With the cost of hardwood these days, it can be prohibitive to turn anything on a lathe let alone practice. Many beginning turners and even the experienced move to the firewood pile for turning wood. While the practised turners will have little trouble mounting the wood, beginners need a couple of hints to get started.
Thursday, February 09, 2012
A lot of firewood will come in sixteen inch lengths and will be spilt in halves or quarters of the log. For spindle practice select a quarter log about three inches on a side with no splits on the end. If there are small splits they can be dealt with in the shop. Cutting an inch off the ends will generally get rid of the small splits in a quarter section of log. If it does not, cut off another inch or get another piece of wood from the firewood pile.
As you examine the face of the quarter log you will realize that you can get about a two inch turning square from the quarter. For all intents and purposes divide the width of the quarter (three inches) by three and multiply by two. If you have a bandsaw you can cut the waste away to leave a rough square or it can be done laboriously with a hand saw. This is not a good cut to do at the table saw.
Another option is to remove the waste at the lathe. Starting at the corner of the section measure in an inch and up an inch on each end. This will give the centers of the two inch square. At the wood lathe choose one end for the headstock and the other for the tail. Center the spur center at the headstock on the center mark of the wood and hit it on the other end with a mallet to drive the spur center home. Some turners object to this for fear of hurting the bearings but this if a bearing will be hurt by such an event it is too light for woodturning.
Bring up the tail stock and center the tail center on the mark for the square center. Tighten the tailstock and advance the center to hold the wood firmly in place. Because of all the extra wood on the log section it will be very unbalanced. Learning to deal with it is a good exercise in lathe work.
Make sure, with the lathe off, that the wood clears the tool rest and tighten the rest down. Stand clear of the wood and turn the lathe on to its lowest speed to make sure the wood is secure in the centers.
Sharpen a roughing gouge and prepare to rough down the wood. The tool should be held firmly on the tool rest and held so that the tip is above the spinning wood. It will bounce on the uneven wood but not cut. The handle of the tool rests on the hip and the planned cut will be very near one end of the wood, usually the tail stock end. As the handle slides up the hip and the tip moves down the wood a chipping cut will begin as the tool nears forty five degrees. Cut towards the end of the log. After the cut is done move down the log a little and repeat. This continues until the other end of the log is reached. At this point move the tool rest in towards the wood so as to give better control and repeat until the wood is round. Now it can proceed as any other spindle.
Firewood is a great source for practice wood and also for advanced projects. It is dry enough to work and provides an excellent supply of local hardwoods for woodturning enjoyment.
Wednesday, November 16, 2011
After the wood lathe itself, one of the most used tools in the woodturning workshop is the band saw. For many woodturners, after the lathe and the grinder have been bought and set up, the band saw is the next purchase for large machinery. A few simple steps make it a better tool for woodturners and other woodworkers.
Like many woodworking machines, the band saw needs to be set up and periodically tuned for safe and accurate use. Most such machines in the home shop are typically two wheel saws, fourteen inches in diameter. The size refers to the diameter of the wheels and not to the depth of cut which will likely be in the six inch range.
Those wheels will look much like bicycle tires with rubber rims. While they will of course be clean in a new saw, as the tool is used the tires need periodically to be brushed clean of dust which will cake on to them especially from green softwoods. They also need to be properly lined up.
This means they need to be parallel to one another and running coplanar. There should be a means to adjust the distance of the free running wheel, that is, the one not powered by the motor. While this may be form shims, set screws or some other method, it should be noted in the instructions from the saw. A straight edge spanning both wheels, placed immediately before the axles, should touch the top and bottom rims of both the top and bottom wheels simultaneously for the wheels to be coplanar and parallel.
Once this is done, the blade should run at the center of both wheels. There will be an adjusting knob to track the blade. With the saw unplugged rotate the wheels by hand and adjust to track in the middle. Tighten the blade so it can be moved a quarter of an inch at center or follow the instructions with your saw. Each blade will need to be tracked and tensioned when it is installed and may need periodic adjustment during use.
A band saw is useful for wood preparation both for small projects and for large. For small, finer cuts a one quarter inch six tooth blade is a good one to start with for general use and wood up to a couple of inches thick. Heavier green wood for bowls and the like will require a three eighths three point blade or something similar. Like all saws, blades need to be kept sharp and clean for good use. Having a couple of extras on hand is a good idea.
