Hymnorq 1/4 Inch Fractional Size M35 Cobalt Steel Twist Drill Bit Set of 10pcs, Jobber Length and Straight Shank, Extremely Heat Resistant, Suitable for Drilling in Stainless Steel and Iron

This set of 10 twist drill bits from Hymnorq is made from M35 cobalt steel, which makes them extremely heat resistant and suitable for drilling in stainless steel and iron. The bits have a jobber length and a straight shank, and they are available in a range of fractional sizes from 1/16 inch to 1/2 inch.

Here are some of the features and benefits of these drill bits:

  • Made from M35 cobalt steel for extreme heat resistance

Hymnorq 1/4 Inch Fractional Size M35 Cobalt Steel Twist Drill Bit Set of 10pcs, Jobber Length and Straight Shank, Extremely Heat Resistant, Suitable for Drilling in Stainless Steel and Iron

This set of 10 twist drill bits from Hymnorq is made from M35 cobalt steel, which makes them extremely heat resistant and suitable for drilling in stainless steel and iron. The bits have a jobber length and a straight shank, and they are available in a range of fractional sizes from 1/16 inch to 1/2 inch.

Here are some of the features and benefits of these drill bits:

  • Made from M35 cobalt steel for extreme heat resistance
1
by Migiwata Tools
Tips for Drilling Holes in Metal
By placing an order of cobalt drill bits, its most likely that you’ll have to drill a
hole through a piece of metal.
Here are some tips to make the task fast, easy and safe.
Protect Your Eyes
It only takes one tiny metal fragment to cause a serious eye injury, so proper
eye protection when drilling metal is an absolute must. For the best protection,
choose safety glasses that wrap around the sides of your face.
Make a Dimple
Generally speaking, drill bits have a tendency to wander when you first start
drilling. To prevent this, measure and mark where you want the hole and then
use a center punch and hammer to create a small dimple. This gives the tip of
your drill bit a place to ride in as you begin to drill.
Although our products are advertised to be self-centering and anti-wandering,
its still suggested you do the dimple if you use a hand drill.
Lubricated Bits Last Longer
For drilling holes in steel thats 1/8 inch or thicker, use cutting fluid,
multipurpose oil like 3-IN-ONE or cool water. Lubricating the bit reduces
friction and heat buildup, which makes drilling easier and your bits last longer.
For easier-to-drill metals like aluminum, brass or cast iron, lubrication isn’t
usually necessary.
Clamps Prevent Stitches
Never hold a piece of metal in one hand while trying to drill through it with the
other. The drill bit for metal could catch, instantly causing the workpiece to spin,
strike and slash (sharp metal edges slice to the bone!). Always use a minimum
of two clamps to securely hold down your workpiece.
Start with a Small Hole
Need a big hole? Start small! Most twist bits are available in sizes up to 1 in. in
diameter, but you’ll get the best results by starting with a 1/4-in. hole and
drilling successively larger holes with your drill bit for metal until you reach the
size you want.
2
by Migiwata Tools
Drill at a Slow Speed
The faster a bit spins, the hotter it gets. And heat dulls bits quickly. In general,
it’s a good idea to drill through metal using as slow a speed as possible using a
drill bit for metal. Hard metals like steel and larger drill bits require even slower
speeds. High speed drilling will often just overheat the drill bit and the metal,
without actually doing anything. Please refer to the RMP chart for common
metals at the end.
High Pressure
Regarding technique, the trick for drilling hard metals is to, beside drill with a slow
speed, put high pressure on the drill. The goal is to get the drill to "bite" the metal,
cutting of shavings. A drill press will be very useful here (if you can get access to
one).
Make a Sandwich
For clean, precise holes in thin sheet metal, make a wood sandwich. Simply
sandwich the sheet metal between two pieces of wood and clamp everything
down on a table or workbench. The wooden ‘bread layers of the sandwich
keep the sheet metal flat and prevent the drill bit from wandering as it bores
through the sheet metal.
Step Up to a Drill Press
While it’s fairly easy to drill most holes in metal using nothing more than a
handheld drill, you’ll almost always get greater accuracy and better results
using a drill press. Most drill presses are actually built with metalworking in
mind. Pulling down on the handle causes the bit to plunge straight down into a
workpiece and make a very precise hole.
Drill presses also come with beefy cast-iron tables with tilt and height
adjustments, and allow a variety of clamping options. Speed changes are as
easy as opening the lid and moving a rubber belt from one pulley to another.
The most expensive drill presses are floor-standing models, but you can buy a
decent benchtop unit for about $100.
Disable the percussion function
Percussion is used for masonry work, and will only damage the drill bit and work
when drilling metal.
3
by Migiwata Tools
Drilling Through Metal Problems and Solutions
Below we have listed some very common problems that people discover when
they drill through metal. I have provided what the problem is likely to be and
how to resolve that.
Problem - The drill bit breaks.
Possible Cause and Solution - This is the most common problem, especially
for small bits. M35 cobalt drill bits are composed of 95% high speed steel and
5% cobalt. While the 5% cobalt makes the bits much more durable as well as
giving them an abrasive quality that helps it to cut through hard materials
repeatedly, it also makes the drill bits more brittle than ordinary HSS drill bits.
The cause of breaking could be shaking, tilted bit, and unsteady workpiece.
