Syringes Put The Squeeze On This Mini Drill Press - drill bit to make big holes

I keep a 2″ diameter 90 degree facemill in my shop as well as a 3″ Glacern FM45 45 degree face mill. The FM45 sees a lot more use for sure.

First, end mills are generally smaller in diameter.  This means it will take many more passes to do the job and all those passes will leave that many more marks on the work.  The end result is end mills will take longer and they will have a much less fine surface finish.

Use of Wiper Inserts can greatly improve the surface finish when Face Milling.  High feed rates and low depth of cut (0.8mm or less) will facilitate this.  PVD (diamond) inserts with very sharp edges can also improve your surface finish.

Be careful where you use 45 and 90 degree cutters. A workpiece that is not well supported, will deflect under a 45 degree cutter due to the high axial forces. A 90 degree cutter will produce a more consistent cut and the corresponding decrease in chatter will extend the life of the cutter.

It’s important to do your research before selecting a tool for drilling through metal to ensure the best results. If you’re planning on completing any hole drilling projects and need help deciding on the right tool for you, the Ohio Power Tool team can help! Give us a call at 800-242-4424, email us at sales@ohiopowertool.com, or leave a comment below for assistance. To be the first to know about new products and deals, subscribe to our e-newsletter and follow us on social media!

One last thought about face mills–they’re horsepower hogs. Don’t try to use too large a face mill on your machine. I’ve stalled the 3 horsepower spindle of my mill running my 3″ pretty easily.  Granted, it’s a smaller mill, but you need to keep in mind even if you have plenty of spindle power that the face mill is going to transfer a whole lot of it into your workpiece.  Make sure it’s clamped down tight!

Of course you can use end mills for surfacing, but it is seldom optimal to use an end mill.  There are two major problems using end mills.

At one time, octagonal face mills were at war with the 45 degree face mills for supremacy. The octagonal inserts have more edges, so you can rotate the insert if one gets chipped. But, tooling costs are usually only about 3 percent of the manufacturing cost, so the greater efficiency of the 45’s eventually won out.

For holes ½” or larger, we recommend using carbide hole saws, RotaCut bits or a mag drill and annular cutter bits. These will be the most precise, efficient, and cost-effective options in any plate, and they are long-lasting options that won’t wear-out easily over time.

Larger I-Beams and thicker metal come with their own set of challenges and solutions. For small holes (less than 1/2″ diameter), twist drill bits remain the best option. They work in any drill, are inexpensive, durable, versatile for wood or metal, and are readily available pretty much anywhere. The thicker the material becomes, however, the more important a steady alignment becomes. At this thickness, a mag drill with a chuck adapter makes a lot more sense. The mag drill with annular cutter bits is going to be the most accurate, precise, fastest and often the most cost effective option for hole making. As mentioned before, however, when we tried cutting through I-Beam with RotaCut bits and a cordless dill, it went nearly as smoothly and quickly as the mag drill and annular cutter bit, so this is a great option that’s more affordable if you don’t need to make as many holes.

The Button Cutter (also called a Copy Mill or Toroidal Cutter) uses a round insert and has many advantages of its own.  Tough to call a winner with a Button Cutter versus these other Face mills, so click through and see about Button Cutters in their own right.

If you’re on a CNC Router, a very common operation is “Spoilboard Surfacing“, and while the router crowd likes to call the milling cutters used for Spoilboard Surfacing “Spoilboard Cutters”, they’re just another form of Face Mill.

Of course if you can afford it, it’s great to have both 45 and 90-degree face milling tools, but what are the pros and cons for each?

First, what are we talking about when we say 45 or 90 degrees?  The answer is fairly obvious from the photo above comparing two Glacern cutters.  Take a look at the angle of the cutting edge on the inserts.

Ohio Power Tool has been in business since 1983 providing premier customer service specializing in sales and factory authorized service for all major brands of pneumatic tools, electric tools and hydraulic equipment. Our experienced staff can help you find the right tool for the job!

You also should be lubricating your drill bit before use. This helps preserve the lifespan of the bit, reduces friction, and keeps the drill steady on its point of contact. Wax, sprays, and oil can be used for this depending on the angle and size of the hole you are drilling. Cutting fluid and multipurpose oils work great for drilling holes 1/8” or larger.

Let’s start by choosing the best type of Face Milling Cutter for your Face Milling needs.  The biggest differences between Face Milling Cutters are:

Technically, that’s face milling, though we typically only refer to it as face milling when we are using special milling cutters called “Face Mills” or “Shell Mills”.  Note that there is literally no difference between face mills and shell mills.

Once you start drilling holes around ¾” or larger, it’s best to switch to bi-metal hole saws for a longer lasting option, or carbide hole saws that are faster and more durable for those larger holes. Bi-metal hole saws usually cost around $9, with carbide hole saws slightly higher, around $15. These options are also durable, versatile, inexpensive, and readily available almost anywhere.

