#8 x 5/8" Stainless Self Tapping Screws (qty x10)

Ten #8 x 5/8 in stainless self tapping screws, sold as one pack for $2.74. Blue Alpine’s part number for them is F00125-00. They’re imperial-sized, which matters if most of what you’re working on is metric.

Decoding #8 x 5/8

The #8 is a gauge number, not a fraction. A #8 screw is about 0.164 in across the threads, a little over 4 mm. The 5/8 is the length in inches, 0.625 in or roughly 15.9 mm.

Where that length is measured depends on the head. Raised heads (pan, round, truss) are measured from under the head. Flat, countersunk heads are measured from the top. Our listing gives size and material but not the head style, so compare the photo with your old screw before ordering. If the head shape or drive matters for your job, ask us and we’ll confirm it.

A #8 doesn’t swap with an M4 even though the diameters are close. Most tapping screws also use a coarser, more widely spaced thread than machine screws, so they don’t belong in a nut or a tapped metric hole.

How stainless self tapping screws hold

A self tapping screw makes its own thread as it goes in. It needs a pilot hole drilled first, sized a bit smaller than the screw, and the thread presses or cuts its way into the wall of that hole. That’s different from a self drilling screw, which has a small drill point on the tip and makes its own hole. Ours are sold as stainless self tapping screws, not self drilling, so plan on drilling.

Getting the pilot hole right

Too big, and the thread has nothing to bite. The screw spins and strips. Too small, and you’re forcing it, which in stainless can mean galling or a snapped screw. For a #8 into thin sheet steel or aluminum, most pilot-hole charts land close to 1/8 in. Check a chart for your exact material and thickness, and test on scrap if you can.

Deburr the hole afterward. A ragged edge lifts the head and keeps it from pulling down flat.

Where stainless self tapping screws struggle

Carbon-steel tapping screws are usually case-hardened so the thread can cut into steel. Most stainless self tapping screws are softer than that. They’re at home in aluminum and thin sheet, and they won’t rust in damp conditions the way plain steel screws can. In thick or hard steel, though, they can gall, strip their own threads or twist off.

A few habits help:

• Drive slowly. Heat from a fast driver makes galling more likely.
• A dab of wax or cutting oil on the thread eases the first entry.
• Stop as soon as the head seats. One extra turn can strip the thread you just formed.
• No impact driver. It hides the moment the head seats.

Driver size

If the head on your screw has a Phillips recess, a #8 normally takes a #2 Phillips bit. A worn bit chews the recess quickly in stainless, so start with a fresh one.

Refitting stainless self tapping screws

Taking one out and putting it back is where a lot of holes get ruined. The first time in, the screw formed a thread. If you drive it straight back in, it can easily cut a second, crossed thread beside the first and wreck both.

The fix takes ten seconds. Set the screw in the hole and turn it backward, counterclockwise, with light pressure. You’ll feel a small click as it drops into the old thread. Now turn it forward by hand for a couple of turns before you pick up the driver. Done this way, stainless self tapping screws can go in and out of the same hole several times.

Stripped hole?

When stainless self tapping screws spin without tightening, the hole is gone. Going up a gauge is the usual fix, but we don’t sell #10 tapping screws. A rivet is the other route if the joint doesn’t need to come apart again. The 3/16 rivet above can go into the same spot once the hole is opened up with a #11 or 3/16 in drill, as long as it hasn’t already worn bigger than that.

Related hardware

The stainless pull handle is listed with our body and door parts, and screws, nuts and washers are under fasteners and tools. For background on thread-forming versus thread-cutting types, Wikipedia’s self-tapping screw page is a decent start. Questions about fit go to +1 (443) 514-5708.