150-400 SFM is the recommended surface speed for drilling aluminum with carbide and this calculator recommended 0.0008 to 0.0018" per rev for the feed.

Helpful GuidesExtra Long Tungsten Carbide BurrsA range of long reach carbide burrs. Ideal for sculptural workRead More...How to Choose the Best Carbide BurrWhen should I use a carbide burr? Which burr shape is best? Read More...Recommended Speed for Tungsten Carbide BurrsHow to choose the right speed for tungsten carbide burrsRead More...

U Drill speeds and feeds Chart

I like the idea of drilling out the center of the 3/8" holes with the 1/8" bit and then milling out to full size. I’m assuming the latter would be done at full depth to spread wear along the length of the cutter.

Solid Carbide Stub Drills Ideal for drilling steel, cast steel, cast iron, titanium, nickel alloy and aluminium Micrograin carbide Sizes available from 1.0mm - 13.0mm Dimensions  Drill Diameter Flute Length Overall Length 1mm 12mm 34mm 1.5mm...

I like the video. I wonder if some of the setups where the mill head is angled over could be avoided with fixturing that holds the workpiece at an angle (or one of those tilt-type tooling vises).

Drillspeedchart Mild Steel

I’m hoping he can reliably run an 1/8" stub drill with air blast and light lubricant mist. He needs 1/8" and 3/8" holes. My thinking is drill everything with the 1/8" drill then use a 3mm Datron single flute stub mill to go from 1/8’ to 3/8" where needed.

IMO 0.001 feed per rev is pushing the minimum I would go, that’s 0.0005" chipload and starts to get iffy on the chips ability to carry the cut’s heat with it. A thicker chip will be better for heat management and should help break them which can be easier on the tool. Ive found that 0.002-0.004" FPR is the magical sweet spot for carbide drills (depending on helix). Might require an HDZ or other ballscrew Z axis to push them with enough force though.

With this thickess of material, the chip being as tightly spiraled as it is, and it being aluminum, I’m not too worried about chip wrapping. Also, it’s on a pretty clear expanse of flat plate. If you’re drilling down inside a pocket or close to a step or a clamp, you can get the “weed-whacker” effect where the chip hits something and bounces back toward the tool. If it doesn’t break, it could potentially wrap.

If it is a hard surface (including hard plastics) - Choose a Diamond Cut burr.  The fine tooth structure will ensure a rapid cut and a finer finish.

Step 1: Choose the shape of our Tungsten Carbide Burrs (also known as rotary files or die grinder bits) that will do the job.

In the Shapeoko, with a spindle capable of running well at low RPM the limit seems to be how hard the Z axis can push down to meet the feed per revolution required to be cutting instead of rubbing. I’m up to about 4,000RPM on the 4mm bits now. At a certain point increasing the RPM and Z feed rate the whole X gantry starts to vibrate and I chicken out and back off. In Aluminium I add small amounts of Isopropanol as lubricant as that’s largely ‘self cleaning’ as it evaporates away.

Dependent on the size of the burr, premium quality carbide burrs are either fully machined from a solid piece of tungsten carbide or the cutting head of the burr is made from a 'blank' of tungsten carbide which is soldered onto a tool hardened steel shaft to create the burr head.

Can you let us know what machine you’re using and what grade of metal it is? The hole looks clean but I can’t help feeling that the spiral chip would get really tangled up if drilling a lot of holes.

Also, this video spurred me to learn something new - that the term quadriplegic includes people affected with partial paralysis of the limbs. I had always associated the term with complete paralysis previously.

The exception to this is when working in a pillar drill type of application or counter-sinking when working at 3,000 rpm or even lower will be effective.

Thanks for posting this I am looking into drilling on a cnc router for a friend that needs to drill hundreds of holes in 3/16 aluminum bar stock.

We stock an extensive range of tungsten carbide burrs in 11 different shapes, 2 different cut forms and a whole range of diameters which will easily fit on to your die grinder.

To avoid tool changes and having to revisit the same holes, the 3/8" holes could be done with a combo drill / end mill. I would think the style with the twist-drill type point would be best (what they call “Drill Style - 2 Flute” here):

Non-ferrous metals and soft plastics can clog up the cutting head of a burr so for this reason the fluted cutting shape makes sense.

