Grade of alloy for indexable tool holders.

[737mechanic]

I want to make a couple custom tool holders for some of the inserts I have and was wondering if there is a preferred alloy or if just about any grade of steel would work. I bought some fly cutters years ago that I think was made from 1045 and they seem to be great.

[pete]

Well what I don't know about metal and tool making could fill a very large library so take this fwiw. I got a dovetail cutter from Randy Richard in the shop over on Youtube. I believe he uses 4140 PH for making these. And he does a really nice job on them as well. Probably almost any metal would work in a home shop environment. But my thinking is with the pre hardened material the hold down screw threads should last much longer. And just maybe the seat where the carbide tip sits should be better if it's hardened a bit. Depends on what exact machine tools you have access to though. You could solder in a carbide seat, but I'd think an EDM would be needed for a clearance hole through the carbide so the hold down screw could reach the threads in the alloy below it. Sorry I can't be of more help.

[GlennW]

The indexable tool holders that I have checked have been 50 Rockwell C.

4140 pre hard (4142) is quite a bit softer than that, but I made a tool holder with it and it did fine with limited use and no crashes!

Crashes and overloading the insert to failure (breakage) is what kills tool holders.

[LIALLEGHENY]

I would use 4140 HT alloy material for any holders. The material falls in the RC28-32 range and is easily machined.

Nyle

[warmstrong1955]

I've built a few, and also used 4140/4142 pre hardened. 30-35 Rc generally...depending on the source.

Bill

[BadDog]

They also sell carbide insert seats. They go beneath the insert in better quality holders to help protect the holder itself in a crash. Or sometimes because the edge broke down and you didn't realize it, inside a bore or something. An insert that is not fully supported to the edge is much easier to break. When you waste a corner and it damages the support, and you can replace it (as long as you don't let it go too long).

That's also what you find quite a bit on ebay with boring bars and holders. You have to look VERY closely at the support edge, often they are damaged, and if they don't take a seat, that becomes problematic for use. I've bought some like that and gotten very good deals on them, including solid carbide boring bars and face mills. TIG weld the edge back on, and then blend to the seat area, and it works very well.

[mcostello]

Tig weld with what?

[LIALLEGHENY]

For welding 4140 the preferred choice is ER80S-D2. Alternate would be ER70S-2

There are other alloys but these are the most readily available.

Nyle