Hello Roger,

It is not difficult, sharpening is done exactly down the radius of each tooth to preserve the form relieved geometry. Correct indexing is important so that you take off the same amount on each tooth, it will then cut with the same load on each tooth.

If you really are not confident enough to do it, send me a PM and I'll give you my address, I have a slim diamond wheel that will get down into the gash to the root without risking a foul on the adjacent tooth..

Regards

Brian

As Brian said ideally you don't index off the front face as you would for a milling cutter but use an independent index method.

John is probably thinking of the Clarkson (or equivalent) fixture that uses a very rigid framework to reference a point part way down the relief face (ie outside edge) of the cutter effectively picking up a point that is exactly the same radius for each tooth. Then given that the relief of each tooth is a consistent angle the front face can be trimmed to the exact same distance from that radius point and hence have the same tooth tip radius.

When I sharpen an involute cutter or a hob, I begin by grinding the backs of all the cutting teeth so they are all consistent by using the original front cutting face as a datum for the detent on the grinder.

Once a cutter has its teeth back ground, I then use the back of each tooth for the indexing detent on the cutter grinder to do the actual sharpening.

My dad taught me that trick years ago, and it works perfectly every time.

Phil

I have seen cold saw blades that have been repeatedly sharpened using a blade in the gullet to index the rotation from tooth to tooth. After repeated sharpening like this the blade gradually goes out of round and becomes more egg shaped as the process multiplies any small error in the original blade. Original manufacturers of industrial blades (and now some third parties) use proper indexing fixtures to sharpen the teeth to keep the blades circular. Current cost for resharpening a Ø350mm blade is about £10.50 +vat. This is based on a batch size of 40, we use them on stainless steel so get through a lot. It is far cheaper though than regularly replacing them. Some have been sharpened so many times they are down to about Ø200mm. At this size they are only good for small stock.

Used in one of these **LINK**

Martin