Destroying blanks when drilling

[JonathanF1968]

Suddenly, I've destroyed three blanks in a row while drilling them out. I've also successfully made three pens from the same wood.

All the ones I'm ruining are 12.5 mm holes for Jr. George tops going through rosewood. The blanks are on the thin side; they are cut from a 7/8 inch board (22 mm).

I'm using a drill press and a new bit.

I'm noticing that my bit is heating up up a lot more than usual with this wood. So, I've been going about 1/4 inch at a time, then waiting for the bit to cool completely before continuing. Which is quite the snail's pace.

The point of failure happens at the very end of the bore. I'm thinking, maybe I should cut the segments longer, and not drill all the way through, and then cut/sand off the end to expose the hole.

It's rare that I've destroyed blanks like this while drilling. It happened once before with cocobolo. But this is a pretty big hole and a relatively thin blank. And maybe something about the wood heats things up more than usual.

Any advice? I'm wondering if it's time to start drilling on the lathe instead of the drill press, for a more perfect center. Not sure if that's where my problem lies, though.

 

[Dr_N]

I'm thinking, maybe I should cut the segments longer, and not drill all the way through, and then cut/sand off the end to expose the hole.

That was going to be my suggestion. I've had to go that route on some blanks that were cutting it pretty close on size.

 

[jttheclockman]

We can not say yes to time to drill on lathe or not. Many people have success drill with a drill press if it is tuned properly and there is no runout. So we do not know how sturdy you are holding the blank Do not know if you are crushing the blank as you are holding it. Do not know if the bit is true. Do not know if the table and bit are 90 degrees to each other. Do not know the speed you are drilling at. Yes a lathe can be more efficient but some of the same problems can creep into drilling on a lathe also.
You are wise if you do not have to drill all the way through the blank and that could help.

Yes rosewood is very dense and heats quickly so speed and clearing are key along with a sharp bit.

 

[duncsuss]

When's the last time you sharpened the drill bit?

 

[dogcatcher]

What do you mean by des.troyed the blank? A picture would help

 

[WriteON]

Step drill. Pre-drill....Start with small bits(1/4") and slowly increase to larger bits. Slow speed. Small bites.

 

[leehljp]

It is easy to drill a hole FAST in a 2x4 in any direction without any destruction happening. But try to drill on a small piece of wood and suddenly there is a different context, environment, situation or what ever you want to call it. ON a 2x4, the wood maintains its integrity simply because of the mass of wood around the hole being drilled. Remove the mass and the integrity of the wood is GREATLY diminished with drilling.

So, the question is, which way, or how can one keep the wood together while drilling lengthwise in a 3/4 x 3/4 by 3" piece of wood?
1. Pen Blank drilling clamps hold the pen together by clamping the edges tightly while drilling the hole;
2. as you surmised, make a longer blank and drill almost to the end and cut off the end.
3. wrap gauze around the blank and CA the gauze. This is a great trick for delicate blanks.
4. Drill on the lathe, but still it can happen, so other steps of reinforcing the blank on the outside.

There are other ways also, but these are the main ones.

 

[Dalecamino]

On a drill press sometimes the drill bit breaks out the wood as it exits the blank on the bottom.
Put a block of wood underneath the blank, setting the blank firmly on top. This stops the breakout.
Strangely, this doesn't happen to me when I drill on the lathe. Just a suggestion.

 

[bsshog40]

When I drill on my press, I always drill about 1/2" at a time. I pull up the drill bit so it can take out the shavings and I also have an old toothbrush I keep by the press to rake across the bit to clear out the flutes. You'd be surprised how much shavings don't always come back up the flutes. They can get compressed in their and cause havoc. Especially if you are drilling a large hole in a small piece of wood.

 

[Displaced Canadian]

Even when I drill on the lathe cut the blank long and stop drilling short. Also even when a bit is new it doesn't mean it's as sharp as it should be. A drill doctor is great for touching up bits.

 

[randyrls]

Even when I drill on the lathe cut the blank long and stop drilling short. Also even when a bit is new it doesn't mean it's as sharp as it should be. A drill doctor is great for touching up bits.

