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Stable mini-drill bits for narrow brass strips

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PT-2

PT-2

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I need recommendations on what type of bits are strongest and run truest for drilling 1/16 x 1/64 brass strips with my drill press in bit sizes 78 - 63. Also the rotation speeds. Mine which I think are for wood have suffered under my use and several have broken getting stuck in the soft aluminum base that I made with coffee stirring strips on top sanded down to around 1/32 inch to hold the strip. All recommendations are appreciated. I see MIcroMark has high-speed and titanium bits but don't what to rush out too fast with the wrong cash outflow. Thanks, Rich (PT-2)
 
Hello Rich, I will try to help you... You should buy only HSS drill bits (for steel), they don't have to be titanium or other 'super-duper' expensive materials. Drill bits for wood will not do. The trick, however, is the endpoint of the drill bit.
Brass has a tendency to grab the sharp edge on drill bits. That same sharp edge that cuts steel so well will also dig in hard in brass and suck the bit into the work. Bits for brass, whether drill bits or turning bits for the lathe are supposed to have a zero rake cutting edge. That way, they will not grab, and, it’s simply the proper tool bit geometry for brass.
To take that sharp edge down, you run the cutting edge of the bit along with a honing stone. The idea is to make it flat, which is no good for cutting steel, but cuts brass very well, and stops the grabbing problem. It usually takes 3-5 strokes to get the sharp edge off and condition it for brass cutting.

1609636112387.png

When you are done it will look like this. The shiny part you see is where the sharp edge has been honed down flat. It only takes a very small flat to be effective. No more grabbing.

1609636169063.png

I found a great video on the YouTube channel, hope it will help you and other members, as we often drill brass material


Happy New Year!!!
 
Hi Rich,

I totally agree with Jimsky and would add that all drill bits "wander" small drill bits more than larger ones.
I would recommend getting good quality HSS bits, I would think there are quality bits made in the USA.

When it comes to small drill bits have plenty of them as they tend to break easily, it pays to watch the bit as it is drilling to see how much it bends, when you see it bending back off on the pressure.

As for how fast to run the drill bit, how fast does your drill press run at?
I would say without seeing your drill press to run it "flat out".

To drill small holes in thin material I would recommend building a simple drill jig.
At a minimum it is good to centre punch the material so that the drill bit doesn't "wander" before starting to drill.

You don't need fancy equipment to build a drill jig as long as your bench/pedestal drill has a table that you can clamp things to it should be possible, it is better to make this jig from bits of steel especially the drill guide.

Cheers,
Stephen.
 
Stevedownunder said:
Hi Rich,

I totally agree with Jimsky and would add that all drill bits "wander" small drill bits more than larger ones.
I would recommend getting good quality HSS bits, I would think there are quality bits made in the USA.

When it comes to small drill bits have plenty of them as they tend to break easily, it pays to watch the bit as it is drilling to see how much it bends, when you see it bending back off on the pressure.

As for how fast to run the drill bit, how fast does your drill press run at?
I would say without seeing your drill press to run it "flat out".

To drill small holes in thin material I would recommend building a simple drill jig.
At a minimum it is good to centre punch the material so that the drill bit doesn't "wander" before starting to drill.

You don't need fancy equipment to build a drill jig as long as your bench/pedestal drill has a table that you can clamp things to it should be possible, it is better to make this jig from bits of steel especially the drill guide.

Cheers,
Stephen.
Click to expand...
Thanks for your added experience and recommendations. For flattening out the cutting edge of a bit per the video for soft metal cutting, I will try it but with the small bits It seems a bit of a challenge to see that against the surface of my diamond sharpening "stone"/block. I had not pre punched starter this last time as with the pilot boat & hand drilling. With the holes for the deadeyes "chain plate" strips being farther apart than for the rudder work it is more feasible. I'll have to work out how many revolutions on the XY table to match those for consistency; which only needs to be determined once.
I will have to reorder some of the bit sizes in quantity that I will be using.
Off to the diamond sharpening (flattening) tool. Rich
 
