Beijing Deckel Tool Grinder

I suspect every amateur machinist gets attracted to the idea of building a Tool and Cutter Grinder sooner or later. All those nifty knobs, all that precision, and all in a machine that is typically able to be both small and useful--a quality not easy to come by in a lot of machine types. I have had the same sorts of thoughts. Heck, even just as a way to sharpen up an end mill or drill point it would be nice to have a simple T&C grinder.

There are many kinds of T&C grinder ranging from those that are not precision at all and are basically just very sturdy bench grinders, such as the ubiquitous Harbor Freight:

At the other end of the scale are complex and exotic machines such as the Qorn:

Or the Bonelle:

These exotic grinders are fascinating to study, and would make a fine project, but they're not something that looks easy to complete quickly!

On the commercial front we have the so-called single lip T&C grinders of which the Deckel is a fairly common motif:

In fact, the Deckels have been widely copied in the Asian import market. I was watching some YouTube videos on how to use such a "clone" grinder when I got my inspiration. Here are the videos:

Grinding a lathe tool...

Grinding an end mill...

Grinding a drill bit...

Watching those videos was very illuminating--it made it easy to understand how the Deckel-style grinders are used. But more importantly, it jogged my memory about a gadget I had sitting in the shop that I had not yet used:

This is a universal vise that I purchased from eBay seller 800watt. They're very inexpensive and seem well made. Also, I've bought a number of things from 800watt without any problems...

Based on the similarity of the universal vise to the tool holder on the T&C grinders, I came up with this idea to create an accessory for the lowly Harbor Freight Tool Grinder that would emulate the more sophisticated style. Here is what it looks like:

The universal vise is mounted to a precision rod that can pivot to stroke the tool against the grinding wheel. The universal vise allows precise control of the angle of the plane at which the tool which sweep the grinder face when the assembly is pivoted. The depth of cut is adjustable with the threaded rod that bears on the end of the shaft. The adjusting rod is mated to a ball bearing pressed into the shaft end. This way the shaft can be rotated for the tool grinding without turning the adjustment rod and move the tool holder left or right.

The shaft itself is held in bronze bushings. For endmill sharpening, one could mount a precision air bearing in the tool holder and go from there.

This sort of accessory looks relatively easy to build, and I don't know why it wouldn't be capable of results very similar to a commercial grinder.

Note that this style of grinder can't do everything. There are grinders with more sophisticated geometries that are more versatile. My focus was to find something fairly cheap and easy to build that could take care of a lot of the more common operations.

A Menagerie of T&C Grinders

Here are some notes on a variety of shopmade T&C grinders that I have collected as inspiration.

The Quorn is probably the most famous. It's a beautifully intricate little machine:

Quorn Cutter...

I have entertained the idea of CNC'ing up a Quorn out of bar stock after I get my machines converted, and I am sure it would be a fascinating project, but there are simpler ways to get the job done.

I recently came upon a tool grinder called the Tinker:

The Tinker Tool and Cutter Grinder by Guy Lautard...

This design is by N.W. Tinker, with plans by Guy Lautard and more information about it on his site. His Machinist's Bedside Reader series is excellent, so I know that what he is offering is likely of extremely high quality and would be worth the price of admission. I quite like the Tinker design. It looks much simpler to build than a Quorn, and I like the idea of harnessing it to an existing grinder rather than having to fabricate a whole new grinding spindle for the machine. It seems to me that doing double duty with the grinder not only saves fabrication time, but also saves space in what will be an already over-crowded workshop for most folks. Here is another Tinker article with a lot of good pictures.

There is also a simpler variant called a Mini-Tinker, and supposedly a design known as the Raymac may be even more capable than the Tinker.

Hall's Sharpener from the Workshop Series, "A Complete Milling Course"...

Simpler Hall Sharpener...

This one is a Bonelle...

A Sieg x2-Based CNC Tool and Cutter Grinder

The idea of a completely CNC small T&C grinder appeals tremendously to me. Various folks like Hoss from Hossmachine and others have done a little tool grinding on their X2's:

More ambitous is this scratch-built Bonnelle style that bears enough resemblance to the Sieg that you could see how to approach modifying a Sieg to do this work:

While many commercial CNC T&C grinders are 5 or even 6-axis, we can see from Hoss's example above that 4 axes would suffice. I need to understand more about the advantages of an additional axis or two to decide whether they truly called for. It would also be nice to set up the spindle so it is removable and could be installed on a lathe as a toolpost grinder. That may be unwarranted additional complexity, though. A belt-drive conversion on the Sieg is likely going to work out well enough.