Yes!  The angle is the angle of that cutting edge–45 degrees for the cutter on the left and 90 degrees for the one on the right.  That angle is also called the lead angle of the cutter.

For repetitive hole making where thousands of holes will be needed, a Hole Punch is a good option. These are limited, however, by shallow throat depth, meaning they’re really only an option when working 1″ – 2” from the edge of a material. The price tag also jumps dramatically (over $2,000), so it’s not a solution most will consider.

I selected my machine, workpiece material, and indexable tool type.  I’m modeling a smallish 2″ diameter face mill with 4 inserts, and I have set the Lead Angle to be 90 degrees.  My Cut Depth is 1/8″.

Steel plates can come in pretty much any size, so it’s important to consider the thickness of the plates you’re drilling into before working because it can drastically impact the performance of your drill. For instance, Magnetic Drill Presses are a common solution for drilling into steel plates, but sometimes the steel plate may not be thick enough to provide a sufficient amount of magnetism to hold the metal in place during use. There are a couple solutions for this. One is using a drill that comes equipped with features that measure magnetic force. Many of CS Unitec’s drills use green/red LED lights to indicate if the tool is safe to use at that level of magnetism, so these are a great option for any steel plate drilling projects. Another solution when working with thin steal plates is to add another piece of steel under the one you are drilling, which will ensure that it is thick enough to provide enough magnetism under load.

Similarly, if you are drilling large holes (2”-4” in diameter), Knockout sets become a great option. These are a common solution for making holes in electrical panels where a punch & die make a nice clean hole. Hydraulic or Manual Knockout Set prices start around $900, with cordless M18 Knockout Sets even getting to $1,000+. These higher price tags are why we don’t see the Knockout tools being that popular outside of the electrical trades, but they are a terrific option. A good, affordable option for larger holes in sheet metal are HolCutters, which top out at 3” but only cost around $30.

Drilling holes into metal isn’t the most straightforward task for those who don’t do it for a living. Even if you do, choosing the right tool for the job isn’t always easy. There are a lot of factors to take into consideration–how many holes are you drilling? What material are you drilling through? What size hole is needed? These factors play a big role in how quickly, efficiently and affordably you can get the job done, so here are some tips on how to determine what type of tool is right for you.

Both Sandvik and Kennametal will suggest the 45 degree cutter is a better bet for general purpose face-milling. The arguments given by these two for choosing the 45 are:

Lately, you can get some face mills that use a 45 degree insert that’s double sided, so we have the best of both worlds since these inserts now have 8 edges like the octagonal inserts.

Now, we can check out the 45 degree face mill / shell mill just by changing the lead angle to 45.  Let’s assume every thing else stays the same, here are the results:

Louis, thanks for raising that issue. You’re quite correct about the 45’s higher axial forces and the issues they may cause for a workpiece that is not well supported or perhaps that is simply a bit thin.

You can get a face miling cutter in a wide range of cutter diameter.  What you want to do is balance 2 factors.  First, the bigger the better.  It will take fewer passes, and ideally maybe even a single pass, which is best for surface finish.  Number two is the counter point to number one.  You must respect the horsepower and rpm limits of your machine.  The bigger the cutter diameter, the more power it takes.  I will also add that spindle speed can be a limiting factor.  In general, larger cutter diameter cutters have to spin at lower rpms, while smaller cutter diameters can spin at higher rpms.

Join 100,000+ CNC'ers!  Get our latest blog posts delivered straight to your email inbox once a week for free. Plus, we’ll give you access to some great CNC reference materials including:

Hopefully this post has been helpful for showing the various ways to make holes in metal, which heavily depend on the diameter of the hole needed and thickness of the metal you’re drilling. There are also other important variables that come into play–how many holes need drilled, how precise they need to be, how much your labor time is worth and if this is a one-time thing or everyday task. Investing in a $3,000 hole punch seems ludicrous when a $5 drill bit will do the same thing, which is of course true if you’re only drilling 10 holes one time. Change those 10 holes to 100,000, though, and things start to look a little different. If you save 30 seconds per hole in labor and say 830 man hours at $30/hour, that’s a $25,000 difference–definitely worth the investment.

Now we see why the 45 degree models are so popular–that’s more than 40% more material removed.  That’s definitely going to pay for the new face mill pretty quickly if you’re using it for very many parts.

Other alternatives include 75 Degree Face Mills and Button Cutters (Round Insert Indexable Mills).  The 75 Degree Face Mill’s primary purpose seems to be providing just a bit more clearance than the 45 degree can.  It might be your 3rd or 4th choice if you already have a 45 and 90 and want more options for difficult cases.

