How often do HSS end mills need sharpening? SOLVED

@rabler Yeah, on your advice, just ordered one, sigh...
FWIW, I did try another mill. I moved to my 11/16" (working my way down the box of mills) and it does cut a lot cleaner. Still have to go slow though so I'll wait until the roughing mill comes in.
Thanks for your help.

Guess I toasted the 3/4". Do I toss it or can it be resharpened?
 
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Feeds and speeds, the great mysteries of machining. I am no expert here, barely even a novice. If you have a chart, by all means use it as a guideline, but also watch the chips and pay attention to the machine. You will get more noise and vibration if you are exceeding your machine capabilities. I leave the chip brush on the top of the head and if it really starts dancing around I am getting close to excessive. I also watch the chips, on a cut like you are doing they will come off looking like straight slivers. You dont want big chunks, rather just slivers. Yours look pretty good by my experience, which is minimal as I stated earlier. Also on aluminum the 2 flute cutter will often work better because the teeth will need a little more time to clear as opposed to harder metals.

Another thing I use, especially on steel is you want the chips to come off in fair little chunks but not dust, as then the feed is slow. I gauge steel by cutting fast and deep enough to start the lube smoking, but the chips should not be coming off blue.

Like anything else, the more you use it the better you get. Keep learning and don't spin the tool too fast and burn up the cutting edge. I have learned to default to slower and speed up as needed.

Just my .02 as another novice machinist in larvae stage, as it were.
 
As someone fairly new to machining, but one who has never dulled an end mill (yet--but getting close) I have chipped the corners of carbide end mills.......

TomWS said:
The specifics are:
Milling a recess in a block of 6061 aluminum, End Mill is a 3/4" 4 flute HSS end mill that I bought from LMS (my Mill is a mini 3990). They're coated with some kind of gold coating. Spindle RPM a little over 1000.
Click to expand...

My G0730 mill (1000 pounds 1.5 HP) would chatter if I were to spin a 3/4" EM at 1000 RPMs, for ½" and above EMs I tend to stay in the 250-400 RMP range.
I also lube aluminum with WD-40 (with no disrespect to tap magic) lube mild steel with heavy cutting fluid, and I tend to move the table (manually) 4-5 Inches per minute for best finishes.

{I am also using 35 YO knives in my kitchen that are as sharp today as when I bought them.}

The speeds-and-feeds people will probably indicate that you are properly loading the flutes of the end mill.
 
Many cheap-o endmills out there- good USA endmills cost more but last far longer. Buying on Ebay can save money, sometimes you find an estate sale lot of cutters in new or nearly new condition for a bargain price. In my experience, a lightly used US endmill can outlast a new import one
-Mark
Good US brands: Morse, Putnam, Union, Cleveland
PS I would cut your speed down a bit- 3/4" endmill is pushing it on a mini-mill
 
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¾" is typically max endmill diameter for a smaller mill. Speed and feed charts are aimed at rigid industrial size machines, compensate accordingly. Slower feeds and/or increased speeds.
 
The ends can be resharpened if you have the right equipment. Generally not worth sending it out for resharpening unless you're getting into really big endmils. Resharpening the spiral flutes is more difficult. But most people just throw it in a bucket of old HSS pieces to keep for possible later re-use as some shop-made tool, or just toss it out.

I'm running a 3HP 2000lb mill, and tend to max out at 1/2" end mills for most work. If I need to face off something or get a wide consistent finish, I use a face mill (or fly cutter). Those big end mills don't justify themselves in smaller machines. The import sets of gold colored HSS endmills are generally not the highest quality.
 
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GrayTech said:
¾" is typically max endmill diameter for a smaller mill. Speed and feed charts are aimed at rigid industrial size machines, compensate accordingly. Slower feeds and/or increased speeds.
Click to expand...
I guess I assumed that, if I used LMS's Speeds and Feeds tables, they would already compensate for that, but, well, I guess that's how ya learn things!

I've ordered a roughing mill, it's coming in tomorrow. I'll report back on how I made out with it.
In the mean time, I want to thank y'all for helping. I'm just that little bit closer to perfection now :D
 
End mills can be sharpened. I bought a Darex E80 or such to do this…turns out there is a learning curve on this and to date I’ve messed up more cutters than I’ve saved. This machine does both the flutes and the tips, but note that sharpening the flutes decreases the diameter of the end mill a bit, and you need to remeasure if that’s important to the current cut.
 
Winegrower said:
...note that sharpening the flutes decreases the diameter of the end mill a bit, and you need to remeasure if that’s important to the current cut.
Click to expand...
Indeed. I have some experience with CNC routing and woodworking and have come to understand that you shouldn't rely on the stated size of a tool. It will get you close, but measure the cuts (not the size of the tool) if you want exact.
 
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