M5 x 8mm Countersunk T25 Torx Stainless Bolt (qty x10)

These T25 Torx screws are M5 x 8mm with a countersunk (flat) head, in stainless steel. There are ten in a pack, priced at $2.50, and Blue Alpine’s part number for them is F00126-00.

How T25 Torx screws like these are measured

A countersunk screw is measured from the top of the head to the tip. The head is part of the length, because once it’s fitted the head sits down inside the material, level with the surface. That catches people out. On these T25 Torx screws, part of the 8 mm is cone-shaped head, so the threaded length below the surface is noticeably shorter than 8 mm.

So when you measure the old screw, put the calipers on the flat top of the head and the very tip. Don’t measure from under the head like you would on a pan head. If you get close to 8 mm and the thread is M5 x 0.8 (5 mm diameter, 0.8 mm between threads), you have the right one.

Short T25 Torx screws like these suit thin parts going into a threaded hole or a clinch nut close behind them. There isn’t room for much else.

Metric heads are 90 degrees

This is a detail worth knowing if you’re cutting a new countersink. Metric countersunk screws have a 90 degree head. US flat head screws are usually 82 degrees. Countersink cutters are sold in both angles, and they look nearly identical.

Use an 82 degree cutter for a metric head and the cone in the hole ends up steeper than the head. The screw then touches only at its outer rim and sits slightly proud of the surface, so it never fits flush and the edge takes all the load. If your T25 Torx screws won’t sit flush in a fresh countersink, check the angle on the cutter first. Countersink on Wikipedia has a diagram of the angles.

Thin sheet

Countersinking only works when the sheet is thicker than the head is tall. Cut a full countersink into sheet thinner than that and you go right through, leaving a knife edge and an oversized hole the head can pull into. That’s why thin panels are often dimpled instead of cut. If you’re replacing a screw, the original hole already has the right shape, so leave it alone.

T25 Torx screws versus the T20 M5s

All three M5 countersunk screws we sell are stainless, but they don’t share a bit. These 8 mm ones take a T25. The 12 mm and 20 mm versions above take a T20. T25 is the more common drive for an M5 Torx head. The two bits differ by only about half a millimeter point to point, so it’s easy to grab the wrong one from a mixed set.

What happens if you do: a T20 drops into a T25 recess with play all around and spins out as soon as there’s load, rounding the lobes as it goes. A T25 simply won’t enter a T20 head. If you’re working on a mix of these, keep both bits on the bench and check each head before you turn it.

We sell a T20 screwdriver but not a T25 one. Any standard T25 bit or driver will do.

Fitting tips for T25 Torx screws

• No flat washer under the head. A washer stops the cone from seating and defeats the countersink. If the screw goes through to a nut, the M5 washer belongs on the nut side.
• Start by hand. Stainless into a stainless thread can gall if it’s spun in fast, so turn the first few threads with your fingers.
• Push, then turn. Keep the bit square and fully seated, especially on the last quarter turn.
• Stop at flush. Once the head is level with the surface, more torque just strains the thread.

Ordering T25 Torx screws

If you aren’t sure whether your old screw was the T25 or a T20 type, tell us the part number from your parts list. You can reach us through our freeze dryer support page. The rest of the range is under fasteners and tools.