Butterfingers said:
Hi Rich, For those thin brass strips I used a hand drill after making small indentation to start the hole. No problem.
Click to expand...
That worked for me for my pilot boat and I was considering about returning to what worked . . . even with some hand irregularities but didn't want to let the cost for the drill press and XY table to go astray. Just learning what I needed to know. Thanks for your recommendation. RIch
 
PT-2 said:
I will try it but with the small bits It seems a bit of a challenge to see that against the surface of my diamond sharpening "stone"/block.
Click to expand...
Never use diamond sharpening tools, they are killer for instruments. There are plenty of stones of different grits (natural or synthetic), to use with oil or water. You can invest in a combination stone (different grits on each side) or buy a stone for each grit. But say NO to diamond sharpening tool ;)
 
Stevedownunder said:
Hi Rich,

I would add that the zero rake is more important for larger drills that can violently grab when breaking through, with your #78 which is about .016" diameter you may not have any problem, just make sure your brass strip is held down, try it and see.

Cheers,
Stephen.
Click to expand...
What drill speed do you recommend? Faster just seems to polish the indention and I am not sure about a slow speed with the cutting grab. I tried to hone down a small bit without any success as they are too small and the entire cutting end is damaged with my very fine stone that I use for sharpening leather working cutting tools. I have emery stuff that I rub onto leather mounted on a block for final sharpening polish to small blades. The Diamond stone is fantastic for blades but I have been warned not to use it for the bits or our "instruments" for too much "damage".
I have a good MicroMark drill press and XY table so a secure jig seems the big factor now and how to secure the strip. I'll try to get direct clamping pressure with the step blocks on each end to the aluminum bottom surface. I definitely want to get a "machined" control on the hole locations as I have found irregularities with hand punching as carefully as I am able with my one-eyed fuzzy vision. I'll keep trying until I get it right before wasting stock for the shroud deadeyes. Rich
 
PT-2 said:
What drill speed do you recommend? Faster just seems to polish the indention and I am not sure about a slow speed with the cutting grab. I tried to hone down a small bit without any success as they are too small and the entire cutting end is damaged with my very fine stone that I use for sharpening leather working cutting tools. I have emery stuff that I rub onto leather mounted on a block for final sharpening polish to small blades. The Diamond stone is fantastic for blades but I have been warned not to use it for the bits or our "instruments" for too much "damage".
I have a good MicroMark drill press and XY table so a secure jig seems the big factor now and how to secure the strip. I'll try to get direct clamping pressure with the step blocks on each end to the aluminum bottom surface. I definitely want to get a "machined" control on the hole locations as I have found irregularities with hand punching as carefully as I am able with my one-eyed fuzzy vision. I'll keep trying until I get it right before wasting stock for the shroud deadeyes. Rich
Click to expand...
Hi Rich.

Try a new drill straight from the pack, the drill you are using sounds like it is blunt or running in reverse.

Are your holes equal spacing?
How many holes are you drilling?

I will post a couple of pics of a jig I made and maybe a sketch tomorrow, if you like.

Cheers,
Stephen.
 
Hi Rich,

I hope you are having more success today.

Please find attached rough sketch, I have drawn an isometric and a partial side elevation.

I noticed that I drew the drawing looking from the wrong way, it would probably be better to have the jig located in the central "T" slot then you can use clamps to hold it firmly in place.

If you are drilling equally spaced holes then using the second hole for a pin allows this quickly and easily.

Hope this helps, if it doesn't help much it might help if you post a couple of photos of your equipment.

I haven't posted the photo of the jig I made because it is quite different to what I have described and may cause confusion, also what I have described is not the only way to do the job there will be other ways, just this is the way I would do it.

If you are not clear on what I am trying to say don't hesitate to ask.

Cheers,
Stephen.
 

