Dulcimers

I am a retired metallurgical engineer with a lot of failure analysis experience. Those are my credentials for adding the following comment.

There are a lot of valid comments about chips flying off the faces of hammers (and other heat-treated tools) in this string of postings. The technical reason for this is that high impact can cause some of the steel in the tool to transform to "martensite", which is the hardest and most brittle form of steel. When you heat treat a tool to make it hard, you first quench it from an elevated temperature to transform all (or most) of the steel to martensite. In that condition it is hard, but it is too brittle to be useful. The next step is to heat the tool to a moderately high temperature to transform the martensite into something called "tempered martensite". The higher the tempering temperature, the lower the hardness and the less brittle the steel. OK, that's the end of the lecture - but I'll be happy to answer questions about steel heat treatment from interested folks.

The key is that hitting a hammer can transform some of the head to brittle martensite, and that is where the danger lies. The next time you hit that spot a chip can break off - as was well attested in precious comments. Probably the most common occurrence is with wood-splitting wedges. They get pounded hard all the time, and they often produce flying chips. Always check your wedge heads before use and grind off any split or cracked areas.

Having said all that, I really doubt that hitting a ball=peen hammer to dimple a miter bar is going to cause a flying chip UNLESS the hammer head already has some martensite from previous abuse. It is just not a hard enough blow. Just be sure to check your hammer heads frequently for chipping and cracking and grind off the chipped area or get a new hammer.

Len Dorsett