Help with grinding a step drill

matthewlee · Nov 17, 2021

Hi PM

I have a job where Id like to use a step drill.
Material for the parts is 6061 alum
The hole is .125" dia and is .10" deep.

Could someone guide me on how to make a step drill that would drill the .125" hole and also generate a small 45 deg chamfer?
Or I could even purchase a couple if someone is proficient in making high quality ones. Id like to learn, but it would probably benefit us both if someone could whip them up for some payment.

I have a import "Deckel" cutter grinder and a Black Diamond drill sharpener but am a little lost on how to generate the proper relief if I was to spin a drill bit down and also how to make the 45 deg section for the chamfer.

TGTool · Nov 17, 2021

You should be able to do it. Spin for the .125 diameter and then for the 45 deg section. Then set up at the 45 deg angle and rotated a little to cut back clearance coming right up to the edge. It will probably take a secondary and maybe tertiary rotation and cut to get enough clearance.

gbent · Nov 17, 2021

Quick and dirty? Just circle grind it and back off everything behind the cutting edge. It doesn't matter how. To much relief is fine, to little and it breaks.

EPAIII · Nov 17, 2021

If you are not too particular about that 45 degree spec., then a multi-diameter drill bit will do the job.

McMaster-Carr

The very first one on that page starts with a 0.125" diameter. I have about seven of the multi-diameter bits and every one has either a radius or a chamfer at the junction of one diameter to the next. I use these bits to both drill and deburr a hole in one operation with a depth stop on my drill press. And after drilling and deburring from one side, you just flip the part over and the same depth setting allows the rear side to be deburred.

The only real limitation with this technique is the length of the steps so it is most useful for sheet metal work. But you said you only needed 0.1" deep so it should work.

The better quality (higher priced) ones tend to have a nicely formed chamfer between steps while the less expensive imports usually have a rounded fillet between steps. Also, if you do need that exact, 45 degree spec., then one of these bits would be a great starting point for grinding your own. A lot less work that way.

stephen thomas · Nov 17, 2021

I made them in the past doing as Gbent describes: spin in a 5c spinner. Then hand grind relief on a hard, sharp corner fine grit wheel.

A few years ago, bought an RA Machine spinner on here, and while there is nothing in the manual about it, seems like it was made for step drills. Almost effortless. Spin the drill straight in under the wheel. Then swing it to 45deg, and set as much relief as desired (amount of relief is adjustable through knurled screw adjuster) Set for 2 flutes. Eyeball the flute so it is coming up on the cam, and crank around a few times while adding infeed on the surface grinder table.

smt

memphisjed · Nov 17, 2021

#4 center drill and modify the countersink angle?

dian · Nov 18, 2021

if 45° is 90° included, maybe this?

Free Shipping 7pcs 3mm 10mm HSS 5 Flute Countersink Drill Bit Set Carpentry Reamer Woodworking Chamfer End Milling Hole Wood|Drill Bits| - AliExpress

camscan · Nov 18, 2021

If you make this from a standard twist drill your 45 degree angle will not be 45 or even a true angle. Make a spade drill.

michiganbuck · Nov 18, 2021

That is such an easy job to make an altered standard, perhaps a 3/8 or 1/2 drill with a .125 lead and 45* angle step you might get a bid for 12.
A tool grinding shop will accommodate the angle to give you a proper 45" considering the helix of the cutter.

Special Drill and Reamer in Michigan will give you a quote over the phone.

There are many flip drives for drill & CB.
DeckWise Drill & Drive Tool for Pre-Drilling, Countersinking & Driving Decking (Hardwood, Composite, PVC, Pressure Treated) - - Amazon.com

camscan · Nov 18, 2021

michiganbuck said:
That is such an easy job to make an altered standard, perhaps a 3/8 or 1/2 drill with a .125 lead and 45* angle step you might get a bid for 12.
A tool grinding shop will accommodate the angle to give you a proper 45" considering the helix of the cutter.

Special Drill and Reamer in Michigan will give you a quote over the phone.

There are many flip drives for drill & CB.
DeckWise Drill & Drive Tool for Pre-Drilling, Countersinking & Driving Decking (Hardwood, Composite, PVC, Pressure Treated) - - Amazon.com

If you make this from a 1/2" drill how much flute depth will be left after grinding down to 1/8"?

michiganbuck · Nov 18, 2021

You would have to check the web diameter and perhaps/likely need deepen the flute.

