problems with colt 7mm pen bit

[sbwertz]

I read here that the Colt bits are supposed to be very good, so I bought the 7 mm bit. I like the long length, but I am having probems with it flexing when I drill blanks. On hardwood, it will flex as it enters the wood. I can actually see it bend to the side as it goes back in the hole after clearing the chips.

Am I doing something wrong? I have been using a 7mm brad point I bought at Woodcraft without this kind of problem. I don't know if it is because of the length of the bit, or if I am running the drill press too fast or too slow, or some other problem.

 

[biednick]

I don't know if this would help, but you might try a center bit to start the hole, then use the colt bit. I might still flex, but I think it would still be on center.

 

[chrisk]

Yes Sharon, the Colt drill bits, while cutting faster and not heating (because of their parabolic shape + 5 cutters on the bit's front), are flexing due to their length, especially the 7mm bits.
That doesn't mean your drilling won't be successful but you have to take care if your blanks aren't that big enough. You could diminish this problem, as the colleague wrote above, that is with a center bit to start the hole. Also, at the starting of the hole with the 7mm Colt drill it's better to go slowly. After a while, it's OK to go faster and exploit all the potential of the Colt drill bits.

Personnally, I found that drilling on the lathe (and always starting the hole with a center bit) helps further and also by using my normal drills for 7mm drilling. Now, I only use Colt drills for the long Clicks (or Clickers for CSUSA) for those blanks are at least 10,5 cm or 4,134" long. But previously I made a lot of holes with my 7mm Colt bit on my drill press.

Hope this helps.

 

[mredburn]

I bought a Colt bit and it was dull right out of the package. I could see light shining off the cutting edge where it wasnt sharpened properly. If your bit is dull it will help to make it flex and wander.

 

[PenMan1]

Sharon:
I use only Colt 5 Star double twists and the Colt 5 Star Pen Makers series bits. With a shorter blank I use the double twist. For longer blanks such as a long click, I use the parabolic PenMakers bit.

As others have stated, a center bit helps negate the flex of the parabolic bit. Additionally, I have found that a shot of PAM cooking spray helps with the tougher woods.

I started using PAM when drilling ebonite, Bakelite and Casein. It worked so well with these materials that I decided to try it on acrylic and then finally wood. It really seems to minimize the flex of the longer Pen Makers bits.

I hope this helps. A slow lathe or DP speed is also not a bad idea.

 

[sbwertz]

Sharon:
I use only Colt 5 Star double twists and the Colt 5 Star Pen Makers series bits. With a shorter blank I use the double twist. For longer blanks such as a long click, I use the parabolic PenMakers bit.

As others have stated, a center bit helps negate the flex of the parabolic bit. Additionally, I have found that a shot of PAM cooking spray helps with the tougher woods.

I started using PAM when drilling ebonite, Bakelite and Casein. It worked so well with these materials that I decided to try it on acrylic and then finally wood. It really seems to minimize the flex of the longer Pen Makers bits.

I hope this helps. A slow lathe or DP speed is also not a bad idea.

Thanks. I'll go back to my standard bit for short blanks and try the Pam for longer blanks.