Tel：
+86 13143444311
Email：sst@szsst88.com
Fax：+0086-755-27322278
Address：Building 9, First Industrial Zone, Tantou Industrial City, Songgang Street, Baoan District, Shenzhen 518105, Guangdong, China
Type:Brass Slotted Cup Head Machine Screw, Turned, Full Thread (Non-Standard)
Materials:Brass
Surface treatment:Plain, cleaned; no plating, no passivation, no oil film specified
Head Type:Cup Head (plain cylinder, flat top, one slot across the face, no flange, no washer face)
Drive:Single slot, straight across the full head face; no cross recess
Thread:Machine thread, cut 60 degree, full to the head bearing face; no plain shank
Point:Blunt end with a small chamfer; no taper, no drill point
Process:Turned from bar, slot sawn, thread cut, deburred, cleaned and sorted
Forming:M1 M2 M3 M4 M5 M6 M7 M8 M9 M10 M14
Number:438
We manufacture brass slot head screws turned from bar, with a cup head, a single slot across the face and a cut machine thread running full to the bearing face. Head and slot dimensions, thread, length and brass alloy are taken from your drawing.
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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.
Brass slot head screws are machine screws with a single straight slot across the head, made from brass and cut rather than formed. The recorded item on this page is a turned cup head version: a plain cylinder with a flat top and one slot across the face, a cut machine thread running full to the bearing face, in plain cleaned brass, quoted from M1 to M14 with Number 438.
Slot head. One straight slot across the full head face. It is the oldest drive there is, and it is still specified where the head has to look plain, where a flat blade is all that is available, or where the screw is decorative and the slot is part of the look.
Cup head. A plain cylinder with a flat top. There is no flange and no washer face, so the head bears on its own underside and the slot is cut straight through the flat top, which leaves a clean line on a polished part.
Turned, not headed. These are produced from brass bar on a lathe: the head and shank are turned in one pass, the slot is milled or sawn, and the thread is cut. That route makes sense for brass and for small batches, because it needs no heading die and every dimension can be set independently.
Plain brass. No plating and no passivation. Brass is a copper-zinc alloy, so it protects itself reasonably in dry indoor air, conducts electricity well, and takes a polish. It also tarnishes, which is a finish question rather than a corrosion failure.
Together these decide the joint: the slot takes a flat blade, the cup head sits flat on the panel, the cut thread engages a tapped hole over its full length, and the brass body gives conductivity and a colour that no plated steel part matches.
The body starts as brass bar, with the alloy grade and heat number on the batch record. On a lathe the bar is faced, the head turned to diameter and height, and the shank turned to the thread blank diameter in the same setup. Turning the head and the shank without re-chucking is what keeps the head square to the shank, which matters because a slotted head that is off square makes the blade wander.
The slot is then cut across the head face. On brass the cut is clean when the tool is sharp and the feed is right, and it burrs on both edges when it is not. A burr on the slot edge is more than a cosmetic problem on a brass slot head screws part: it stands the blade off the slot floor, the blade bears on the burr instead of the slot, and the slot deforms at a lower torque.
The thread is cut rather than rolled. Cutting lets the thread be produced on a turned blank without a set of rolls, and on brass it leaves a clean flank that gauges well. Rolled brass threads are stronger in fatigue, but for a decorative or electrical part the cut thread is the normal choice and it is what the recorded process says.
Deburring follows the slot and the thread end. The thread start gets a small chamfer so the first thread enters a tapped hole cleanly, and the slot edges are dressed so that no burr stands above the face. On brass the deburring has to be controlled, because a heavy hand rounds the slot edge and makes the slot look worn before it is used.
Cleaning is the last step. Brass is degreased and dried rather than passivated, and no oil film is specified on the recorded configuration, so the parts arrive dry and bright rather than with a protective coating that would need removing before soldering or plating.
The family is quoted from M1 to M14, with M1, M2, M3, M4, M5, M6, M7, M8, M9, M10 and M14 in the recorded range. Custom lengths up to 2,000 mm are subject to DFM review after drawing submission; on turned brass slot head screws the length costs little to change, because the bar is cut to length rather than the part being formed from a fixed wire volume.
| Item | How it is defined | What we control |
|---|---|---|
| Thread | Metric machine thread, cut, full to the bearing face | Gauged per batch with GO/NO-GO |
| Head diameter | Cup head, plain cylinder | Turned diameter checked with a micrometer |
| Head height | Flat top, set on the drawing | Measured on the projector |
| Slot width | Matched to the blade supplied | Checked with a blade on the first article |
| Slot depth | Leaves enough material under the slot | Checked on the section |
| Chamfer | Small on the point and on the thread start | Checked on the first article |
| Length | From under the head to the tip | Measured on the shop plate |
The slot depth is the dimension that decides how a brass slot head screws part fails. Brass is soft, so a slot that is too shallow leaves the blade standing proud and the slot edges deform; a slot that is too deep thins the material under the head and the head can bow. The depth is set against the head height, and the two are turned and cut in different operations, so both are checked on the first article.
