What bit to use for boring?

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Ionut Batrinache
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What bit to use for boring?

Post by Ionut Batrinache »

Hello guys,

i am trying to make a romanian caval (http://www.eliznik.org.uk/RomaniaMusic/cavals.htm) from plum wood, but i don't have a lathe.
What drill bit can i use for this?

I can buy some cheap wood augers like in the picture attached. Do you think that i could make it with it? Would i be able to keep it centerd in the wood ( the kaval needs to be at least 65 cm)?

From what i have read, the best option would be a flute maker gimlet, but i don't have one, and i can't find one to buy.

Thanks!
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Yuri Terenyi
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Re: What bit to use for boring?

Post by Yuri Terenyi »

In the far past I have tried doing it this way, too. It is not totally impossible, but you are aiming at best at one success to perhaps 4 or 5 ruined ones.
You could try using elder (Sambucus). It has a hollow centre, so only needs expanding it, which is easy following the existing bore. It also is a really traditional material. There is heaps of it growing your way. (You need to dry it, though. If you drill it out straight after harvesting, and carve down the outside (both not to quite the final dimensions), you can probably get away with no more than half a year or so of drying. Just seal the two ends with wax or oil paint, so they do not crack easily.)(I also recommend a good oil bath once the instrument is finished. A couple of days immersed in raw linseed oil. (raw is important. Boiled linseed oil is bad news, It has all sorts of heavy metal salts added for really quick drying. It just doesn't do what it is supposed to do.)

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Dave Weir
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Re: What bit to use for boring?

Post by Dave Weir »

I drill 5/16"x18" deep holes in guitar necks with a bell hangers bit. I take them out of the package and roll them on a flat surface to make sure they are straight. Most of them at Home Depot are not. Harbor Freight has them also.
It works a little better in a lathe, but in most woods I can get within an eighth inch of the target with a hand drill. That becomes the center and I carve the neck around it.
I have found a few things really help.
Make sure the bit is very sharp.
Visualize it going where you want as you drill. Sounds silly, but it seems to work.
Don't push very hard. If you push hard, the bit will bend, and head off in some errant direction.
Clear the chips often. Like every half inch
If you don't have a lathe, you can drill a block of hardwood about 2" thick and then clamp it a guide.

Ionut Batrinache
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Re: What bit to use for boring?

Post by Ionut Batrinache »

I want to use plum wood because this is the favorite wood for this instrument.
Dave Weir wrote: If you don't have a lathe, you can drill a block of hardwood about 2" thick and then clamp it a guide.
Can you explain better that last part? I can't understand what you are trying to say, sorry. Aslo, wouldn't a auger like that in the picture be better than a bell hanger bit?

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Dave Weir
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Re: What bit to use for boring?

Post by Dave Weir »

I've never used the auger, so I don't know if it would work better. I'm pretty sure you should not put it in a power drill. I would think it would be hard to hold straight and crank it by hand. I know this is how it would have been done back in the day.

I would start with a 1/4" brad point, 4" long. (you could use 5/16 or 3/8. I don't know about bigger than that.)

I bought some hardwood two by four from a decking lumber company. Merbeau, but it doesn't matter. I cut a block about 6" long. You can use any 2x4, doug fir just won't last for many holes. I drilled a 1/4" hole through the width as much in the center as possible. This is the hole your long drill is going to go in. (the block in the picture has some extra holes in it for different size bits.)
I drilled three more holes for 1/4 20 screws through the height. One centered 1/2" from one end, the other two 1/2" from the other end, and 1/2" from. I tapped them for 1/4 20 screws. I just ran a tap into the wood. It worked fine. I put screws into those holes, so they stuck out the bottom. These are going to be used to level the drill bit, relative to the base.

I got a piece of melamine shelving from home depot about 3 feet long. This is the base. I drew a dark line about down the center the long way. You could also just use your work bench, or any flat surface.

To level the bit, use the two adjusting screws. put the bit in the guide hole so the block is about in the center. turn the two screws until it is level.

Measure your work piece and determine the height of the center. the work piece is going to be attached to the base so that the hole you want is right on to of the line you drew. But not yet.
I guess I am assuming you are staring with apiece of wood with a flat side. If not, you will need some way to clamp it or stablise it while you drill.

Once you determine the height the hole will be above the base, raise or lower the single adjustment screw until it if the right height. You might want to tun the drill bit to see if it a little bent. If it is a little bent, try to the the height correct when the tip of the bit is in it's average height.