Can be done by hand or with a TC grinder..I don't know if a Deckel can grind flite depth (think not).

Easy for Special Drill & Reamer or any tool grind shop.

Plus back off the step diameter OD on a spiral..can be done by hand or grinder.

QT Op: [ but it would probably benefit us both if someone could whip them up for some payment.]

stephen thomas · Nov 18, 2021

If you make this from a standard twist drill your 45 degree angle will not be 45 or even a true angle.

What are you trying to say?
It will generate a true 45 deg on the work so that part of your statement is not true.

If you mean the flute will be helical to cut 45 on the work, "so what?"

If i had to do a lot of these, i would buy or make a counter sink with the requisite angle, and put a repaceable stubby/DE 1/8" drill in the center held with a SS in the shank. Resharpening the tool becomes trivial, and the drill is cheap and replaceable.

smt

PS, to the OP: I don't know what your your app is, but i find it faster to just drill holes, especially pattern drilled or layed out holes, with a conventional spot and center drill. Then chamfer (in deep holes, thick parts) with a piloted countersink on a flex shaft in the mill, or a hand held drill motor.

For sheet metal or precise depths, i use my aircraft micrometer countersink.
This is not necessarily the best place to buy them or more specifically the cutters, you can shop on your own:

MICRO-STOP COUNTERSINK CAGE | Aircraft Spruce

countersinks are available in most angles and pilot diameters.

camscan · Nov 18, 2021

stephen thomas said:
What are you trying to say?
It will generate a true 45 deg on the work so that part of your statement is not true.

If you mean the flute will be helical to cut 45 on the work, "so what?"

smt

The helix angle will generate a compound angle which will not be 45.
Read bucks post 10,he certainly agrees.

michiganbuck · Nov 18, 2021

If you spin circle grind at 45 it will be 45*. This is the common way to make this tool. Stephen's correct reply and the flute will be helical.

If you TC grind it and roll the edge below center to make the clearance then you will need to bump the dial number about 1/2 degree (or so) to get 45. Yes more or less depending on the clearance. Aluminum likes 15 to 25 primary(about some time/parts even 30*).

If you put the edge at centerline average and tilt the wheel head angle you may need to tweak the dialed number.

The old rule was 1/2 degree ok, unless otherwise specified, that one can often eyeball check with using a loop and a 45 gauge/template.

stephen thomas · Nov 18, 2021

The helix angle will generate a compound angle which will not be 45.
Read bucks post 10,he certainly agrees.

you are confused on both points.

do you make/grind any complex tools?

smt

matthewlee · Nov 18, 2021

Wow!
Thanks to everyone for jumping in here to help.
It looks like I now have several viable options that I didn't think of previously.
This job is 1000pcs with 29 holes in each part, so a sharp precision drill and debur tool is needed so I can maximize speed and not have any burs to deal with.
I'm going to order a couple things and also see how it goes with yours truly step grinding.
Thanks again!

camscan · Nov 18, 2021

stephen thomas said:
you are confused on both points.

do you make/grind any complex tools?

smt

Not now but I did. Drills were made on a Christen drill grinder and the helix angle and the radius of the flute threw the angle off.

michiganbuck · Nov 18, 2021

matthewlee said:
Wow!
Thanks to everyone for jumping in here to help.
It looks like I now have several viable options that I didn't think of previously.
This job is 1000pcs with 29 holes in each part, so a sharp precision drill and debur tool is needed so I can maximize speed and not have any burs to deal with.
I'm going to order a couple things and also see how it goes with yours truly step grinding.
Thanks again!

If you have an altered standard made consider making the step length long enough for a number of end/drill point resharpenings. Likely the 45 will outlast the drill point.

Some times better to sacrifice a little time to make longer-lasting tool life when using special cutting tools.

Booze Daily · Nov 18, 2021

I've used one of these before. It works fairly well.
McMaster-Carr

matthewlee · Nov 18, 2021

Booze Daily said:
I've used one of these before. It works fairly well.
McMaster-Carr

Thanks
That could work. Im shooting for as short and stout at possible so I can hold location without using a spot drill. This countersink option seems to leave alot of drill hanging out there and would compromise rigidity.

Help with grinding a step drill

Hot Rolled

Titanium

Diamond

Diamond

Diamond

Titanium

Titanium

Titanium

Diamond

Titanium

Diamond

Diamond

Titanium

Diamond

Diamond

Hot Rolled

Titanium

Diamond

Titanium

Hot Rolled

Similar threads