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:Custom Shoulder Screws
Materials:Carbon steel
Surface treatment:Liquid Black Fade Treatment
Head Type:Truss Head
Size:M1 M2 M3 M4 M5 M6 M7 M8 M9 M10
Drive type:None (no slot; per drawing)
Thread:Partial (half) machine thread
Forming:Multi-station cold heading with shoulder
Number:1602
We manufacture custom shoulder screws in carbon steel with a truss head, a liquid blackened finish and a partial machine thread, from M1 to M10. Shoulder diameter and length, head profile, step radius, thread class and blackening are checked before the batch ships.
Watch the factory video·Email sst@szsst88.com
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.
A custom shoulder screw is a screw made to a drawing with an unthreaded shoulder below the head and a smaller machine thread below the shoulder. The shoulder locates the part it passes through and the thread clamps it, so the fastener does the work of a pin and a screw in one part.
Shoulder as a locating surface. The shoulder runs through a hole and sets the fit and the stack height. Its diameter and length are the dimensions that matter: a shoulder a few hundredths off changes the clearance in a linkage, and a shoulder that is too long holds a plate off its datum.
Truss head. The head is wide and low, with a bearing face that spreads the clamp load over a thin panel. It sits above the surface rather than sinking into it, which keeps the profile low and the panel undented.
No recess. The head carries no slot or socket, and the drive is defined on the drawing. Where no recess is used, the screw is turned with a fixture on the head or the shoulder, or it is used as a locating pin with a nut on the thread; the drawing states which.
Together these decide the joint: the shoulder locates, the head bears on the panel, and the thread clamps the part that is bolted on behind it.
This custom shoulder screw is formed from carbon steel wire on a multi-station header, thread rolled and given a liquid blackening treatment. The grade comes from the drawing, and the wire heat number stays traceable to the material certificate.
The truss head is formed in the die, and the shoulder is produced behind it. The shoulder and the thread are produced on the same axis, so a shoulder that is not concentric with the thread binds in its hole even when both diameters are on size.
Liquid blackening is an immersion conversion coating. It colours the steel evenly, including the shoulder and the head edge, and it adds no measurable thickness, so the shoulder diameter measured before the bath is the diameter that fits the hole.
The partial thread leaves a plain shank between the shoulder and the thread. That plain section is what passes through the locating hole without touching the sides, so it is measured from the head face rather than from the tip.
Custom shoulder screws are quoted from M1 to M10 shoulder sizes and in lengths to suit the drawing, with the shoulder and the head measured on the projector and the thread gauged. Where a long version is required, custom lengths up to 2,000 mm are subject to DFM review after drawing submission.
| Item | How it is defined | What we control |
|---|---|---|
| Shoulder diameter | The fit in the locating hole | Measured with micrometers on the first article |
| Shoulder length | The stack height under the head | Measured from the head face |
| Head diameter and height | The truss head profile | Checked on the projector |
| Thread size and length | Partial machine thread below the shoulder | Gauged per batch |
| Step radius | The transition from shoulder to thread | Checked on the projector |
| Total length | From the top of the head to the tip | Datum stated on the drawing; measured on the shop plate |
Each size is quoted against the hole it locates. The shoulder diameter and the hole are a pair, and the shoulder length and the stack are another, so both are reviewed with the drawing rather than scaled from a similar part.
Shoulder length is measured from the head face and the total length from the top of the head. The batch is checked on the features the process can drift on: shoulder diameter, shoulder length and thread class.
The truss head gives a wide bearing face on a low profile, so it works on a thin panel or a soft boss. On a shoulder screw the head also sets the axial position: it stops the shoulder at the face it bears on, so head height and shoulder length are read together.
The head has no recess. That is a deliberate choice on this part: a wide truss head is thin at the centre, and a recess would remove the material that carries the clamp load. The drive is defined on the drawing instead, using a fixture on the head or the shoulder, or a nut on the thread.
The shoulder is the working surface. It runs unthreaded through the hole, and the clearance between the shoulder and the hole decides whether a linkage moves freely or binds. The thread below it is smaller and engages the tapped part, so the shoulder never carries thread.
The step between shoulder and thread is a stress point. A sharp step concentrates the clamp load, so the drawing sets the radius and the first article is checked at that transition.
This custom shoulder screw is liquid blackened. The parts are immersed in the blackening solution, which converts the surface to a dark oxide, and the parts are then oiled. The coating is thin and even, so it colours the shoulder and the head edge without changing the fits.
| Finish | How it protects | Effect on shoulder and thread | Typical use |
|---|---|---|---|
| Liquid blackening | Immersion conversion coating, oiled | No measurable build-up | Indoor fixtures and mechanisms |
| Black oxide | Conversion coating, minimal thickness | No measurable build-up | Indoor parts where black is required |
| Zinc plated | Sacrificial zinc layer | Build-up on thread; gauged after | General indoor assembly |
| Dacromet flake | Zinc-aluminium flake layer | Thin film; thread checked over it | Outdoor and wet joints |
| Plain stainless (equivalent part) | Passive film forms in air | No coating build-up | Wash-down and medical parts |
Salt-spray exposure is agreed per project and written on the drawing. Liquid blackening on carbon steel is an indoor finish; where the part sees condensation or wash-down, a zinc or flake coating is specified instead and the thread is gauged after that coating.
