Spindle boring

[Allan]

I need advice on boring a long (11"), small (1/8" diameter) hole through a spindle. All my attempts have resulted in holes which have drifted up to 3/8" off center.

My lathe speed was 500 rpm. Initial bit used was 2-5/8" long; subsequent bits were 8" and 12" long. The bits were secured in a chuck at the tailstock, advanced slowly, and retracted often to clear the wood chips from the bits' flutes. Ironically, the closest to center boring happened when I hand held the bits in a vise grip.

I've been told the off-center drifting is a result of the longer 1/8" diameter bits' flexibility. If anyone has a method of minimizing/eliminating the drifting, I would really appreciate your sharing it with me. Thanks.
Allan.

 

[Andrew]

First of all, must the turning be drilled? Can it be, instead, cut lengthwise; both halves routed down the middle; glued back together; and then turned?

Can you drill from both directions (cutting down the length drilled into the wood by half) instead of from just one direction? Still will "wander" but not nearly as much.

Have you tried what's called a "lamp auger"? It's designed for exactly this purpose.

What kind of bits are you using right now, by the way?

 

[Allan]

Andrew,
I've done the cut in half, route grooves, and glue back procedure. I want to save production time by boring the spindle blank. Lamp augers have diameters (5/16" - 3/8") which are too big for my project. My long 1/8" bits are HSS bits from www.jamestowndistributors.com

I'll try boring from both ends as you suggest. As long as the blank is fairly well centered when it's rechucked after the first half-boring, the two holes should link-up with some accuracy. Thanks for your response.
Allan.

 

[Mark Mandell]

Allan,

Have you tried boring before you turn the spindle? While I think you're always going to have trouble with a 1/8 (or larger) bit flexing, you might try boring a blank first, then, using the holes on each end to locate your two centers, turn your spindle and the hole will be centered automatically. Course you do run the risk of exposing your bore-hole if it's actually curved and you cut too deeply, but it may be worth a try.

It's the same proceedure that was explained to me for making a wood flute, although I haven't tried it (yet).

Good luck!

 

[Andrew]

Allan,

I have a 3/16" lamp auger bit and assumed that there were smaller ones out there too. It's 18" long and works well although I have no use for it. It was passed down to me. Frankly, I can't tell you that it wasn't just custom/hand made and not a commercial product. If you need such a bit for lots of holes, you should be able to find someone to make you one in the size you need. It doesn't look terribly difficult to make for a machinist.

 

[dkulze]

Curious what your project is that it require 1/8 and can't do any larger. I've found that freehanding my drilling using the morse taper chuck as a handle for the bit works better than most other methods. All I can suggest is clearing the bit about every 1/8-1/4 inch and using minimal pressure.

Oh, concept......Are you familiar with the Bitmaster drill bit sharpener? A friend who is a production turner got one and is thrilled with it. It can be set to regrind bits to a spur tip, which might take care of your centering problem.

Good luck,
dk

 

[Whit]

Allan,

About the only success I've had in getting centered holes over any distance is, as Mark suggests above, drilling the blanks first, then turning the outside using the hole to center the thing on the lathe. I've tried twist drill, bradpoint and forstner bits. They all take the path of least resistance through the wood, especially the smaller diameters. Drilling in half way from each end also helps some, as does clearing the hole often but it's still going to wander. Even if you do drill first and then turn the outside there's no guarantee that the hole will be straight through the middle the entire length of the piece. As a matter of fact, holes this small may not even meet at the half-way point.

Not much encouragement, I know, but good luck.

Whit

 

[john lucas]

Allan
I think you will have a great deal of difficulty ever getting a 1/8" hole centered. Normal drill bits just won't do it. I played with all sorts of 3/8" bits and finally bought the Lamp Auger. I've never seen them in 1/8.
I would drill the hole first and then align the drive and tail centers with this hole.
There is a thing called Gun Drills that are designed for deep hole drilling and have a hole in the center for fluid or air to blow out the debrie. I didn't look for these in small sizes so I don't know if they exist.
I spent quite a while researching this because I had to drill a hole through the center of a 48" piece of solid wood for a customer. I had a lot of failures until I reworked my lamp auger. I sharpened it much sharper than it came from the factory and slowed the feed rate down tremendously. I also cleared the shavings very frequently. Lamp augers cut with only one flute so it tends to follow the center line of a spinning object. This acts more like a boring bit than a drill. A standard drill cuts with both flutes and will tend to follow the grain of the wood.

