Wednesday 15 June 2011
Mark Sanger makes this stunning scorched and textured floor sculpture from an oak post which can be placed inside or outside, or can even be scaled down
For this project I wanted to make a tall sculptural form that could either be placed in a living room or garden. An unseasoned 180mm (7in) square x 1200mm (48in) long oak (Quercus robur) post was chosen for several reasons. Oak will withstand the natural elements if placed outside. It is also not possible to obtain wood of this thickness that is fully seasoned so the natural cracking that will occur over time has to be taken into consideration, and included within the design process.
The sculpture has been kept organic with texturing and scorching being incorporated that will complement the cracks that will naturally occur over time. All tooling marks have been left with no sanding or scraping being used, thus adding to the overall texture of the form.
If you do not like the idea of your project cracking then you can simply scale it down and use a piece of 100mm (4in) square seasoned wood, meaning it could then be displayed in a cabinet or on a shelf.
It is important, however, to recognise that, at times, cracks within wood are a natural process if you are using stock that is sized over 100mm (4in) square.
Oak has been used as a building material for hundreds of years with the maker having the knowledge that the wood will move and crack and using this to advantage to secure joints etc. It is only recently that we have become accustomed to viewing wood as needing to be perfect in its finish. There is, however, so much more that can be achieved and embraced with this wonderful material, and hopefully this article will provide you with some new ideas. Allowing the wood to naturally crack without control is an exciting part of the process.
Tools used: 32mm (1 1/4in) spindle roughing gouge, 12mm (1/2in) bowl gouge, 10mm (3/8in) bowl gouge, 10mm (3/8in) spindle gouge, 6mm (1/4in) parting tool and 12mm (1/2in) skew chisel
The first step is to accurately mark the centres at both ends of the base blank with a four-prong drive, and then place between centres on the lathe. Next, you need to rough down to the round using a 32mm (1 1/4in) spindle roughing gouge. Once the blank is adequately round, you can take a few fine cuts to refine the finish. For roughing, the speed of the lathe should be around 400rpm
The next step is to clean up both faces of the blank using a 6mm (1/4in) parting tool. You need to part in at a slight angle at the base of the form - this will allow the form to eventually sit without rocking - which you do not want
Mark the length of base from the drive centre end. Mark the diameter of the spigot on the end face and using a 10mm (3/8in) bowl gouge, turn just short of this line. Continue along the length of the spigot. I chose this method as holding callipers and the parting tool over this distance of overhang can be problematic. Using a 12mm (1/2in) skew chisel horizontally in a trailing mode, refine the spigot to size. I used a waste piece of ply drilled out with a 40mm (1 5/8in) sawtooth bit that is to be used for joint/holes within the central section for the fit. Check with the gauge and remove fine amounts until you get an easy fit
Using a 32mm (1 1/4in) spindle roughing gouge, produce the outside profile of the form, working back from the spigot and downhill. Aim for one flowing curve from the base to the spigot shoulder
Using a 10mm (3/8in) spindle gouge, produce a curve on the front face leading in towards the spigot so that there is approximately 10mm (3/8in) of the shoulder remaining. This flat area/shoulder will be concaved later to allow you to achieve a good fit with the adjoining piece
Using a 10mm (3/8in) spindle gouge, produce coves along the length of the form with the gouge in trailing mode, using the profile of the tool. Try to achieve an equal distance between each cove you make. Finally, slightly concave the flat leading to the spigot
Due to waste material at the tailstock end of the piece, mark the spigot length up from the base to produce a spigot of 20mm (3/4in) in length and part in to around 10mm (3/8in) with a 6mm (1/4in) parting tool. Stop the lathe and cut the remaining waste from the base
Accurately mark the centres on apposite faces of the 220mm (8 3/4in) length/blank, also mark the centre of both ends through the 200mm (8in) axis. Place between centres and mark the 60mm (2 3/8in) diameter on the front face with a pencil. Using a 10mm (3/8in) bowl gouge, blend the profile from the 60mm (2 3/8in) diameter mark outwards but ensure to leave 5mm (1/4in) of material from the centre line on the outer face. The lathe speed was set to 500rpm. Due to the intermittent surface, only take fine cuts here. Once complete, reverse between centres and mark the 60mm (2 3/8in) diameter as before and replicate the profile with the bowl gouge
Drill a hole through the centre - which was earlier marked - with a pillar drill and a 40mm (1 5/8in) sawtooth bit. Due to the 60mm (2 3/8in) measurement there is a flat on each side of the blank. However, take all necessary precautions and clamp/fix positively during the drilling stages
Mark 20mm (3/4in) in from one end of the 360mm (14 1/2in) x 180mm (7in) square blank and the centre axis at each end. Draw onto this the design and mark the centre of the 50mm (2in) hole. Make sure all the marking is square and produced from two datum edges for all
Using a bandsaw, cut through the top curve/profile of the design you have drawn on the blank
Drill the 50mm (2in) hole with a pillar drill using a 50mm (2in) sawtooth bit. Here I am using an extension for the bit due to the depth being drilled
Replace the section that was cut away and sandwich this between centres with the waste area at the drive centre end. The waste is used as a friction drive for the main profile. Using a 12mm (1/2in) bowl gouge, rough the tailcentre end to the round using the marked profile as a gauge - this can be seen as the piece rotates. Turn at a slow speed, in this case 400rpm
Next, mark and produce the spigot to 40mm (1 5/8in) diameter as before and mark 60mm (2 3/8in) diameter on the front face of the form. Using the 12mm (1/2in) bowl gouge, produce the main profile of the form using the drawn profile as a guide - this can be seen as the piece rotates. Take small cuts and regularly check that everything is locked off and secure. Produce the profile flowing into the 60mm (2 3/8in) dimension
Using a power carver and a 'V' profile cutter, carve radiating lines outwards from the drilled hole. Once the carving has been produced on the outside profile, assemble all of the parts and continue to carve the top face so that the texture runs through the same axis as the 50mm (2in) hole
Taking into account all fire and safety precautions and after clearing all the area of wood shavings/dust, scorch the form using a hand-held blowtorch. The scorching highlights all of the textures left by the tool marks and carving
Spray the form all over with oil. I used teak garden furniture oil. It is better to use a spray, as brushing the oil on can smudge the scorching into the texture. Allow to dry as per the manufacturer's instructions and coat 2-3 times - this will seal the scorching onto the wood if the project is to be displayed indoors - otherwise the scorching can be left to weather naturally outside. The oak floor sculpture is now complete and is ready to be placed either inside
or outside - the choice is yours