Grinding carbon steel gouges and blades can be tricky, so Chris Grace opts for a DIY solution
In recent years I have embarked on carving with the intention of using it as a complement to my woodturning. I belong to a carving group and have discovered why many experienced carvers have so many tools – using the right tool makes life easier. Having bought a number of used carving tools and experimented with making some of my own, I realised there must be a better option than using a bench grinder, where it’s easy to blue the steel, or the wet grinder which is so slow. Even the finer wheel of a wet grinder leaves an edge that requires a lot of additional work before it’s usable.
So I started thinking about a dedicated carver’s grinder that could grind efficiently, which means quickly but as cool as possible, produce a fine finish and then hone the edge – all in one machine. It was clear that a standard bench grinder couldn’t do all of this, but I had seen grinders with a conventional wheel on one side and a wet wheel on the other, that I might be able to adapt to my needs, so the hunt was on.
Research
I often visualise what I want but have no idea whether it has been done before, so I do an internet search. It’s typically cheaper to buy a tool rather than develop one. Unable to find a machine to do what I required, I found something I could adapt. I also wanted diamond discs and found some used in the lapidary trade. With this piece of information it’s easy to source inexpensive parts.
Modifying the grinder
The inexpensive grinder I found had a grindwheel on one side and a wet wheel on the other driven through a reduction gearbox. Similar units are sold under a number of brands, so I picked the cheapest, hoping I could modify it. I discarded the water bath and wet stone, realising that it wasn’t ideal having the slow wheel vertical and started to think of alternatives. A bit of exploring with a screwdriver revealed that the gearbox could readily be removed.
Unfortunately the mounting holes were in a rectanglar, rather than a square pattern. I carefully measured them in relation to the centre of the shaft, added masking tape to the housing, and simply marked up the case for some new holes. I centre punched the case carefully to ensure I had a good start for my drill to ensure accuracy, and drilled four new holes. This enabled me to reassemble the gearbox on the shaft at 90° to its original position, providing a horizontal wheel.
Making MDF discs
I cut a series of MDF discs to use with honing compound all about 225mm in diameter. I used different thicknesses of material to provide flexibility later. The honing discs were trued up on my lathe by pressing them against a cork-covered faceplate using the pre-drilled centre hole. The wide discs were simply smoothed while the thinner discs were shaped so that the inside profile of curved or vee gouges can be honed.
Making a leather disc
I used one of the MDF discs as a template to cut some 4mm leather for a honing wheel. The leather required a heavy pair of scissors and a strong hand to trim roughly to shape before sandwiching between two MDF discs so that I could trim it to an exact circle using a skew chisel on my lathe. The centre hole could then be punched using a heavy duty hole punch with a selection of interchangeable cutters.
Adding leather to a disc
Having determined leather holds compound better than MDF, I decided to wrap my wide wheel with that. I marked the leather slightly oversize before cutting a strip with scissors. This time it was much easier as the leather was just under 2mm thick. I primed the MDF with PVA as the cut edges of MDF can soak up glue even more than end grain and provide a weak bond.
I spread glue with a discarded plastic card. With the PVA well spread I wrapped the leather around the wheel. Cutting it at an acute angle minimises the chances of it separating in use and helps when butting the edges perfectly on assembly. The carefully aligned leather was taped in place to allow the glue to dry. I cut the excess leather away with a skew chisel. However I wasn’t satisfied with the edges so these were sanded, and the leather face roughed up slightly to help it retain the compound better.
Testing
When seeking different solutions to problems it is a good idea to do some testing. I needed to determine if MDF would hold honing compound so I loaded up a disc and tried it. It was OK, but I felt it could be improved, so I added leather to the periphery of one wide disc. This gave better results, so for shaped discs the MDF would work, but the more regularly used flat disc benefited from a leather tyre.
Changing the grinding wheel
Modifying tools safely
- Any changes you make to a machine will invalidate any warranties and are undertaken at your own risk
- Adapting tools is often worth while, however it is essential that changes do not expose you to risk of personal injury while making the changes or compromise the safety of the tool in future use
- If the tool is powered, ensure the power is switched off and disconnected while making changes -however simple
- Guards are an important safety feature, so ensure any guards provided by the manufacturer of the donor machine continue to serve the necessary function following your modifications
- Do a risk assessment before you start: are the changes appropriate, safe, and are you competent to make them?
- Here there were no changes to the electrics or the high-speed grind wheel. I changed the slow-speed side, and ensured the machine would be stable and safe in its new configuration. I tested the modifications at each stage to ensure there were no unintended consequences
- If in any doubt, seek appropriately qualified assistance.
Conclusion
This combination machine allows me to quickly shape carving tools before refining the edge using the slow-running diamond disc and then power stropping the gouge to its final finish, no matter what shape it is. Finally, an almost finished 32mm straight lettering chisel created in a remarkably short time. The star knob on top of the stack of discs allows for quick and easy configuration changes to set the machine up for any type of carving sharpening job.
