They can't be used at high RPM and high feed rate as they are used in wood in any of those metals, so if you want a short answer, the short answer is "No". If you can deal with a long answer, then the answer is "Aluminum and brass only and even that depends on your router's RPM". The long answer follows, but most of the bits in this particular set aren't shapes or diameters that will prove to be useful so this particular set may not be a good choice anyway.
In a general sense carbide edge bits are hard enough and sharp enough to cut softer metals like brass and aluminum, and they can cut steel but it's not practical because the feed rate is too low to reliably push that slowly. You can't set the feed rate of a router, you'll have to judge from the chips, you would be trying to shave off about about 0.004 inches per cut or less in aluminum, i.e. the cuttings should about as this as the thinnest aluminum foil. For steel you would want to be removing around 0.000 140 inches per cut, about 1/30th as much, its incredibly thin, like the thickness of peeling chrome plating. The push velocity is the cutting thickness times the RPM. You need the velocity of the cutting tip in feet per minute to be 1,000 fpm or less in aluminum, and 300 FPM in brass. for a 1/2 inch diameter straight bit that's 7,639 RPM or less in aluminum, and the push speed will be 30.5 inches per minute or less. To find the maximum RPM for a 1/2 inch bit and 1,000 FPM maximum speed the calculation is ((1,000 × 12) ÷ (0.5 × 3.14159)) = 7,639 RPM. The push speed is just RPM × cut, in this case 7,639 RPM × 0.004 inches = 30.5. I didn't multiply by 2 flutes because a wood router isn't made precisely enough for such a low feed rate and the bit *will* chatter and only one flute will cut at a time. The push rate in steel would have been a constant 1 inch per minute, which really can't be maintained by hand. The tool overheats quickly in steel so the first brief push too fast overheats the cutting edge and dulls it, and then it just rubs at the steel and overheats without doing much cutting at all.
Many routers have a fixed speed that's too fast to use with any of these bits. For a fixed speed 25,000 RPM router the maximum tool diameter for 1,000 FPM at the cuting edge is ((1,000 × 12) ÷ (25,000 × 3.14159)) = 0.152 inches , roughly 5/32, or just over 1/8 inch. The smallest bit in this set is a 1/4 inch straight bit which would be used at no more than ((1,000 × 12) ÷ (0.25 × 3.14159)) = 15,270 RPM.
So the long answer leads to the conclusion that you *can* use these for soft metals but you need an unusually low RPM router or a variable speed router with low speeds available and even then you'll only be able to use small diameter bits, so most of a set like this would be unusable for metals.
Answered by: Whoever
Date published: 2020-01-12