Packing protects the shoulder and the head. Screws are packed so the shoulders do not knock, and the label carries the batch, the material heat and the blackening lot.
Three assemblies where custom shoulder screws are chosen to locate as well as clamp, and what the screw has to do instead:
| Where it sits | The shoulder locates a plate against a datum, and the thread holds it to the fixture body. |
| When it goes wrong | A shoulder that is a few hundredths off lets the plate move, and a shoulder that is too long holds it off the datum. |
| Why it happens | The fixture is set to a datum, the plate is located by the shoulder, and the joint is adjusted during set-up. |
| What we control | Shoulder diameter and length checked, and the first article assembled with the plate. |
| Where it sits | The shoulder acts as the pivot while the thread fastens the joint together. |
| When it goes wrong | A short shoulder lets the link move under the head, and a rough shoulder wears the bore. |
| Why it happens | The joint moves, the bore is reamed, and the screw is assembled once. |
| What we control | Shoulder diameter and step radius checked, and the pivot cycled on the first article. |
| Where it sits | The part both locates a component and provides a threaded point for a nut or a bracket. |
| When it goes wrong | A shoulder that is not round binds in the hole, and a blackened shoulder that is not oiled rusts in storage. |
| Why it happens | The parts are indoors, the joint is assembled once, and the head is visible. |
| What we control | Shoulder roundness checked, the blackening and oil recorded, and the thread gauged. |
Four reasons that matter on a custom shoulder screw, each tied to what the drawing has to prove:
|
Shoulder and hole reviewed together
The shoulder diameter, the shoulder length and the locating hole are reviewed before the die is cut, so a screw that would bind or hold a plate off its datum is raised first. Basis: Shoulder, hole and stack reviewed before tooling. |
Headed, shouldered and threaded in one route
The head, the shoulder and the thread are produced in one route, so the shoulder stays concentric with the thread and the truss head stays square. Basis: One route for head, shoulder and thread. |
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Shoulder measured on the part
The shoulder is measured with micrometers and the length from the head face, and the thread is gauged, on the first article and per batch. Basis: Shoulder diameter and length checked on the first article. |
First article to repeat production
The first article fixes the drawing revision, wire heat, die set and blackening lot; repeat orders are compared against that record. Basis: First article signed off before the batch is released. |
Shi Shi Tong forms these custom shoulder screws on a multi-station header: the truss head is struck in the die, the shoulder is produced behind it, the partial thread is rolled below the shoulder, and the parts are liquid blackened. The first part of every run is measured on the shoulder and the head, and gauged on the thread, before the batch continues.
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Between runs the die insert is changed to the drawing head and the shoulder tool is set with the thread length; the first part goes to the projector and the gauges before the run continues, and the setting is recorded. Blackened parts are oiled and packed so the finish is not rubbed before assembly.
What decides whether a custom shoulder screw passes is not only the thread: it is the shoulder diameter and length, the truss head profile, the step radius and the blackening. The inspection agreement covers those, and the criteria come from the drawing and the locating hole.
Head, shoulder and step on the projector |
Thread gauging against GO/NO-GO gauges |
Hardness testing where the drawing requires it |
Salt-spray testing of the blackened finish |
Each batch is recorded against the drawing revision: shoulder and head from the first article, the step checked, and the thread gauged per batch. If a gauge or the shoulder check fails, the parts back to the last good setting are held and re-checked.
A report from an outside laboratory, where one is required, is organised before the batch runs so it can be filed under the same batch number.
Every custom shoulder screw shipment is traceable to the wire it was made from. The grade, heat number and standard 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 material or the finish. 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. Shoulder parts are approved with the locating hole, so the shoulder and the stack are signed off as a pair. Buyers visit during the process to review samples and to see how the shoulders are formed.
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8,678+
customers served
|
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 header and the blackening 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 |
It is a screw made to a drawing with an unthreaded shoulder below the head and a smaller machine thread below the shoulder. The shoulder locates the part and the thread clamps it.
The shoulder diameter matches the locating hole and the shoulder length matches the stack. Both are on the drawing and both are checked on the first article with the mating part.
The drive is defined on the drawing: a fixture on the head or the shoulder, or a nut on the thread where the part is used as a locating pin. The drawing states which.
Custom shoulder screws are quoted from M1 to M10 shoulder sizes and in lengths to suit the drawing. Where a long version is required, custom lengths up to 2,000 mm are subject to DFM review after drawing submission.
An immersion conversion coating that colours the steel evenly, including the shoulder, and adds no measurable thickness. The parts are oiled after the bath, and the finish is an indoor one.
Shoulder diameter and length, head diameter and height, the step radius, thread size and length, total length and datum, material, finish, and the locating hole and stack.
How a custom shoulder screw project runs from drawing to repeat delivery:
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1
Send the drawing or sample
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→ |
2
Shoulder and hole review
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→ |
3
First article approval
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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 custom shoulder screw quotation, send the drawing with the shoulder diameter and length, head diameter and height, the step radius, thread size and length, total length and datum, material, finish, and the locating hole and stack.
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Shoulder diameter and length
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Head diameter and height
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Step radius
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Thread size and length
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Total length and datum
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Material 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