The machine profile of the carbide burr is important for it's application.  There are many older styles of cut profile but at AFS we took the decision to focus on the best options for all applications.  We therefore have two cut profiles available as standard.

Finally got around to trying this out. 0.089" (2.25 mm) is the tap drill size for a 4-40 thread. Carbide circuit board drills are typically 1/8" shank and come in a range of sizes, including sizes larger than 1/8":

Fluted Cut Burrs = Softer metals and soft plastics tend to heat up quickly when grinding into the material surface.  For this reason we supply the fluted cut profile on all our carbide burrs designed for aluminium.  Fluted cut carbide burrs have long curved cutting profile which allows for efficient removal of the grinding swarf and also allows for more air to get near the cutting surface in order to keep the workpiece cool.

Those ones you show look like they have a decently high helix angle, which was also recommended in the above link. I’d say give 'em a try if the price is reasonable. I don’t think the tip angle is going to be super-critical. 118 is the common angle for jobber drills that have been used for years and years.

“The threshold for aluminum is something like 60,000 sfm, which is enormously fast,” he said. “I’ve seen aluminum run at 24,000 sfm with an uncoated carbide insert, and it didn’t harm the aluminum or the insert. I tell our customers that, within a safe working environment, don’t be afraid to crank it up because I’ve seen that higher speeds in aluminum gets you both better tool life and a better surface finish.”

I’ve found that both chip extraction and some small amount of lubricant / coolant are key to using the carbide drills and not getting a hot workpiece, I’m not up to the SFM where the temperatures start to drop back down and I’m not sure this machine can get there.

Aluminum drillspeedchart

I looked into them as the first option but I don’t know long the sharp point will last with non stop drilling. From my understanding they are for light drilling not for constant drilling as the point quickly wears out. I couldn’t find any drill mills with 118 degree tips.

I went with 10,000 rpm for a surface speed of 233 SFM and feed rate of 10 IPM for 0.001" per rev. Put a little drop of 3-in-1 oil on the plate and a little on the bit and voila!

DrillSPEEDCHART pdf

Yes, the mill/drills could be one of those situations where you compromise some of the attributes of each of the two tools by combining them into one. This page recommends 130 to 140 degree angles for aluminum:

Diamond Cut Carbide Burrs - for hard metals such as stainless steel and titanium. Diamond cut tungsten carbide burrs are identified as Code 6 ( /6) at the end of our part (sku) number. The multi-faced diamond cut burr ensures rapid low vibration cutting on steels and other hard metals.

I was using a clearance plane of Z 0.125" and went down to Z -0.166" (0.125 material + 0.021" drill point + another 0.020" to make sure it went all the way through). 0.291" total travel at 10 IPM is about 1.75 seconds. Rapiding back up out the same distance at 100 IPM would be about 0.175 seconds. Total cycle time of about 1.93 seconds.

HSS drill speeds and feeds metric

Tested on scrap 1/8" plate, drilled all in one go. I read up on peck drilling and that wasn’t recommended unless you’re going deeper than 3x the diameter of the bit. This page seemed to have some good recommendations on peck depths:

HSS drill speeds and feeds chart pdf

Looking at a carbide burr in a box it is very difficult to tell one burr from another.  Here are three tips which might help you to separate the sheep from the goats (so to speak)...

Aluminium grinding swarf will stick to the head of the carbide burr if too much heat was generated in the grinding process.  Keep the heat down and allow air to get to the workpiece will prevent fluted cut carbide burrs from loading.  Assuming you have not been able to prevent swarf build up and you haven't got a pot of hydrochloric acid handy (which will dissolve aluminium) then the next best option to clean the carbide burr head is to use brass wire brushes to clean away the aluminium swarf.

Diamond Cut Burrs = This is a finer tooth head which has a knurled appearance on the surface which creates a large number of smaller cutting faces.  Ideal for harder metals including steels, stainless steel and aerospace metals.  The finer burr cut profile also improves the quality of finish from the burr.

