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:

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.

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

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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.

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.

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.

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.

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.

In my experience as a machinist, this topic of discussion is always confusing because I can ask 3 different machinist on how they calculate their feeds and speeds and I can get 3 different answers. At my shop, I am finally doing set-ups which is great, fun, and I'm getting a lot of experience, but when it comes to trying to tune my cutters for them to last longer it's a struggle. How do you guys calculate your feeds and speeds? I was cutting titanium today and my lead happened to pass by and I asked him what is the formula, but he said there really isn't a formula and it's all about the experience and noise it makes. Now I believe this to be true but there has to be something to get you close to what you want. I asked another machinist and gave me his formula which was (4XCS/ tool diameter). So what is the best way to calculate/approach it? Especially on tough materials like heat treated titanium/ heat treated inconnel or even aluminum. Looking forward for great answers.

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

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

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.

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.

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).

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.

A Reddit for Machinists of all varieties. From Old School conventional guys, to CNC Programmers, to the up and coming next generation.

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

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

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...

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.

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,...

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