larger diameter tube drilling; a couple of questions

[Painfullyslow]

I am not having good luck with drilling for some of the larger diameter tubes on even very basically segmented blanks. I am sure that it is a combination of process and equipment and so I would like to ask for some advice.

I have been working lately on blanks requiring a 12.5mm tube. I am using a benchtop drill press and because I have metal layers I am using standard jobber bits, brand new and sharp.

To start, my drill press isn't high quality and I am sure there is some runout and I am drilling at 675rpm.

My process is center drilling bit to get things started then 7mm, 10.5mm, and finally 12.5mm bit. If disaster is going to strike, its always on the 12.5mm bit and always where there is a metal layer (brass or aluminum). The bit will snag and that's the end. It doesn't seem to matter how light I am with the pressure.

So, the obvious first question is if there is something wrong with my process. I am wondering if I should be skipping the 10.5mm step?

Secondly, I am looking at upgrading my lathe (I have a really tiny penpal) to some form of MIDI which I will ensure that it can handle drilling. Would I be better off drilling blanks on the MIDI or would I also need to upgrade my drill press to one which is better suited to the task at hand?

Any other general advice relating to all of this would be welcome.

 

[KenB259]

Make sure your drill bits are sharp, cool with DNA while drilling, and encase your blank, on all 4 sides with some sort of waste material. I usually glue on thin strips of a hardwood like maple. I never step drill, never seemed to work for me.

 

[MedWoodWorx]

I am not having good luck with drilling for some of the larger diameter tubes on even very basically segmented blanks. I am sure that it is a combination of process and equipment and so I would like to ask for some advice.

I have been working lately on blanks requiring a 12.5mm tube. I am using a benchtop drill press and because I have metal layers I am using standard jobber bits, brand new and sharp.

To start, my drill press isn't high quality and I am sure there is some runout and I am drilling at 675rpm.

My process is center drilling bit to get things started then 7mm, 10.5mm, and finally 12.5mm bit. If disaster is going to strike, its always on the 12.5mm bit and always where there is a metal layer (brass or aluminum). The bit will snag and that's the end. It doesn't seem to matter how light I am with the pressure.

So, the obvious first question is if there is something wrong with my process. I am wondering if I should be skipping the 10.5mm step?

Secondly, I am looking at upgrading my lathe (I have a really tiny penpal) to some form of MIDI which I will ensure that it can handle drilling. Would I be better off drilling blanks on the MIDI or would I also need to upgrade my drill press to one which is better suited to the task at hand?

Any other general advice relating to all of this would be welcome.

There is a great article about drilling segmented blanks somewhere in the forum, try the penturning subforum ( i don't remember where i red it. Also avoid brad point drill bits, cheers

 

[jttheclockman]

A couple things. First drilling on a well tuned lathe can be better but also a well tuned drill press can do the job as well. The key is to be able to hold the blank as solid as possible. People like lathes more because the chucks lend themselves to be able to do that. Thes blank holding devices for drill presses have slop in them and that will cause problems. I have a PSI one that I should really sell. Used probably a few times and learned right away it is a piece of junk.

Next is when making segmented blanks I always make the blank at least 1" wide. I drill with same bits but only drill with a starter bit and then the smallest sized bit required for the lower half of pen kit in both cap and body. Then I switch to the required sized bit for cap. I do not do alot of step drilling. Slow advancement is more important than slow speed. Slow speed comes into play with real large bits because heat will kill a bit as well as loosen glue. Use of addition aide on the sides is good for drilling if you can accurately drill in center of the blank as needed. One reason I stay away from that practice. But others have had success. I am working on a way to drill segmented blanks that are prone to blow up with better technique. Just do not want to reveal process until I have time to try it. I have a very very very suspect blank made that I know will blow apart and it is leading me down this path. Just no shop time. Reminds me I better take a photo of the blank before I even attempt drilling and turning to say I did it. Forgot who said this here a long time ago but it does make sense.

 

[egnald]

I drill both on my lathe and on my drill press. I prefer the drill press for drilling segmented blanks because of the extra support the blanks have using the centering vise on my drill press. The procedure I follow is outlined below:

I use a drill press set to a low speed along with a blank centering vise. The jaws on the vise are 90-degrees so they clamp on the corners of the blank. I never use brad point bits as they can be very "grabby" and put a lot of stress on the blank. I never drill pilot holes even when drilling a large 31/64 hole for the cap of a Legacy Jr. Gent. I do however use a 60-degree centering bit for making a shallow lead-in or starter hole to help guide the bit into the blank. I use very sharp drill bits.

