Help with drilling down the center of blanks

[sequoia]

Hi All,

I have been waiting to ask this question for a while. It was actually the reason why I searched for a forum like this. I have been trying to figure out a way to make sure I drill a hole down the center of my blank without it wandering off center on the opposite side of the blank. Sometimes the other side of the blank has a hole that is so close to the edge of the blank (way off center).

This has been happening to me, especially on narrower blanks (1/2 inch or so). At first I thought it was my drill press so I tried to use a chuck with pen jaws and a drilling chuck on the tail stock and it happened there as well.

I'm sure I am missing something very basic. I try to make sure the drill press platform is level and perpendicular to the drill bit. I use a cheap drill press vise that I clamp down to the table and try to get the pen blank plumb using a small level before starting to drill.

The fact that it is happening on a lathe as well leads me to believe I might be taking something for granted or missing something very obvious.

Any suggestions or tips would be appreciated,

Matt

 

[ed4copies]

Align your drillpress, like this:
http://www.youtube.com/watch?v=HoJ_0EzaIv4

Hold your blank like this:
http://www.youtube.com/watch?feature=player_embedded&v=4vxjMTtHLio

Follow these procedures and your hole has to go straight.

 

[magpens]

However you drill, on a lathe or using a drill press and vice, you need to drill in small increments ... drill a bit, then back off the drilll and clean the drilled material out of the flutes of the drill. Then drill a little bit more.

Also, try drilling a pilot hole first .... about half the diameter of the final diameter .... and then drill the full size hole.

Do you have the problem with both wood blanks and acrylics ?

I am very acquainted with your problem. Another help I have found is to get some short drills, called stubby drills. The shorter the drill the less it will wander. After drilling a short hole (could even be the full length of the stubby drill) you can switch to the longer drill (usually a "jobber" length drill) to go the rest of the way.

It takes some care to drill the holes, but you should be able to do it most successfully on the lathe.

 

[robertkulp]

If you're using a brad point bit with the center point off-center, you'll have terrible holes. Found that one out the hard way.

 

[randyrls]

Matt; The one common thing is the drill bit. It needs to be sharp with cutting edges the same length.

A Drill Doctor and a drill ruler will work wonders.
Multi-Use Rule/Gauge

 

[TimS124]

Which bit(s) are you using? I've had the most issues with wandering during drilling when using bits with parabolic flutes, especially the really long bits. In blanks with inconsistent hardness, the deep flutes allow the bit to flex slightly towards whatever is softer during drilling.

They can also deflect slightly if the top surface of your blank is slightly angled (not all pen blanks are nice and square across the top and not all pen blanks are straight/vertical along their sides).

I find, as magpens noted above, that drilling a starter hole with a short/stiff bit helps minimize deflection. But internal differences in hardness can contribute...Elk antler for example has very soft/porous interior and hard exterior which can nudge a bit off track if you're not careful.

 

[monophoto]

Matt

This is a problem that we all encounter. And I suspect that 100% success is probably an unrealistic dream - there are tricks you can use to increase your success rate, but you will almost inevitably encounter a few failures. Just deal with it.

The issue is that wood grows on trees in both summer and winter - that's what produces the grain pattern. But summer growth is faster, and that wood is less dense. The problem is that the drill bit tries to follow the grain lines staying in the softer summer growth, and the challenge is overcoming that tendency.

Whether you are using a drill press or drilling on the lathe, the problem comes down to matching the speed at which you advance the bit into the wood with the speed at which the bit is cutting a hole in the wood - if you advance the bit too fast, forcing it into the wood, the bit is far more likely to wander off into that summer growth wood. To be successful, the rotational speed of the bit against the wood has to be fast enough to cut a hole before the bit attempts to move into that hole.

Conventional wisdom is that you don't want the rotational speed too high because that causes friction that leads to burning. And like turning, rotational speed is related to the diameter of the cut. I make a lot of giveaway Bic pens (so-called '12 cent pens') that use a 5/32" bit, and my experience is that 400-500 r/min works well. If you are drilling for a kit pen with a brass tube where the bit will be 7 or 10mm, you probably will want to use a slightly slower rotational speed. But whatever the rotational speed, the speed at which the bit advances into the wood has to be SLOW - let the bit cut the hole first, and then advance the bit into that hole.

Obviously, sharp bits are important - a diamond hone can be used to tune up a bit in a few seconds. You want to back the bit out of the hole to clear the swarf - sawdust compacted in the flutes of the bit causes undesirable friction and heat. You can reduce the friction by lubricating the hole - Brendan Stemp squirts BLO into the holes he drills when he makes recorders. I've found that waxing the bit with paraffin helps. But if you plan to glue a brass tube into the hole, using an oil- or wax-based lubricant may not be a good idea. That raises the question of whether a water-based lubricant like KY would work - I haven't tried that yet.

 

[lwalper]

I'm with you. I'd like to do some more segmenting, but have yet to figure out how to drill a straight hole. The best I've done is with drilling on the lathe in a collet chuck; sharp bits and sharpened on center with equal flutes (Drill Doctor); center drill; stubby bit starter hole; drill through with a smaller bit first, then incrementally increase to your desired final size; rotational speed higher than normally suggested and slow feed rate - let the bit do the cutting; frequent swarf clearance. That has generally gotten me pretty close on both ends.

If you're trying to match the center grain on two blanks drill from the center cut on both blanks. At least then they will meet correctly in the middle of the pen.

 

[Paul in OKC]

Good advice above. Drill into the blank slowly and clear often. Align table with the spindle as shown in Ed's video. Once the blank is in the vise align the 'open' side up with the drill bit to be sure it is in line with the bit.

 

[sequoia]

That's a really practical tip! Thanks for that one. And thank you to everyone for replying. Nice to see so many replies after just one day.

 

[sequoia]

Thanks for the reply Ed! Thanks for the videos!

 

[Lenny]

Many, including myself, have found that drilling on the lathe is the way to go. You would need a drill chuck with a morse taper to fit your tailstock and a chuck to hold the blank in the headstock. I use a collet chuck because it's extremely versatile for other pen related functions ... Many use a scroll chuck or special pen blank chuck.
A center drill also helps get the hole started on center. Slow speeds and backing out often to clear chips. Lock the tailstock down and advance the bit with the wheel of the tailstock. Keep your hand on the drill chuck, especially as you retract the bit, just in case it wants to pull out of the morse taper.

 

[raar25]

Lots of good advice so I will add one thing about a pen vise on the drill press. Besides using a center drill so the drill does not wander when it starts, make sure your blank is backed up agains the drill table or the bottom of the vise. The jaws of the vise flex allowing the blank to tilt while your drilling. I do 99% drilling on the drill press and almost all of the drills that dont stay on center do so because they wandered entering the blank. I usually know as soon as the drill enters if it will be exactly on center or off. If your holes grow so the exit hole is larger than the entry hole its because you are not clearing your chipps enough.

 

[jttheclockman]

Sometimes the simple answer comes down to the grain of the wood. You are drilling into the heart of the grain when drilling endgrain. It will deflect the best and sharpest bits. Some woods are just more prone to this because of their make-up. You do the best you can using the above methods but if it happens do not fret about it. Make sure all things on the checklist were followed and move on. Drilling on the lathe is probably the most accurate if using the proper method and tools. The use of sharp bits is always paramount. Good luck and have fun.