Forstner Bits and Extentions

[Bob Haverstock]

Hey Folks,

Those of you who turn hollow forms and urns, or do deep drilling, whose Forstner bits and extentions are you using? Drilling holes on my Nova 14'' deep is not uncommon. I finally found a 1 3/4" bit and compatible extention and bought it. The bit is single flute and has a long replacable auger screw in the nose of it. I find that the single flute Forstner wants to wonder the deeper I drill.

I have a fear of loosing the bit out of the extention while deep into the wood. I suppose I can make an extention. ( I have the metal tools to do so) Surely, I'm not the only person with delema.

Have any of you found a good Forstnerbit / extention set-up that you would recommend?

TIA,
Bob Haverstock

[Doug W Swanson]

Hi Bob,
I haven't drilled 14" with my setup but I have a set of Forstner bits from Rockler. I also have one of their extensions and they drilled through a pepper mill just fine....

[Jim Burr]

I use these from CSUSA. They work well. I do pepper mills to 12" and no complaints.

http://www.woodturnerscatalog.com/store/Shop___Safety___Shop_Supplies___Maxi_Cut_Extension _Shank___maxi_cut_extension?Args=

[George Guadiane]

Bob,
I went out to the "studio" and brought these back, because I think they can save you some money and do what you want.
MOST of my Forstner bits are from a boxed set made in china. The larger one (1 1/2 inches) pictured is from that set and the smaller one (1 inch) was bought on eBay.
The augers are both OLD. I bought them at garage sales. I probably have 30 or 40 in various sizes, up to 3 inches, with lots of duplicates. I have a rule, never pay more than $1/$2 each, mostly much less. I cut the square ends off of both of these so I could use them in a regular Jacobs chuck.
(THIS IS IMPORTANT): I also ground off the threaded point (after learning how quickly it draws the auger into the wood - you don't want or need to make THAT mistake). I also ground off the little wings and did a grind across the whole blade, much like an ordinary drill bit. The idea was to get a fairly flat bottom without a point or hacked out edges...

First, I start the hole with the Forstner bit, deep enough to capture the auger bit... Then, I can drill with the auger to depth. The 1 inch pictured is will go about 9 1/2 inches and the larger will go 12 1/2 because I can fit the smaller circumference of the Jacobs chuck into the opening being drilled...

With the three inch setup I can drill about 18 inches deep because the 3 inch hole is big enough to take my largest Jacobs chuck completely...
Clear often and move the tailstock up and back as much as necessary.

Longer augers are available and once I got the hang of it, freehand sharpening them was simple.

I have a PM 3520A so I can turn the rotations WAY down. A slow feed rate will compensate some, but slower gives more control.

I hope this helps.

[Wally Dickerman]

I never use forstner bits on HF's or bowls. I use a hand held (wood Handle) 3/8 in. drill. I mark it for depth with a piece of masking tape. Serves as an aid in hollowing and as a depth gauge.

Wally

[Art Kelly]

Woodcraft sells a couple different sizes.

I've taken pieces of 1/2" hot-rolled steel--the longer the better--drilled a hole through it axially (offset and alignment errors don't matter as long as you drill through in one setup), and put a couple of tapped holes for set screws. Stick a smaller piece of hot-rolled of the correct diameter in one and and the bit in the other end. I also grind a little groove in any shafts that don't have flats. This allows full thread engagement of the set screw in the tapped hole and also keeps the shaft from spinning.

You lose a little precision which may effect peppermills, but for deep hollowing, who cares. It's wood. Wait till tomorrow and it'll be a different shape anyway.:)

[Richard Bell CA]

Bob:

I made extensions at approximately 6", 12" and 18" lengths from 3/4" dia cold finished steel bar stock. I bored a 3/8" hole to accept the bit, and drilled and tapped for two 1/4-20 set screws to secure the bit. The hole is slightly shorter than the length of the shank on the bit, so it doesn't slip in use. I turned the opposite end to 1/2" diameter to fit the Jacobs chuck in the tailstock.

I have been using Woodline carbide tipped Forstner bits - I bought the set shown below.

http://www.woodline.com/p-2116-7-pc-carbide-forstner-bit-set.aspx

For awhile Amazon was selling the 7 pc set for $43 shipped - a decent price for carbide tipped bits. Even $55 is a pretty good deal. They are all 3/8" shank, so my homemade extensions will work for all of the bits 7/8" and larger (I normally use the 1", 1 1/8" and 1 1/4").

In use, I start with the bit directly in the chuck and bore as deep as I can. Then I switch to the 6" extension, then the 12", etc. I found I have to stop about every 1/2" to clear chips. It helps to steady the longer extension with one hand close to the vessel while advancing it with the quill. I have used this method to bore over 20" in depth (see photos). I also use a Sharpie and a tape measure to mark the depth on the extension.

Hope this helps

Richard

[Roger Chandler]

A few months ago, I purchased a forstner bit [1-1/16 inch and an extension] so I could drill out pepper mills. On my first attempt at one, I had a nicely figured walnut blank, turned into a very nice shape, and then went to drill the hole. The thing went off to one side, and I noticed that as the blank rotated the jacobs chuck in the tail stock wobbled in the tailstock morse taper.

I was wondering if using the jacobs chuck in the headstock would be a better way, letting the bit spin, and have the blank in the chuck mounted in the tail stock. Of course it would require being able to hold the chuck in one position while the bit was advanced in the blank.

Has anyone tried to drill pepper mills this way?

[robert baccus]

my standard setup for some years is a P.F. 1 7/8" forster bit with two heavy extension bars from craft supplies. in a jacobs chuck of course. if slippage is a problem i grind a small flat on the round shaft under the lock screw.. if there is a secret it is to back out more often as you go deeper. a good air gun helps too. good luck--------------ol forester

[Bob Haverstock]

Hi Folks,

I'd to thank you for the great ideas. I had not thought of modifying old augers and I'd forgotten about the long hand fed bit. I usually rough turn and bore while the blanks are "green". I was locked on Forstner bits and didn't think past them. Compressive wet chips are an issue, the Forstners deal well with that. Thanks for the extention info, now I have more options. Hopefully,this thread will help others.

Bob Haverstock

[Harvey M. Taylor]

Woodcraft sells a line of forstner bits and extensions named "colt'. I purchased an extension and a one and a sixzteenth in. bit for peppermills. I have bored 2 fourteen and one 18 in.mills with it and the hole is as clean as a gun barrel. Of course I drilled from both ends. Kinda pricey, but no problems should be worth something. Max

[Bernie Weishapl]

I am with Wally. I have a long 3/8" bit with a homemade handle. I tape to mark the depth I want. Haven't found a need for any bigger as I mainly use it as a depth gauge.

[Thomas Canfield]

At SWAT this year I saw a 3/8" x 10" long masonary bit used for a starter hole, hand held. Yes, he was questioned about it and demonstrator said that the carbide tips had extra clearance and allowed the shavings to be pushed out without building up heat or packing. I bought a bit, but still need to sharpen it some to get it to work well in wood. For a Forstner bit extension, Woodcraft has a 10" extension http://www.woodcraft.com/Product/2020430/21302/Forstner-Bit-Extension-38-x-10.aspx and also has 1/2" extensions.

[John Coloccia]

I never use forstner bits on HF's or bowls. I use a hand held (wood Handle) 3/8 in. drill. I mark it for depth with a piece of masking tape. Serves as an aid in hollowing and as a depth gauge.

Wally

How do you get the drill to stick in the handle without twisting?