Problems with Colt Pen Drill Bits

[dbarbee]

A few weeks ago as part of my initial pen turning tool purchase I bought a Colt 7mm pen making drill bit. I soon noticed that the hole in thewooden pen blanks seemed to be distorted at the entry point and the were not running true though the blank. After careful observation I noticed that the bit was wandering when starting the drill bit in the blank. This would cause the bit to flex and make the top of the hole a bit oval. I thought maybe if I center punched the blank it may do better. The bit still seemed to wander. I switched to the 7mm brad point bit that come with my mandrel and it drills straight through the blank with no problems. The colt bit does however seem to drill though acrylic blanks with out any major issues. Am I missing something?

My drill press table and homemade blank holding jig are holding the blanks in perfect alignment with the bit. I'm not drilling though any type of exotic materials...walnut, cherry, oak, and elm. As the bit touches the wood I'm advancing very slowly. The bit doesn't appear to be bent but definitely flexes during the cut. I just can't think of anything else I can do to keep the bit from wandering on me...Suggestions?


David

 

[mredburn]

If the bit is dull on one side at the tip it will pulll to one side. If it was dropped on the tip it may be dull right at the point itself. My first thought would be to examine the tip of the bit. If you can see light reflecting back off the cutting edge it is dull in that spot.

 

[wizard]

I had the same problem. It is a problem with the bit tip?. The folks at Woodcraft knew about it and gave me another brad point bit which does great. I had the same problem with an entire set of Colt bits ($100) and the folks at Woodcraft took it back and sent it to the manufacturer along with the blank I tried to drill. Their larger bits seem to do better. I've started using a different brand. Doc

 

[renowb]

I had the same problem with the more expensive bits from PSI. It really vibrated when I drilled. It seems the ones with the sharp twisted flutes do this. I use the regular brad point bits. I don't like them expensive ones. Expensive is not always better.

 

[weiner9696]

I use the 7mm bits from wood n whimsies and have had no problems with wandering.

Try them.

George

 

[renowb]

On the other hand, the Gorilla Grind bits from PSI are awesome.

I had the same problem with the more expensive bits from PSI. It really vibrated when I drilled. It seems the ones with the sharp twisted flutes do this. I use the regular brad point bits. I don't like them expensive ones. Expensive is not always better.

 

[mredburn]

One other thing that is food for thought. When I was researching drill chucks for my lathe I found that run out for different chucks was as low as .004 but those were the expensive chucks. The chuck companies make a lot of cheaper chucks with a large amount of slop in them.

 

[keithkarl2007]

Boy I'm glad this came up. I was just about to look up a few of them for the kits i use. I don't know what brand of brad drill bits i use at the moment but they drill really well.

 

[Chasper]

I tried a few Colt bits, after a few crooked holes they found their way to the trash.

 

[dbarbee]

This was a brand new bit, not dropped or abused. Personally, I think these bits have two main issues...

1) There isn't really a center spur. It has two small spurs in the middle. I think this is causing the bits to skate.
2) The parabolic flute design in such a long bit lends itself to bending very easily.

If it were slop in my drill press it would be the same for my other bits. This is the only bit I'm having trouble with.

I may try the gorilla bits next time or even the HSS brad points from Lee Valley.

David

 

[Lenny]

2) The parabolic flute design in such a long bit lends itself to bending very easily.

David

That's the problem I have with them. Why do they make them sooo long. :frown:

I'm setting mine on thw shelf and sticking with my original brad point.