Slot width has to match the blade, and blades vary. A slot cut for a thin blade will not take a heavier one, and a slot that is too wide lets the blade rock and rounds the edges on brass quickly. Where the customer uses a specific driver, the slot is checked with that blade and not only with a gauge.
Turned brass slot head screws are specified for reasons that have nothing to do with torque. They are chosen for conductivity, colour, machinability and the look of a plain slotted head, and the specification should be honest about where those advantages stop.
| Feature | What it gives | What it costs |
|---|---|---|
| Turned from bar | Any dimension to order; no heading die | Higher unit cost than a headed part at volume |
| Single slot | Plain look; any flat blade will turn it | Slot deforms easily in soft brass |
| Cut thread | Clean flank; easy to gauge | Less fatigue strength than a rolled thread |
| Brass body | Conductivity, colour, machinability | Tarnishes; softer than steel |
| Plain finish | No coating to interfere with contact or solder | No corrosion barrier in wet or salty air |
The slot is the weak point, and it is a deliberate one. On a brass part the slot edges are soft enough that a blade which is too thin will cut into them, and a blade which is too thick will not seat. The usual failure is not a snapped screw but a slot that rounds over, and once that happens there is very little to grip. The first article is therefore driven with the blade the customer uses, at the torque the drawing specifies.
Turned production also changes what can be quoted. Because the part is machined rather than formed, a change in length or head height is a change in the program, not a new die, and small batches of an odd size are practical. In return, the unit price carries the machine time, and a turned brass slot head screws part is only economical where the volume or the size makes heading unattractive.
Brass conducts, and that is often the real reason for the part. In a terminal, a grounding point or a busbar connection, a brass screw is part of the conductive path rather than just a fastener, and a plated steel screw in the same place adds a dissimilar metal junction. Where that matters, the drawing should say so, because it changes both the alloy and the finish.
Plain cleaned brass is the recorded finish. There is no plating, so nothing changes the thread dimensions after cutting, and the part can be soldered, plated or lacquered later without stripping a coating first.
| Option | What it does | Effect on the part | Typical use |
|---|---|---|---|
| Plain cleaned | Degreased and dried; no film | No dimensional change | Electrical contacts and indoor parts |
| Clear lacquer | Slows tarnish, keeps the bright colour | Film can fill the slot if heavy | Decorative and visible brass |
| Nickel plated | Silver tone, harder surface | A few microns; thread gauged after | Parts that must match steel hardware |
| Chrome plated | Bright, hard, corrosion resistant | Thicker; thread re-checked | Sanitary and decorative fittings |
| Antique or oxidised | Deliberate dark patina | Surface only; slot re-checked | Reproduction and heritage hardware |
Tarnish is not corrosion in the way rust is. Brass darkens because the copper in the alloy reacts with sulphur and oxygen in the air, and the film is thin and self-limiting; it changes the colour long before it changes the strength. For a decorative part that is a problem, and a clear lacquer is the usual answer. For an electrical part it is often irrelevant.
A lacquer film and a slot are a poor combination if the film is heavy. It bridges the slot edges and reduces the depth the blade can reach, which on a soft brass head is exactly the condition that rounds the slot. Where a lacquered brass slot head screws part is specified, the slot is checked with the blade after coating rather than before.
