CNC Cutter examples

What Bit do I use in the CNC Router is a loaded question. The Answer is it depends on the thing you want to make.
One thing for certain is a conventional brazed carbide router bit is not recommended. Unless perhaps You want the CNC router to produce flying bits of carbide. Not recommended.

So what to buy?

In class you received a two flute carbide end mill cutter. Prices vary depending on the source.
If you are willing to wait for delivery, the tools I’ve bought through Aliexpress have been solidly functional and priced significantly lower than US based sources.

The following examples of search terms for AliExpress should help your research. Do note that most of the items are metric. (6 mm /25.4 mm = 0.236 inch)

Regardless of the source, Include search terms and prepare to wade through the listings.
Tungsten Carbide - (Do note: HSS = High Speed Steel is acceptable, but will wear significantly faster)

End mill (without adjective is commonly flat) or Ball End or 60, 90 degree

Examples without direct recommendations.

2mm 3mm 4mm 5mm 6mm 8mm 10mm 12mm 2 Flutes HRC45 Tungsten Carbide Flat square End Mills Spiral Bits CNC Endmill Router Bits

63260L 2 Flute Carbide Cutter Ball Mill for Wood Carving Engraving, Router CNC Bits Ball Nose Wood Milling Tools Cutters

Free shipping-1PCS,CNC tungsten carbide aluminum and steel Chamfer milling cutter,30&45&60 degree tialn coated 3 flutes end mill


Nice post!

More sources for mills is good (or are good…)


I also would not forget Amazon.

I’ve gotten some great deals on name brand mills by babysitting a particular term (1/2” carbide square center cutting endmill). Sometimes prices drop from $50 to $8 because of excess inventory or new part numbers.

Keep looking!

Well yes, but that requires planning ahead! ; p

It's worth noting that a lot of us accept the risk of flying carbide and use the brazed carbide ones anyway... The cut nice, are the right price, and the risk is pretty low.

We didn’t say “forbidden”, just “not recommended” (for reasons noted above).

You pays your money, you takes your choice.

Along this discussion I’d like to remind everyone that you should wear appropriate Personal Protective Equipment (PPE) when around the active CNC.
This would include hearing protection and eye protection.
If a bit decides to “grenade” (shatter) those little, super sharp, pieces will go flying out at pretty high velocity. That is one reason pretty much all industrial CNC machines are in total enclosures. Our broom-like dust collector will not do much to capture those projectiles.
If you are across the room you are probably OK, if you are within 10 feet I’d say you should have eye/ear protection on.
We have been pretty lucky with the CNC so far. Let’s keep it safe!

I’m very fond of HSS. People rarely talk of the advantages - It’s not as brittle as carbide (hard = brittle), and is more forgiving of runout, misalignment, etc. It has more give and flex, which means it won’t shatter on misaligned chuck or collet, or minor wobbles and CNC weirdness. Of course, the same “give” is what makes them wear out faster (under light usage, they still last a long time). I especially recommend them at small diameters like 1/8", where carbide is sure to snap easily. Sometimes, carbide seems like bringing a gun to a knife fight, especially with older or wobbly machinery.


I appreciate your comments on HSS for small mills. Although I knew of it as cheaper, sharper (at first!) and faster wearing, I hadn’t thought through to the idea that it’s relative flexibility is an advantage at smaller diameters.


Update on AliExpress sourcing. Two orders placed Feb 20 delivered Mar 18.

In order to compare the products from different suppliers two orders for essentially the same item were placed. Average cost per cutter $2.27 - That’s a very good price.

1 each 10 and 12mm HSS-AL Straight Shank 4 Flute End Mill Cutter Drill Bit Tool $ 4.10 delivered in 21 days Shop4500010 Store

1 each 10 and 12mm HSS CNC Straight Shank 4 Flute End Mill Cutter Drill Bit Mayitr Metalworking Tool for Milling Machine $ 4.96 delivered in 21 days Fannie Tool Parts Store

You can see from the picture the cutters came from the same factory. YMMV

My project requires making a squared bottom hole of a precise diameter in delryn plastic, so HSS is perfect.

Time v. Price, I guess.
Looks like a fair trade-off to me.


From the Western Spiral Arm


Do you think it would be worth it for you to use the warden funds to purchase,
say, ten 6mm 2 flute mills from AliExpress for the class stock?

The price (today?) says $4.22 ea for 5 or more, and shipping (via DHL) is ~ $30, for a per piece fee of ~$7.22 each, down from $11 at present.
(Even less with the China postal rate, although the wait is over a month, as you have pointed out.)

(Or we could offer 2 mills at about $11, so no fear of breakage!)

Let me know what you think.

John S.

I’m already planning on making that purchase for 10 to 20 mills 2 flute, 6mm dia. probably > 15mm cutter length. Probably carbide, though that is price dependent.
I’ve been looking for free shipping by China post. Speed is not of the essence here.
Class fees already have provided the funds required for this refill.

AliExpress is running one of their periodic sales 3/28 through 3/31. Up to 50% off.
Put things in the cart now, buy then.


Thanks for the class buy and for the heads-up.

I may get a couple mills myself.

John S.

So, in viewing the AliExpress site, I see that mills get cheaper as the HRC hardness goes down (60->55->45).

Am I right to assume that an HRC45 Tungsten carbide mill is still going to cut any wood, plastic or Aluminium (sic) I throw at it?


John S.

pretty much. Typically as hardness goes down, toughness goes up, so the tool is more durable and tends to last longer, but won’t be as sharp, so cutting speed and surface finish may be slightly degraded and it won’t be as capable of cutting harder materials.