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I was just drilling using a Kreg step-drill bit. My goal was to have pocket holes centered precisely in the middle of some triangular pieces of plywood to act as the supports for some simple shelves-- after screws the holes will get plugged with pieces of dowel, but there will still be something visible, thus my desire for being precisely centered.

Didn't happen-- can't happen-- there is play in one of the bearings in the quill (I guess), so the little bit of play there means that 6 inches away at the tip of the drill bit there is like --3/16"-- 3/64" of play.

That's not the end of the world for the shelves, they'll still function well, but now I realize I've got a full headstock rebuild needed, or at least replace all the bearings which I guess is the same thing...

PS to admins-- enabling strike through would be nice.

freedomlives wrote:I was just drilling using a Kreg step-drill bit. My goal was to have pocket holes centered precisely in the middle of some triangular pieces of plywood to act as the supports for some simple shelves-- after screws the holes will get plugged with pieces of dowel, but there will still be something visible, thus my desire for being precisely centered.

Didn't happen-- can't happen-- there is play in one of the bearings in the quill (I guess), so the little bit of play there means that 6 inches away at the tip of the drill bit there is like 3/16" of play.

That's not the end of the world for the shelves, they'll still function well, but now I realize I've got a full headstock rebuild needed, or at least replace all the bearings which I guess is the same thing...

A 3/16" lateral movement at the tip of the bit is excessive but may be the result of nothing more that worn quill bearings.

If the quill bearings are that bad, it seems to me that you would also have excessive runout on the saw blade.

But, before we get too deep into "fixing" this - I must ask! Are you securing all of the locks before you do any drilling or cutting.

Locks = headstock, table height, table tilt, quill, and carriage.

dusty wrote:A 3/16" lateral movement at the tip of the bit is excessive but may be the result of nothing more that worn quill bearings.

If the quill bearings are that bad, it seems to me that you would also have excessive runout on the saw blade.

But, before we get too deep into "fixing" this - I must ask! Are you securing all of the locks before you do any drilling or cutting.

Locks = headstock, table height, table tilt, quill, and carriage.

Are you sure the drill is straight?

If the bearing(s) is/are that bad there should be visible side play of the shaft.

3/16" is quite excessive at 6" for the quill bearings alone to be causing that unless the shaft is also bent.

Maybe it is time for a double bearing quill 'upgrade'.

dusty wrote:A 3/16" lateral movement at the tip of the bit is excessive but may be the result of nothing more that worn quill bearings.

If the quill bearings are that bad, it seems to me that you would also have excessive runout on the saw blade.

But, before we get too deep into "fixing" this - I must ask! Are you securing all of the locks before you do any drilling or cutting.

Locks = headstock, table height, table tilt, quill, and carriage.

OK, I better stop trying to guess distances. I measured now... the tip of the drill bit is 5" from the mouth of the chuck, and the movement side-to-side at that distance is a bit more than 1mm, or 3/64".

Its quite visible when trying to center a 10mm hole in the 19mm edge of a piece of plywood, especially since the edge of plywood shows the plys. Given how the drill tends to move and because of how I was flipping around the piece to drill a symmetrical hole, the difference between the centers of the two holes ends up as 2mm.

All of the locks except for the quill are secured-- how can I drill if the quill can't move?

You can't drill if the quill is locked, but I think that your comment was tongue in cheek. Is the movement in the quill or the quill housing? The housing is the cylinder that moves in and out of the headstock. If the play is at that part it would be a difficult fix. If it is between the actual quill (the part that rotates ) in relation to the housing then the bearing/s may be bad. Also a bent quill (not uncommon) may be the fault. A bad bearing in the single bearing quill may also cause excess wear of the nylon drive sleeve on the splined end of the quill. A two bearing quill would help.
Bill V

freedomlives wrote:OK, I better stop trying to guess distances. I measured now... the tip of the drill bit is 5" from the mouth of the chuck, and the movement side-to-side at that distance is a bit more than 1mm, or 3/64".

Its quite visible when trying to center a 10mm hole in the 19mm edge of a piece of plywood, especially since the edge of plywood shows the plys. Given how the drill tends to move and because of how I was flipping around the piece to drill a symmetrical hole, the difference between the centers of the two holes ends up as 2mm.

All of the locks except for the quill are secured-- how can I drill if the quill can't move?

You can't but I guess you already know that. But, you can check runout (even with the quill locked when extended).

freedomlives wrote:OK, I better stop trying to guess distances. I measured now... the tip of the drill bit is 5" from the mouth of the chuck, and the movement side-to-side at that distance is a bit more than 1mm, or 3/64".

Its quite visible when trying to center a 10mm hole in the 19mm edge of a piece of plywood, especially since the edge of plywood shows the plys. Given how the drill tends to move and because of how I was flipping around the piece to drill a symmetrical hole, the difference between the centers of the two holes ends up as 2mm.

All of the locks except for the quill are secured-- how can I drill if the quill can't move?

Let's see: 19mm is about 3/4", 10mm is about 3/8", plywood consists of grain oriented layers at 90 degrees to each other.

So we be trying to drill a 'centered' hole in 3/4" plywood with a 3/8" od in a substance with wildly varying grain across the diameter of the hole(in horizontal boring mode I hope!).

I would think that is an excellant way to 'discover' runout/end play etc.

I would not attempt that in one pass let alone a step drill!

I would sneak up on the od with progressively larger twist bits of the variety normally used on metal. That 'end' grain(more likely you are drilling at an angle to the grain of all layers is difficult to drill straight. The bit will wander, but by sneaking up on the larger od 'may' help. That ability to 'wander' may help 'recenter' a previous off center hole.

Truth be told, I would not likely try this at all. A router bit will be more cooperative, but the plywood adhesive would dull it quickly.

Not sure the plywood/hole would endure the stress of the shelf weight.

I think I would be inclined to use 'solid' wood cleats glued to the plywood and drill 'straight'(90°) holes in them.

How sure are you that the problem is not in the chuck jaws?

I'm certain it isn't the chuck.

Serial number: 14931
Vandalia, Ohio

So unless an upgrade was done it didn't come from the factory with the two bearing quill. Is it possible to tell just by removing the belt cover and/or access hole, or is major complete dissasembly required?

It's doubtful someone else did the upgrade but who knows?

Unless someone else knows a trick to see if it's a 2 bearing, I think you will have to slide the quill out of the front of the headstock. If you are only replacing quill bearing(s) you don't have to tear the headstock apart that much.

Another thought, the plastic coupler where the rear of the quill mates with the drive assembly may be worn. On the single bearing quills, that's the only thing holding the rear of the quill shaft.