Cheap End Mills

[MrWhoopee]

I stumbled across this assortment of end mills a few days ago. Scarcely believing my eyes (or the ad), but willing to gamble, I ordered them.
I mean really, 6 end mills for $16 delivered, what could possibly go wrong?

1/8" 3/16" 1/4" 5/16" 5/8" 1/2" Milling Cutter Carbide Center Spiral Drill Bits | eBay

6PCS HSS 4 Flute End Mill Cutter Milling Cut Bit 1/8" 3/16" 1/4" 5/16" 5/8" 1/2".

www.ebay.com

They arrived yesterday.


First, they are not carbide (I knew they weren't, it says HSS in the text of the listing) and there is no 5/8", it's a 3/8".

On checking them out, they are literally ±.002 for size.
They are 4-flute, not center cutting.
They do cut steel, at least the 1/4" I tried did. It cut smoothly and left a nice finish.
No clue or claims as to how they might hold up.

YMMV

 

[Parlo]

I tried some similar a while ago, they were HSS butt welded to soft shanks.

 

[woodchucker]

I tried some similar a while ago, they were HSS butt welded to soft shanks.

can you weld HSS? I thought it didn't weld well.
So what was your opinion?
Was your similar set worth it?

 

[Parlo]

They were made the same as HSS drills, with a soft shank. I only used one for a counterbore, the rest are still in their boxes unlikely to be used. The finish on the cutting edges was rough.

 

[MrWhoopee]

can you weld HSS? I thought it didn't weld well.

That is how HSS drills are made, friction welded I believe. It's hard to grip a HSS shank, and HSS is expensive, so money is saved by not using it for the shank where it's not needed.

 

[markba633csi]

I have a few of those- they are very brittle (I fractured one by accident) but ok in the smaller sizes

 

[mattthemuppet2]

I bought a few a while back. They're ok for roughing and using on nasty materials as they're literally throw away cutters, but they produced pretty poor finishes in any material.

 

[RJSakowski]

That is how HSS drills are made, friction welded I believe. It's hard to grip a HSS shank, and HSS is expensive, so money is saved by not using it for the shank where it's not needed.

All the drills (about 20) that I checked spark tested as HSS with one exception. A 1/4" drill tested as high carbon on both the shank and the business end. I checked drills from the 1970's as well as more current and diy vs. name brands.

 

[MrWhoopee]

All the drills (about 20) that I checked spark tested as HSS with one exception. A 1/4" drill tested as high carbon on both the shank and the business end. I checked drills from the 1970's as well as more current and diy vs. name brands.

I believe that if a drill shank can be damaged when spun in the chuck, it's not HSS.
I have turned down the shanks on a set of U.S. made drills to use in a 3/8 drill, they were not particularly hard.

I hit the shank on a couple of these end mills with a file. They're hard, but can be cut.

 

[RJSakowski]

M2 HSS has an annealed hardness of around 23 Rc. Hardened and tempered at 1400ºF, the hardness will be around 34 Rc and at 1200ºF, the hardness is 53 Rc. I have spark tested some drills with damaged shanks and they test as HSS.