Three applications where brass and a plain slotted head are chosen together:
| Where it sits | The screw clamps a conductor or a lug in a terminal block or a grounding post, and the brass body is part of the conductive path. |
| When it goes wrong | A plated steel screw introduces a dissimilar metal junction, and a slot that deforms under repeated tightening stops clamping evenly. |
| Why it happens | The joint carries current, it is opened for inspection, and the contact resistance matters. |
| What we control | Alloy grade confirmed, thread gauged per batch, and the slot checked with the driver used on the line. |
| Where it sits | The screw holds a movement, a bezel or a small bracket where the head is seen and the part has to stay non-magnetic. |
| When it goes wrong | Steel screws are magnetic and can disturb a movement, and a cross recess looks wrong on a period instrument. |
| Why it happens | The assembly is small, the head is visible, and the screw is often hand-tightened. |
| What we control | Head diameter, slot width and slot depth checked on the first article. |
| Where it sits | The screw fixes a plate, a handle or a trim on a brass or bronze fitting, where the colour of the fastener has to match the part. |
| When it goes wrong | A plated steel screw reads as a different colour under light, and a heavy lacquer fills the slot and makes it look worn. |
| Why it happens | The fixing is visible, it is cleaned regularly, and the finish is part of the product. |
| What we control | Colour and tarnish behaviour agreed on the drawing, slot checked after any coating. |
Four reasons that matter on a turned brass part, each tied to what the drawing has to prove:
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Slot and head reviewed as one head
The slot width, slot depth and head height are reviewed together, so a slot that would thin the head is raised before the program is cut. Basis: Slot and head height reviewed as one set. |
Turning, slotting and threading in one route
The head and shank are turned in one setup, the slot is cut across the face and the thread is cut full to the bearing face, so the head stays square to the shank. Basis: One route from bar to cleaned screw. |
|
Slot and thread checked on the part
The slot is checked with the blade the customer uses, the thread is gauged per batch, and the slot edges are checked for burr under a light. Basis: First article driven with the customer blade. |
First article to repeat production
The first article fixes the drawing revision, bar heat, program and tool set; repeat orders are compared against that record. Basis: First article signed off before the batch is released. |
Shi Shi Tong turns these brass slot head screws from bar: the head and shank are turned in one setup, the slot is cut across the head face, the machine thread is cut full to the bearing face, and the parts are deburred, cleaned and sorted. The first part of every run is measured on the head, the slot and the thread, and driven with the customer’s blade, before the batch continues.
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The program is what makes a turned part repeatable. Once the head diameter, slot width and thread are set, every part in the run comes off the same tool path, and the checks are there to catch tool wear rather than to correct the setup. A worn slotting tool shows first as a burr on one edge, which is why the slot edges are checked under a light rather than only measured.
What decides whether brass slot head screws pass is the head, the slot, the thread and the surface. The inspection agreement covers those, and the criteria come from the drawing.
Head and slot on the projector |
Thread gauged per batch |
Hardness testing of the bar stock |
Salt-spray testing where a coating is specified |
The slot is checked in three ways on the first article: width against the blade, depth against the section, and edges under a low light for burr. A slot can pass the first two and still fail in service because of the third, and on brass the burr is what stands the blade off the floor.
Brass is checked for alloy as well as for dimensions. A free-machining brass and a standard brass machine differently and solder differently, and a substitution shows up as a change in colour or in how the part takes a thread, long after the batch has shipped. The alloy is stated on the drawing and confirmed on the certificate.
Every shipment of brass slot head screws is traceable to the bar it was made from. The alloy grade and heat number are recorded 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 batch we supply the material certificate, the inspection record for the criteria on the drawing and, where it is listed, the third-party report for the alloy. The documents carry the drawing revision and the batch number, so the paperwork can be matched to the parts.
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 turned part the first article also confirms the alloy, because a brass that machines well can still be the wrong brass for a contact. Buyers visit during the process to review samples and to see how the slots are cut.
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8,678+
customers served
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87%
of orders from repeat customers
|
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 turning cells and the finishing 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 |
Machine screws in brass with a single straight slot across the head. This version is turned from bar with a cut thread and a cup head.
For conductivity, colour or non-magnetic behaviour. Brass is also easy to machine, so odd sizes and small batches are practical on a lathe.
Yes. Brass darkens as the copper reacts with air, and the film is thin and stops at the surface. A clear lacquer slows it if the colour has to stay bright.
A hollow-ground flat blade that matches the slot width. A blade that is too thin cuts into the slot edges on soft brass; one that is too thick will not seat.
Cut, on these parts. Cutting suits a turned blank, gives a clean flank and gauges well. Rolled threads are stronger in fatigue but need a different route.
Thread size and pitch, head diameter and height, slot width and depth, length and datum, brass alloy, and the finish, with the driver type if it is fixed.
How a brass slot head screw project runs from drawing to repeat delivery:
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1
Send the drawing or sample
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2
Slot and alloy review
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→ |
3
First article driven with your blade
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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 thread size and pitch, head diameter and height, slot width and depth, length and datum, brass alloy, finish, and the blade type if it is fixed.
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Thread and pitch
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Head diameter and height
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Slot width
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Slot depth
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Length and datum
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Alloy and finish
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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
