Endmill quality

C

CDH

Joined
Jun 8, 2007
Messages
283
I was looking at endmills to use for slotting guards and was stunned by the price range. Since I am a complete beginner with them, I thought I'd see what the extra $$$ bought me.

Since I'm slotting guards and handles, I figure extremely close tolerances are unnecessary...and I will be using a light duty lathe and a milling vise/table attachment.

I am looking at Enco and for example the price for a 1/8" double ended HSS mill ranges from $3 to $15. :eek:

http://www.use-enco.com/CGI/INLMK32?PARTPG=INSRAR2

I'm thinking that 5 of the $3 would serve me better in this application than one $15 one...assuming the cheapies aren't going to shatter the first time I use them! What do you guys think?
 
I have experience with both ends of that price range you mentioned. The lower priced end mills are imports, and are hit and miss quality. Some I've gotten haven't even been sharpened. As the price goes up, so does the quality control. I still use a lot of the import stuff for tasks that do not require high precision, but when it comes to being precise, or cutting tougher materials, I go with the higher end tools.

Even with the higher quality end mills (3/16" or less), you'll still have to take care using them. Go slow, with minimal pressure on the mill, otherwise you will break them faster than you can change them out.

If you decide to go with carbide, you'll get an end mill that lasts, but is very fragile in the smaller sizes...just dropping it on a concrete floor can break it. You'll also need to experiment with speeds/feeds for carbide....most operations where carbide end mills are used require higher speeds to realize their benefit.
 
I have been a machinist for 10 yrs now. I have used and broken so many end mills I don't even want to think about it. The cheaper end mills will work if you are doing minor work, Milling brass for guards etc. Higher priced end mills , like Ed pointed out, will break just as easy as the cheap ones. I have found if you want consistent quality but US made. In the carbide I like ATRAX. They are reasonably priced. I compared them to a "better" brand that cost 3-4 x as much and they performed the same. I normally use carbide unless i am cutting gummy materials like copper.
 
Hi CDH,
For non ferris materials like nickel silver, copper, aluminum, etc...
A good quality high speed steel end mill coated with titanium nitrite is a good place to start. If you buy one with cobalt it will tolerate more heat and abrasion. MSC Industrial supply has a Good selection.
The coating will reduce some of the clogging of the flutes.
But any tool used wrong won't last long. Try using the recommended RPM's first and adjust them as needed.
Where I work when time is more costly than the cutters I usually find out about the max feed and speed the cutter and the part can tolerate and the back off just a little.
Good Hunting:)
 
I guess I machine a little different than the others is some ways. I use carbide for copper, normal chip loads and very high SFP (500 to 1000) to prevent welding (sounds counter intuitive, I know) and use carbide exclusively for aluminum and plastics for the abrasion resistance (again, sounds counter intuitive, I know), and I use HSS sometimes for steel and titanium because it is tougher, saving the carbide for finishing cuts.

I had a truck come on Monday to pick up 15 gaylords of plastic chips I'd cut dry with just three carbide cutters. Would have require dozens of HSS. That's a truck load fellows...

I also use carbide for hard milling, which is cutting hardened steel. These are shallow cuts, and depending on the coating are sometimes performed dry.

To answer the question, IMO, nicer cutters give a better finish and last longer in a production environment than cheaper cutters, but they're both about the same for tolerating abuse, which is what makes 5 $3 cutters sound like a better deal than 1 $15 cutter for a beginner in an application where burrs and surface finish are not important. And a good cutter for finish work.

Nathan
 
The 1/8 EMs are very delicate. If you want to have a "blind" slot made with these, first drill out a series of closely-spaced holes with slightly undersized drill bits and then mill out the remaining web. Go ez on DOC (depth of cut), don't "plunge-mill", as em will inevitably flex when milling such slots.

If the slot is "open", as opposed to "blind", I use me old trusted BS and a magnifying visor to carefully cut the slot, slightly under and then size it up with a flat file. You need to first drill the "end" hole, of course.
 
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