Drills, Bits, Jigs and Techniques

[Mark Mortimer]

I'd like to ask what drill bits other bambuseros use in their work. I've always used high speed steel bits and they generally work fine. I always need to drill various sizes so I splashed out on a set with drill bits from 0.5mm to 13mm in quarter mm increments. Lots of money but worth it. (I also use a lot of hole saws but I want to talk about smaller diameter holes for the minute)
My problem has always been the splintering which occurs when the drill bit exits on the other side of the culm. The entry hole is usually fine. I've tried everything from adjusting drill speed, force, using tape, something solid at the exit hole etc. So I have limited the splintering but only to a certain degree, and it is usually a hassle to use some of the techniques if I have many holes to drill.
Of course turning the culm round and drilling from the outside in is the best option, but again not always practical.
So I've been trying different bits, and I'd like to hear your experiences. I've tried brad bits, fostner bits and spade bits. Brads and fostners are the best for the entry holes, spades the worst, digging in and causing untold damage if not extremely sharp. But they all splinter more or less the same at the exit hole.
Any help?

[Mark Meckes]

My problem has always been the splintering which occurs when the drill bit exits on the other side of the culm.

Likewise, I too, encounter the same problem.

When I've had a lot of holes to drill..as when making windchimes, it took a lot of practice drilling holes from the top...turning the bamboo over and drilling the other side, and trying to make sure the holes would line up... even with practice, it's easy to not get it right on target.

One idea that I wish a mechanically ingeneous person would come up with, is a `Two-Drill Jig ', that would drill both sides at the same time.
The bamboo is set on the jig, and the 2 drills automatically adjust to it's center, (or what ever setting you could presumably choose).

Centering mechanisms aren't all that complex, and a jig to clamp to, and align the 2 drills shouldn't be that difficult to design and manufacture... There would probably be two sizes...one for use with smaller `dremel' type drills.

Now, if someone would make this device, I'll be a first customer!
Mark

[CaroleMeckes]

My favorite tool is a Dremel and I use it with the
"Tool Holder and Base" (Dremel's stock # 2217).
This base has been "excellent and invaluable!"

Using the base, allows one to have two hands free to hold the bamboo while drilling.

To further steady my hand, I often rest my hand on the table while drilling.

I love to drill holes! I like to use the smallest drill bits I can find!

Of course, I am drilling small pieces since I am primarily working with the Dremel tools.

Have you worked with using a drill press?
Carole

[Mark Mortimer]

Yes Carol,I have used a drill press, especially when working with Angel and Mariana. I don't currently use one. They are very useful when making many similar holes in small pieces. I find I can't get the double bed I'm making under the drill press! :) The final thing I do when making a piece of furniture, once everything else is finished, is to put it together and do the final dowelling. So most of my holes are 6 or 8 mm, and usually involve drilling through the culm and a smaller diameter plug inside it. not easy to drill from both sides and meet up. i sometimes drill nearly all the way through, feeling the other side, and stopping when I can feel the heat of the drill bit just about to punch through. then i know exactly where to drill.

[Mark Meckes]

Yea, that's the size hole where splintering on the exit side really becomes a problem.
Perhaps masking tape placed on the exit side might help a `bit'.
I wonder if a similiar shaped block of wood, or a dense flexible rubber/foam pad was held tightly against the exit side, if this would help prevent any fraying and splintering?

[Mark Meckes]

Here's an idea, which, if designed and constructed with precision and practicality in mind, could be one way to prevent excessive splintering or fraying at the exit hole, when drilling bamboo.

Essentially a hollow metal tube would rest firmly over the exit hole, for the drill to pass through, hopefully preventing splintering of the outer surface `skin' of bamboo.
A rough sketch ...
http://www.bamboocraft.net/gallery/data/531/thumbs/1DrillJig479.JPG (http://www.bamboocraft.net/gallery/showphoto.php?photo=22)

Anyone know where I can pick one up?

Mark

[Mark Mortimer]

Yup, the idea of using a block behind the piece you're drilling, to stop splintering on the exit hole is a good one. It has to be a perfect fit though. And some kind of rubbery material which closes back up once the drill bit is removed would be ideal, or you'd end up with lots of holes in your "back stop pad". It has to be held against the exit hole side of the bamboo quite tightly.
With your drill jig, Mark, you'd have to have a hollow tube for each sized drill bit, no? It would certainly be precise, and useful when many same sized holes need to be drilled on a drill press, or when the bamboo can be taken to the drill. I'm still trying to find a method when the piece is large and unwieldy and the drill has to be taken to it.
The brad points certainly help a bit. But I guess due to the nature of bamboo, there is no magical bit which will not splinter on the way out.