Now that your guide height is set, clamp it and your base to your work bench. Line up the block at one end of the base, with the bit directly above your line. Clamp it down, and check your height again. Check it with the tip about as far from the block as you want to drill.
Now remove the drill and secure the workpiece directl over the line, with the end about 1/2" from the block. I use double sided duct tape from Lowe's, but you could also clamp it. Think through how you are going to do it. If you are going to use clamps, figure out where and how you can clamp it and draw you line acordingly.

Now you can drill it. Again, make sure your drill bit is very sharp. Brand new should be fine if you don't have a sharpener. Go slow and don't push very hard. Think about not bending the bit and aim it as best you can exactly where you want it to go. Every inch or less clear the chips. They will pile up behind the block, so clear that once in a while. If the bit starts screaming or smoking, I rub it on an old candle to get some wax or it, or spray some WD40 on it. Mark the bit with tape if you aren't going all the way through.

For guitar necks, I use a blank about 1/4" over size. I'm usually very close to my target. I drill a blind hole, so I find the deep end with a magnet stuck to the end of a long 1/4" dowl and another sphere magnet on the outside, that follows the probe.
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Alan Block
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Re: What bit to use for boring?

Post by Alan Block »

a wind instrument make I knew used a spoon bit to bore straight holes over long distances. It looked like a long rod with one end formed into a half-tube the diameter of the bore and abot 3 or 4 inches long. The end was fashioned into a cutting edge.

Ionut Batrinache
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Re: What bit to use for boring?

Post by Ionut Batrinache »

I know how it should look, but i can't find one here.
I made a Caval from PVC pipe. but i still want to make a wooden one. The auger from the first post doen't work, it is very hard to bore straight due to his screw tip.

Steve Senseney
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Re: What bit to use for boring?

Post by Steve Senseney »

Here is a link to a site that demonstrates making spoon bits.

Ionut Batrinache
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Re: What bit to use for boring?

Post by Ionut Batrinache »

Steve Senseney wrote:Here is a link to a site that demonstrates making spoon bits.
Please paste the link in the post :D

Steve Senseney
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Re: What bit to use for boring?

Post by Steve Senseney »

http://www.bladesmithsforum.com/index.p ... opic=10290

Sorry!

I am away from my shop for a few days. I did take a steel rod, flattened the end some, made the flat into a rounded shape, curved the nose of the tool, and ground the outside into a rounded contour. Then I sharpened the leading edge of the nose. It did kind of work.

Ionut Batrinache
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Re: What bit to use for boring?

Post by Ionut Batrinache »

Thanks, that looks interesting. I tought that spoon bits worked only on a lathe and i need a gimlet like this http://www.iforgeiron.com/uploads/month ... 591400.png
I will definitley try to make a spoon bit :D Thanks for the info, and if you have any idea about how i could make a gimlet like the one in the picture i will apreciate it.

Bob Francis
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Re: What bit to use for boring?

Post by Bob Francis »

I thought that Roy Underhill said spoon bits were the first auger bits. . . . . but I'm old.

Steve Senseney
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Re: What bit to use for boring?

Post by Steve Senseney »

I imagine the evolution of drilling tools starting with a metal rod which you flatten with a hammer on the end. Then you grind (or hammer) it into a pointed tool leaving part of the width wider than the shaft it started with. Sharpen the leading edge and you have produced an awl or drilling type of tool.

Advance this a little further by heating the end of the flattened area, and giving it a twist. Sharpen the leading edges, and file a screw point on the end, and you have a Gimlet type of drilling device.

If you flatten the main part of the shaft, keep it warm and twist it, then grind it so it is perfectly round, sharpen the advancing edges, and leave a small screw point on the end, you now have a Irwin wood working twist drill.

Of course there are other variations, like the forstner bit, spade bits, hammer bits, etc.

Spoon bits are a little different. But someone made them a long time ago using hammers and coal or wood fire. These cut primarily on the leading edge, and center by having a half round contour the size of the hole.

Ionut Batrinache
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Re: What bit to use for boring?

Post by Ionut Batrinache »

Hello again :)

How safe and precise do you think this method of boring is?:
2:10 https://www.youtube.com/watch?v=aVcq0mnXGDY
0:59 https://www.youtube.com/watch?v=t3PnuobYNGA

Now i am designing a lathe with a steady device that will allow me to bore the wood like Yuri does in the fipple making tutorial post, but this looks easier... In the first video it looks like he is using a D Bit or something similar, in the second it looks like a spear :D

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