T18 Can't get a grip ??

[Dick Mahany]

I recently drilled an MFT grid array in MDF with a 20 MM bit but couldn't get the T18 to grip tightly enough on the bit.  The result was occasional spinning / scoring on the shank and bluing at the shank end.  I wiped the new bit with acetone to remove any machining oils prior to chucking, but still got the following results.  I wasn't overfeeding the bit and was surprised at what weak hold it seemed to have.

Is that bit more than the T18 keyless chuck can handle ?  I tried to grip and tighten it more, but couldn't get a better grip.  Am I expecting too much from this drill?  Frankly I expected more.

[attachimg=1][attachimg=2][attachimg=3]

 

[ear3]

Interesting.  I've run larger forstner bits on my T18 with the keyless chuck and never had a problem with them slipping.  And with the PDC, which uses the same chuck I believe, I've run forstner bits >2" and never had an issue except for an occasional beep overload when I came in with too angled an attack.  Have you tested any other bit of comparable size to see if the problem repeats?

 

[mrboult]

No never had any issues with the chuck you have there. I have two right now and others in the past. The original T18 had a woefully weak/crap chuck, but I've never had issues with the new ones used on all current 18v drills

 

[RKA]

It’s possible you’ve already damaged the jaws in that chuck, but I would try cleaning them with a Q tip and solvent in addition to the shanks.  Don’t drop solvent inside the rest of the Chuck, just the jaw faces.

The second issue is that drill guide you are using.  Are you lubricating it?  Are you sure that isn’t binding the bit? (Undersized or feeding at an angle)

 

[Jiggy Joiner]

I buy any larger diameter bits with the triangular shanks, which eliminates any slip.
I would expect that drill/chuck to handle your bit going into wood or MDF though.

 

[AlexThePalex]

Never had a problem with this chuck. As said, the older chuck before this one was crap, but this one is just fine. You do have to make sure you tighten it thoroughly and hear it click when the sleeve locks in place.

 

[Dick Mahany]

Thank you all for the input and good suggestions.  I'm glad to hear that this shouldn't be happening and that the chuck design is good.  So it's either my technique or possibly a problem with this particular chuck.  I have run much larger Forstner bits however they all have hex shanks so I really can't compare. The guide that I used is an excellent fit for the bit and shows no signs of having bound up on the drill bit. I'll take a look at the chuck jaws and do a light clean as suggested.

 

[Euclid]

Isn't the answer to the slippage problem a Centrotec ('Zobo') forstner bit?

I've always found one of the most attractive features of Centrotec is that the chuck doesn't have to grip or drive the bit, but merely stop it from falling out of the drill.

(Having said that, the 'guide bushing' used in Dick's particular application is perhaps more suited to a regular 'fluted' bit.)

 

[six-point socket II]

What is the diameter of the shaft on that drill bit?

Kind regards,
Oliver

Edit: added "is".

 

[RKA]

What the diameter of the shaft on that drill bit?

Kind regards,
Oliver

Great observation!  That case and label looks a lot like my lee valley BP bits, but their 20mm indicates a 10mm shank and this picture appears to be closer to 15mm.  I think you might have hit the drill bit on the head Oliver. 

 

[Dick Mahany]

What is the diameter of the shaft on that drill bit?

Kind regards,
Oliver

The shaft diameter = 12.7mm so I think it should be within the acceptable limits ? 

Edit: Both the drill bit and guide bushing are from Lee Valley and appear to be very well made.

 

[RKA]

Rats, I thought Oliver was on to something.  13mm is the max for that chuck, so it should take a 1/2" shank bit.  If you retract the jaws all the way and look inside the check, do you see anything unusual that might interfere with the ability of the jaws to tighten down?  As you close the chuck so the jaws move forward, do each of the jaws move smoothly without any sticking?

 

[six-point socket II]

If I may say so, I still think I'm onto something.  [scared] [eek] [big grin]  [wink] [wink]

I honestly don't doubt the quality of the drill bit. But 12,7mm that's a thick shank - even for a chuck with 13mm spec. I think it was a contributing factor. As is the drill bit itself by design. It also looks like the bit was seated in a very forward position. Seeing the dust extractor I know why - but it's also not optimal and another contributing factor, imho.

I've had the exact same happening with the keyless chuck on one of my Bosch machines, now gone (Not because of this, obviously.).

Give the chuck another chance, by seating the drill bit deeper. That might help a lot.

I'd also give that chuck a throughout inspection, I doubt it suffered any damage, but it's always good to make sure.

Kind regards,
Oliver

 

[Dick Mahany]

If I may say so, I still think I'm onto something.  [scared] [eek] [big grin]  [wink] [wink]

I honestly don't doubt the quality of the drill bit. But 12,7mm that's a thick shank - even for a chuck with 13mm spec. I think it was a contributing factor. As is the drill bit itself by design. It also looks like the bit was seated in a very forward position. Seeing the dust extractor I know why - but it's also not optimal and another contributing factor, imho.

I've had the exact same happening with the keyless chuck on one of my Bosch machines, now gone (Not because of this, obviously.).

Give the chuck another chance, by seating the drill bit deeper. That might help a lot.

I'd also give that chuck a throughout inspection, I doubt it suffered any damage, but it's always good to make sure.

Kind regards,
Oliver

Thank you Oliver.  I initially had the drill bit fully seated in the chuck.  The dust collector was large enough that the chuck could actually pass through the black brushes. 

I'm thinking your observation may be a good one because when the drill bit first spun in the chuck, I believe I simply tightened the chuck more without checking to see if the drill bit was fully seated.  It did that several times over in the course of drilling the array and I may never have fully reseated the bit during those subsequent spins.

As soon as I have some time, I'll inspect and clean the chuck and I also have an ER32 20mm collet for my wood lathe so I can try and lightly clean up the drill shaft.

Many thanks for your insight.

 

[RKA]

[member=61712]six-point socket II[/member]
[not worthy]

[big grin]

 

[Sino]

Also when you tighten the chuck and hear clicking and cannot go further then go backwards one click. This is position where chuck is locked then.