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From the Shop: Keyways on the Shaper

Note: I haven't found yet the time to translate my home page. If you want, you can use Google's translation service to look at the rest of my Home Page in English. But be aware that their translation is even worse than mine (would be). Sorry for the inconvenience, I'll fix that.

Here is a linked list of the parts already translated:

I needed to cut a keyway in some flywheel. As I didn't have the right broach for it, I decided to use the Gack HE 20 shaper I bought not so long ago.

I asked in RCM, and got answers, but I didn't like them that much. They were not unique enough. Not that I didn't think they work, but I like to try new or different concepts. And if I fail, at least I learned something.

I'll explain while showing the pictures …

The Tool

The tool is of the type found in slotters. This tool has its advantages when you want to make a form tool with a more complicated shape than just a rectangle for a keyway.

This tool has the following dimensions (in the slim part on the left):
Length nearly 45mm, height 9mm, thickness 5mm (width of keyway).
It was made out of drill-rod (silver-steel), hardened and tempered.

When you have a closer look, you see some land on the cutting face. It is 1…2 mm wide. It has no built-in relief. But to reduce rubbing and friction, the part behind that land is set back for 0.2mm.

The Tool-Holder

Overall dimensions are 35 x 35 x 140 mm.

The tool holder has a built in reliev of 5° that you can clearly see. It goes where the clapper-box is. Of course, the holder was made on the shaper.
You might argue, that you need a clapper-box. This is both wrong and right. When cutting keyways and you have a clapper-box, chances are that the clapper swings upwards on the return-stroke and is ruining the sides of the cut. I didn't want to happen that. Of course, it is better to manually feed when the cutter is outside of the work. Albeit, a bit of flex of the tool is enough.

One disadvantage of a non-clapper-box is obvious: Beware of chips that get rubbed in on the return-stroke. So clean your tool.
The tool-holder seen from the front. I have stamped the relief (5°) onto the holder.

You have to adjust the tool to be dead straight to the direction of feed. There is enough play in the tool holder to adjust that. Also, the tool itself has a flat milled that works as a reference to align it in the tool-holder.

An advantage of the non-clapper-box is, that it won't swing upwards on the return stroke and ruin the work. I have read suggestions to block the clapper-box for such work.

Work

Work in progress, seen from the rear.

Again, with that kind of tool-holder, it is best to feed when the tool is outside of the slot. But you can feed when inside, risking to dull the tool faster and rubbing in chips.
I frequently cleaned the tool with a brush and oiled it with cutting oil.
Here you see the tool sticking half in the keyway. The chips come out quite nice.

Don't think it only works on brass. I have since used the tool to make rectangular holes in CRS and I got the same good results.

The precision is well better than 1/100mm. The width of the tool makes exactly a keyway as wide as. The width can be fine-tuned by oil-stoneing the tool.

Conclusion:

I'm still happy with that concept. It certainly is not my invention.
I think it is worth considering. Especially when you are working with form-tools, because these are much easier to be made. An other advantage is the rigidy, because the tool is more compressed than bent.
I got no chatter at all, even in CRS.