One reason saw tips come off

[Tom Walz]

One reason is that carbide is made to be wear and corrosion resistant. This can make it hard to braze. The solution is to treat the carbide. However some folks are not very good at it.

In the picture are two sets of 5 tips each. These are pretinned tips which means that braze alloy is on the carbide tip and the tip is ready to go on the saw blade.

The top five are from one source and caused serious failure problems. In the middle three you can see globs of braze alloy. (This is something like trying to finish a table with grease spots on it.) If the braze alloy won’t stick to the tip then the tip won’t stay on the blade. The outer two tips show the opposite problem. The braze alloy flowed over the edges of the tip leaving very little left for bonding.

The bottom five tips show the correct, even, smooth flow.

[Mike Henderson]

Tom - thanks for the info. Just for interest, how is a carbide tip held in place to be brazed? Seems like there needs to be something that holds the tip in place but leaves room for the application of heat, and doesn't act too much like a heat sink.

Or does the thing that holds the tip supply the heat?

Mike

[Greg Cole]

Ditto what Mike said.
Doesn't matter what "it" is, I just like knowing how things are made....

Greg

[Cliff Rohrabacher]

how is a carbide tip held in place to be brazed?

Very thick calluses.

[Tom Walz]

There are several ways. There are couple simple fixtures to hold one tip in place however they tend to be awkward and take a lot of set up time for more than one tip.

At the “Pro Shop” level where they build custom tools to order they typically use a steel plate about 3 feet across or more and about six inches thick. They lay the saw plate flat on the steel and then shim it up for the amount of side clearance they want.

If you go to www.carbideprocessors.com you will see a link called “Brazing Video” on the far right, second down from the top. This shows Don Wallinger of West Coast Saws who is shop foreman of one of the best shops in the country. It also shows the Hartleys in an Arkansas sawmill. The web site is being rebuilt and there are broken links all over the place but that one works as of noon Saturday.

In automated tipping machines the tip is indexed in place then the saw plate is rotated to be in contact with the plate and then it is heated with an induction coil. They have tried resistance heating by passing current through the tip but it doesn’t work well.

tom