When the hardness increases, the tensile strength and yield strength increase, while the elongation, section shrinkage and impact energy decrease.

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Conservative feed rate could be part of the problem, if your taking a light cut at such high rpm the bit spends a great deal of time just rubbing on the material. A heavier chip load can greatly reduce heat buildup, I use cheap single flute endmills to cut aluminum and get great results. That is spinning the endmill at 2500 rpm on a cnc mill though, not 25,000 rpm on a router.

I’ve just used my standard speed&feed calculator for this (10% lower feed than recommended because grbl was capped to a max x/y speed). The low chip load is mostly a function of the sheet of aluminum being much thinner in this instance than otherwise.

Most martensitic steels are magnetic, which makes it easier to classify, but makes it more difficult to weld, anneal, and harden

Compared with it, martensitic stainless steel has higher strength and hardness. But it plasticity ,weldability and corrosion resistance are pool. It is suitable for making parts with high mechanical properties and general corrosion resistance.

Best used for: Standard milling, dadoing, and boring. Cutting Diameter: 1/8" Cutting Height: 1/2" Shank Diameter: 1/4" Overall Length: 2" Flutes: 2 Up-cut end mills direct woodchips up and away from the milling area leaving an unobstructed path for...

Specification: Material: Carbide Number of Flutes: 2 Flute Cutting Diameter: 3.175mm (1/8") Shank Diameter: 3.175mm (1/8") Cutting Edge Length (Flute Length): 22mm Total Length: 38mm Quantity: 1 box /10pcs Features: High-density polished,...

With the increase of C content in martensitic stainless steel, the strength and hardness of the steel are improved, and the highest value can reach above RC60. This kind of steel alloy has good wear resistance but poor toughness.

The steel contains Cr and a certain amount of C. The content of Cr determines the corrosion resistance of steel alloy, while the content of C determines the strength and hardness of steel alloy. In addition to martensite, there is a small amount of austenite and ferrite in the steel. It is mainly used to make parts with high strength and hardness

Martensitic stainless steel is a stainless steel whose mechanical properties can be improved by heat treatment. It is a stainless steel that can be hardened. It has a higher hardness after quenching and has different toughness at different tempering temperatures.

http://www.ebay.com/itm/4Pcs-Of-1-2-3-4mm-Finish-Profiling-Carbide-End-Mill-Bits-Milling-Cutter-/221627543209?hash=item339a07eea9

Tools Today is very reliable source if money doesn’t a problem. Anything I purchased, works perfect. No burs, no splits. I’m sure they have special bits for different materials.

Shop Amazon for HQMaster CNC Router Bits 1/8" Shank CNC Bit End Mill Flat Nose Carbide Endmill Two Flute Spiral Upcut Milling Cutter Tool Set for Wood PVC MDF Hardwood 10Pcs (3.175 mm) and find millions of items, delivered faster than ever.

The weldability is poor, and there is a strong tendency of quenching during welding. Cooling in air after welding heating can lead to quenching, which makes the welding gap and heat-affected zone form a hard martensite structure. Under the combined action of the thermal stress caused by temperature difference and the stress of transformation from austenite to martensite, the residual stress after welding is relatively large.

Stainless steel with ferrite chromium content of 12% ~ 30% and ferrite matrix structure in service state; stainless steel with martensitic chromium content not less than 12% and martensitic structure as used state.

If you’re into V carving at all, I bought one of these (which is what I was referring to above), I cannot recommend one of these enough… http://www.toolstoday.com/p-6015-in-tech-series-insert-v-groove-router-bit.aspx Very very very good

http://www.ebay.com/itm/1-pc-Solid-carbide-3Fl-Mills-Aluminum-End-mill-Cutting-dia-2mm-HRC-45-Endmills-/121774813436?hash=item1c5a5830fc

This kind of alloy steel has low C content (≤ 0.10%) and a certain amount of Ni. Some grades also have higher Mo and Cu contents. This kind of steel has high strength, high toughness, and corrosion resistance. This alloy steel is often used to make structural parts with low corrosion resistance but high strength

I agree with @Shawn1, 25k RPM is much faster than recommended and will cause excessive heat on the bit, which is never good.

Ferrite has the characteristics of high thermal conductivity, small expansion coefficient, good oxidation resistance and stress corrosion resistance; martensite has higher hardness after quenching, and different tempering temperature has different strength and toughness combination.

We have some recommendations and a section on eBay vendors on the Shapeoko wiki: Shapeoko CNC Router, Rigid, Accurate, Reliable, and Affordable

edit: oh I forgot to say here: I don’t really have much use for Drillman1’s items, as they’re overwhelmingly imperial sizes and stationed in the US. With shipping it’s more expensive than damencnc for what I assume is basically the same quality. I’m specifically looking for metric bits.

I also purchased bit holder and two different blade for it. They’re awesome. When you buy holder you can either buy a set or single blades you need, including ball end mill blade.

Because of the large amount of Ni and Cr, austenitic stainless steel has good plasticity, toughness, weldability and corrosion resistance. It is suitable for making acid resistant and corrosion-resistant instruments and equipment.

I’ve upgraded my machine to a Kress FME1050-1 spindle and really the first thing to notice is OH MY GOD THIS THING FLIES. Compared to the 24V default spindle, this spindle is just unimaginably good on aluminum. However, this also immediately highlighted how crappy my $2 eBay HSS mill bits are. The edges of an aluminum routing job I did yesterday are just all messed up, even with cooling and a relatively conservative feed rate (25krpm at 400mm/min, 0.5mm step-down).

For accurate work, I’d suggest measuring them as their diameter isn’t exactly 1/8th, but at less than a dollar each, who cares.

So it’s time to get some good mill bits. I have a really good source for mill bits near me, DamenCNC. They sell very competent uncoated carbide mills specifically for milling aluminum for about €20-€30 (http://damencnc.com/en/tools/cutting-tools/milling-cutter/240). However, now I wonder: how do non-lowest-bidder eBay mills compare? For instance stuff like this:

Agree with @AlanDavis, I bought a 90 degree V Bit from ToolsToday that takes replaceable carbide tips and it’s perfect. It’s razor sharp and goes though wood & polycarbonate like a knife through butter. Beautiful cuts with sharp edges and zero sanding. Worth every single dollar and then some.

http://www.toolstoday.com/p-6009-in-groove-cnc-insert-engraving-tool-body-replacement-solid-carbide-insert-knives.aspx?&variantids=11445,0&keywords=AMS-210

To ensure the formation of martensitic steel during heat treatment, the higher the Cr content, the higher the C content required. The high content of C gives this type of steel a strong molecular structure.

At the same time, I’ve also bought a couple of 10-packs of Chinese 1/8th spiral carbide bits on eBay that were so cheap, they’re essentially disposable. They’re sharp, they cut reasonably well and if I lose one or break one, it’s not a problem.

Cr is the main component of martensitic steel. In most martensitic steels, the proportion of Cr varies from 11.5% to 18%, which makes martensitic steel have corrosion resistance.

So far, I’ve been stocking up on cheap eBay bits. I figure I’ll be breaking a few while getting to know the x-carve and better to break the cheap ones than the expensive ones. As most of these Chinese eBay sellers sell a wide range of stuff, e.g. clothing, toys, etc as well as the CNC bits, I’m not sure that there will be a lot of difference in the quality of the bits from one seller over another. A better bet might be to go through aliexpress and deal with a specialist tool supplier.

Has anyone tried and compared this stuff already? Especially as I’m still exploring my machine, I’d like to be able to just break or dull my tools like there’s no tomorrow without going broke, so it’d be nice to save on the mills.