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+86 13143444311
Email：sst@szsst88.com
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Address：Building 9, First Industrial Zone, Tantou Industrial City, Songgang Street, Baoan District, Shenzhen 518105, Guangdong, China
Type:Star Stainless Screw Countersunk Head Self Tapping
Materials:Stainless steel
Surface treatment:Plain
Head Type:Csk Head
Drive:Six-lobe star recess (Torx)
Thread:Half thread, self-tapping
Point:Sharp, tapered
Forming:Single Die Heading
Size:M1 M2 M3 M4 M5 M6 M7 M8 M9 M10 M14
Number:883
We make star drive screws in plain A2 stainless with a countersunk head, a six-lobe recess and a half self-tapping thread, quoting them from M1 to M14. Recess size and depth, cone angle, thread length and point come from your drawing, and the first article is driven with your own bit.
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ISO 9001:2015 · Manufacturing since 1998 · 8,678+ customers · 89 countries and regions
Made to order – there is no stock catalogue. Each part is produced to your drawing, and production starts after drawing review and first-article approval.
These star drive screws are countersunk, six-lobe-driven self-tapping screws in plain A2 stainless, quoted from M1 to M14 with Number 883. The cone sinks into a matching countersink until the head is flush, a Torx key drives from the centre of that cone, and the sharp point forms its own thread in the pilot hole.
Countersunk head. A 90-degree cone that seats flush in a countersink, leaving no edge above the surface.
Six-lobe recess. A star-shaped socket cut into the flat top of the cone, driven with a Torx key or bit, size T1 to T30 depending on the screw.
Half thread. The thread covers part of the length and a plain shank sits under the head.
Sharp self-tapping point. A tapered, hardened point that cuts its own thread as the screw enters.
Plain stainless. A2 grade, passivated and uncoated, so the recess and the point are exactly as formed.
Star drive screws are chosen where a flush head and a secure drive have to coexist: appliance panels, electrical enclosures, sheet-metal covers and hinges that are assembled on a line with a bit driver and serviced later with the same key.
The countersunk head leaves almost nothing to drive from. Eighty-five percent of the head is the cone; the only flat surface left is a small circle at the top, and the star recess has to be cut inside it. That single constraint decides the recess size, the recess depth and the torque the screw will take.
A six-lobe recess earns its place there because it drives from the inside of the shape rather than from the edges. A cross recess pushes the driver outward as torque rises and lifts the bit at the moment the thread starts cutting; a star holds the bit in the lobe walls and takes the forming torque without climbing out. On a countersunk head, where the bit is the only way in, that difference decides whether a panel can be assembled at all, and it is the reason most star drive screws are specified with a Torx bit rather than a cross.
The half thread is the second structural choice. The plain shank under the head carries the clamp and keeps the head sitting down in the countersink; the thread only needs to be long enough to hold in the material. On a short screw the thread may be most of the length, and on a longer one it is deliberately short, which is why thread length belongs on the drawing as a number and not an assumption.
The point is the third. It is tapered and hardened so it cuts a path rather than pushing material aside, and it is concentric with the axis because a point that sits off-centre makes the screw walk out of the pilot hole on the first turn.
Together the three give star drive screws that close a joint flush, drive without cam-out and need no tapped hole behind them. The cost is that every one of them is a formed feature on the same small blank, and each has to be right before the next can work.
The recorded range is M1 to M14, with lengths made to the drawing. Custom lengths up to 2,000 mm are subject to DFM review after drawing submission. For star drive screws the quotation carries head diameter and cone angle, recess size and depth, overall length, thread length, point and the pilot hole.
| Item | How it is defined | What we control |
|---|---|---|
| Head | Countersunk, 90-degree cone | Head diameter and cone angle |
| Recess | Six-lobe star, T-size per diameter | Lobe size, depth and floor condition |
| Thread | Half thread, self-tapping | Thread length and point of first thread |
| Point | Sharp, tapered | Point length and concentricity |
| Length | Overall, head included | Length tolerance and thread position |
| Material | A2 stainless | Grade and heat number on the certificate |
| Finish | Passivated, plain | Surface condition and recess edges |
Recess size is fixed by the screw diameter, not by preference. A T10 bit in a screw cut for T8 will turn until the lobes are destroyed; the right bit is the one the recess was formed for, and the drawing should name it.