True - this is definitely a thin chip at 0.0005". I’m fairly confident that I could double the feedrate without issue. I will have to try that next time I fire up the machine.

Drillspeedchart for steel

High Speed Machining (HSM) What is High Speed Machining (HSM)? High speed machining (HSM)--also called trochoidal milling, adaptive clearing,

As a grinding tool, carbide burrs are unforgiving. The shape of the burr will directly reflect the shape of the cut achieved, so when you are selecting the burr it is important to check that you have the correct shape for the finished profile you aim to achieve.

What's inside? A guide on how to choose the best cutting shape for you. Recommendations for use. Cutting speed tables.  And our full range of 80+ burrs organised by shape and size. Available here.

25Deg Right Hand Helix, Two Flute, 118Deg Four Facet Point. Milling & Special Form Tools. Loc-Line® Modular Hose System. Vises & Work Holding. Ultra-Tool® USA Part #52008. Hand Tools. SPT is an Authorized vendor of ULTRA TOOL/TOOL ALLIANCE.

Yes it will ramp down to full depth then open it up. I figured pre drilling will help take the plunging load off the endmills work and speed up the cycle time. The work will be done on a Tormach 24r which is a linear rail ball screw machine that should be fairly rigid. Had the HDM foot print been large enough I would of had him go that route but he needs 40" of travel for his parts.

For a softer surface  - Choose the Fluted Cut burrs.  The open fluted structure allows the swarf to be removed quickly without clogging up the surface and generating more heat.

Those Kyocera PCBs I have are 130 degree. I think the angle is slightly different when they get over a certain size ( I think I saw that in the ebay listing description for them).

He has been hand machining and drilling 1000’s of holes to make adaptive reachers for quadriplegics every year for the past 20 years on an old bridgeport knee mill so I’m excited to help my friend to get into doing Cnc work for the first time. His tools changed my life and I couldn’t live independently without them so to help him help others is a pleasure and the least I can do.

Step 2: Select the correct cutting edge for excellent carbide burr performance. To keep it simple we only supply the premium performance carbide burr forms.

In principle we recommend the highest effective speed for carbide burrs.  This will assist in removing swarf and reduce the chattering against the workpiece which will, in turn, improve the finish from the burr cut.

Let the burr do the work.  High pressure at the contact point will only increase heat and therefore the risk of a burr head failure.  Enough pressure is needed to ensure a consistent contact with the workpeice but no more than that.  Lower pressure will also allow for easier swarf removal which will in turn lead to a cleaner and smoother cut with your burr.

Brass is significantly softer than the carbide burr so a good quality brass wire brush will be able to remove the swarf leaving the cutting tip undamaged and ready to carry on working.

Harder metals won’t clog up the metal, but the metal breaks off in small chunks, so lots of small cutting edges which you get on a diamond cut head speed up the grinding process.

Drillspeedchart mm

Instead of retracting a drill, you could go right into milling with the same tool in the same hole with it already at full depth.

I pretty regularly use a carbide spot drill to pre-drill holes to then open out with an end mill running a bore or adaptive toolpath in Aluminium, I started doing that after killing a couple of endmills in the initial helical ramping.

These Are Specifically For Use On Aluminium 90 Degree Point 2 Flute Standard Length Micrograin Carbide Dimensions  Cutting Diameter Flute Length Overall Length Shank Diameter  3mm 8mm 50mm 3mm 4mm 10mm 50mm 4mm 5mm 15mm 50mm 5mm 6mm 15mm...

The holes will be drilled prior to bending with only 2 holes being drilled in a angle jig. I had him try it flat but those hinge holes deformed when bent so they have to be done after the bend.

Fluted Cut Carbide Burrs - for non-ferrous metals and plastics are identified as Code 3 ( /3) at the end of our part (sku) number. The open fluted cut face aids fast swarf removal on soft materials such as aluminium and soft plastics.

I’ve also used regular ‘jobber’ drills in the spindle for repetitive drilling ops where I didn’t want to wear out nice carbide tooling and that works well too, at well under $1 per drill bit you just replace them as they blunt.