Problem boring cocobolo
- Thread starter knowltoh
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VisExp
Member
I'm guessing that your drill press table is not at 90 degrees to the travel of the drill bit. An easy way to check that the table is perpendicular in all axis is to chuck a piece of coat hanger in the drill chuck. Turn it 90 degrees so it is horizontal, then turn it back another 90 degrees so that it is just touching the table. Rotate the chuck by hand and as the tip of the coat hanger scribes a circle you will easily see where the table is high or low.
hrigg
Member
Two things I'd check first, and that's the drill bit and the drill press table. One flute of the bit could have gotten dull somehow, and then see if the table is square to the quill travel.
knowltoh
Member
Actually, I am drilling the blanks on a lathe. It is lined up perfectly with the tailstock live center and spur center on the headstock. I turn the square blank to round, cut the 2 pieces to length and put in a Nova chuck. I drill using a drill chuck in the tailstock.
This is the first problem I have encountered boring a blank. Maybe I should try a new drill bit?
Herb
This is the first problem I have encountered boring a blank. Maybe I should try a new drill bit?
Herb
JohnU
Member
Ive had bits wander on me, especially in hard stuff like cocobolo. Bradpoint bits help and slow drilling. When I drill, I start with the blank ends that make the middle of the pen, where the two parts meet the center bands, so I know the grain line up. If the bit wander after that, its ok, because the top and bottom of most pen kit blanks are tapered and will allow you to be off center without showing.
GBusardo
Member
I am going to go with the problem being the bit. Do you have a Drill Dr? Thats the first thing I would try. Maybe one flute is clogged with the wood? Try a smaller bit and see if it tracks true. If it does, then enlarge the hole with the, I am guessing, 7mm bit. Good luck!
NewLondon88
Local Chapter Leader
I'm going to guess an alignment issue.
Could be something as simple as a mis-mounted jaw on the chuck (causing the blank to be mounted off-center) or dirt/grit on the threads of the chuck adapter .. (causing the chuck to be mounted off center) or could even be mis-alignment between the headstock and tailstock.
Maybe a flashlight would help .. mount the drill chuck and bit in the tailstock and shine a flashlight on it. Then put your eye up to the hole where the knockout bar goes and peer right through the tailstock. This should tell you if alignment is the problem.
Might even be a bit of sawdust buildup where the tailstock tightens to the ways. Anything that interferes with the parts lining up ..
Sometimes I'll get a slight wobble in the chuck, so I'll take it off, rotate the spindle by hand and re-mount the chuck. Sometimes the wobble goes away, sometimes not. I need to have someone make me a better adapter for the chuck .. one with tighter tolerances. The adapters we get with the chucks aren't usually all that close..
OK, those are my guesses..
Could be something as simple as a mis-mounted jaw on the chuck (causing the blank to be mounted off-center) or dirt/grit on the threads of the chuck adapter .. (causing the chuck to be mounted off center) or could even be mis-alignment between the headstock and tailstock.
Maybe a flashlight would help .. mount the drill chuck and bit in the tailstock and shine a flashlight on it. Then put your eye up to the hole where the knockout bar goes and peer right through the tailstock. This should tell you if alignment is the problem.
Might even be a bit of sawdust buildup where the tailstock tightens to the ways. Anything that interferes with the parts lining up ..
Sometimes I'll get a slight wobble in the chuck, so I'll take it off, rotate the spindle by hand and re-mount the chuck. Sometimes the wobble goes away, sometimes not. I need to have someone make me a better adapter for the chuck .. one with tighter tolerances. The adapters we get with the chucks aren't usually all that close..
OK, those are my guesses..
knowltoh
Member
Thanks for all the comments. I have it narrowed dowm to the bit. I used a new 5/16 pilot point bit in place of the 8mm bit and the bore was perfect. The brad point metric bits I have just don't seem to hold up very well.
Herb
Herb
randyrls
Member
Herb; Most people will advise you to stay away from brad point bits. They work well when drilling across the grain, and help prevent split out when exiting the blank. But I cut blanks in half and drill without breaking thru the opposite end. I then cut off the un-drilled end to exactly the correct length.
Brad points can't be sharpened easily. A Drill Dr. is a good investment as someone else pointed out. But the Drill Dr. can't sharpen brad point bits.
