Drill Bits

[rf33]

For cutting steel, I find that using oil, very low RPMs and alot of pressure (I want to basically see one peel of metal, not dust coming off the bit) cuts best and leaves the drill bits in much better shape than if I smoke the heck out of them by running them at a zillion RPMs. This is not based on anything scientific, but just practical experience. I have not conducted any MChakley style comparisons (Few of us seem to have his dedication to trying to get to the unbiased truth), but it seems to work best to me.

rf33

/w3tcompact/icons/wink.gif

 

[Egon]

Drill technique:
I agree with rf33. The object is to keep the temperature as low as posible and the lubrication as high as possible.
Egon

 

[TonyC]

I guess it's always a crap shoot when buying low cost foreign tools. Some are a pleasant surprise and some are not. I guess I'll roll the dice! A follow up question to your reply...what is the deal with the lettered drill bits? I never really understood what they are for.

 

[TonyC]

I guess drilling smaller holes first is something I've always known but I appreciate the reminder. In my constant state of impatience it's something I don't always think about. Maybe I should put a "post it" reminder on my drill index! Thanks.

 

[Harv]

<font color=blue>what is the deal with the lettered drill bits? </font color=blue>

Indexed drill sets just make it easy to find the bit that you're looking for. I have two different sets -- the numeric set goes from #1 to #60 (pretty small stuff), and a fractional set which goes from 1/16" to 1/2" in 1/64" increments. Don't have the letter set, but that would go from A to Z and cover many of the fine increments between the fractional sizes.

The index itself is a great way to keep the bits where they are easy to find. You don't have read a number stamped on the side of the bit (not easy on the tiny ones), you just have to find the correct position in the index which is clearly labelled and easier to read (i.e. 25 as opposed to 0.1495).

A must-have, I believe, is an index chart like the one I keep on the wall next to my machinist's lathe. It tells you at a glance which indexed bit you need for a given clearance or tap hole. /w3tcompact/icons/cool.gif

 

[therrien]

These are sheets I have used for years.
I hope they help someone out.I've never
posted an attachment so here goes?

Doug T B1700 TLB

 

[therrien]

I'm going to try once more,If it doesnot work
I give up.

Doug T B1700 TLB

 

[therrien]

It worked! here is the 2nd one.

Doug T B1700 TLB

 

[HR_Mutt]

You might also want to get a drill point gauge. Keeping the bits sharp is a must! If you have not used one before, check your new drills with it, especially noting how the clearance is ground and how both cutting edges are equal.
regards
Mutt

 

[Harv]

Doug -

Yup! That's the kind of chart I'm talking about. /w3tcompact/icons/smile.gif

Just for the heck of it, I've attached a snapshot of my wall poster chart. I'm not saying I've had it for a while, but take a look at the phone number at the top of the poster. /w3tcompact/icons/laugh.gif