I bought a chunk of scrap decoy cork and mad a handle out of it. I think it turned out very nice. I like the variegated look of it. I found it very difficult to get a 1/4” center hole through the 1 1/4” x 1 1/4” x 8” block. Started center on one end but crept off to the side by the time I got through to the other end. I chucked the cork into the lathe but it is somewhat flexible, so when I ran the 1/4” x12” drill bit through the cork it came out not centered. Thoughts on the best way to get a straight hole in a long block of cork?

I just cut four piece about an inch thick and drilled a 1/4” center hole in them and have them glued in the press to see if that is the route I need to take. When drilling both the long block and the inch blocks, the drill bit chews the cork up quite a bit as well. Not sure how to remedy that…not a deal breaker but not ideal either.

I would build an adjustable 3 sided cradle out of 2x4's.

David,
Even a very stiff / rigid bit such as solid carbide may still deflect some over 8in. The cork itself may be inconsistent enough to persuade the bit off-center as well. A “brad point” or possibly a “Forstner” drill bit may help but you may have difficulty finding them in extended length. When I need a nice, crisp edged hole in cork, I use miniature (modlers) brass tubing sharpened on one end, but it is difficult to drill more than 1in at a time. You will also need something the next size down which fits inside the tubing to remove the cork left inside and also to keep the tubing from collapsing when chucked- up.
The best that I can offer is making the grip in shorter sections of cork, drill them to the desired size, and then either glue the sections up on a mandrel or taper bore them and glue them up on the blank. I am curious of methods used by others; I am here to learn.

Mark Talmo
FISHING IS NOT AN ESCAPE FROM LIFE BUT RATHER A DEEPER IMMERSION INTO IT!!! BUILDING YOUR OWN SIMPLY ENHANCES THE EXPERIENCE.

You did not mention the type of drill bit you used, I find a brad pint bit is very far less likely to wander off center. That said, 8" is a long way to drill a non-ridged material, drilling from each end, may be the solution.

I’m using a regular grill bit. I’m hoping the one inch blocks that I glued up is the solution.

David,
Don't fight it.
Cut the 8 inch block in half and then drill the 4 inch deep holes. Drill 2 inches in from each side.

Then, when the two 4 inch holes have been complete, take a threaded rod with washers and nuts for the end to form a clamp, and glue the two half handles back together with epoxy.

In times past I have built up 20 inch tennessee grips. I use that process during both the drilling as well as the shaping of the grips. If the rod blank is fairly small, the thru hole may not be much bigger than 1/4 inch. If so, there is too much flex using a 1/4 inch mandrel on a very long grip. So, it simply works better to machine each piece close to the finished measurements. Then, glue the two pieces together and do the final light machining on the full length piece.

----------
If possible for your grip, do not drill a 1/4 inch hole through the grips. What is the size of the rod blank, on which the grip is going to be installed?

If, for example, the grip is between 3/8th and 1/2 inch or even larger, then use a 3/8ths or a 1/2 inch aircraft bit for the boring.

---------------------------

[www.rodbuilding.org]

Notice that the grip is chucked into the head stock chuck - which in this case is a 3-jaw - full face Taig chuck that is mounted on the wood lathe head stock.

Then, the turned end of the grip is held stationary by a ball bearing rod support that I had made a long time ago, when I used to turn grips on full length rod blanks.

Finally, the drill bit is chucked into a keyless chuck, that has been mounted in the tail stock.

Before starting the drilling, the drill bit and tail stock were slid up along the lathe bed to the center of the head stock to confirm that the drill would hit the dead center of the head stock for the drilling operation.

Then, be sliding the tail stock back, insetting the keyless chuck and the drill bit into the chuck, we were set. We only had to turn on the lathe to spin the grip, and the, use the tail stock advance wheel to move the drill bit through the full length of the grip.

--------------------------
Over the years, I have accumulated a set of 18 inch drill bits of sizes starting from 1/4 inch on up to 1/2 inch that makes such operations pretty simple and straigh forward.

Summary:
1. If possible, spin the grip material and keep the drill bit stationary for a perfect through drill operation.

2. If 1. is not possible, cut the grip material into smaller pieces that will allow the hole to come through straight and then glue the pieces back together again.

