Initial End Mill considerations

A

architard

Active User
Registered
I just placed an order for a Grizzly G0704 mill, and I'm starting to work on the initial tooling that I will need. I think I have a pretty good idea on the basics that I'm going to need such as a vise, parallels, edge finder, R8 collets, etc. But when it comes to end mills I'm not exactly sure what is a good list for the beginner.

I'm leaning towards cheaper stuff for now, as I've never operated a mill (only a lathe) and I am sure I will break some, but I wouldn't mind getting a few solid carbides just to see what they are like in comparison.

The first thing I'll be working on with this will be the parts (mostly aluminum) to convert this mill to CNC, but I will want to be able to work with steel as well. I understand the ideas behind the differences of square end, ball end, number of flutes, etc. but I just don't have any practical knowledge of what might be the best choice to start with.

So I guess the question goes out to the experienced mill operators, if you had to start out with just a handful (thinking no more than 5 at this point) of end mills, which would you choose?
 
Get a 2 flute for aluminum and a 4 flute for steel, I would get a 1/4, 3/8 and a 1/2 to start off with.

Back in 2002 I got a bunch of new China end mills they were costing between 1 and 2 bucks each.
And you could get a lot on resharps in us made endmills cheap but those days are gone. I'm glad I got enough to last my life time.

Paul
 
Carbide doesn't like interrupted cuts. They chip. You do a lot of interrupted cutting on a mill. Start out with HSS end mills. 2 flute for slotting and counter boring, 4 flute for facing and edging.

Ken
 
Center cutting mills cost about the same as non-center cutting and you can drill a little bit with them. Makes cutting a pocket to exact depth easier.

I personally find the limiting factor for depth of cut on my mico-mill to not be chip evacuation (that's what 2-flute end mills do best), but cutting power. I will go against the conventional wisdom and state that I really like my fine-tooth roughing end mill for taking deep cuts in aluminum. They are really designed for cutting steel, but on a low power machine, they work great. Your machine has more power than mine, but it's still on the small side.

Walt
 
Get yourself an assortment of high speed steel 2 flute double end end mills. As long as you run them at the proper speeds and keep the chips clear, they shouldn't break. The proper speed for an end mill is four times the cutting speed of the material (250 surface feet/minute for aluminum), divided by the diameter of the end mill. Carbide is expensive, very unforgiving and therefore not for beginners. I would suggest steering clear of it on the mill and the lathe until you master the use of high speed steel. Even then, there are few applications in the home shop where it will perform any better than HSS.

Tom
 
When I got my first mill, I got one of the TiN coated end mill assortments. I don't recommend them. I ended up chipping the ones I used a lot, and the less commonly used sizes lay in plastic. The set I got was also not that great in quality, even as far as imports go. Maybe you could find a better set. My recommendation would be grab some HSS endmills (2 or 3 flute for alum, 4 flute for steel) in some common sizes (1/4, 3/8, 1/2). Shop around the tool houses, somebody is usually having a sale. Buy at least 2 or 3 of each size. Small import end mills are often only $3. Odds are you are going to break some when you are learning. Once you figure out how _not_ to break tools (or at least, reduce breakage), then you can get some nicer mills (they are worth it, but only if you don't snap em` in half in the first 5 minutes). Stick with square end mills unless you have a specific reason for a ball end or taper mill.

I would also recommend some sort of cutting fluid for aluminum. It is "sticky" and chips weld themselves to the part, your cutter (the dreaded "built up edge", and themselves). A little spritz of WD-40, or a shot of KoolMist 77 from a squirt bottle can keep things from getting too exciting.
 
If you know you are going to have interrupted cuts, use a 4 flute, soft materials like aluminum, use a 2 flute, For aluminum, I really like the High Helix (55 degrees) 2 flute end mills. If you are going to put a groove through aluminum, use a 2 flute with adequate lubrication. Not so much for cooling as it is for chips loading up and adhering to the flutes.

And remember that a smaller end mill can do a large job, but a large endmill can't do a small job. Size things up appropriately. If you have a slot that is .250 wide, DO NOT use a .250 diameter end mill. Ise a 3/16" endmill to cut through the slot centerline, then you will have cleanup on each side. Using a .250 diameter on a .250 wide slot will leave you with a crappy looking finish along with the probability of the slot being oversize. ALWAYS leave yourself enough room for a cleanup cut.

I've probably mentioned it before on here, and I know I mentioned it numerous times to the ones that I mentored, but I always told them......"become one with the machine, become one with the cutter".

By that I mean, know the machine and what errors the machine has. Backlash for one. Does the mill table drop when you get it out so far? Learn and understand what the machine does.

When it comes to end mills, the same thing. Learn what an end mill does when it's cutting. Visualize it in your head like you are watching it in slow motion. How much is the end mill flexing. How much does the material change when it gets heated up? How much does the end mill change when it starts getting warm?

Once you become one with both, you'll learn what you need as far as tooling. There is a science to it.

As far as consideration, remember that little can make big, but big can't make small depending on the operation. End mills have come down in price and even the China stuff will last if you treat it right. When you order an end mill, order two. Order a 4 flute, and order a 2 flute of the same size. Almost every week ENCO, Travers, or a similar tool vendor has sales. Get signed up to their websites so you can get their flyers and Promo Codes. Before long, if you take care of the tooling, you'll have a nice supply of end mills to get you through almost any project. Keep the end mills either in their original containers, or get something like the plastic cutting boards at WallyWorld, cut some radiused slots into them, and cut the board to fit into your toolbox drawers and store the end mills that way.
 
architard said:
I just placed an order for a Grizzly G0704 mill, and I'm starting to work on the initial tooling that I will need. I think I have a pretty good idea on the basics that I'm going to need such as a vise, parallels, edge finder, R8 collets, etc. But when it comes to end mills I'm not exactly sure what is a good list for the beginner.

I'm leaning towards cheaper stuff for now, as I've never operated a mill (only a lathe) and I am sure I will break some, but I wouldn't mind getting a few solid carbides just to see what they are like in comparison.

The first thing I'll be working on with this will be the parts (mostly aluminum) to convert this mill to CNC, but I will want to be able to work with steel as well. I understand the ideas behind the differences of square end, ball end, number of flutes, etc. but I just don't have any practical knowledge of what might be the best choice to start with.

So I guess the question goes out to the experienced mill operators, if you had to start out with just a handful (thinking no more than 5 at this point) of end mills, which would you choose?
Click to expand...

I suggest you buy center cutting end mills so if you need to plunge cut you can without drilling a pilot hole. If there isn't a shop around you that resharpen end mills I would buy the cheaper ones and throw away the ones that are worn out. Good luck
 
You must log in or register to reply here.
Back
Top