I drill using a pecking type of procedure that takes an agonizing amount of time to drill through the blank, well agonizing for me anyway. I never drill more than 1 to 1-1/2 the drill diameter in depth in each peck, retracting the bit to clear the flutes and let it cool for a few seconds each time. At least twice, when I reach about 1/3 and 2/3 the depth respectively, I leave the bit out for about 30 to 45 seconds to let it and the blank cool down. As a reminder, I keep several very nice blanks that I have blown up when drilling by being too hasty beside my vise.

I don't know if it is absolutely necessary, but I spray a dry lubricant called Blade-Kote on my bit before starting to drill. It is supposed to help reduce heat from friction and help prevent the flutes from packing while drilling.

On exceptionally precious blanks, I cut them long and drill to the depth of the tube leaving plenty of excess on the end that is not drilled through (aka drill a blind hole). Then I saw the leftover piece of blank off on my bandsaw which exposes the hole. It has been my experience that catches and blowouts happen most often when the drill is breaking through the other end of the blank.

Regardless of drilling on the lathe or on a drill press, the best take-aways are 1) Don't use Brad-Point drills. 2) use very sharp drill bits. 3) avoid overheating by using a pecking method that gives the bit and blank plenty of time to cool off while drilling and/or a lubricant.

I know how frustrating it can be to blow up a special blank while drilling. Good luck developing a process that works successfully for your materials and equipment set.

Regards,
Dave

 

[Alan Morrison]

Michael, you don't mention the rate that you are drilling. As you are probably aware .....slow or even slower...use a lubricant if needbe.
I have a pretty decent drill press but only drill my blanks on the lathe. I use pen jaws which hold the mjority of the blank quite firmly.
Havent had too many problems with this.

 

[greenacres2]

Make sure your drill bits are sharp, cool with DNA while drilling, and encase your blank, on all 4 sides with some sort of waste material. I usually glue on thin strips of a hardwood like maple. I never step drill, never seemed to work for me.

I'm not in the same league as most of these folks--but similar to Ken...i use a wrap or two of gauze and coat the outside with CA glue. Gauze only because it's easy to cut without running out to the garage-shop!!
earl

 

[Painfullyslow]

Thank you all for your responses!

I kind of felt like the step drilling was hurting rather than helping so I think that I will try without it on my next blank.

I also should have added that I use the 'pecking' method as well, typically taking me over a minute to drill through a standard blank piece. I do not have a cooldown pause but also my bits are typically only warm.

I do agree that the blowouts tend to happen at the bottom of the blank, the issue that I have is often I have a different band of material there which may not be very thick. Perhaps I could epoxy another 1" of some wood on the end as @egnald mentioned.

The idea of using some external material to stabilize things is a good one, and one that I had used on an earlier blank. I glued 4 tongue depressors to the sides. I cannot say if this made a huge difference but I did not have any issues with the drilling process. I don't know why I didn't bother doing this with this blank. I guess I felt that it was basic enough that it shouldn't have been necessary but I admit that I have a very limited pool of experience to draw upon.

I know my press has runout and cavitation but my current lathe does not have the ability to drill blanks. I am currently in the market for a new MIDI and will likely move my drilling process to this as soon as humanly possible. This alone should improve my success rate.

 

[MedWoodWorx]

another question folks:when you say sharp drill bits, do you mean the tip or the shaft or both?
if that's so can you sharpen a drill's "main body"?
cheers

 

[KenB259]

another question folks:when you say sharp drill bits, do you mean the tip or the shaft or both?
if that's so can you sharpen a drill's "main body"?
cheers

Only the tips, the flutes just remove the swarf. A drill dr is your friend.

 

[howsitwork]

I use a pillar drill ( drill,press) . Note frequent withdrawal is also important as swarf can jam in the flutes, expand and blow the blank . At best it only heats up the drill, at worst it can blow the blank.

I use a V cradle to hold the blank ( actually 2 V sections of wood across the blank corners but suspect the gauze and CA would be even better at all round support. I ALWAYS put a sacrificial bit of ply under the blank for the drill bit to exit into. On resin blanks this helps stop end blowout and chipping. On hybrid or wood blanks it lets me feel when the drill has exited the blank. I also use a cross vice to allow me to locate the drill where I want it on the blank then lock up the two ways solid whilst I drill it.

 

[leehljp]

Like Ken and Earl (Greenacres2) and others, use gauze tightly wound, use CA liberally, let it harden and drill. Been doing that for about 13 14 years. Patience.

If one takes the slow road, plenty of patience and maybe 3 to 4 hours and then finishes the drilling process intact, the next time it will take 2 to 3 hours, the next 1 to 2 hours and next even less. The point is to learn the process, practice the process, get the feel of the process, and then a pen is made. Technique is developed, skill in increased, the quality rises!

 

[Painfullyslow]

Much appreciated all. I will make sure to bond supporting material to the outside of all my blanks in the future. I honestly don't know why I didn't do it on the last few that I tried. I guess I simply forgot to do that step.