3. To help with both operations, use the largest drill bit possible that will still fit within the parameters of the size of the rod blank where the final grip will be mounted. The larger hole, means a larger drill bit, that means a stiffer, and stiffer drill bit as the bit gets larger.

Example of an inexpensive set of long drill bits that are satisfactory for drilling grip material. Not good enough for steel, but certainly good enough for wood, cork or carbon.

Here is a nice set of brad point 12 inch long drill bits that make quick and easy straight work through various grip materials. The brad point is the secret. The brad point cuts cleanly and straight:
[www.amazon.com]

Here are some inexpensive sets of 25 inch long twist drills that may be useful:

[www.harborfreight.com]

--------------------------------
This set in particular, is the one that i have used many times working with long grips to get nice holes all of the way through and still be right on for the rod blank being used:

[www.harborfreight.com]

Here is a set of smaller diameter long drill bits if you have such a need, but don't want to spend much money to drill through soft stock.

[www.harborfreight.com]


-------------------------------------------------------
On a slightly different vein, I have picked up a couple of deep hole drilling when one needs to drill long holes through walls to string wires. IN this case, there are multiple extensions in the set so that you can drill 6-10 feet. These particular drills also have a small hole behind the drill head so that you can tie on a thin wire or strong string that you end up using as a pull cord to pull wire through the series that one has drilled through finished walls that need additional wiring installed.

In the rod shop this set of drill bits and extensions come into play if additional wiring is needed behind finished walls with no easy access.

Be safe





Finally, if you have a lathe, and the right chuck and tail stock, set up the lathe so you spin the cork and do the drilling with the stationary drill bit in the tail stock.
I do this all of the time to drill deep holes in material and have the hole come out perfectly.

I will post a picture of a setup that I used when boring a center hole in a wood grip that I had turned on the lathe.

Thanks Roger. The 1/4” hole is needed for some ice rods that I am working on.

When I’ve needed to drill a lengthwise 3/8” hole through 1”x1”x6” wood blanks (on my lathe), I use two brad point bits. First I bore with a 5” length bit. Less drill bit length equals less initial wobble/wandering. I then use a 10” length bit to complete the bore. Good results are achieved.

Perhaps this method will also work with long bores through cork.

"The greatest barrier to discovery is not ignorance, it's the illusion of knowledge" - Daniel J. Boorstin

David,
One other thing I forgot to mention which is important with any machining operation; Speed and Feed. In your case, a higher speed with a slower feed will probably produce the best results.

Mark Talmo
FISHING IS NOT AN ESCAPE FROM LIFE BUT RATHER A DEEPER IMMERSION INTO IT!!! BUILDING YOUR OWN SIMPLY ENHANCES THE EXPERIENCE.

Thanks everyone!

I cut my blocks into 2" by 2" by 15" long blocks and bore out with 3/8 inch bit on the lathe. I drill half way then flip the block. I use slow speed and back out frequently to clean out the cork shavings like Shane mentioned.[www.rodbuilding.org]
Steve



Edited 1 time(s). Last edit at 03/31/2022 03:22PM by Steven Paris.

I will admit I haven't drilled a lot of cork but as a hobby machinist I have drilled lots of long holes in a lathe. In softer material it is tempting to just force the bit through. This can cause the drill flutes to become packed with material. The deeper the hole, the worse the problem is. If one flute (or both) is not expelling your cut material it is clogged. When one flute is clogged it can not get a bite on the material and cutting with just one cutting edge can cause the bit to wander.
The solution is to remove the drill frequently during the drilling operation and clear the flutes with a stiff chip brush. It may also be helpful to start with a short drill and work your way up to the long one.

This may not be a cork issue but it's worth watching for.

Shane,
In addition to your comments.

I have a blow gun with a foot long small diameter pipe on the end of the blow gun.

So, when I am drilling deep holes, I frequently extract the bit, and then use the blow gun to remove all of the chips from the interior of the hole as well as from the flutes of the drill bit.

Without a doubt, it really helps with this sort of operation.

Note:
Also, if you are using a drill and tap to make threads in a piece of metal. The same thing applies, every few turns of the tap, remove the tap, blow all of the debris from both the hole as well as the threads on the tap and the newly created threaded hole will have much cleaner threads and they will be made much easier that if the hole is tapped in one operation, without removing and cleaning the hole a and the tap of chips.

Best wishes.