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Metal/Drill bit question...

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KBeitz

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#1
I have three shops at my home. weld shop... Machine shop... and a woodworking shop.
I like to have a full set of tools in each shop. I was making up a set of drill bits for my
wood shop and I was missing a needed 1" bit. So off to our local surplus supply store
I go... I found a 1" bit but the shank was 1" all the way. No step down. My drill press chuck
is only 1/2" . So I said no problem. I'll just turn it down. Right... It took me 1-1/2 hours
to turn down the shank to 1/2" Very very hard. The shavings look and feel like a Brillo
pad. Could this be a solid carbide drill bit? I've machined a lot of steel in my days but
nothing as hard as this.

DSC08541.JPG DSC08542.JPG DSC08543.JPG
 

T Bredehoft

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#2
You couln't have turned a carbide shaft. period. Its ground, only. Your bit is hard steel. nice job, BTW.
 

MrWhoopee

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#3
Definitely not carbide, but not a soft shank welded on either. You got one of the good ones, but it may have a tendency to slip, being that hard. You might consider putting 3 flats on it for better grip.
 

KBeitz

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#4
So... There is no way to turn carbide ? I have turned the shanks of many drills that I thought
was hard but this bit I needed to sharpen my cermets about 20 times to get this one job done.
It would only take a very small curl off no matter how hard I would push the cutter. I was using
a diamond stone to sharpen my cermets . A few time I could not get it to cut at all. I would resharpen
over and over until it would cut again. I tried different angles, speeds and feeds. Nothing seemed
to help. My carbide cutters would not touch it. If not carbide what might it be?
 

derf

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#7
I would not use a twist drill that big for wood, a Forstner bit would do a better job, without binding up and tearing out.
 

P. Waller

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#8
What do you mean when you say cermet?
If you can grind them it is an insert material that I have never used, from the picture it appears to be a common sintered carbide insert.
 

KBeitz

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#9
When I bought them i was told they was used cermet inserts.
A magnet will not stick to them. A diamond stone is the only thing
I found the will put an edge back on them. i have a few hundred
of them. Enough so I will never need to buy any other cutters.
It seem like only one side of one point on each insert was ever
used. I can flip the insert so I have 6 points to work with. I use
them until they break before I go to the next. I make my own
tool holders to fit the inserts.
 

Bob Korves

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#10
Your drill is probably high speed steel. It is quite difficult to machine other than grinding if it is at or near full hardness.
 

benmychree

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#11
So... There is no way to turn carbide ? I have turned the shanks of many drills that I thought
was hard but this bit I needed to sharpen my cermets about 20 times to get this one job done.
It would only take a very small curl off no matter how hard I would push the cutter. I was using
a diamond stone to sharpen my cermets . A few time I could not get it to cut at all. I would resharpen
over and over until it would cut again. I tried different angles, speeds and feeds. Nothing seemed
to help. My carbide cutters would not touch it. If not carbide what might it be?
You were cutting HSS. The suggestion to grind 3 flats is a good one.
 

ELHEAD

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#12
I would not use a twist drill that big for wood, a Forstner bit would do a better job, without binding up and tearing out.
Or re-grind to a brad point type drill. Think wood cutting auger bit.
Dave
 

Janderso

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#13
A lesser quality bit would not have been that hard at the shank. I agree, you have a good one there.
I would not have spent the time. You have the patience of Job.
Nice work!
 

KBeitz

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#14
Thanks for all the reply's an help. The bit might not get used for wood but I
wanted a full set for in the wood shop... Thanks again...
 

dlane

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#15
Don’t get a set like these, but I bet they turn down easy. 7F6A34B9-5C19-44F2-A6FB-093B15EB633D.jpeg
 

mmcmdl

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#16
Got some of those in at work ! :grin:
 

Janderso

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#17
I bought a set of Rushmore 118 jobber size from McMaster last week. 1/8 to 1/2” in 64” increments.
They had TTC for about 30% less, I chose American made.
No more will I spend money on cheap drill bits.
 
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