Please watch out for snapping of the bit on the exit hole, never angle the drill
while drilling and use a drill press.
Problem - The drill bit cant penetrate the workpiece.
Possible Cause and Solution - The material of workpiece could be too hard
for the drill bit. M35 cobalt drill bit is suitable for metals less than HRC 38
degree, not suitable for hardened steel, heat treated steel, high carbon steel
and steel blended with unknown impurities. Youll need to use carbide bits to
drill these hard metals.
High speed drilling will often overheat both the drill bit and the metal. The
overheated workpiece becomes much harder and cant be drilled by the same bit.
The solution is to slow the RPM and try a different drilling spot.
Another possible cause is that the drilling device isnt powerful enough. Then
you need to change the drill.
Problem - The drill bit is making a high pitched squealing noise.
Possible Cause and Solution - Most likely the drill bit is running too fast. You
can either slow down the speed, or if you don't have a variable speed, drill in
short bursts, leaving time in between each drilling session
Problem - The drill bit becomes very hot or even fries/melts.
4
by Migiwata Tools
Possible Cause and Solution - This can be caused by one of two things. Like
the problem above the drill bit is going too fast. If that is the case, then the
same solution as shown above will help solve that problem.
Secondly the drill bit may require some lubrication. You can buy spray tins of
drilling and cutting oil to help resolve this problem. You can also use water to
help keep the drill bit cool.
Be careful with water though especially if you are using a power drill plugged
into an electricity supply.
Problem - Your drill bits get blunt very quickly.
Possible Cause and Solution - The solution to this is that your drill bits are
overheating and you should use lubricant as explained above. Just be aware
though that if the drill bits have been over heated a lot, they are practically
useless and may need replacing.
Most drill bits can be sharpened, but that takes some skill, and it is always
better to buy a drill sharpener machine.
Problem - The drill bit is wobbling.
Possible Cause and Solution - The bit may not be centered in the chuck, so
always check that first. That is always a big problem when using very small bits,
such as when you are drilling a pilot hole. Often the drill bit gets caught in just
one jaw of the chuck, and it is off center.
The other problem could be that the drill bit has been damaged, and is bent or
even slightly warped. If that is the case, then it will need to be replaced.
Problem - The drill bit slips and skids across the metal surface.
Possible Cause and Solution - No matter what type of metal you are drilling,
its suggested that there should be a pilot hole drilled first. Usually this is done
using a very small drill such as a 3 mm drill bit.
However before that, a center punch should be used to make a dent in the
metal, that will accommodate the pilot hole drill bit. Makes sure that you do that,
and that it is deep enough to allow the small metal drill bit to grab the metal.
Problem - Drill bit jams in the chuck at the end of the drilling.
5
by Migiwata Tools
Possible Cause and Solution - This is one of the most common problems
when drilling through metal. The honest answer is that this is usually caused
by our impatience. It is all too easy when getting near the end of the hole, to
force it through.
Too much pressure or weight on the drill bit will cause the drill bit to jam or lock
up in the chuck if we try to force it through. Go easy on the pressure and allow
the drill bit to cut all the way through the metal.
Drill Bit RPM Guide & Chart for Drilling Speeds
Please note the drill bit size is shown in inches, and the RPM is shown as the
maximum RPM the drill bit should be used when drilling.
Drill Size
Aluminum
Mild Steel
Cast Iron
Stainless Steel
1/32"
36600
13446
12224
8557
3/64"
24448
8964
8149
5705
1/16"
18336
6723
6112
4278
5/64"
14669
5379
4890
3423
3/32"
12224
4482
4075
2852
7/64"
10478
3842
3493
2445
1/8"
9168
3362
3056
2139
9/64"
8149
2988
2716
1902
5/32"
7334
2689
2445
1711
11/64"
6668
2445
2223
1556
3/16"
6112
2241
2037
1426
13/64"
5642
2069
1881
1316
7/32"
5239
1921
1746
1222
15/64"
4890
1793
1630
1141
1/4"
4584
1681
1528
1070
17/64"
4314
1582
1438
1007
9/32"
4075
1494
1358
951
6
by Migiwata Tools
Drill Size
Aluminum
Mild Steel
Cast Iron
Stainless Steel
19/64"
3860
1415
1287
901
5/16"
3667
1345
1222
856
21/64"
3493
1281
1164
815
11/32"
3334
1222
1111
778
23/64"
3189
1169
1063
744
3/8"
3056
1121
1019
713
25/64"
2934
1076
978
685
13/32"
2821
1034
940
658
27/64"
2716
996
905
634
7/16"
2619
960
873
611
29/64"
2529
927
843
590
15/32"
2445
896
815
570
31/64"
2366
868
789
552
1/2"
2292
840
764
535
Hopefully we have provided you with enough information to allow you to drill
metals successfully.
If you follow the tips above but still cant get a good result, please contact us by
sending message through Amazons system. Our helpful customer service will
respond your email and solve your issue as soon as possible.
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Hymnorq 1/4 Inch Fractional Size M35 Cobalt Steel Twist Drill Bit Set of 10pcs, Jobber Length and Straight Shank, Extremely Heat Resistant, Suitable for Drilling in Stainless Steel and Iron

This set of 10 twist drill bits from Hymnorq is made from M35 cobalt steel, which makes them extremely heat resistant and suitable for drilling in stainless steel and iron. The bits have a jobber length and a straight shank, and they are available in a range of fractional sizes from 1/16 inch to 1/2 inch.

Here are some of the features and benefits of these drill bits:

  • Made from M35 cobalt steel for extreme heat resistance

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