Ragged pocket holes

[Jerry OBrien]

I have the K4 pocket hole jig. When I use it the right side of the hole is always ragged. It is not a big problem- just aggravating. Anyone got an answer.

[Ken Darga]

Chip,

What kind of "social dancing" were you doing?

Could you take another pic without waving your arms?

Chip Atchison said:

Here's a blurry pic of the bottom of my pocket hole jig with the ridges in the plastic holes.

[Chip Atchison]

Hi Ken,

I was doing the '60s twist:)

I've uploaded 3 more pics with slightly better quality, but it's the best my smart phone can do at close range. 

I hope you can see the ridges in the plastic holes.

Thanks,

Chip

[Ken Darga]

Chris,

The slightly visible ridges, are in the area leading into the hole in the sleeve.

Is that what you're referring to?

Perhaps the sleeves are incorrectly molded into the plastic housing.

The drill bit shouldn't touch the plastic housing during the drilling operation.

I have several jigs---the drill guide bushing (sleeve) is adequately positioned so the drill bit flutes do not come in contact with the plastic housing, during the drilling operation.

If a 1/4" dia bit is used, in the sleeve intended for a 3/8" bit, then the drill bit flutes could rub on the plastic housing.

Insert the drill bit and rotate it by hand, and see it you get any wobble.

Lemme know.

[Chip Atchison]

Hi Chris,

Yes, I was referring to the ridges. The drill bits don't have any wobble in the metal sleeve and don't appear to touch the plastic either. However, the metal sleeve fit tightly around the Kreg supplied drill bit the 1st few times I used it. Also, I bought a second Kreg drill bit and there's no wobble, fit is smooth, it doesn't appear to touch the plastic sleeves but the holes are still ragged.

Got any advice or tips?

Thanks,

Chip

[Chip Atchison]

Yes, that does work a bit. Just wondered why the holes get so ragged in the 1st place. 

Thanks and best wishes,

Chip

[Chip Atchison]

Any ideas?

[Ken Darga]

Re: CHIP-OUT

Drilled many pocket holes yesterday, in red oak, 

using a NEW drill bit.

Holes were drilled "perpendicular" to the grain direction.

“Chip-out” occurred on the 'LEFT-SIDE" of the hole ONLY,

where the drill bit flute cuts in an 'UPWARD" direction.

(akin to using an UP-CUT spiral bit in a router).

The "up-cutting" causes the wood fibers to tear out.

This phenomenon is more noticeable since the drill bit is slanted during the drilling operation.

On the right-side of the drilled hole, the drill-bit flutes are cutting in a downward direction, the hole was clean---no noticeable “tear-out”.

Sucks, don't it, when one wants a clean looking drilled hole.

Perhaps just something we have to deal with, and put all the pocket holes on the "inside" of the project piece.

The next batch of holes I drill, I'm going to spray the drill bit flutes with "Dri-Lube", and check the results.

[Chip Atchison]

Thanks Ken,

That's an very interesting experiment. Good luck and please keep me posted!!

[Ken Darga]

Chip,

Thanks for your timely reply.

It was an "observation", of my results,

drilling pocket holes, using the Foreman Pocket Hole machine.

 

The "up-cutting" action of the spiral fluted drill bit, on the left side of the hole, is the reason for the tear-out.

That’s just the nature of this type of spiral drill bit, when drilling in soft materials, such as wood.

 

Is a spiral needed the long length on the drill bit???

Yes---it suffices to carry the chips out of the drilled hole.

 

Perhaps a "pause & go" action in short bursts, while drilling, will help relieve some of the problem.

(It'll result in a slower process, of drilling the pocket holes.  It's mentioned in Kregs drilling instructions).

 

I'll do some testing, in the near future, and report my findings.

 

In many cases, chip-out may not be of concern with some materials on some project pieces;

such as with some soft woods, and building items from 2x stock. 

 

Perhaps Kreg could look into this matter and come up with a solution to prevent/minimize  "chip-out".

An alternate fluted design ???

• “FAST” spiral bits ? (Smaller/closer flute spacing?    

(Standard drill bits are “CONVENTIONAL” (SLOWER) spirals, resulting in faster chip removal).

•  Auger style ?
• Spiral style wood bit ?
• Drill saw style bit, with a shoulder & pilot, (vs the point as shown)

Chip Atchison said:

Thanks Ken,

That's an very interesting experiment. Good luck and please keep me posted!!

[Ken Darga]

Upon review of videos, drilling pocket holes with the Foreman machine, 

I noticed that the drilling function is shown using a "continuous" motion---

there's NO pausing.

A SLOW steady motion, is shown in the KREG video.

[Chip Atchison]

OK, I'll try that sometime this weekend!

Thanks Ken,

[Ken Darga]

Chip,

While drilling a pocket hole---

allow the drill to get to full rpm speed.

Insert drill bit and drill-out the hole a short distance---

keep the drill running full rpm and pull-back the drill allowing the shavings to exit the guide block, without removing the drill bit from the guide block---

reinsert and drill deeper into the hole---

pull back the drill a short distance, allowing the bit to remove the shavings.

Repeat this 3 times in each hole, until the pocket hole is drilled out.

Don't apply excessive pressure while drilling---let the drill bit do the work.

(I drilled several holes in softwood, and they appeared to come out cleaner---less visible chip-out).