to work with wood turning tools so as to give them a good edge and get quickly back to work.

For this I like a general purpose grinder available at most hardware stores. Mine is a high speed grinder, 1350 rpm. I realize that some like a slower sharpener but again to each his or her own. The reason stems from older tools make of carbon steel and also from a lack of experience. Improper technique on a fast sharpener tends to build up heat that will destroy the temper of carbon steel tools. Today's high speed steel (HSS) tools will be fine. Good technique makes a world of difference as in almost everything else.

Most grinders come with wheels well suited for grinding, not sharpening. One is likely coarse and the other medium. I like to put the medium one on the right side for grinding away nicks or dents in tools or to shape them when necessary. I do not like the little tables that come on most grinders and made a larger one for mine.

The left side becomes the sharpening side with an 80 grit or 100 grit aluminum oxide wheel. Some people like the white wheels but I find them too easy to wear and prefer a normal consumer wheel which for some reason wears better and costs a lot less.

Keep the wheels clean and round with a wheel dresser. I have used both a diamond dresser and a star wheel dresser and both work well. Clean wheels cut better and cooler.

On the left side goes a jig for sharpening. I simply find it gives a better, more easily repeatable grind. While some people like the jig for eliminating facets on the tool the best reason for using it is the repeatability of the grind. This allows your body to become used to the angles and learn to turn with the same tools, building habits of control. This is especially important for beginners. Once a lot of practice has been made you can more easily compensate for a different grind.

Monday, February 04, 2008

Sharpening Wood Turning Tools (2)

As Derek was saying (see his site by the way at Seafoam Woodturning )The motions used in freehand sharpening are similar to those we use in turning. For instance, to sharpen a roughing gouge one

  1. presents the tool resting on the grinder table (that rest in front of the wheel) with the flute up and the tool not yet touching the wheel.

  2. if right handed the handle is held in the right hand against the right hip

  3. the left hand steadies the tool on the grinder table

  4. raises the handle until the heel of the bevel touches the wheel gently and a hair more until sparks move over the edge

  5. roll the tool to the right as sparks move over the edge

  6. roll the tool to the left as sparks move over the edge

In theory the tool has moved through the same motions as cleaning a fine shaving right and left. The sparks coming over the edge indicate that a sharp edge has been formed and you are ready to turn.

In reality I find this is the time turners move the tool in wide arcs as they inspect the edge for sharpness and for facets on the bevel. If you are unsure of your sharpening enough for this to happen, you will likely consider

  1. the edge not good enough

  2. too many facets on the bevel

  3. the angle has changed

and back to the grinder you go until you have really messed things up or give up in disgust and go to the work anyway and find the edge works fine, but could have been better.

One of the big problems is simply you moved before returning to the wheel. The practice is sound but it needs practice. Try a couple of things.

  1. practice the motions with the grinder off. Feel the bevel on the wheel and do it several times. So it takes a few minutes; hopefully you are going to do this for the rest of your life.

  2. ignore the facets. No one else will see them and they will not really affect the final cut no matter what the jig using people like me say.

  3. ignore the angle. You have not likely changed it enough to matter. A degree or so is not the damage most people think. If you are off five degrees or more you really need a coarser wheel to reshape it and that is another subject.

  4. most important of all, do not move your hands from their anchor as you look at the edge. The left stays on the tool shaft and the right on the handle at your hip. That way you become the jig and the tool returns to the same place each time

I hope this helps. More thoughts to come.

Sunday, February 03, 2008

Sharpening Wood Turning Tools

There has been a discussion in progress over rec.crafts.woodturning dealing with some of the ins and outs of sharpening wood turning tools. I thought I would post a few of my views.

First of all, there is no definitive way to sharpen out tools and the same person will use different methods of sharpening say a skew versus a roughing gouge. I, for instance, would sharpen a skew free hand but use a jig for the roughing gouge, at least most of the time. A bowl gouge I would almost always sharpen with a jig for long wings but likely freehand for straight across but sometimes would reverse that. While I would like to give coherent reasons for doing so it probably depends more on mood than logic.

One of the problems that beginners have and continue having as they begin turning is the mastery not of sharpening, but of sharpening turning tools. Many turners begin their woodworking careers with flat work of some sort. There router bits and table saw blades are generally sent out for sharpening while chisels and plane irons are sharpened with an assortment of stones or sandpaper and possibly a few jigs. There also tends to be a fairly long interval between sharpenings. Not so with wood turning.

A wood lathe simply moves wood over the edge of the tool faster than does most other wood working methods. Wood turners also tend to use wood that is rougher than flat woodworkers and it may still have bark and grit in it. The edge of the tool simply does not last for very long under such circumstances.

Flat workers tend to use grinders to remove large amounts of metal under circumstances such as dents and nicks that call for a tool to be reshaped. A wood turner uses a grinder to quickly sharpen and get back to work. The fine edge of the wood plane simply disappears under the speed and fury of the lathe but the edge from the grinder lasts sufficiently well and cuts sufficiently well to be considered more than adequate for the job.

So a grinder should be thought of as a sharpener and only enough metal should be intended to be removed so as to leave a good cutting edge. For this reason some turners think a slow speed grinder is best for the job as it is cooler to work with and supposedly removes less metal. Others such as myself like a high speed grinder as with high speed steel heat is not an issue and I only intend to remove enough steel to leave a good edge. Enough is enough whether one uses a fast or slow grinder.

Over the next few days I will add some thoughts on free hand sharpening versus the jig.