Drill (wood boring bit) lubrication

I am making Armenian duduks out of Apricot wood. and I need to drill/bore either a 29/64 hole or a 12mm hole down the center of the flute. I have one nearly completed, and I managed to use my wood lathe and a 12mm boring bit (with the center screw) to make the distance though, using a steady rest. However, it smoked and squealed a lot in doing that. One thing it was going too fast for how fast I could keep up in feeding the drill. I "was" using a Harbor Freight (Central Machinery) lathe with a small mini chuck on the head and a 1/2 drill chuck with #2 Morse tape on the tailstock to hold the boring bit. Slowest I could go was 750 rpm. I have since retured that lathe (have had about 2 weeks) back to HF as I figured if I upgraded later on, my chance of recovering what I have in it are slim. Now, within the first 30 days, where I get 100% of what I paid is probaby the best time for upgrading. I went with a Rikon 70-050VS (variable speed) lathe at the local Woodcraft store (now on order) since they had that on sale, it has a lowest speed of 300 RPM, and has #2 Morse tapers in head and tail.

My question is, could I use somehting like bees wax, or some sort of grease or lubricant to lubricte the drill bit as I drill, giving lubrication to the sides of the wood, lessening the smoke and and squealing? I also have a can of a dry lubricant, similar to Silicone I could spray in there intermittently to help lubricate the side of the hole.

Armenian Duduk, which I can't call Armenian, rather Duduk proudly crafted in U.S.A. (at least when "I" make them)

Attachment 230800

With the double reed mouthpiece in place on the mouthpiece end. The end that has the mouthpiece is about 1.112" diameter in a sort of "bulbous" look, with a taper on the outside down the main part of the flute that is equally sized. Inside the moutpiece there is the hole,but here it is tapered to accomodate the tape of the reed mouthpiece. I found that a large hand reamer (tapered) on the headstock worked excellent and duplicates the master duduk I have exactly.

Attachment 230802

That is an interesting project. As far as the drilling goes I am guessing that if you get the speed slowed down that will take care of a lot of the problems. I have never used any lubricant for drilling wood.

The 29/64 is a fairly small hole and the chip removal will be a problem. I find that heat builds up very fast when wood chips start to pack in the grooves of a 7/8" twist bit that I use in a #2 MT to drill to depth, and I need to pull the bit back after about 1" of drilling or less due to swell on the chips, especially if the wood is wet. At SWAT last year, one of the demonstrators was using a masonary bit to drill his starter hole since the carbide cutter is larger diameter than the groved shaft providing more space for chips to escape. I have tried that, but need to sharpen the carbide tip more for better cut.

One thing I just thought about today is to use some of the Walnut oil I have. A lot of duduk makers use Walnut Oil for the finish, inside and out. With Walnut oil, it might keep the sides of the drill bit from burnishing and getting hot, thus getting tight. The tighter it get the more it squeals from friction, which makes it hotter. Kind of a snowballing effect.

use air. it keeps the chips coming out and cools it down at the same time.

I have no idea whether dimensions are critical in this application, but consider that any lubricant will temporarily swell the wood to a degree, and the resulting hole ultimately will be larger than intended when the lubricant cures, evaporates or dissipates.

If I am making a hollow form with a 1" hole or larger, I use a forstner bit and lubricate with WD40. It doesn't affect the wood, though I hollow away much of what gets lubricated. Best practice is to drill a little at a time and not try to take out too much wood. Green wood swells as it gets wet and won't move through the flutes even if they are lubricated. If your hole is 3/8" you can also try a lamp auger or as some call it a shell auger. They are made to drill end grain.

I have a similar problem when making pens. My slowest lathe speed is 250 RPM. Some dense oily woods like ebony are very sensitive to heat buildup. If they get too hot they will warp and crack. Even the driest wood (6%MC) still has water in it. When the water gets hot, it expands, and forces the wood to swell, both outward (splitting the wood), and inward (binding the bit, causing more friction). Once I actually bound a twist bit in ebony so badly that I had to take the blank out and split it with a chisel to get the bit out.

