SPEED TIGER Micrograin Carbide Square End Mill - 4 Flute - ISE3/8 4T (5 Pieces, 3/8") - for Milling Alloy Steels, Hardened Steel, Metal & More – Mill Bits Sets for DIYers & Professionals

I use these in production everyday, all day, these 2 are still running. I am currently running 6000 rpm, 3/4" DOC with a radial cut of .058" in 304 Stainless DRY with NO COOLANT(chips rooster tail 6 feet)...ready for this:102" Inches per minute! 65 parts later still cutting!

UPDATE: I upped my rating from 2 tp 4 stars. Customer service was very helpful and responsive. They actually contacted me when they saw my original review. I found that my spindle speed was too slow. Obviously it depends on the material but these bits have to be spun pretty fast and the depth and feed rate must be shallow and slow as well. My mill only spins at max 2800rpm. So I spun it at 2800rpm and took a more shallow cut along with a slow feed rate and these things cut pretty decently. I assume they would work better at an even faster spindle speed. They are still very brittle and will snap if you apply to much side pressure. Overall they did the job I needed them for.Item came packaged well and they looked good. I ordered the 1/16th size and these things snap at the slightest pressure. I almost messed up my project so I had to discontinue using them due to them snapping so easily. I tried another set I had and had no issue.

I'm new to machining but I bought these because they were cheap and I needed endmills that wouldn't have me selling a kidney to replace after a mess up. After using these for a while, and dang, these aren't half bad at all. I've never had one fail on me that wasn't my own doing. Everyone who is saying they failed on them just doesn't want to admit they totally messed up somewhere in their cam program or pushed it way too hard. I get a great finish with these on aluminum, which is satisfying. Great product, they're my go too for making prototype parts for my company.

I seen a few reviews about these bits breaking. I do not know the experience level of the reviewers who claimed these bits break easily but I am just learning CNC. I have had a project in the works for a while of milling a 9MM 1911 slide. I purchased a Rock Island slide from ebay to do my testing. These are hardened steel slides (not stainless steel). I tried some other bits I purchased on amazon. I burned up two bits before I purchased these. I am using the same speed, depth per pass and RPM on my converted harbor freight mini mill to cnc. This bit is eating the metal. I am of course running very slow passes and very shallow depth per pass. But it is working and I couldn't be happier.Using the same settings, the same material I have to assume these are just a better end mill than the other end mills I have purchased on amazon. I will be buying more :)

I ordered these for cutting stainless steel.They worked perfectly for cutting 1/8 inch stainless steel counter top sink hole. I used a router with speed control and used the lowest rpm setting around 2,000 rpm. ( High speed 30,000 was too fast and the cutter got too hot) with a vacuum for heat and chips. The endmill cut perfectly with little heat. No melting of insulation below cut. I am ordering another pack to have for friends.

The build quality of these end-mills is impressive, especially for price. I am a hobby machinist, using these with a Sherline mill fitted with a standard headstock and an optional 11K RPM spindle motor. Even at 11K RPM, there is no noticeable vibration. Solid carbide, the shafts are highly polished, and the flutes are sharp along their entire 3/4" length. When plunging into AL, the endmill cuts easily, without excessive tool loading. I would recommend these to friends.

Let me start by saying these are great end mills for alluminum! How ever this time I needed a large one and ordered a 3/8". First it was lost in the mail then when I got it, I ended up getting a very tinny one that is completely useless to me.Update:So I originally gave them 2 two stars but.... even after I returned the bit and had my money reimbursed, the seller went out of their way to contact me and offer to make it right. I understand ratings are important or them but I have never had a seller contact me to correct a mistake. That's fantastic customer service in my book!I should also add that I have used several of the 5/16 size bit from this seller to mill aluminum and steel, there great bits. They last far longer then any other end mills I have tried in this price range.

I use the 1/16" carbide end mills for multiple purpose of my firearm builds and require a relative sharp and sturdy lasting end mill. These function well enough per single operation for me in my small mill. The edge left after cutting is defined and clean cut. The most difficult topic for these and other small end mills is Patience. Do not place any heavy load, try to travel fast or they will break. I have also used this end mill to drill for fibre optic sites, again with extreme patients and a very light touch.