Learning the Basics About Sharpening

Image courtesy of Problogger for the latest group writing project.

Yesterday I received an email from a fellow sculptor regarding what was the best solution for sharpening wire tools. Julie wanted to know what oilstone to use and was there any particular make or brand that was best.

I thought this would make an ideal start for the now famous “Problogger Group Writing Project” that everyone anticipates each month.

You may well ask, “What is a wire tool?” These particular tools are used in the sculpting industry for working fine details mostly relating to the industrial arts such as automotive clay modeling. They are most widely used when modeling interior detail parts and apertures.

This type of tool is constructed from spring tempered wire or music wire which will hold a keen edge without blunting quickly, making it ideal for the abrasive nature of the industrial modeling clays. Wire tools are available through a handful of specialized tool suppliers and when you receive them they are normally ready to go, straight out of the packet.

So, we have a quick synopsis of what the wire tool is all about and you can appreciate that once one of these hardened tools become dull then it has to be sharpened in some way.

Selection of Steve Austin's wire tools.

There are several ways that can be used to sharpen these tools and each method has its own set of merits and this will all depend on whether you purchase the tools from a supplier or end up making your own.

Your choice will eventually determine the best course of action but we will start with, if you decided to make your own with round straight spring tempered wire.

The most common methods of sharpening are:-

  • Files
  • Oil stones
  • Diamond stones

OK, we’ve bent the wire to the desired shape and have epoxy resin the wire into the wooden handle. To take the wire to the next step we have got to place a flat around the area we deem to be used for cutting the clay. To retain the most strength in the wire we should not lose more than half its thickness so filing or grinding the flat is a critical process that should be done without haste. If grinding, do not grind it too hot or the molecular structure of the wire will be changed from being very hard to soft, in other words you would have annealed the wire making it more malleable.

Once we have achieved that flat around the outer edge we now have a half circle in profile. This would in itself cut the clay but to fully realize the potential of the tool it needs to be shaped to a triangular cross section. The best way I have found to achieve this is to file from the leading edge on both sides to create a central peak thus giving you a triangle in shape.

Sketch, showing method of sharpening a 3/4 inch wire tool.
The critical stage in filing is the intersecting corners, care must be taken so as not to undercut the side element of the wire tool. Take plenty of time and use a triangular Swiss file to make the corners crisp, the width of the wire should remain constant and not waver due to undercut. The straight cutting edge will be the controlling factor when sculpting delicate areas.

With the cutting faces filed in, the bottom face of the wire tool can be honed with an oilstone or a diamond stone. This you do by rubbing the flat face on the oilstone, be sure to use oil to eliminate clogging from the grindings. You will notice when the edge is sharp by the small burr that forms on the edge. This can be remove by lightly running a fine Swiss file parallel along the face of the cutting edge.

With existing purchased wire tools the majority of the work has been done and it is a simple case of honing the bottom of the tool with a fine oilstone such as an Arkansas or Washita stone. These natural stones are used primarily on woodworking edge tools such as plane blades, chisels, carving gouges and even good quality cutlery.

The Washita stone is the coarsest of the natural stones used for sharpening, with the Arkansas ranging from coarse to fine. With these stones you can acheive a remarkable edge which is very desirable with fine carving knives.

For the purpose of sharpening the wire tool, it is just as easy to use one of the combination stones that are available on the market such as a Norton or India stone.The same method is used as in the sharpening of the home made wire. The fact that the purchased wire tool is machined makes it that much easier to refine the edge. If your choice of sharpening system is the diamond stone then I would use a combination of coarse and fine on the same plate. A very good system is by DMTsharpening systems and I would use the combination of blue one side (coarse) and red (fine) on the other side for a good flat stone.

For getting into those tricky areas they have a Diafold® compact folding file in both coarse and fine grade and this will sharpen the face just as good as any oilstone without the additional mess of the oil as this file is used dry. Whatever your preferred sharpening system is, the methodology is the same, retain the structure of the wire without undercutting to preserve strength.

These specialty tools only need to be made or purchased once and with the proper care they will provide service for a lifetime.

The Complete Guide to Sharpening

13 thoughts on “Learning the Basics About Sharpening

  1. Your topic brought back great memories of my lessons learning to throw pots and hand modelling in what appears now to be another lifetime! We were using the tools in your photo to decorate the surface and trim clay. I had no idea that they could be sharpened. I have always regretted that I was never able to continue. Your explanation is excellent.

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