I have heard of people who use wax to lube the hole, but I have never tried it. If I am going to glue a tube in the hole, I don't need the wax to cause adhesion problems. If I am drilling a deep hole like you describe, I drill in stages. I start with a smaller bit for the first stage, then move up in sizes. Depending on the diameter of the hole, I can sometimes drill as many as 4 stages. The small bit (preferably a forstner) is doing less work than a large diameter bit, so there is less friction, The progressively larger bits now have less chips to clog the flutes, resulting in less friction. It is still necessary to clear the chips often (especially with the first stage), but this works very well. The bit for the next to last stage is close to the final diameter, so that on last stage the bit is removing less chips, and stays cooler, resulting in less swelling and a very clean cut that is more accurate in size. When I first started doing this I thought it would take forever changing bits and repeating the same procedure over and over, but it is actually faster at times, because I spend less time clearing chips, and replacing split blanks. Good luck, and let us know what works best!

When I'm doing pepper mills I use WD-40 or wax. The heat in the forstner bit melts the wax and then I re-insert and drill some more. don't try to drill too deep or you're going to find yourself in trouble when you can't remove the drill bit because the hole is clogged with chips.

Bill

Look into a gun drill. It forces the bits out with compressed air and is what a lot of bag pipe maker
s use to drill out the chanter and drones. You can find them cheap on Ebay.

I remember hearing once that you clear the bit when you have gone in 1/2 to 1 times the diameter of the bit, so for a 1/4 inch bit, you clear every 1/8 to 1/4 inch. They all seem to pack the chips in the flutes as you go deeper. I did see a bag pipe maker once at a demo. I don't remember exactly, but his bit was a round rod with the cutting end ground down to half round, and the nose profile was maybe 30 degrees off of square, and a relief bevel on the under side. Almost like a spoon bit, but not round on the nose. He could drill all the way through, with no going off course.

robo hippy

Good suggestions, all. The moisture content and how to control excessive moisture is probably a key. Obviously, we are working with wood and can't pump water in there, like I used to do when I worked at Boeing and Egging Company - (Caterpillar vendor) as a Drill Press Operator. I could use beeswax, as I have that around as well as walnut oil. My dimensional tolerances are enough, from 11.25mm to 12.0 mm that I don't think the absolute size of the hole is extremely critical. I want to get as close to the "BEST" duduk I have for dimensions, as that should produce a better result.

I've never worked a lot with drilling wood, just steels, like stainless steel, aluminum (nasty stuff) and some titanium and magnesium (flammable in the WORST sort of way). Flutes are on drills for a reason. For most drills, you have 2 cutting surfaces and the flutes get the cut material out of the way. As long as you can see the flutes you should see material leave the hole, and I do. Other reason is that you can re-sharpen a twist drill when it get's dull by shapening both sides equally, and this continues as long as you have flutes. Other drill is a boring bit, the one I have and used. It, too, has long flutes, but only one cutting edge as opposed to 2. It has a tapered screw that sort of pulls it into the wood, and probably disrupts the wood for the single cutter to grab and cut.

Gun drills are nice, but rather expensive. They also need to incorporate some sort of coolant, either liquid or air to work, since, by design they really only have a single, non-spiraling flute. At least the gun drills I saw at Boeing were that configuration. I am looking at about 13.5" of drilling.
I just got a new bit in the mail today, a 29/64th HSS drill bit, of normal 115 deg head and 18 inches overall length. I'll test it out and see how it does with drilling wood. Just wish it had a split point on the end.

I think what is happening with the 12mm boring bit of 15" length, is that the outside is quite smooth and as the drilling progresses the end of the bit gets hot as does the wood to a lesser degree, there is enough metal swelling to create more drag and friction on the outside edges of the boring bit making the squeal, and etc. I believe, with something like wax or walnut oil (and thinking best is latter) that there will be just enough lubrication to negate the friction of the wood rubbing the outside of the drill bit or boring bit's metal.

BTW, the best feed for a drill bit is that which is necessary to keep the cutting edge grabbing fresh material constantly. Sit too long in one place and the hole end will become polished and make it more difficult for the cutting edge to "bite" in to the material and cut again. I remember drilling holes in some track guards at The Egging Company on a large (6' span) radial arm drill and setting the feed rate at 0.045" feed with a 7/8" bit. Even with water based coolant pumping strait into the hole, chips come flying out of there blue hot. I still have the scar on my arm where a chip came out fast enough to cut my arm and cauterize it (so hot) at the same time. They were not fussy, like Boeing, about the finish of the sides of the hole. All they wanted was a hole that a bolt would drop though and with nut and washer no one would ever see the inside of the hole on the heavy equipment anyway.

Many good points already. I've used paste wax to lubricate when drilling really hard woods (Ipe) and also built up using progressively larger bits as well. When drilling ebony pens, (and don't want wax in there) I pick the slowest speed and back out often.