Workshop Wednesdays - Routing Detail on the Lathe archive

Wednesday 17 June 2015

Anthony Bailey and Mark Baker explain the subtle variation of graduated fluting

Gallery

Previously we have looked at creating multiple flutes of even depth on the lathe. This time, we examine how to create tapered depth flutes, which is subtly different but easy to do. Here on the manufactured mounting, the shroud or surround for the cutter cannot be used to keep consistent depth, so the means of guidance is most easily done at the base of the device holding the router. The same baseboard is used and either the same homemade or manufactured mounting, which we have seen previously, has to be employed, but the MDF block clamped on the baseboard is at a slightly different angle to give the graduation effect. The MDF profile mimics the bowl shape using shadow guidance, as seen in the previous article. There is no reason why you can't use the same shadow drawing, but the resulting shape can always be adjusted before cutting out. I simply altered the position of the template on the baseboard, although the radius can be slightly wrong as a result. Allowing a flute to reduce from the rim of the bowl down to the stem or base can look visually correct, but you need to try this for yourself and this depends on whether you want the graduation.

Using a fixed template

STEP 1

One method for creating a graduated curve is to make a template, which the router holding unit can follow. Start by holding a bright, narrow beam torch above the vessel to create a shadow you can draw around. Once you have a faint outline, you can over-draw to strengthen it. The paper is simply spray-mounted on 18mm MDF plywood or block board

STEP 2

Cut out the shape carefully following the line using the bandsaw. The slight step at the neck of the vessel is ignored because the router cutter will stop short of this

STEP 3

The best way to clean up the profile is to use a disc or belt sander; however, a rasp followed by a wood file will do the same job, as will abrasive wrapped around a block

STEP 4

The profile is clamped to the baseboard after checking how far in the top of the cutter will be at each end of the machining run. It should be noted that the router setup can foul the square end of the timber if you aren't careful

STEP 5

You will need to adjust the template position; this will allow you to get the depth of cut needed at the starting position and the position required for the end of cut. We are after a graduated cut rather than a uniform depth one. You will need to experiment a little with the positions. The cutter profile used is up to you, but a pointed fluting cutter is ideal for this type of work. Use either the manufactured router holding unit or the homemade one. The manufactured one has a cutter shroud, which might get in the way as you move around the work and come up against the lower section stem. Note how the base rubs against the MDF profile; this is the same as for the homemade mounting. It is important to keep the router cutter at 90 degrees to the work at all times. If you do not and use different shaped cutters, you could end up altering the profile cut. Whichever router holding unit version you use, the cutter is likely to be exposed at some stage so you need to take care and keep your fingers out of the way. Best practice would be to use a cutter shield when you can and if you cannot, make sure your hands are always behind the cutter router holding unit and never in front of it

STEP 6

The fluting fades out quickly and evenly towards the neck. Experimentation is essential to learn what gives the best and most pleasing result. Note how the project isn't fully turned yet. The stem is left thicker than required so you have strength when routing the detail and also, it is far easier to refine and clean up the piece once the decoration has been cut. If you end up with any micro splinters, etc. these can be turned or sanded at this stage prior to final adjust of the internal profile, stem and base

Using a flexible template

STEP 1

Rather than using a fixed cut template to follow, a flexible one can be used. This comprises a strip of polycarbonate sheet, which can be fixed to blocks. The blocks are slotted to allow for movement and fixing down - via bolts - in a convenient position on a baseboard. The advantage is that you can create any curve you want within the constraints of the material

STEP 2

Even a double bend is possible, depending on how long the strip is. The polycarbonate must be pre-drilled to avoid splitting when fixing it to the template blocks. Also, don't over-tighten the screws for the same reason. Using more than one screw in each block is advisable. As with the cut template, you need to adjust the bend/curve and block positions to get the shape you need

STEP 3

You can use just a single point guide to run against the template. You can use a point base guide but you may find it wiggles out of alignment, causing an error in the depth of cut

STEP 4

An alternative to the point guide would be to fix a two-point guide for a more predictable shape following cut. Note the use of adjustable bolts as the guide points; this allows you to cant the presentation angle of the cutter in a precise way to alter the profile cut with some cutters. Depending on the thickness of the polycarbonate used and the length of the curve, there is a risk that the polycarbonate can flex in the unsupported area. You could use a thicker piece of polycarbonate, but the thicker section might not give you the curve you need, so an easy option is to clamp or bolt down a support batten/block or more in the middle to stop this happening. Whatever method you use, experimentation is key to discovering the best way to get the decorative effect you want

STEP 5

Gentle pressure and a smooth sliding movement will ensure a clean cut. Remember to keep pressure on the lower base section; this will help you to minimise the risk of the cutter riding up as the router is moved along the work


Woodworkers Institute

Tagged In:

anthony bailey , Mark Baker , Routing Detail on the Lathe

Safety

1. PPE to be worn at all times and it is advisable to use ear defenders too
2. Be aware of the cutter at all times. Shield the cutter in some way if possible and always keep your hands behind the cutter position
3. The lathe is always unplugged as there is no need to switch it on when routing. Also, when using a router, remove the plug from the wall socket when changing cutters, moving jigs and suchlike
4. Ensure your work is held securely and the router table on the lathe is secure