Thread length is the number most often left off star drive screws. Two screws of the same diameter and the same overall length can differ by several millimetres of thread, and the half-thread version on a joint that needs grip near the head will strip long before the full-thread one.
Three features carry the performance of these star drive screws, and each one trades something away:
| Feature | What it gives | What it costs |
|---|---|---|
| Six-lobe recess | Torque without cam-out | Only a Torx bit fits; a worn bit reams the lobes |
| Countersunk cone | Flush, self-centring seat | Seat angle and countersink must match |
| Half thread | Grip close to the head | Thread length must be specified |
| Sharp point | Forms its own thread | Pilot hole has to suit the material |
| Plain stainless | Recess and point as formed | Galls dry; softer than a coated steel screw |
The recess is what most buyers notice first on star drive screws, because it changes the assembly line. A bit that fails to seat is obvious in seconds, and the same T-key fits every screw of that size on the panel, which is why appliance and enclosure builders moved to star drive screws in the first place.
The half thread is the feature that is hardest to see and easiest to get wrong. Where the joint is thin sheet, the thread has to reach the sheet and no further; where the joint is a plastic boss, the plain shank spreads the load and keeps the head from crushing the seat.
The recorded finish is passivation on A2 stainless with no coating. That matters more on this screw than on a plain machine screw, because the recess is the drive and the point is the cutting edge: a coating thick enough to be useful would narrow the lobes and blunt the point, and both failures appear at the moment of assembly.
| Option | How it protects | Effect on recess and point | Typical use |
|---|---|---|---|
| A2 stainless, passivated | Passive chromium oxide film | Recess and point as formed | Appliances and wet areas |
| A4 stainless, passivated | Passive film with molybdenum | Recess and point as formed | Marine and food equipment |
| Steel, zinc plated | Sacrificial zinc | Thin build; recess re-checked | General indoor assemblies |
| Steel, black zinc | Sacrificial zinc, dark | Thin build; wear shows on lobes | Dark enclosures and cabinets |
| Steel, black oxide | Conversion film, oiled | No measurable build | Internal mechanisms |
Where the screw is driven into an aluminium panel or a stainless bracket, galling is the real risk rather than corrosion, and a dry A2 screw can seize in the hole before the head is seated. A small amount of assembly lubricant, agreed on the drawing, removes the problem without changing the part.
Where the joint is indoors and dry, a zinc-plated steel version works for less money, but the recess has to be gauged after plating. On a countersunk head the recess floor is shallow, and a coating that passes on a pan head screw can close a star recess enough to stop the bit seating.
Three assemblies where the star recess and the flush head both earn their place on star drive screws:
| Where it sits | The screw closes a panel that is handled, cleaned and serviced, and nothing may stand above the surface. |
| When it goes wrong | A worn bit reams the lobes, and a flush head gives nothing to grip afterwards. |
| Why it happens | The joint is flush, the drive is a bit, and the fastening happens on a line. |
| What we control | Recess size and depth checked; first article driven with the production bit. |
| Where it sits | The screw holds a cover, bracket or earth strap where the head must sit flat against a painted or powder-coated face. |
| When it goes wrong | The bit climbs out of the recess and scars the coating around the hole. |
| Why it happens | The seat is painted, the drive is a Torx bit, and the head must stay below the paint. |
| What we control | Seat checked on a coated sample; first article assembled and released. |
| Where it sits | The screw forms its own thread in thin sheet or a soft extrusion, where a tapped hole or an insert would be another operation. |
| When it goes wrong | A pilot hole that is too small splits the sheet, and one that is too large never holds. |
| Why it happens | The material is thin, the thread is formed by the screw, and the head sits flush. |
| What we control | Pilot hole agreed; first article driven into a sample sheet. |
Four reasons that matter on a countersunk star screw, each tied to something the drawing has to prove:
|
Recess and cone agreed together
Recess size, recess depth and cone angle are agreed as a set, because on a countersunk head each one leaves room for the other two. Basis: Recess and cone agreed as a set. |
Formed, rolled and passivated in one route
The cone and star recess are formed in one heading stroke, the half thread is rolled, the point cut, and the parts passivated as a batch. Basis: One route from wire to passivated screw. |
|
First article driven with your bit
The first article is driven with the production bit at the joint torque, because a recess that takes a new bit and fails a worn one is not a pass. Basis: First article driven with the production bit. |
Countersink seat checked on your part
The first article is seated in the customer countersink, because flushness is a property of the head and the hole together. Basis: First article seated in the part. |
These star drive screws are headed on single-die machines that form the countersunk cone and the six-lobe recess in one stroke, roll the half thread and cut the sharp point before the parts are passivated. The first part of each run is measured on head diameter, cone angle, recess size and depth, thread length and point.