To Join the Thread; I do this for all acrylic blanks just for this reason. It adds another step to the process, but the elimination of a point of failure is worth it.

Jonathon; If you do this. Mark the center of the blank(s) when cutting the blanks. Drill from the center outward (mark up). Drill to proper depth. Mark depth with tube on drill bit. Drill and cut to exact length

 

[JonathanF1968]

Illustration uploaded, showing the sad, sorry affair. I have three blanks that look pretty much identical to this. The thing shattered at the end each time.

To answer some questions:

1. After drilling every 1/4 inch, I pull up, vacuum away all sawdust, in and out of the hole and on the bit. I wait for the bit to cool completely before doing another 1/4 inch. (Not my usual procedure; just after the first of these blew up.)

2. There is wood under the blank being drilled that I would continue through, if I had the chance.

3. The drill speed is 1720. I wonder if this is too fast; it was slower when the first blank bit the dust and I increased it, per the directions on the drill, but I'm reading about lathe speed drilling recommendations being a lot slower than that, so maybe that's part of it?

4. I'm definitely not going exactly parallel through the segment. But I've successfully drilled around 70 or 80 segments with my method, so I'm not sure why the current problems are surfacing, other than this wood is relatively finicky.

--Jonathan

 

[leehljp]

Are you using any kind of clamp? Or, What are you using to hold the blank while you drill on the drill press?

 

[Dalecamino]

I'm with Hanks question. It looks like you are squeezing the blank too tightly, or something.
500 RPM speed is what I use.

 

[bsshog40]

My RPM's are around 750. At 1720, I would think you are heating everything up way too fast. Not sure if that's grain or burnt wood. Could be making it brittle drilling too fast. Just my guess.

 

[jttheclockman]

If I were you I would give drilling on a lathe a shot.

 

[John Eldeen]

I would have to be with the other drill speed adout 500 rpm and best guess to much clamp pressure. With that I have also had much better luck drilling on the lathe.

 

[JonathanF1968]

I tried setting the drill to its lowest speed (620) and holding the clamp as lightly as I could. Successfully did one section, but then the next one I tried blew apart. The first one did have some extra beef on the end and I cut it short. The second blew up with what I would think would be extra meat on the end, but I had precut it before I planned to do that, so maybe it wasn't enough.

I'm going to step into the world of drilling on the lathe. Plan to order a Barricuda system today.

 

[JonathanF1968]

One more comment: I had tried pre-drilling smaller diameter holes and then stepping it up, but for some reason, the bigger bit was catching a lot. It was murder to get through. Not sure what that was about.

I don't think bit sharpness is the issue here. It goes through very easily and cleanly for the first 90 percent of the bore. And then it blows apart.

Again, I'm constantly cleaning the bit and the piece, every 1/4 inch.

 

[Woodchipper]

Never had one break like that photo. Biggest problem is having the bit drift offcenter at the bottom. I mark centers on both ends. So I can judge the amount of material at the exit point. As long as I have enough material to turn, I'm OK with that.
Here's my setup.

 

[hbillings]

My 2 cents - go slow on the lathe. The resulting holes are generally centered and straight. The biggest exceptions to this are diagonally cut hard woods, which slightly move the bit in an attempt to follow the grain.

 

[Dalecamino]

Take a look at these drilling jaws.

 

[JonathanF1968]

Just ordered the Nova chuck, 30th anniversary set. Let's see what happens in a few days when I try this out.... Thanks all for your input.

 

[Dalecamino]

Good move! At least you have more options.

 

[randyrls]

One thing I think no one mentioned. Roll the bit across a dead flat surface like a drill press or table saw table. See if the bit might be bent.

 

[Dalecamino]

Just for principles, you might check for lateral movement in your drill press quill with it fully extended.
I think Randy and I both are suspecting wobble somewhere. Just another thought.

 

[TonyL]

Didn't read all responses, but as Duncan asked, make sure drill bits are sharp. I started sharpening mine by hand on a grinding wheel (i own a drill Dr, but like this better). The 8 mm and larger are very easy to sharpen (trust me, if I can do it......).

