by Thomas Clark
Julie-Thomas Designs
June 2009
I scribe a series of axial lines over the face of the cab with an aluminum scribe. I make these up from a 6″ length of aluminum 1/8″ welding rod, and sharpen the point on the genie from time to time. I usually make what amounts to a 6 or 8 pointed star (looks like a star sapphire) covering the entire top of the cab.I do this once just before I leave the 220g galaxy wheel, and once again as I’m finishing up with 280 nova wheel.
Once you have the scribe marks on your domed cab face, do another quick once over on the entire cab face on the 280 nova, making sure to keep your wrists in constant motion, never allowing the cab to sit still as you are against the wheel. Even while the cab is wet, it is a snap to see any residual scribe marks, which is a sure sign that there is a flat spot in that area.
Before I start sanding on the 600 wheel, I will dry the cab completely, and check to see that the entire surface is a consistent 280g matt surface with no deeper marks showing, and no remaining traces of the scribe marks. This is also an excellent time to spot and treat any partially healed fractures or tiny flaws with a drop of hot stuff, or similar crack sealer. Once your sealer has dried, re-sand the surface of the cab on the 280 nova wheel, before moving on to the 600g and finer wheels. I advocate sealing any cracks, because It will help keep the polish out of the cracks at the final stage.
After the pre-polish on 3000g wheel, I dry the cab again, and attempt to read the reflection of the printing from the face of my 60w incandescent light bulb, which should be clean and crisp on the surface of the cab as I rotate it under the work light, with no variations from any location on the cab. Now I can go to polish, with no reservations, and very few disappointments.
Incidentally, this scribe can be laid flat on the table, and you can scribe a uniform girdle thickness line on the side of your cab preform. With a backed stone, or a double domed cab, I sometimes scribe down from the top face, as well, to get a cut line for the backing material.
The process is straightforward; hold the scribe still, and drag the girdle of your preform against the point of the scribe, and rotate the preform, until you have a line all the way around. The Aluminum rod is ideal, as it is bright and easy to see on any colored stone, and it’s ultra soft, so it won’t be scratching your 5-6 hardness stones, but rather, it will leave a nice easy to see mark, even under the water spritzer.
If you want to scribe a thicker girdle line, you can lay your scribe flat on a shim. I usually use one of my cab templates to elevate the scribe off the table a bit, as needed.
Page 2 Pictorial How to Remove Flat Spots
Happy Cabbing!!!
Tom