[jbest]

I've never drilled bamboo before (new to all of this) but one very simple solution might be to make a jig that fits into the hole in the table of a drill press. Imagine a 6 inch square by 1 inch thick piece of wood. On the bottom of the center it has a short piece of dowel (1/2 inch should be long enough) which fits into the hole in the table with little play. On the top center is either a piece of dowel that is about the diameter of the hole being drilled or, for general use, a dowel carved to a point to make a cone that will work for a range of hole sizes.

First drill one side of the bamboo without the jig, then insert the jig into the table. Turn the bamboo over then place the drilled hole over the dowel on top of the jig and drill the second hole. The cone would allow for centering the bamboo for a variety of hole diameters but might not keep the bamboo at 90 degrees. For smaller holes, a metal rod or wire might work better.

If this doesn't make sense, I can draw a picture then figure out how to post it!

Something else just occured to me...if you don't have a drill press, you could use some calipers to find and mark the places to drill on opposite sides of the pole, then just drill one side then the other.

Jason

[Magic]

I have an idea after reading your problems with the splintering of the second side which seems to be the worse as the bit comes out. Would using a very small bit first, no matter what size hole you need,that would go completely through and this would mark where the next bit is placed and both larger holes drilled from the outside, and on each side would be aligned up and cleaner looking? Hope this has helped. --Magic

[Herb Smith]

One idea that I wish a mechanically ingeneous person would come up with, is a `Two-Drill Jig ', that would drill both sides at the same time.
The bamboo is set on the jig, and the 2 drills automatically adjust to it's center, (or what ever setting you could presumably choose).

Centering mechanisms aren't all that complex, and a jig to clamp to, and align the 2 drills shouldn't be that difficult to design and manufacture... There would probably be two sizes...one for use with smaller `dremel' type drills.

Now, if someone would make this device, I'll be a first customer!
Mark
LOL. Newbie here. Hope you don't mind that I resuscitated this thread.

I worked for years in a paint brush handle factory where we encountered the same problem. Most paint brush handles have a string hole in the tail. To drill these holes without tearout, the company designed and built several dual spindle drills.

The workpiece is positioned and clamped to the drill table. The carriage lowers at a controlled rate drilling the top part of the hole, then the carriage rises at a controlled rate drilling the bottom part of the hole.

The motors are direct drive, their speed controlled by a little controller, but I'm sure something could be built in the average shop with pulleys.

Here is a crude illustration of the principal:

(Edit (link removed - not working .. MM)

[Mark Meckes]

Thanks for reviving this topic! Interesting idea.

Drilling a solid piece of wood, you would need to have it to drill one side, then drill the other side past the center point, but as bamboo has a hollow core, the bit doesn't need to drill to the center line.

Maybe it would be technically more difficult to make one that drilled both sides on one lever stroke. (?)

The other thing needed is a centering device to hold the piece of bamboo.
I'm imagining dual rails (that the bamboo is placed between) that can expand by some sort of scissoring bracketing thingy, always centered to the drill bit.

Mark

[Mark Mortimer]

Very interesting Herb,
Just goes to show there are solutions to just about anything.
The only thing for my work is the ever changing nature of it, and the fact that I have to do most of my drilling on the piece of furniture, once assembled. Hard to get a double bed under a bench drill! However, maybe I 'll put my mind to coming up with a portable version.
I don't do a lot of those pieces any more. And if I do, I usually feel for the drill bit to come out the other side (you can feel the heat way before it perforates) then let it just peep out, then drill from the other side now that I know where exactly to drill.
Regards

[Herb Smith]

Maybe it would be technically more difficult to make one that drilled both sides on one lever stroke. (?)
I might avoid complicated gearing and go neumatic, turning the axis horizontal for balance. A cheapy twin rail lathe bed might make a good base. I picked one up for $20 or $30 once. Flowcontrols would regulate the speed of the cylinders. I would add a strong, mechanical stop and check that the drill bits don't touch.

Something like this:

(Edit: Link not working. MM)

The other thing needed is a centering device to hold the piece of bamboo. I'm imagining dual rails (that the bamboo is placed between) that can expand by some sort of scissoring bracketing thingy, always centered to the drill bit.

Mark
I was thinking of a simple V-block, but that may not be precise enough for something lacking uniformity like bamboo. Have you ever seen this gizmo? http://www.aloghomestore.com/pics/st0103-barker-clamp.jpg I'd rather something that is air activated.

Hard to get a double bed under a bench drill! However, maybe I 'll put my mind to coming up with a portable version.