 

[Allan]

"Thanks," to all for your comments and advice.

Perhaps the course of least resistance for me to take will be "the drill the blank first and align the centers on holes" procedure. Less than straight holes will suffice and will certainly save time over my currrent "cut in half, route groove, and glue halves together" routine.

I'll give your ideas a try and will report back if I learn something that hasn't already been mentioned.
Allan.

 

[Mark Mandell]

Correct er, Addition

Allan,

I did forget to mention that when drilling the blank first, you need to use larger blanks so that if/when your bore wanders to one side, you will have enough "meat" to use the hole as center and still make your planned diameter on the spindle.

I should also note that if your finished spindle will have a block on the end, you'd better plan of a M&T joint to join the square to the round as it'll be very unlikely that your bore will dead-center the square blank.

Let us know how it worked out.

Mark

 

[Ken Grunke]

Another thing to try is use an electric hand drill with the work chucked in the lathe. Start the hole with a short bit in the tailstock, then switch to the long bit in the hand drill. With both the work and the drill bit rotating at a slow speed, backing the chips out often, the bit is more likely to stay on center. Use wax to lubricate the bit.

 

[Allan]

Progress Report

Using a combination of Andrew's "drill from both ends" and Ken's "hand drill/lubricate the bit" suggestions, I've had a measure of success. The longest pair of holes to connect has resulted in a 14" bore. The connections have been less than accurate but sufficient for my needs. I used a 1/8" diameter X 8" long HSS bit with a 9.6V cordless drill. Lathe speed was 500 rpm.

I'm going to have a machine shop join a 3/16" HSS brad point bit and an 8" long X 3/16" shaft. Perhaps the brad point and larger diameter bit will improve the connection accuracy.

Thanks to everyone for your suggestions and comments.
Allan.

 

[Chuck Ludwigsen]

Bit sharpening == bit wandering

I was thinking about the sharpness too. In a bit as small as 1/8", it would seem that even a slightly off-centered sharpening would amplify into the bit wandering in that deep of a hole.

I agree with others, that if possible, drill it first, use the holes for the centers and turn around that. The hole would certainly be straight down the middle then.

 

[Allan]

Progress Report Addendum

I did not mention in my previous post that I tried "single" boring through 11" spindles again, and some exit holes were up 1/2" off center. The 1/8" diameter holes were not straight, either. They were curved which reflected the bit's flexing/wandering.

For those who choose the single bore method with long, small diameter bits, heed the advice in Mark's 5-30-04 post: use larger blanks to compensate for the bit's wandering.
Allan.

 

[john lucas]

Alan
I welded a 3/8 shaft onto a 3/8 bit. It wanted to bind up. If I did it again I would weld something smaller onto the 3/8 bit. This would allow for more clearance but if you don't clear the sawdust frequently you could jam the whole thing inside.
I may have plans somewhere for a homemade boring bit. The one I made was moderately successful. It bored holes quite easily up to 12 or 14 " but didn't work for the really long hole I had to drill.

 

[Mr. Don]

step no. 1)
Draw an "X" to establish the center of one end....prop the wood in the crotch of a tree in your yard....stand back about 30 yards with the trusty 30-30......

step no. 2)
Forget it and fire up the woodstove!!!!

 

[Randy Rice]

Solution (Expensive)

At last year's S.W.A.T. Symposium, I watched a demo on making bagpipes. It involved making a long, thin hole in a piece of wood using a gun drill. The demonstrator got his drill from:
http://drillmasters.com/

I am hoping to get them to make me a custom 10" long drill for 1 3/8" holes (their shortest stock drill for that size hole is 28").

 

[john lucas]

I think another good tip when drilling from both ends is to start with a shorter bit. It will be stiffer and less likely to wander. Drill both ends with the short bit and then use one a little longer and finally go all the way through with your long bit, hopefully connecting the holes.