Before you begin, you should make sure that all of your tools are prepped accordingly. Firstly, the material you’re drilling into will determine the type of hole drill that you should use. When drilling into metal, slower RPMs are actually better than fast ones. This is because it gives a smoother and more precise outcome, unlike drilling into wood, which requires high RPMs. You can check if your drill is going too fast by looking at the chip sizes that come off of the metal. If long, curly ribbons are coming out as you drill, that means you’re working with a good RPM. If the chips are coming out as a fine dust, your drill is spinning too fast and you should slow it down. 200-400 RPMs are recommended for the best results.

It’s easy to compute Feeds and Speeds to compare these two face milling solutions using our G-Wizard Calculator software (click the link for a free 30-day trial if you’ve never played with G-Wizard).

By the way, round insert cutters are also called “Button Cutters”.  We have an entire article about Button Cutters if you’re interested.

Louis, thanks for raising that issue. You’re quite correct about the 45’s higher axial forces and the issues they may cause for a workpiece that is not well supported or perhaps that is simply a bit thin.

RotaCut bits are an excellent choice for holes ranging from ¾” to 1-1/2”. They can be used in handheld drilling applications and are specifically designed to cut through sheet metal. In our testing, we found that RotaCut bits easily cut even through I-Beam using a cordless drill, so they are definitely something to consider when cutting through different materials. These typically far outlast traditional twist drill bits and run around $9, making them a great long lasting and inexpensive option.

If you’re primarily after a great finish, then you probably want a fly cutter.  The lowly fly cutter gives the best finish in most cases.  BTW, you can easily convert any face milling tool to a fine fly cutter by simply removing all but one cutting edge.

If there’s a slot or other recessed feature in the surface you’re Face Milling, you’re going to be doing some interrupted cuts.  This is hard on the inserts, so if you’re dealing with a tough material, you may want to reduce the feedrate up to 50%.

Be careful where you use 45 and 90 degree cutters. A workpiece that is not well supported, will deflect under a 45 degree cutter due to the high axial forces. A 90 degree cutter will produce a more consistent cut and the corresponding decrease in chatter will extend the life of the cutter.

Sheet metal is used in some fashion in almost every trade. When drilling into this material, there are a variety tool options based on the type of hole you are trying to achieve. The first are twist drill bits, which are great for cutting precise holes less than ½” in diameter. These bits are incredibly durable, inexpensive, and easy to find in stores. They also work in any drill, which makes them arguably the most common solution, but these are not ideal if you’re going to be drilling a lot of holes. If you aren’t sure exactly what size hole you’ll need, step drill bits are also a relatively inexpensive, efficient option when drilling a small amount of holes.

For large holes (3″+ in diameter) in thick metal, there are very few options. This is a tough task that only a few tools can handle, and we recommend the CS Unitec MAB1300–the monster of all mag drills. With a 5” diameter and 4” depth of cut capacity, this tool stands nearly 3’ tall and weighs 112 lbs., but it is a beast that gets the job done well.

Try to roll into the cut with an arc.  It will improve your finish as well as your insert life.  More toolpath ideas here.

When it comes to making small holes, a lot of the same products you can use in sheet metal are similarly effective in steel plates: twist drill bits, step drill bits or a hole punch. With all of these, however, the thicker the steel plate, the less efficient. Silver and deeming bits are a popular option for drilling somewhat larger holes into steel, but this is more the ‘old school’ approach–pushing through the metal rather than carving out a hole. These are not necessarily the most efficient, especially when working on thick plates.

I did do a couple of jazzy things.  First, I’m doing a 60 percent width pass.  This will give a better finish and go easier on the inserts in tough materials than a full width pass.  Second, I have specified this as an HSM cut.  That’s HSM for “High Speed Machining.”

I can do that since I will use a toolpath that arcs gently into the cut and I will arc the end of each pass to avoid a sharp corner and also to avoid completely leaving the cut.  Those are CAM toolpath tricks that can really help you out on tool life, surface finish, and in this case, they let you opt for a big increase in feeds and speeds too.  If your CAM won’t do those things the Conversational CNC Face Milling Wizard in G-Wizard Editor will do them very easily.

Bob is responsible for the development and implementation of the popular G-Wizard CNC Software.  Bob is also the founder of CNCCookbook, the largest CNC-related blog on the Internet.

And lest we forget button cutters, they combine some of the advantages of each plus they are also the strongest.  So if you have to deal with nasty materials, a button cutter might be your best choice.

What is Face Milling?  Think of milling with the side of an end mill.  The general term for that is “peripheral milling”.  Now, what if we cut strictly with the bottom?

There are a few options we really would not recommend for drilling into materials this thick. Hole saws are still used by some, but this is certainly not the intended use and has very little life expectancy. You’ll likely see breakage and wear after just 1 use on this type of material. We also don’t recommend any twist drill bits or silver and deeming bits (that’s not in a press of some sort), however, reamer bits are extremely common for hole enlarging and hole alignment in structural steel.