Long Horizontal Boring Help.

wearymicrobe · Post by **wearymicrobe** » Mon Oct 20, 2008 12:11 pm

Does anybody have a suggestion on how I can do a 15 inch horizontal bore on a shop smith accurately. I have tried it using the 3/4 inch boring bit on a extender with no luck and all my 20' plus bits wander quite a bit through the piece.

I have had some luck marking center and then using the lathe tailstock to support with the deck in place and some clamps but I can only use a standard 6 inch bit and its not long enough to bore both sides out.

billmayo · Post by **billmayo** » Mon Oct 20, 2008 12:47 pm

These are the kind of projects that I enjoy playing with. I have a few 18" long boring drill bits with center spur(http://www.harborfreight.com/cpi/ctaf/d ... mber=93892) that I use in a 1/2" chuck with #2 MT in the tail stock. I have modified a couple of 500 table bar and tube by adding 2 large plastic wheels to center the item being turning ( modified steady rest ). I made the wheel mounts with adjustable slots so I could move the wheels in or out to fit what I was turning (way and bench tubes in one case). I use the table height adjustment to raise and lower the wheels. I place the wheels just before the where the drill spur will enter the item being drilled. I marked the center of the piece being drilled and by holding the drill bit (does not turn), insured that the spur entered that center point. I moved the headstock each time the quill reach maximum extension and go again. Once started, I have actually locked the quill and just pushed the unlocked headstock to do the rest of the drilling. Let me know if any questions.

wearymicrobe wrote:Does anybody have a suggestion on how I can do a 15 inch horizontal bore on a shop smith accurately. I have tried it using the 3/4 inch boring bit on a extender with no luck and all my 20' plus bits wander quite a bit through the piece.

I have had some luck marking center and then using the lathe tailstock to support with the deck in place and some clamps but I can only use a standard 6 inch bit and its not long enough to bore both sides out.

Ed in Tampa · Post by **Ed in Tampa** » Mon Oct 20, 2008 2:14 pm

Frankly I'm not sure it possible, once your in the work even slight fluctuations in the grain can deflect the bit.

I don't think it matters how true your bit, how perfect you hold it, hold well you have the wood supported a slight change in grain applied to on end of a 15" plus bit can and will cause it to deflect slightly. Add up all the changes in grain as it penetrates the wood and it is easy to imagine it being off by quite a bit. I think those that are able to bore it exactly are more lucky than skilled.

What I would do is split the wood on my band saw cut the groove either with a router bit or dado blade depending on the type of hole I needed and then I would glue the two pieces back together.

Ed

wearymicrobe · Post by **wearymicrobe** » Mon Oct 20, 2008 3:35 pm

Ed in Tampa wrote:
What I would do is split the wood on my band saw cut the groove either with a router bit or dado blade depending on the type of hole I needed and then I would glue the two pieces back together.

Ed

That is what I currently do, but I want to do a seamless flute at some point. I have had luck making 12 inch sections by drilling 6 inches from each side to the middle then turning the end to a tendon on the lathe and then cutting pocket in the extension piece. Looks much better and the lines I can hide with a decorative collet if I really want to get fancy.

I think I am going to try one of the gunsmith lathes that we have at the office with a 3/4 inch carbide flat blade like on the Ci1's, and just feed it in till about 1 inch from the end and then do a quick cut to complete the tube.

billmayo wrote:These are the kind of projects that I enjoy playing with. I have a few 18" long boring drill bits with center spur(http://www.harborfreight.com/cpi/ctaf/d ... mber=93892) that I use in a 1/2" chuck with #2 MT in the tail stock. I have modified a couple of 500 table bar and tube by adding 2 large plastic wheels to center the item being turning ( modified steady rest ). I made the wheel mounts with adjustable slots so I could move the wheels in or out to fit what I was turning (way and bench tubes in one case). I use the table height adjustment to raise and lower the wheels. I place the wheels just before the where the drill spur will enter the item being drilled. I marked the center of the piece being drilled and by holding the drill bit (does not turn), insured that the spur entered that center point. I moved the headstock each time the quill reach maximum extension and go again. Once started, I have actually locked the quill and just pushed the unlocked headstock to do the rest of the drilling. Let me know if any questions.

So are you supporting the work with the table and wheel mounts or are you using the wheel mounts to hold the drill bit in position like you would on a bore cut with a metal lathe? Also do you have trouble with the bits trying to self follow/tap, because mine can really put some pressure on the quill/motor locks.

anmius · Post by **anmius** » Mon Oct 20, 2008 8:31 pm

What may be of help is a Lamp Auger Bit originally designed to drill long holes in turned lamp columns.
See the following link:
http://www.highlandwoodworking.com/inde ... rodID=5578

charlese · Post by **charlese** » Mon Oct 20, 2008 10:59 pm

anmius wrote:What may be of help is a Lamp Auger Bit originally designed to drill long holes in turned lamp columns.
See the following link:
http://www.highlandwoodworking.com/inde ... rodID=5578

This looks like the answer to me! The bit may be a little expensive, but would end a lot of heartache. We already know that a flat bit is more effective in boring end grain than either a Forstner or a brad point - and this small 5/16" bit looks like just the thing.

I am thinking of removing the wood handle from this bit, inserting the shaft into a chuck and horizontally boring a hole prior to turning. (You would use the miter gauge with extension to keep the wood parallel to the bit.) That way, when you fix the hole onto the tail - the turning will follow the boring.

Good first post, anmius!!:D Welcome to the Forum! Keep those suggestions coming!

Randy · Post by **Randy** » Tue Oct 21, 2008 11:17 am

One of the biggest problems in deep hole drilling is chip removal. You have go to keep the flutes of the drill clear. Constant extraction is the order of the day. IN---OUT---IN---Out repeat until through. Also 1/2 the job per side and meet up in the center.

I would go no more than 1/2 the diameter of the drill deep at a time. So a 3/4" dia drill would me a ± 3/8" depth per shot.

Just because it looks like the chips are coming out while drilling does not mean that all of them are.

Ed in Tampa · Post by **Ed in Tampa** » Wed Oct 22, 2008 12:23 am

I don't know about the speciality bit referrenced in the earlier post but I do know most bits will deflect.
However I'm told by people that claim to know that a spoon bit will drill straight. The bit gets it's name from the fact it looks a lot like a spoon. They usually were used in hand braces but I'm told new modern ones in HSS are designed for drill presses and lathes.

Unfortunately I don't where they are sold but if I was you I would look into it.
Ed

Randy · Post by **Randy** » Wed Oct 22, 2008 8:09 am

You can also use what is called a "Gun Drill" made for drilling deep straight holes.

dicksterp · Post by **dicksterp** » Wed Oct 22, 2008 6:13 pm

The auger bit referenced in post #5 might be your best bet. Looks very similar to a spoon bit. A gun drill is for drilling long holes in metal. It may be affected by the grain in the wood.

Dick