LOL. I don't know how large the holes are that you are drilling, but I was thinking about flexible shafts. Years ago there was a cheap gizmo that bragged you could run two tools off your drill (when clamped to a bench). Can't seem to find it on the web, but let's ASSume we have a small gearbox with two take offs. The Vise-Grip isn't perfect because it will rotate the drill bits into the work. I'm not sure how much that would elongate the holes. Plus, I would get rid of the lock and add a return spring to open the jaws. Assembled neatly, it could be an accessory for a portable drill.

[Mark Meckes]

I was thinking of a simple V-block

hmmm may simplicity is all that is needed for a centering, though it would be handy if it was attached to a robot arm, always ready and able to assist when an extra hand is needed. ;)

Whatever the centering device, it doesn't need to be long, as it only needs to center the position that the holes are to be drilled.

I have a portable electric drill and a portable press that the hand drill fits in to, though I don't use it because I also have an all in one drill press.

Anyway, maybe one could use 2 electric drills - connected to a pedal On/OFF switch, and put 2 of these drill press holder/levers on one shaft ...

[Herb Smith]

I have a portable electric drill and a portable press that the hand drill fits in to, though I don't use it because I also have an all in one drill press.

Anyway, maybe one could use 2 electric drills - connected to a pedal On/OFF switch, and put 2 of these drill press holder/levers on one shaft ...
Yeah, that could work. I need to find a good pic...

Here's something that would be a bit cheaper and you wouldn't need any extra parts. Having each hand on the pistol grip of a drill should give decent control. The guide bars limit access, though, and it might wrack.

(Edit: Link not working. MM)

[Mark Meckes]

Wow I better start saving up my pennies!

There will probably need to be 3 sizes of jigs to correspond with the size of bamboo.
Mini - Medium - Big

Mini - 1/2 " or about 1cm and smaller - Dremmel/rotary tool size

Medium might be for 1/2" - 3+ diameter ... that's the range I would use most.
I use 1/8 - 1/4" hole for a lot of things in this diameter boo. It's is good to thread wire or string through ...

Big - for the big stuff

If large straight-through holes need to be drilled, one could just drill a pilot center hole through the bamboo as a guide then drill each side with large bit using a standard drill or drill press.
... though a well designed, accurate, easy to use. reasonably priced jig would pay for itself by the time saved ... if it was used enough ;)

Mark

[Herb Smith]

Wow I better start saving up my pennies!
LOL. Some of my Rube Goldburgs would only be worthwhile developing for production shops - like the neumatic, double head drill. Solutions shouldn't cost an arm and a leg.

Back to centering... It occured to me that a bar clamp could be fitted with conical jaws. The cones would be relieved to have three flutes insuring three points of contact on either end. This might be appropriate for short lengths of square cut boo. The centerline between points of the cones should be pretty darn close to the centerline of the boo. Then, that centerline would need to be placed in the same plane as the drill press's centerline.

The bar clamp could be mounted to a board or square stock for positioning at pre-set stops for multiple drill holes.

A low tech (cheap) version of the neumatic drill could be built with a straight length of 2x4, scrap plywood, two sets of drawer slides, and various hardware. I seem to be stuck on the flexible shaft just now. They allow for virtually any power source - like a free washing machine motor.

This still doesn't give you single lever operation, but it's cheap and should make short work of limited production runs.

[Troppo]

Hi Herb,

If you're still around could you repost your pix from your hard drive or photobucket.com?

There are a few of us who would like to see your pix. ;)
Thanks,
Troppo

[Mark Meckes]

Thanks for bringing this to our attention Troppo.
It's for this reason of lost images that we'd prefer images be uploaded into posts as attachments or uploaded at the galleries and linked to posts.
Herb, if you are hopefully still around you should be able to edit and add them to your your existing posts, or you can add them to a new post.

Cheers,
Mark

[JEBeck]

If anyone is still reading this topic,
I use multiple layers of painter's tape, wrapped tightly around the pole.
Drill a pilot hole the whole way through with a very small bit.
Drill both larger holes from the outside of both sides.
If the required hole size is much larger than the pilot bit hole, do it in steps.
Use a bottle brush to clean the tape bits out of the inside if the pole is hollowed.

Hope this helps,
John

[drlashambe]

While it would probably be frustrating if you are doing lots of pilot holes, I have recently been using a small drill bit to make the initial holes, then using a "rasp" bit (common for metal work) to clean up the hole and increase its size. It has the added benefit of burning the inside of the hole rather than cutting the bamboo, so it strengthens the hole as well.

[Denis Ko]

I've used drill bits that are specifically made for drilling plastics. I still use masking tape to prevent tearout on a through cut. The only limitation is available sizes. 1/8" to 1/2". I have not found any larger than 1/2". I found my bits at a plastics and fabrication store. These bits have a steep taper to prevent shattering of plexiglas and work great for bamboo.

[bootoyoutoo]

Post deleted due to lack of response.