Where to buy small metric counterbores
 

I am looking for small metric counterbores 3mm and smaller, MSC and McMaster
only have 3mm and bigger. I can get custom made counterbore made to spec.
but they cost too much, and min. qty.of 6 each. per size.

Thanks in advance for your help, Jack

Where to buy small metric counterbores
 

On Aug 29, 8:16*am, "Jack Lai" wrote:
I am looking for small metric counterbores 3mm and smaller, MSC and McMaster
only have 3mm and bigger. I can get custom made counterbore made to spec.
but they cost too much, and min. qty.of *6 each. per size.

Thanks in advance for your help, Jack

Are you aware you can grind any drill bit, including Metric, flat on
the tip and use it for counterboring? First, start the hole with a
normal drill bit of the size you need, and then finish it with the
flat bottom drill.

I learned this when I bought a set of letter drills at a machine shop
auction and they were all ground flat on the bottom. Work like a charm
for counter boring.

Paul

Where to buy small metric counterbores
 

Where to buy small metric counterbores
 

Bob Engelhardt wrote:

wrote:
Are you aware you can grind any drill bit, including Metric, flat on
the tip and use it for counterboring? ...

Without a pilot? It doesn't wander? If not, why not?


"Paul wrote:

Are you aware you can grind any drill bit, including Metric, flat on
the tip and use it for counterboring? First, start the hole with a
normal drill bit of the size you need, and then finish it with the
flat bottom drill."

The drilled hole using a conventional hole is the pilot. The flat ground one guides on
the previous drilled hole and takes out the drill cusp.

Wes

Where to buy small metric counterbores
 

Wes wrote:
The drilled hole using a conventional hole is the pilot. The flat ground one guides on
the previous drilled hole and takes out the drill cusp.

That's just flattening the bottom of a blind hole, that's not
counterboring - where the counterbore is larger than the drill hole. Or
maybe that's called counterboring, too, even though it's a very special
case.

Bob

Where to buy small metric counterbores
 

On 8/29/2010 4:12 PM, Bob Engelhardt wrote:
Wes wrote:
The drilled hole using a conventional hole is the pilot. The flat
ground one guides on
the previous drilled hole and takes out the drill cusp.

That's just flattening the bottom of a blind hole, that's not
counterboring - where the counterbore is larger than the drill hole. Or
maybe that's called counterboring, too, even though it's a very special
case.

If the result is a hole with the position, dimensions, profile, and
finish that you want it doesn't really matter how you got there.

Where to buy small metric counterbores
 

On Sun, 29 Aug 2010 10:16:38 -0500, "Jack Lai"
wrote:

I am looking for small metric counterbores 3mm and smaller, MSC and McMaster
only have 3mm and bigger. I can get custom made counterbore made to spec.
but they cost too much, and min. qty.of 6 each. per size.

Thanks in advance for your help, Jack

=========
try
http://mdmetric.com/
http://www.pts-tools.com/cgi/CGPTSRI...=01_08_001_004

-- Unka George (George McDuffee)
...............................
The past is a foreign country;
they do things differently there.
L. P. Hartley (1895-1972), British author.
The Go-Between, Prologue (1953).

Where to buy small metric counterbores
 

Bob Engelhardt wrote in
:

Wes wrote:
The drilled hole using a conventional hole is the pilot. The flat
ground one guides on the previous drilled hole and takes out the
drill cusp.

That's just flattening the bottom of a blind hole, that's not
counterboring - where the counterbore is larger than the drill hole.
Or maybe that's called counterboring, too, even though it's a very
special case.

Bob

I think you missed a part of the process involving different size
drills....

Drill the shank hole for fastener, through, blind, tapped, whatever.
Switch to a normal drill of a larger size to clear the head of the
fastener. Drill on the same location to the required 'counterbore' depth.
Then switch to a modified drill with a flatted end to clean the corners of
the counterbore and leave a square shoulder in the hole.

Where to buy small metric counterbores
 

Charles U Farley wrote:
I think you missed a part of the process involving different size
drills....

Yes, I did. Well, Paul said "... start the hole ...", where he meant
"... start the counterbore ...". But I did have a failure of
imagination that would have filled it in.

Thanks,
Bob

Where to buy small metric counterbores
 

On Aug 29, 3:08*pm, Bob Engelhardt wrote:
Charles U Farley wrote:
I think you missed a part of the process involving different size
drills....

Yes, I did. *Well, Paul said "... start the hole ...", where he meant
"... start the counterbore ...". *But I did have a failure of
imagination that would have filled it in.

Thanks,
Bob

Sorry, I kinda got in a hurry to get the job done and didn't explain
each step very well. Easier done than said, I guess.

Pual