I am working on an old Japanese Clock and need to replace an arbor and the top of the lantern pinion for the center wheel. I have not had to machine a part that will take this much tension before and am concerned that it be of the right material. I understand that there are two types of brass, 260 and 360 and the difference is the zinc content but that is about it. Does anyone know if either of these will work for the top of the lantern pinion?

Thanks

Rick

I was not aware of those differences in brass. Perhaps there are some engineers out there who can help us with this.

From onlinemetals.com/brassguide.cfm

360 Brass (Free Machining Brass)
Free Machining brass is the most commonly used of the brass rod and bar items. The presence of lead in the alloy creates a highly machinable material that can easily be cut and shaped into whatever you need. It is not so good, however, at forming operations.


C360 Free Machining Brass
Minimum Properties Ultimate Tensile Strength, psi 58,000
Yield Strength, psi 45,000
Elongation 25%
Rockwell Hardness B78
Chemistry Copper (Cu) 60 - 63%
Zinc (Zn) 35.5%
Iron (Fe) 0.35% min
Lead (Pb) 2.5 - 3.7%

260 Brass (Cartridge Brass)
260 Brass is known by about a zillion different names, but the most common are yellow brass and cartridge brass, the second because it is generally used for shell casings. As a rule, it is only available in sheet, and is not very machinable, but is a great combination of formability and workability.

C260 Cartridge Brass
Minimum Properties Ultimate Tensile Strength, psi 61,600
Yield Strength, psi 52,200
Elongation 23%
Rockwell Hardness B77
Chemistry Copper (Cu) 68.5 - 71.5%
Zinc (Zn) 28.5 - 31.5%
Iron (Fe) 0.05% max
Lead (Pb) 0.07% max

Most machined clock parts should use the 360 brass. The hardnesses are about the same but the 360 will not "gum up" on the cutter so much.

The 230 red brass is more "coppery" in color and won't match other parts well.