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Drill bits come in a wide selection of sizes to certain each task can acquire completed through precision. Every one supplies a different naming convention to promote accuracy, including letters, numbers, and also fractions.

You are watching: What size drill bit for #8 screw

When you measure up drill bits infractions, all of them room a component of 64ths. That way the the smallest one is 1/64, if the biggest size is 63/64. You would then reduce them come the shortest fractional equivalent: a 2/64 little would actually be a 1/32.

You’ll likewise see numbers the go indigenous 1-80, with the biggest number gift the the smallest drill bit.

When you pick the drill little size for #8 or #10 screws, several various features must be component of that choice. You have to account for the screw type, the materials used, and also the thread design.

Pilot feet Drill little Size Chart

What dimension drill little bit should you usage for pilot holes for timber screw? This handy pilot hole size chart should assist you.
Screw SizePilot hole size for softwoodPilot hole dimension for hardwood
#21/16″1/16″
#31/16″5/64″
#41/16″5/64″
#55/64″3/32″
#63/32″7/64″
#73/32″7/64″
#87/64″1/8″
#91/8″9/64″
#101/8″9/64″
#129/64″5/32″
#145/32″11/64″
#1611/64″3/16″
#1813/64″7/32″
#207/32″15/64″
#241/4″17/64″

Why Pre-Drill a Pilot Hole?

Since screws have actually a sharp end to them, why is it necessary to pre-drill holes to accommodate the fastener?

It is true that the self-tapping screws can conveniently penetrate right into softwood with the assist of a drill driver or an influence driver. However, as soon as it involves larger diameter holes and also tough products such as hardwood and also metal girlfriend will must drill pilot holes. This pilot holes make it much easier to place the screw in the correct location. As soon as you have multiple boards to fasten, this occupational guarantees the the materials won’t crack or the screw division off while working.

When threading thick steel plates, you must drill the feet to the dimension of main point diameter and use a threading tap.

When you work-related with hardwoods, the pilot hole have to be the dimension of the screw’s “minor diameter.” It deserve to be slightly smaller sized for softer woods.

If girlfriend skip the pilot feet (or drill one that isn’t large enough), inserting the screw can cause hairline cracks to kind in the material. This problem is particularly prevalent in MDF, plywood, and also engineered products, however it can additionally occur in heavy wood.

Although you might not view the crack at first, they can at some point widen together the surroundings ages. If given sufficient time, your wood joint or fastening job-related will at some point fail.

Enlarge the Pilot feet in a top Board

If you close two lumber products, try to do the pilot hole more extensive in the height board 보다 the bottom one. This style makes it easier for the screw to pull the item together.

For this step, the clearance hole have to be at least the size of the major diameter because that the screw.

When this action gets skipped, you’ll regularly see a small gap between the 2 boards or surfaces jointed together. Depending upon what you’re making, glue could seal the bond with this result, but it isn’t effective if your spacing is bigger than the thickness the a typical sheet of printer paper.

What dimension Drill little bit for a #8 Screw?

If you have form A, AB, or B self-tapping screws or form 25 thread-cutting screws, you’d require a #29 drill bit for your pilot hole.

When you have high-low thread-forming screws, the suggested drill bit for a #8 screw is the #30 for products with a flexural modulus of more than 200,000 PSI. If you have actually materials that rate under that figure, a #31 drill little is a much better choice.

If you are using #8 hammer journey or U-drive screws, your pilot hole’s encourage drill little bit size is #27.

When you should use standard wood screws for your project, the straight size is 1/8-inch because that the #8 screw. If you require a tapered result, an 11/64-inch little works far better for hardwood, while a 5/32-inch little is perfect for softwood. You’d use a C8 countersink.

What dimension Drill little bit for a #10 Screw?

If girlfriend have type A, self-tapping screws, kind AB self-tapping screws, form B self-tapping screws, or type 25 thread-cutting screws, you’d need a #21 drill little for her pilot hole.

When you have high short thread creating screws, the suggested drill bit for a #10 screw is the #27 for products with a flexural modulus of much more than 200,000 PSI. If you have materials that price under the figure, a #29 drill little bit is a better choice.

If you are using #10 hammer drive or U-drive screws, the recommended drill little size for her pilot feet is #20.

When your project supplies hardwood or softwood, a traditional #10 wood screw is an ideal for the fastening work. You’d usage a 9/64-inch bit for a directly pilot hole, although some softwoods might benefit from having a 1/8-inch bit.

If you require a tapered pilot feet for her project, hardwoods would require a 13/64-inch bit, when softwoods would use a 3/16-inch bit for the #10 screw. You’d desire to usage a C102 countersink.

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Once you have the equipment ready, it help to clamp her boards gently to ensure lock don’t move. Drill native a fully vertical or horizontal place to create specific pilot hole. ~ that job-related is finished, you have the right to place the #8 or #10 screw through precision to do a certain bond.