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Posted by Doug White on April 14, 2008, 6:49 pm
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Keywords:
>Ah ha... Relief angle. I did a search and they say the Drill Doctor
>750 has adjustable relief angle. Thanks guys.
I was in Sears over the weekend with time to kill. They had several
models of Drill Doctor on sale at a significant discount. The 500 had
several features I didn't recall from the original model, and they were
sold out of the 750, so I couldn't see what sort of features it had that
would warrant the higher price. It looked like they had added several
adjustments to the 500, which could be good or bad. More stuff to fiddle
with & misalign, but in theory you can fix stuff you don't like.
Doug White
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Posted by Bruce in Bangkok on April 15, 2008, 2:20 am
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On Mon, 14 Apr 2008 22:49:45 GMT, gwhite@alum.mit.edu (Doug White)
wrote:
>Keywords:
>>Ah ha... Relief angle. I did a search and they say the Drill Doctor
>>750 has adjustable relief angle. Thanks guys.
>
>I was in Sears over the weekend with time to kill. They had several
>models of Drill Doctor on sale at a significant discount. The 500 had
>several features I didn't recall from the original model, and they were
>sold out of the 750, so I couldn't see what sort of features it had that
>would warrant the higher price. It looked like they had added several
>adjustments to the 500, which could be good or bad. More stuff to fiddle
>with & misalign, but in theory you can fix stuff you don't like.
>
>Doug White
Just out of curiosity, why not learn to sharpen the drill by hand? I
learned when I was 14 years old and it couldn't have been that complex
if a 14 year old kid with a different type of drilling on his mind
could master it -- sure wish I could have mastered some of those girls
I was thinking about :-)
Bruce-in-Bangkok
(correct email address for reply)
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Posted by on April 15, 2008, 12:38 pm
Please log in for more thread options On Tue, 15 Apr 2008 13:20:45 +0700, Bruce in Bangkok
>On Mon, 14 Apr 2008 22:49:45 GMT, gwhite@alum.mit.edu (Doug White)
>wrote:
>
>>Keywords:
>>In article
>>>Ah ha... Relief angle. I did a search and they say the Drill Doctor
>>>750 has adjustable relief angle. Thanks guys.
>>
>>I was in Sears over the weekend with time to kill. They had several
>>models of Drill Doctor on sale at a significant discount. The 500 had
>>several features I didn't recall from the original model, and they were
>>sold out of the 750, so I couldn't see what sort of features it had that
>>would warrant the higher price. It looked like they had added several
>>adjustments to the 500, which could be good or bad. More stuff to fiddle
>>with & misalign, but in theory you can fix stuff you don't like.
>>
>>Doug White
>
>
>Just out of curiosity, why not learn to sharpen the drill by hand? I
>learned when I was 14 years old and it couldn't have been that complex
>if a 14 year old kid with a different type of drilling on his mind
>could master it -- sure wish I could have mastered some of those girls
>I was thinking about :-)
>Bruce-in-Bangkok
>(correct email address for reply)
It's pretty easy to learn how to hand sharpen a drill
and lots of advice on this has been posted.
BUT this can produce, at best, a drill that cuts well
and produces a hole that is oversize by a variable and
uncontrolled amount.
A drill can only produce its nominal size hole if the
drill point geometry is precisely symmetrical. It's reasonably
easy to come close to with a well designed drill jig but nearly
impossible with a freehand drill grind.
Can you gaze at your freehand sharpened drill point
geometry and be sure that your efforts have produced a point with
asymmetry less than 0.005"
Even this degree of asymmetry will produce a hole of
up to +0.010" on nominal.
Jim
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Posted by James Waldby on April 15, 2008, 3:34 pm
Please log in for more thread options On Tue, 15 Apr 2008 17:38:48 +0100, pentagrid wrote:
...
> It's pretty easy to learn how to hand sharpen a drill
> and lots of advice on this has been posted.
...
> A drill can only produce its nominal size hole if the
> drill point geometry is precisely symmetrical. It's reasonably easy to
> come close to with a well designed drill jig but nearly impossible with
> a freehand drill grind.
>
> Can you gaze at your freehand sharpened drill point
> geometry and be sure that your efforts have produced a point with
> asymmetry less than 0.005"
...
I'm sure the answer to that question is yes. 0.005" is easy to
see by eye. For example, if someone hands you a #11 and a #12
drill bit, about .002" different, you don't have any trouble
telling which is larger, do you?
-jiw
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Posted by Gerald Miller on April 15, 2008, 7:35 pm
Please log in for more thread options On Tue, 15 Apr 2008 13:20:45 +0700, Bruce in Bangkok
>On Mon, 14 Apr 2008 22:49:45 GMT, gwhite@alum.mit.edu (Doug White)
>wrote:
>
>>Keywords:
>>In article
>>>Ah ha... Relief angle. I did a search and they say the Drill Doctor
>>>750 has adjustable relief angle. Thanks guys.
>>
>>I was in Sears over the weekend with time to kill. They had several
>>models of Drill Doctor on sale at a significant discount. The 500 had
>>several features I didn't recall from the original model, and they were
>>sold out of the 750, so I couldn't see what sort of features it had that
>>would warrant the higher price. It looked like they had added several
>>adjustments to the 500, which could be good or bad. More stuff to fiddle
>>with & misalign, but in theory you can fix stuff you don't like.
>>
>>Doug White
>
>
>Just out of curiosity, why not learn to sharpen the drill by hand? I
>learned when I was 14 years old and it couldn't have been that complex
>if a 14 year old kid with a different type of drilling on his mind
>could master it -- sure wish I could have mastered some of those girls
>I was thinking about :-)
>Bruce-in-Bangkok
>(correct email address for reply)
As the high school shop teacher explained " you put the drill over
your left index finger resting on the tool rest and bring it up to
touch the wheel, then you just rock and roll it" (mid '50s)
Gerry :-)}
London, Canada
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>750 has adjustable relief angle. Thanks guys.