Tuesday, January 30, 2007

Marking dark wood

A pencil line on many exotic woods is nearly invisible. The bark of most trees is equally difficult to mark before cutting. One answer is a white china marking pencil, available from office supply stores. Its is designed to mark on glossy surfaces, and the white line is easily visible.

Friday, January 26, 2007

Building my lathe bench

My lathe bench is made from construction grade spruce and plywood. It is 26" wide and 60" long to accomodate both my Nova 3000 and Delta. It is square with no splayed legs but the width makes up for this. The legs and cross members are 4x4's. The frame joints are all mortice and tenon.

Plywood has been fitted to the bottom and sides. This will help keep it square and add rigidity. Eventually sand will be added as ballast. Fishing line has been stretched diagonally between the corners to check that they are planar. They should touch where they cross.

I fixed 2x4's (on their edge) to the top of this frame to support the top. They are easily planed to make the top as flat as possible.

Before the long plywood panel was fitted, I added vertical 2x4's between the beams. When the plywood is screwed to these, there are no large areas of unsupported plywood that could flex or vibrate.

The top is 4 layers of plywood glued and screwed together. Care had to be taken to make sure screws weren't used where bolt holes are needed to secure the lathe.

One invaluable tip for anyone building a workbench is to wire in some power sockets, so that you have somewhere to plug in lights, power tools, vacuums and the like.

Inside the frame I have added plywood panels (the black ones you see here) and filled the resulting cavities with sand. This not only adds weight to the bench, but it adds that weight higher up than if I had merely thrown some sandbags in there. It also reduces any vibration in the exterior panels.

The dimensions are:

61 inches long. That accommodates the Nova headstock and two extensions. I mounted the headstock flush with the end of the bench incase I want to add the outrigger at a later date.

27 inches wide. This is wide enough to have another lathe on the other side, but the important thing is the stability a wide bench gives you.

33 inches high. This was calculated to put the Nova spindle at elbow height, the 'norm' quoted by most books, and it seems good for most things except hollowing vases where it seems to be a bit high. You can always stand on a raised board if the lathe is too high, but you can't make yourself any shorter.

The only other items which seem to be dimensionally important are the positioning of the cross members that the bench top sits on. You need to make sure they won't be in the way of the bolt holes. Apart from that, I think I figured everything else out to maximize usage of 4x8 sheets of plywood.

I did a few sketches to help in determining dimensions, but nothing I would consider a plan! I tried to use materials I had on hand where possible, so a lot of my dimensions are specific to that, and my own circumstances. You will probably be best off figuring out what suits you best. But if you have any other questions, please ask.

What did I do wrong?

Actually, not a lot! I do wish that I hadn't been in such a hurry to try the lathe out, and had given the bench a coat or two of finish. It would probably have been easier to keep clear of dust.

I positioned the 2x4's that support the bench top so that they are either side of the holes where the Nova is bolted down. I positioned them close together so that they would provide maximum support where they are most needed. Unfortunately I didn't give myself enough space to get my hand in to fit the nuts, so that job became really tricky.

Other than that it works pretty good.

Wednesday, January 24, 2007

Wood 2007 - exhibition

The Stephanie Ann Roper Gallery at Frostburg State University (Maryland, USA) presents “Wood 2007”, on view Feb. 10 through Feb. 28. The exhibition looks at how the craft of woodturning is gaining popularity with local artists. It will feature an interesting mix of expressions in woodworking by craftspeople of all levels. It opens with a free, public reception from 2 to 4 p.m. Saturday, Feb. 10.

“Wood 2007” will feature work of the Quad-State Bodgers, a group of regional craftspeople who explore different sculptural forms and objects through woodturning. The Quad-State Bodgers meet on the third Saturday of every month in FSU’s Fine Arts building, room 101.

“Wood 2007” will also highlight pieces by cabinetmakers and other artists just beginning to explore woodworking. The opening reception on Feb. 10 will include a woodturning demonstration and provide more information about the craft’s presence in Western Maryland.

The Stephanie Ann Roper Gallery has free admission and is open to the public Sunday through Wednesday from 1 to 4 p.m. For more information about the exhibition, please contact FSU Department of Visual Arts at ( 301 ) 687-4797.

Tuesday, January 23, 2007

Box lids and wood movement

I once took some nicely fitting boxes to a craft show and by lunch time the lids were all stuck. Since then I have have pretty much given up trying to make boxes as a commercially viable product. Never the less, here are a few thoughts that may help boxmakers refine their process.

First, it's important to realise that a round box and lid will become oval as their moisture content changes, so they may need to be turned upto 90 degrees to get them aligned properly before they will fit.

Rough turning and leaving for several months before finishing may help, both in drying and relieving stress in the wood. In practice I have not found this to be a complete solution to the problem.

Choice of wood may be critical. Look for a wood that shrinks very little, or has similar shrinkage characteristics in both tangential and radial directions. Some of the lowest North American T/R ratios (1.2 - 1.3) are yellow birch, southern magnolia, eastern hophornbeam. Some of the highest are beech, black cherry, American elm, sugar maple, up in the 1.9 - 2.2. I have to admit that most of the boxes I have tried in the past were maple, so maybe I will have to try again with yellow birch or hophornbeam.

Treating the wood to limit movement might be worth trying. Rough turn and leave to dry, then soak in a finish like danish oil before finish turning. There may also be mileage in trying one of the solutions that some bowl turners use for green wood, such as LDD or alcohol, or a proprietary product like pentacryl. I'm not sure though how well these will work on dry wood.

Another thing to consider is the climate you turn in. It might be worth turning boxes only when the RH is mid range, maybe 60%, rather than at an extreme like 30% or 90%.

Turning Boxes, Fine Woodworking DVDTurning Boxes, Fine Woodworking DVD
Richard Raffan shows step-by-step the techniques and tricks to make elegant turned boxes with perfectly fitting lids. You’ll see firsthand how to do the work, the tools, the techniques, and the subtle rhythm of each process. 55 minutes.View sample video clip.

Turning Boxes with Richard Raffan, revisedTurning Boxes with Richard Raffan, revised
Revised and updated full-length study of box-turning. When it comes to turning, there is no greater master to learn from than Richard Raffan. Here in Turning Boxes, Raffan reveals the tricks you need to know when turning boxes, from the cutting and seasoning of the wood to finishing the piece.

Wednesday, January 17, 2007

Zero clearance bandsaw throat

Do you ever cut tiny slivers off with the bandsaw, only to find that they get stuck between the blade and the throat?

When I am cutting small pieces I use a couple of sheets of fridge magnet material on the table, set so there is zero clearance between them and the blade.

I used to stick cardboard to the table, but the magnetic sheets are much more convenient. When they are not in use I slap them on the top door of the saw.