Band saws are versatile for straight or curved cuts and a valuable asset for the woodturner. They are easy to set up and use as well as being one of the safest cutting tools in the shop.
Tuesday, October 18, 2011
While it is obvious that wood lathes spin wood around, it is not always obvious to the first time buyer that spinning wood, if out of balance, vibrates tremendously. In addition, wood lathes may be asked to spin very heavy sections of wood and need to be able to withstand considerable force. There are a couple of simple things to look for to ensure that a lathe is sturdy enough for the work at hand.
If you have a small shop and intend to turn small objects, it may seem as if sturdiness will not be a factor, but this is simply not so. Most small lathes turn at high speeds and have a very high minimum speed. Just as on a car, an unbalanced wheel does not seem a problem at low speeds but vibrates at high ones, the same thing happens on a lathe with unbalanced wood or with unbalanced lathe parts. While a small piece on a small lathe may not try to walk across the floor, vibration encourages poor cuts and difficulty in a good finish.
Larger lathes tend to have lower minimum speeds and thus allow for less vibration in unbalanced pieces. However they also are generally bought with the purpose of handling larger pieces of wood and thus more weight. A bowl blank of forty pounds is not unusual on a lathe with a twelve to sixteen inch swing and can literally walk a light lathe across the floor of the shop.
The solution to the problem is to have a lathe sturdy enough to handle the work. It starts with a good foundation such as a stand that is well made and heavy enough to not move under the forces of turning. Sand is a good vibration absorber and many turners design their lathe stands to hold hundred of pounds of sand.
The lathe itself should have lots of cast iron and steel in its construction. Stamped metal parts tend to give little support. Good welds should be looked for. Check with your woodturning friends and find out what lathes they use for the type of turning you intend to do and then find out if they are satisfied. Good bearings are a must and even more important are the bearing housings. Bearings are easily replaced but not where they live in the lathe.
One of the best tests of sturdiness is common sense when looking at the lathe. If it looks solid it likely is. This would not be just a catalogue look but rather a chance to stand at it and see if the steel is substantial and the iron castings are solid and well finished. The mechanisms to hold the headstock, tailstock and tool rest should be strong and lock firmly. Speed controls should move easily and switches readily accessible.
The final test of the lathe will happen as you turn on it. Many turners will push the envelope of size and speed and safety is each individual's responsibility but much of it can be ensured with good planning and a little foresight.
Friday, October 07, 2011
One of the best and worst things to happen to modern woodturning is the invention of the four jaw chuck for holding wood. While it is a great addition to the woodturner's asenal, it is also an expensive tool and many beginners find that it costs more than their wood lathe. Also, like many tools a cheaper version is aggravating and in some cases simply dangerous to use. One thing to remember is woodturning has been around for thousands of years and there are many ways to mount the wood without the newest fashions. The Jacob's chuck is a great tool for all turners.
A Jacob's chuck is designed for holding drill bits. It is the chuck on the end of the drill press or the electric hand drill. As such it is often used held in the tail stock of the lathe to hold a drill bit for putting a hole in a piece of wood in the head stock or vice versa. However, it may also be used to hold a piece of wood for turning.
The difficulties in using a Jacob's chuck for holding wood are
- its size which is generally limited to one half inch although slightly smaller or larger ones are available for some lathes
- its having three jaws which make it awkward to hold onto a square piece of wood
- it is made for holding metal and may well crush the wood in its jaws
These limitations are easily dealt with.
The time to use a Jacob's chuck is generally to turn a spindle that needs to be held on one end only. This means that the stronger grain orientation of long grain is being used as opposed to face grain. In such circumstances a piece of one half inch wood such as maple is easily strong enough to support a three inch spindle of reasonable length. It remains to mount the spindle first between centers and turn it round, allowing for a short length at one end to be turned down to one half inch so as to fit in the chuck. Now it can be remounted in the chuck, trued up and finish turned.
Note that this also removes the second difficulty of trying to fit a square piece of wood into a three jaw structure. The tenon to fit the chuck is now round. It also deals with the third problem of crushing the wood. This would serve to mar the wood and also to move the piece off center for turning. A truing cut will put it back on center and the tenon is considered waste wood and removed from the finished piece.
The old and established technology of the Jacob's chuck is not as versatile as the newer four jaw chuck but it is reliable at a much lower cost and opens new avenues of wood turning to the beginner without a lot of expenditure. Besides which, a Jacob's chuck is a welcome addition to every turner's arsenal.