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Forming a star recess into a countersunk head is the step that limits the whole part. The punch that cuts the lobes works inside the small flat face, and it has to reach full depth without thinning the metal between the recess floor and the cone. A punch set half a tenth too deep produces a screw that gauges correctly and fails under the driver, because the material under the recess is no longer thick enough to carry the forming torque.
Rolling the half thread is the second controlled step. The thread run begins at the point and stops at the start of the plain shank, and that stop is a position, not a taper: a thread that runs a little further into the shank leaves the joint without its grip near the head, and one that stops early cuts into the countersink seat.
What decides whether star drive screws pass is the recess, the cone, the thread length and the point. The inspection agreement covers those four, and the acceptance criteria come from the drawing and the agreed standard.
Cone and recess on the projector |
Thread and thread length checked |
Point and core hardness |
Salt-spray testing of the grade |
The recess is checked for lobe form, depth and floor thickness, and the seating is proved with a go gauge of the correct T-size; a bit that seats but rides high is a fail even when the lobes measure. The cone is checked for angle and contact width on an optical projector.
Thread length is gauged, not estimated. The required thread length is a measurable distance from the point to the last full thread, and it appears in the first-article record so that repeat orders can be compared against it rather than against the drawing alone.
Every batch of these star drive screws is traceable to the wire it was made from and to the passivation batch that finished it. The grade and heat number appear on the material certificate supplied with the parts, and the inspection records follow the criteria agreed on the drawing.
ISO 9001:2015 |
RoHS test report |
Registered trademark |
Patent: security screw and driver |
With each shipment we supply the material certificate, the inspection record for the criteria on the drawing and, where the grade is listed, the third-party report that covers it. The documents carry the drawing revision and the batch number, so a repeat order keeps the same recess size and the same thread length.
More than 8,678 customers in 89 countries and regions have ordered from Shi Shi Tong; 87% of orders come from repeat customers and 56% through referrals. Most projects follow the same route: drawing review, first-article approval, then batches checked against that sample. On a star drive screw the first article is driven with the customer’s own bit, because the recess and the bit are a pair and only the pair proves the joint. Buyers visit during the process to review samples.
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8,678+
customers served
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87%
of orders from repeat customers
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56%
of orders through referrals
|
89
countries and regions shipped to
|
Buyers and quality engineers visit for sample review, process discussion and supplier audits; the visit is arranged around production so the headers and the passivation line can be seen on the day the parts run.
Customer group visit – sample review |
Customer group visit – process discussion |
Customer group visit – factory tour |
Customer visit – project kick-off |
Danish customer – drawing review |
Industry exhibition – meeting customers |
A Torx bit of the T-size the recess was formed for. The size follows the screw diameter, and the drawing should name it.
A star drives on the lobe walls and does not lift the bit as torque rises, which a countersunk head needs because the bit is the only way in.
The plain shank under the head carries the clamp and keeps the head down in the countersink, while a shorter thread holds in the material.
Yes. The sharp point forms its thread in a drilled pilot; without one it will not start cleanly in sheet or plastic.
A2 covers ordinary exposure and A4 covers chlorides. Nothing is coated, so the recess and the point stay as formed.
Head diameter and cone angle, recess T-size and depth, overall length, thread length, point and the grade.
How a star drive screw project runs from drawing to repeat delivery:
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1
Send the drawing and the countersink
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→ |
2
Recess, cone and thread length agreed
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→ |
3
First article driven with your bit
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→ |
4
Batch production and repeat orders
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Each step is confirmed with you before the next one starts; the drawing revision from the first article is what repeat orders are checked against.
For a quotation, send the drawing with the head diameter and cone angle, recess T-size and depth, overall length, thread length, point and the grade.
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Head diameter
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Cone angle
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Recess size
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Recess depth
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Thread length
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Grade
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Sending a drawing? The form below does not take attachments. Email the PDF, DXF or STEP file to sst@szsst88.com with the part name and quantity in the subject line – the drawing is reviewed and a quotation follows.
+86 13143444311
sst@szsst88.com
