Most of us seem to have our own experiences practices, which is just fine. mentioned above is the point about a mandril or maybe even the chuck having runout. I am still pissed about the really large floor drill press made by JET. Talk about runout! I am hoping that new chuck might help but I have my doubts.
One easy thing to do to decrease runout at least at the point of the bit is to use a shorter bit. Also have the material closer to the tip of the bit on the table. Again less travel may help machine error.
One easy thing to do to decrease runout at least at the point of the bit is to use a shorter bit. Also have the material closer to the tip of the bit on the table. Again less travel may help machine error.
Sorry, just lots and lots of practice. We had a Tabaco tin full of blunt 3/16 drill bits at work, so I tried sharpening them, by the end I wasn't too bad. Sometimes it takes me a few goes to get it right, even after 30+ years of practice. But it's a useful skill to have. I usually use a four facet point.
Man my eyes wouldn't let me sharpen something like 3/16. I even bought one of those fancy bit sharpeners. Don't bother, just buy new ones Takes less time and frustration. If you are fortunate, there will be a selection of different bit types and metals, but if you live in a cow town, you are SOL.
You must use a bigger press, good for 25 mm, and clamp firmly.
Many light duty machines are no good at large holes, I prefer getting holes laser cut or done on a milling machine, after having checked for run-out and squareness with a dial gauge.
And there are different cone angles for hard and soft materials, cutting speeds, lubricants and many other things that take a lot of theory and practice.
The short and sweet answer is that if it is not part of your regular work, get it done outside if it is convenient.
I work in the plastics industry, so I have access to many tool making machinery, run by skilled operators who do this all the time.
I prefer that, as the quality of work done is better than mine, and money if offered is refused, it is personal!
I have a 19 mm drill press, and a 8" diameter x 54" lathe, and some hand drills / grinders, they do not compare to a milling machine capable of 75 mm holes.
You can get the fascia laser engraved at the same time, if needed.
Think about it.
Many light duty machines are no good at large holes, I prefer getting holes laser cut or done on a milling machine, after having checked for run-out and squareness with a dial gauge.
And there are different cone angles for hard and soft materials, cutting speeds, lubricants and many other things that take a lot of theory and practice.
The short and sweet answer is that if it is not part of your regular work, get it done outside if it is convenient.
I work in the plastics industry, so I have access to many tool making machinery, run by skilled operators who do this all the time.
I prefer that, as the quality of work done is better than mine, and money if offered is refused, it is personal!
I have a 19 mm drill press, and a 8" diameter x 54" lathe, and some hand drills / grinders, they do not compare to a milling machine capable of 75 mm holes.
You can get the fascia laser engraved at the same time, if needed.
Think about it.
THAT.
This is my own version.
Some details to make it work even better:
1) wing tips are in the same plane as the center "guide" tip.
2) wing tips are so sharp and pointy that they can draw blood if scratching skin, not kidding.
3) every cutting surface must be kept sharp
4) you can easily sharpen any drill bit (not too small, this one is 10mm) like this with firm hands, a Dremel wheel and practice.
5) with the dimensions I suggest tips actually cut *a disk" out of aluminum shert metal.
Too late now but can post an example tomorrow.
Look at the wing tip angle.
This trick saved my life when my shop caught fire in '89 and I lost everything, to boot Argentina was in the middle of one of its recurrent crises.
I needed to sell "something* to rise my head again so I had to make do with what I could afford.
Designed a VERY simple Guitar/Bass 100W head, bought 1mm Aluminum sheet (pop riveted to double thickness where needed), and since I had lost my punchers, did "everything" with just 2 drills: a 10mm one for 3/8" neck pots, jacks and Neon lights, also found a 10mm neck toggle switch, I sharpened that 10mm drill exactly this way, and a 4 mm one for mounting screws (1/8") for boards, TO3 transistors, power Transformers, etc.
Cheesy spray can paint to substitute my burnt compressor and so on.
Burning silkscreens under noon Sunlight.
A real exercise in Zen minimalism 😫
All good advice.
Drill bit angle and relief can matter too.
https://www.regalcuttingtools.com/sites/default/files/asset/document/Lip Relief Angles For Drills.pdf
https://books.google.com/books?id=GxBIAAAAIAAJ&pg=PA16&dq=Drills+and+drilling#v=onepage&q=Drills and drilling&f=false
https://archive.org/details/machinetooloper00burggoog/page/n16/mode/2up
https://archive.org/details/in.ernet.dli.2015.126411/page/n11/mode/2up
Also for metal a good cutting lube can helpful. Best I have found so far is this one: https://www.amazon.com/Anchorlube-A...5&psc=1&mcid=223cbf2f0ddb3d5799a27a88d036e954
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Yes.
There are commercially made wood drills, but they are a bit "optimistic" because wood is soft after all and even if you use harder wood it disintegrates into "dust" or very small chips, while d*mn Aluminum is plastic and will give you very long sharf.
Cast and some extruded aluminum gives out small chips which is fine, but laminated sheet not only creates long sharf but also sticks to cutting tool, specially drill tips.
The angle I show, found experimentally, deals with that.
This is the "brad point" drill bit you mention.
Looks similar but the cutting angle is too steep, it tends to "stick" to Aluminum.
It bites too aggressively into somewhat "plastic" aluminum.
On fact there are specially ground regular drills which work quite well:
There are commercially made wood drills, but they are a bit "optimistic" because wood is soft after all and even if you use harder wood it disintegrates into "dust" or very small chips, while d*mn Aluminum is plastic and will give you very long sharf.
Cast and some extruded aluminum gives out small chips which is fine, but laminated sheet not only creates long sharf but also sticks to cutting tool, specially drill tips.
The angle I show, found experimentally, deals with that.
This is the "brad point" drill bit you mention.
Looks similar but the cutting angle is too steep, it tends to "stick" to Aluminum.
It bites too aggressively into somewhat "plastic" aluminum.
On fact there are specially ground regular drills which work quite well:
3-in-1 oil works for me, plus it cleans up nicely with 99% isopropyl alcohol (IPA) (I have a stash left over from making shellac, worked a treat). Run IPA-soaked fat pipe cleaners through the holes to get the oil off.
there are many alu alloys, some are much easier to machine than others. The extruded alu is usually ok. Drill bits for alu are different from steel. The top angle is much flatter. Cutting speed is much higher in alu. If the alu show a soft buttery edge it is not a really machineable material. Cobalt alloy based drill bits give some relief.
Hi Jan,
I don't have the specs handy for my drill press so I'm not sure. Unfortunately, I believe the speed of my drill press is fixed. (Unless there is some adjustment under the belt guard). I suspect the speed is higher than desireable. When I (slowly) increased the feed rate in an attempt to tame the chatter, the piece began to heat up and led to what looked liked galling on the sides of the hole.
Best
Dave M.
I don't have the specs handy for my drill press so I'm not sure. Unfortunately, I believe the speed of my drill press is fixed. (Unless there is some adjustment under the belt guard). I suspect the speed is higher than desireable. When I (slowly) increased the feed rate in an attempt to tame the chatter, the piece began to heat up and led to what looked liked galling on the sides of the hole.
Best
Dave M.