 

[MedWoodWorx]

Only the tips, the flutes just remove the swarf. A drill dr is your friend.

There is no way sharpening the drill by hand? The drill dr looks nice but its really expensive.

 

[KenB259]

There is no way sharpening the drill by hand? The drill dr looks nice but its really expensive.

Yes you can do it by hand, if you have the expertise, I do not, so I'll leave that to others to explain how to do it.

 

[Painfullyslow]

There is no way sharpening the drill by hand? The drill dr looks nice but its really expensive.

It can be done by hand but it is tedious and less accurate. If you continue with this hobby you will be sharpening bits a lot, making the drill doctor a worthwhile investment to consider at some point.

 

[randyrls]

To join the thread; There are two things I do to eliminate the dreaded breakage.
1. "wrap" the blank in pieces of plywood to reinforce the segmenting.
2. I modify the drill bit so the flute doesn't dig in, but rather "scraps" the hole bottom.

 

[egnald]

Although I do not use reinforcing very often, when I have a blank I think will be particularly susceptible (like the metal and stone segments) I sometimes glue on a reinforcement before drilling.

For blanks that are 3/4 x 3/4 inches or slightly larger, I have found that 1-1/4 x 1-1/4 unfinished pine Outside Corner Moulding works fantastic as a drilling reinforcement splint. I just cut two pieces the length of the blank and epoxy them to opposing corners of the blank, being particularly careful to avoid having voids in the glue in the spots where the segmenting is. This keeps the blank square (square-ish) so it still works well in my self-centering drilling vise. Although the splints could be turned off, mine get cut off after the tubes are glued in and I run the blank through the bandsaw using my corner rounding jig.

Regards,
Dave

 

[jttheclockman]

OK this topic comes up many times and usually leads to many talking about adding splints and gauze and things like this to strengthen the blank when drilling. All good ideas but let me ask this question because I do not do this type of reinforcing. I make segmented blanks and most of my blanks require dead on center of design drilling. When you do this type reinforcing how are you chucking the blank to be drilled accurately? What are you using to strengthen? If using wood or even cloth it has to be dead on accurate all around and then take in glue thickness. I am thinking maybe get away with a pen jaw chuck where you contact just the edges of 2 sides to hold. What say you?

 

[egnald]

OK this topic comes up many times and usually leads to many talking about adding splints and gauze and things like this to strengthen the blank when drilling. All good ideas but let me ask this question because I do not do this type of reinforcing. I make segmented blanks and most of my blanks require dead on center of design drilling. When you do this type reinforcing how are you chucking the blank to be drilled accurately? What are you using to strengthen? If using wood or even cloth it has to be dead on accurate all around and then take in glue thickness. I am thinking maybe get away with a pen jaw chuck where you contact just the edges of 2 sides to hold. What say you?

Hi JT, although it is mounted vertically on my drill press, my blank holder for drilling is like a pen jaw chuck that contacts about 1/2-inch on two diagonal edges of the blank and about 2-1/2 inches of the length of the blank. I do my best to keep the blank and the splints as square as possible for all of the reasons you indicated. In fact I am usually successful drilling without any splints by just using sharp bits and by preventing heat build up. When I do reinforce it is only for a little extra insurance on a blank that I really - really don't want to lose.

Dave

 

[KenB259]

OK this topic comes up many times and usually leads to many talking about adding splints and gauze and things like this to strengthen the blank when drilling. All good ideas but let me ask this question because I do not do this type of reinforcing. I make segmented blanks and most of my blanks require dead on center of design drilling. When you do this type reinforcing how are you chucking the blank to be drilled accurately? What are you using to strengthen? If using wood or even cloth it has to be dead on accurate all around and then take in glue thickness. I am thinking maybe get away with a pen jaw chuck where you contact just the edges of 2 sides to hold. What say you?

I start with a dead square blank and then glue on thin maple that are 100 percent the same thickness, so after they are glued on, the blank is still perfectly square and then I drill on the lathe with pen jaws. I should add, I don't do this every time, just when I think the blank is more delicate than usual.

 

[jttheclockman]

I start with a dead square blank and then glue on thin maple that are 100 percent the same thickness, so after they are glued on, the blank is still perfectly square and then I drill on the lathe with pen jaws. I should add, I don't do this every time, just when I think the blank is more delicate than usual.

This is the key for those that think of doing this It is important little detail that does not get talked about when this comes up. Thus my questions. Thanks

 

[KenB259]

This is the key for those that think of doing this It is important little detail that does not get talked about when this comes up. Thus my questions. Thanks

This is why I can't get my head around using gauze and CA. I understand how it might hold blanks together, but I have no idea how you keep things square.

 

[farmer]

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