 

[JonathanF1968]

I drilled through a three-inch 2x4, longways, and the hole seems straight. Very easy bore.

 

[ed4copies]

One more comment: I had tried pre-drilling smaller diameter holes and then stepping it up, but for some reason, the bigger bit was catching a lot. It was murder to get through. Not sure what that was about.

I don't think bit sharpness is the issue here. It goes through very easily and cleanly for the first 90 percent of the bore. And then it blows apart.

Again, I'm constantly cleaning the bit and the piece, every 1/4 inch.

Since we don't know the reason, I would use a different bit. No point in ruining another bunch of blanks!
FWIW,
Ed

 

[JonathanF1968]

@ed4copies, I'm a little puzzled about how to test for the bit straightness, other than drilling the hole as described. When I roll it on a flat surface, I'm not sure if it's uneven or just the normal contour of the bit.

(Note, I bought this bit from Exotic Blanks a couple weeks ago! Part of the junior set with bits and bushings.)

 

[bsshog40]

Take a look at these drilling jaws. View attachment 225725

I have one of these 4" jaws for gluing. Lol

 

[dogcatcher]

Has this all happened with the same type of blanks? Have you tried drilling any other species of wood?

 

[JonathanF1968]

Has this all happened with the same type of blanks? Have you tried drilling any other species of wood?

Yes, same rosewood. I also tried a test on a 2x4 and it didn't blow apart, though I should probably cut the 2x4 down to the same dimensions as the blanks that are failing and try that.

 

[ed4copies]

Send me your name and I will send you a new drill bit, just in case!!

 

[WriteON]

Just ordered the Nova chuck, 30th anniversary set. Let's see what happens in a few days when I try this out.... Thanks all for your input.

Very good purchase. You'll enjoy the Nova & lathe drilling.

For now as said.... try different type wood blanks. Is it material or technique. Any problems I had with wood had to with technique.

 

[pshrynk]

Were the two blanks from the same piece of wood? Maybe there was a weak point in the blank itself...

 

[dogcatcher]

Were the two blanks from the same piece of wood? Maybe there was a weak point in the blank itself...

That is also my guess. Get some more wood and cut into pen size blanks, dumpster dive at a cabinet shop, they will have pine, maple, oak, birch and other hardwoods. Usually ather plain for pens, but good they make good test and idea blanks for pen making.

 

[penicillin]

Just ordered the Nova chuck, 30th anniversary set. Let's see what happens in a few days when I try this out.... Thanks all for your input.

Think about adding the Nova Pen Plus jaws to your set. The pin jaws that come in the 30th anniversary set are good and can be used for drilling pen blanks, but the pen jaws are extra nice and easy to use. I like them because they are a two-jaw set and they are longer than the pin jaws, so you can see the drill bit emerge from the back of the blank between the spinning jaws when it happens.

My local Rockler store had a stack of special pen jaws marked down on clearance. The only difference is that they had special etching to honor veterans. They may be sold out by now. I would have bought them, but I already had a regular set.

The Pen Plus jaws fit nicely in that 30th anniversary case. Put them in the finger holes around the chuck. I turn them so the square grips that hold the blank face out, away from the chuck.

 

[JonathanF1968]

Send me your name and I will send you a new drill bit, just in case!!

You are extremely kind. I'm about to send you another order, so I'll add a note.

 

[JonathanF1968]

My new chucks arrived. I drilled four 12.5 holes and then six 10.5 holes on the lathe, and none blew apart. This is after ruining the previous three out of four that I tried via the drill press.

Same drill bit, for the 12.5. I'm actually not totally sure that it isn't slightly warped, but no blanks bit the dust in this process, so it's usable.

The bits still get super hot. After about a half inch, it is smoking, if I don't stop. So, I'm going just 1/4 inch in or so, then removing the bit and waiting for the whole mess to cool down before continuing.

I'm thinking there are a variety of factors at work, but using the lathe rather than my drill press is alleviating them. It's also a much quicker process.

Thanks all for weighing in.