Drilling between centers problem - Solved, Thanks!

[PMisiaszek]

For several months, I have been doing all of my drilling between centers on my Jet 1014 mini. I turn the blanks between centers to 3/4", cut to size and insert my Beall collett in the headstock and the drill in a chuck in the tailstock. I drill at the lowest speed. My problem is that the drill "wobbles" with the result that I am getting oversize holes. The bearings in the tailstock don't seem to have any slop, and I don't seem to have the problem on all of the blanks I drill. This leads me to the conclusion that this is a case of operator error, but I'm not sure what to try first. Any suggestions?

I watched Johnny's video, read the recommendations, and did the following: Took better care in assembling my Beall collett, did a better job of turning the blank round, and tightened up the tailstock feed. End result: perfectly drilled and centered hole. Thanks to all who offered suggestions.

 

[snyiper]

Try a different bit and do not tighten up on the flutes that will put it just out of round.

 

[PMisiaszek]

Brand new bit, high end model and very, very sharp.

 

[Russianwolf]

check that the Moris Taper in the Tailstock is clear also.

Depending on the bit size and the material, you can still get drift in the bit. The bit will want to follow the path of least resistance. I've had this happen a couple times on crosscut pieces.

The tailstock alignment may be off also. You may get point to point up close, but when backed up it may be off a little. Try checking it at both full extention and none.

one last thing. once you have the blank mounted in the beale, with the lathe on, touch a fingernail to the body of the beale where it's smooth. Your nail should skim across it perfectly as it's spinning. now touch the exposed portion of the blank. Does your nail skim on it's surface or do you feel a wobble there.

 

[PenMan1]

Additionally, make sure that you seat the blank and the collet in the front retaining ring of the collet instead of inserting the collet into the body and tightening the front retaining ring around the collet.

I had a similar problem once and this proceedure cured all my ills.

 

[Lenny]

Additionally, make sure that you seat the blank and the collet in the front retaining ring of the collet instead of inserting the collet into the body and tightening the front retaining ring around the collet.

I had a similar problem once and this proceedure cured all my ills.

Me too! It seems like such a simple thing but if you don't know (and apparently I didn't) there is a correct way to install the collet. johnnycnc posted this quick video on how to do it correctly....
http://www.youtube.com/watch?v=xrqjoJCFoTU

I now pay attention when I install mine! :wink:

 

[KenV]

Specs on most drill chucks are +/- 0.1mm which is not high precision, The bits, especially those of lower cost/specs can be ground off center. The drill chuck mounts onto a Jacobs Taper and that can be missaligned a bit.

If you clean the MT on the headstock, and mount the MT- Drill Chuck and drill bit there you can progressively check the runout at the three parts. Dial indicators are one way and the Pencil clamped to the tail rest also works.

Check the MT fit into the taper -- this should be very close.

Check the drill chuck at the back (how well is the alignment on the JT). This can be adjusted with a brass or lead hammer with some care.

Check the drill chuck at the jaws -- if the back is well mounted, this should reflect the error with the chuck machining

Check the point of the drill bit. If the point is not consistent, here is a point you can address with a regrind. (Tormek now has a jig for sharpening drill pits that looks to be close to the precision of a tool grinder -- better than drill doctor in precision).

Note that your drill chuck at the lathe is likely as good or better than the one on drill presses.

 

[jaywood1207]

Make sure you remove the bit often during drilling to clean out the debris. I have had problems in the past that if I don't clean out the debris enough as I go it will cause the blank to start to wobble which will then cause your oversized hole.

 

[LEAP]

Starting the hole with a centering bit then switch to your regular drill bit will solve a lot (but not all) of off center or wobble problems.

 

[DurocShark]

Phil has the right idea.

A shortcut is to hold the quill clamp just loose enough to allow the quill to be cranked out, while SLOWLY cutting into the blank. Once you're in past the grind you can relax the clamp. You'll kill off any wobble if you do this.

 

[Shannon]

What was the solution?