Help needed in preventing this

[siric]

Hi,

I have noticed that when I drill 27/64" holes, I always end up with a gap on the side that the drill enters.

I drill on the lathe and make sure to clear the bit every 1/4" or so and to let it cool after about 1/2" to 3/4". I will test the bit for heat when I clear it.

But even after doing this, I still get this space between the tube and the blank. This only seems to happen with the 27/64", 7mm and 8mm are fine.

As usual appreciate any help.

Thanks

Steve

 

[nascrdad]

I read this on the Forum, and started doing it, it helped me. I cut my blank a 1/4" too long, drill, then cut off the end. You might try it if you have the extra wood.

 

[Justturnin]

Start you hole w/ these. Prevents wandering

5 Piece Center Drill Countersink Set

 

[walshjp17]

Is your 27/64" drill bit appreciably longer than the 7 or 8 mm bits? You may be getting some wobble from the drilling motion. Make sure you hold the Jacob's chuck firmly, with backward pressure, when drilling.

 

[08K.80]

I drill with a small drill bit, then use the size I need to drill the hole for the tube. Has worked so far.

 

[siric]

Ok,

The 27/64" is no longer than the 7mm or 8mm and I do not detect any wandering when I am starting. It is a brad point bit, so it grabs a center pretty easily.

@nascrdad; I will try this suggestion and see how it works.


Thanks for the quick responses!!!:biggrin:

 

[paintspill]

two things i just started doing that have dramatically improved my lathe drilling are:
start with the centering bits shown in one of the above comments. they can't wander or move like a long bit will ensuring you drill bit will go in straight.
the other is so get some kind of small water bottle and squirt water in the hole as you cut. ACRYLICS ONLY not wood of course. this prevents over heating. 2 new things i learned and man what a difference

 

[mredburn]

roll The bit on something you know is flat and look to see if its bent.

 

[edstreet]

This is classic 'chatter' from the drill bit making contact with the surface. Few ways you can remove it entirely.

a) clean up the face of the drilling surface. Best way you can do this is with a chuck and a chisel. chuck the blank and flatten the end of the blank then dimple the center for the drill bit to hold.

b) Start off with a smaller drill bit to form a pilot hole. This will also provide an index point for future use.

c) use something like a screw starter, nail and make an indentation for the center point to touch. I would personally like to discourage this practice.

d) change drill bit tips to something like a brad point tip. This may allow larger bits to be used but trade off as for damage potential

e) Look at and adjust the tailstock alignment.

Rule of thumb is if the bit is large then you want to drill a smaller hole then ream it to size. Something around 1/2 to 1/4 the size is a good starting point to use.

 

[siric]

Thanks for all of the tips. Will keep you updated.

 

[JD Combs Sr]

Based on your photo I would take a real long hard look at the alignment of your lathe tail-stock to headstock as noted above as item e) of edstreet's post. Especially look at how much side to side play there is in the tail-stock. Are you unlocking the tail-stock from the ways when you withdraw to clear the bit? The photo appears to show that that is what is happening. When it is lock back down its appears to be in a different side to side alignment.