Attachments

Jim Nailed this. there is the other problem with these tiny bits, they flex very easily. for this reason I drill by hand with these bits. if I have a lot of drilling to do I use my micro mill machine because it has a micro feed control knob in addition to the pull down handle. using micro feed allows for fine feed of the bit into the piece I'm drilling. if you absolutely have to use the lever let the bit do the work if you see any flex your forcing it so back off the pressure. Brass heats up fast when worked so I use tap ease as a coolant just dip the bit tip in it and drill you don't need to keep wetting the part and bit unless your drilling a thick piece. this will save your bits cutting surface and make holes drilled much cleaner
 
Stevedownunder said:
Hi Rich.

Try a new drill straight from the pack, the drill you are using sounds like it is blunt or running in reverse.

Are your holes equal spacing?
How many holes are you drilling?

I will post a couple of pics of a jig I made and maybe a sketch tomorrow, if you like.

Cheers,
Stephen.
Click to expand...
Yes I have three holes, equally spaced, and on the center line of the 1/16 inch x 1/64 th strip. I'll have to produce 20 of these three-hole strips. My jig is two 1/16 inch spaced parallel wood strips CA glued to a soft aluminum rod base. The wood is being worked down to the 64th inch matching the brass but I am working it more thin at the ends for clamping down on the XY drill press platform. I would be glad to see your suggestions. After breaking a couple of #69 bits and without punched guides points I realized that the bit has to be very short in the chuck to reduce any wobble from the cutting edges. I cannot dull those for brass cutting as the bit point and cutting edges are too small. (As instructed on an earlier recommendation and explanatory video for larger bits. . . 1/8 and larger. Thanks for your continuing support and assistance. Rich
 
Thank you for the well drawn jig in XY table. Here are a few photos of the jig made to hold the strip. These do not show it on the table with bar extensions secured to hold it parallel to the table or the step clamps that are place on each end of the jig to hold that and the strip in place.
First the jig marked for strip placement and the drilling points at one end with a strip placed alongside for illustrationJig for strip drillling.jpg
I thinned the side wood pieces down quite a bit following my rudder drilling. Now with a strip placed (loosely) for illustration of where the three holes go almost at one end. I may have to change this and waste some strip to have it held down and after drilling trim it to length.Jig for strip drillling.jpgJIg with strip placed for drilling no clamping.jpgJig end view.jpg
Now a backside view of the aluminum base followed by an end view of the wood side pieces and base which would be clamped down securing the strip with step clamps on each end. I have not tried this since thinning it down to await arrival of a good punch and more bits. Suggestions welcome and I will examine how to use your suggested system. Thanks, Rich
 

Attachments

  • JIg back side.jpg
    JIg back side.jpg
    296.5 KB · Views: 8
PT-2 said:
Thank you for the well drawn jig in XY table. Here are a few photos of the jig made to hold the strip. These do not show it on the table with bar extensions secured to hold it parallel to the table or the step clamps that are place on each end of the jig to hold that and the strip in place.
First the jig marked for strip placement and the drilling points at one end with a strip placed alongside for illustrationView attachment 203328
I thinned the side wood pieces down quite a bit following my rudder drilling. Now with a strip placed (loosely) for illustration of where the three holes go almost at one end. I may have to change this and waste some strip to have it held down and after drilling trim it to length.View attachment 203328View attachment 203329View attachment 203331
Now a backside view of the aluminum base followed by an end view of the wood side pieces and base which would be clamped down securing the strip with step clamps on each end. I have not tried this since thinning it down to await arrival of a good punch and more bits. Suggestions welcome and I will examine how to use your suggested system. Thanks, Rich
Click to expand...
I see that I duplicated the first view and omitted the back view which is attached nowJIg back side.jpg
 
Hi Rich,

Do you intend to drill down through the aluminium using the aluminum as your drill guide?

It is important that your jig and therefore the workpiece is parallel to the table, that is to say that the groove used to locate your brass strip is parallel to the table.

I would trim off the wood on either side of the aluminium as from what I can see it is not necessary or straight this may aid setting up.

Are the centre distances between holes similar?

Cheers,
Stephen.
 
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