Hope this helps..
NewLondon88
Local Chapter Leader
OK, then I'm going to change my guess to "THE BIT".
There. That's my guess and I'm sticking with it.
Someone in another penturning forum turned me onto some DeWalt drill bits, and I guess down under they called them Extreme bits or something like that.
I found them here for around $60 for a set and they're called Pilot Point bits.
They cut very well and I haven't had a blowout yet. Might be easier to sharpen than the brad points .. the drill doctor may sharpen the pilot point. But I suspect you'd have to sharpen the flute edges by hand. I haven't had to sharpen one yet.
There. That's my guess and I'm sticking with it.
Someone in another penturning forum turned me onto some DeWalt drill bits, and I guess down under they called them Extreme bits or something like that.
I found them here for around $60 for a set and they're called Pilot Point bits.
They cut very well and I haven't had a blowout yet. Might be easier to sharpen than the brad points .. the drill doctor may sharpen the pilot point. But I suspect you'd have to sharpen the flute edges by hand. I haven't had to sharpen one yet.
randyrls
Member
I just sprung for a 115 piece set of Chicago and Latrobe bits. These are intended for metal drilling. They are VERY GOOD BITS, but I should have waited..... About a week later, I saw complete sets of Norseman bits. :crying:
PenPal
Member
OK I confess twas me
De Walt Extreme 2 bits are the only ones I use, made in the USA, sold by one or two trusted sellers on this site.
For Slimlines these bits last and last do not track , do not break out on exit with care.
Have success. Peter.
De Walt Extreme 2 bits are the only ones I use, made in the USA, sold by one or two trusted sellers on this site.
For Slimlines these bits last and last do not track , do not break out on exit with care.
Have success. Peter.
wolftat
Product Reviews Manager
Is it just with one type of wood or with all? If it is just cocobolo, don't use it.
NewLondon88
Local Chapter Leader
Rick_G
Member
I prefer the HSS brad point bits Lee Valley has haven't had any of them wander on me but I have cut myself many times when I touched the cutting tip. They are expensive so I buy them one at a time as I need them.
ELCAMINO63
Member
i have seen this problem when the bit is dull , it tends to wander because it gets hot in the wood and tries to take an easier path .
my solution would be to switch bits or sharpen the present one when i have done this it straightened out and also wit every little cut bring the bit out to keep the bit clean often till you break through the other side.
my solution would be to switch bits or sharpen the present one when i have done this it straightened out and also wit every little cut bring the bit out to keep the bit clean often till you break through the other side.
Rifleman1776
Member
That is a very misleading post. I hotly disagree with what you said about brad points. I believe, from experience, they are vastly superior to other types of drills for end grain drilling and boring. Brad points are my standard for pens, duck calls and other times when I do end grain drilling and boring. I make duck calls and found, after numerous failures with other types of drills, that brad points do the job and do it well. I frequently bore at 3/4" with brad points. Other styles, like twist, twist with split points and forstner do more burning than boring on end grains, whether soft or hard woods.
Blind_Squirrel
Member
I have sharpened many brad point bits with my DD! When I was through they were split points :biggrin:
Rifleman1776
Member
I missed this other incorrect statement earlier.
Randy S. said, in part, "....Brad points can't be sharpened easily."
Wrong as can be.
Brad points are very easy to sharpen. It is one feature about them that I like. It does have to be done by hand but is simple. I use a small, flat, diamond file, usually fine grade. The INSIDE of the cutting edge is touched up and you are back to work in no time. If you spend more than a minute you are doing something wrong. Must emphasize, sharpen the INSIDE only. If you sharpen the outside you probably will ruin the bit.
Sharpening brad point bits is very easy and quick and doesn't take any real expertise.
Randy S. said, in part, "....Brad points can't be sharpened easily."
Wrong as can be.
Brad points are very easy to sharpen. It is one feature about them that I like. It does have to be done by hand but is simple. I use a small, flat, diamond file, usually fine grade. The INSIDE of the cutting edge is touched up and you are back to work in no time. If you spend more than a minute you are doing something wrong. Must emphasize, sharpen the INSIDE only. If you sharpen the outside you probably will ruin the bit.
Sharpening brad point bits is very easy and quick and doesn't take any real expertise.