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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:Truss Head Tapping Screw
Materials:Stainless Steel
Surface treatment:Plain
Head Type:Truss Head
Drive:Phillips
Thread:Self Tapping
Point:Gimlet Point
Forming:Single Die Heading
Size:M1 M2 M3 M4 M5 M6 M7 M8 M9 M10 M14
Number:479
We make truss head tapping screws in passivated stainless with a wide shallow head, a cross recess and a gimlet point, quoting them from M1 to M14. Head diameter, point lead, thread and grade come from your drawing, and the first article is driven into your own board.
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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.
A truss head tapping screw is a self tapping screw with a broad, shallow head that spreads the clamp load over a wide face, and a sharp point that starts its own hole in soft material. The recorded item on this page is stainless steel with a plain finish, a truss head and a gimlet point, quoted from M1 to M14 with Number 479.
Truss head. A wide, shallow dome with a large flat bearing face, broader than a pan head and lower for its diameter. The wide face is what lets the screw hold a thin or soft panel without a washer and without sinking.
Gimlet point. A sharp taper with a short run of thread behind it, made to bite and start its own hole. It is a start, not a drill: it works in wood, board and soft polymers.
Self tapping thread. A coarse thread with a sharp crest that forms its own way into the material, so the joint needs no nut and no pre-tapped thread.
Stainless, plain. Passivated and uncoated, so the alloy is the whole of the protection. On a fixing that goes into damp board or decking, that is what keeps the screw from bleeding rust into the timber.
A truss head tapping screw pairs two features that solve the same problem from both ends. The head is wide so the load is spread over enough material to stop it sinking; the point is sharp so the screw starts without a pilot in a material that would not hold one. Put together they describe a fixing for soft or thin material where a narrow head would pull through and a blunt point would not start.
The truss profile is specific. The dome is shallow and the face runs almost flat to the rim, so the head is wider and lower than a pan head of the same thread. That gives the bearing area of a washer with a low profile, and it also covers an oversized or damaged hole that a pan head would drop into.
The point has to keep its thread. A gimlet point is formed after the thread is rolled, and the last few threads run down onto the taper; that threaded lead is what pulls the screw in once the tip has started. A point that has been ground back after rolling leaves a plain cone, and the screw then needs pressure to start instead of drawing itself in.
The thread is coarse, and in soft material that is deliberate. A coarse thread in wood or board removes less material per turn and holds with more of the material between the threads; a fine thread would cut more and hold less. In stainless the crest also has to stay full, because stainless work-hardens as it is rolled and a crest that is under-filled will not bite.
Plain stainless is passivated after forming. The passivation removes free iron left by the tools and rebuilds the oxide film; without it a stainless screw can leave a rust stain in the board that looks like a failed screw and is actually tool contamination.
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 a truss head tapping screw the head diameter and the point lead are quoted with the thread, because they decide how the part behaves in soft material.
| Item | How it is defined | What we control |
|---|---|---|
| Head | Truss, wide shallow dome | Diameter, height and face flatness |
| Recess | Phillips cross | Depth and width, bit tried on the part |
| Thread | Coarse self-tapping, full length | Gauged per batch |
| Point | Gimlet, sharp tip with a threaded lead | Point angle and lead length |
| Finish | Plain stainless, passivated | Surface condition and tone |
| Length | From under the head to the point | Measured on the shop plate |
Head diameter is the functional dimension. In softwood or MDF a head that is too narrow compresses the surface and leaves a crater; too wide and it fouls a moulding or a neighbouring fixing. The diameter is chosen from the material and the spacing, not from the thread size.
Length is measured from under the head, because that face bears on the material. In board the useful length is the thread that is actually in the material, so the point and the head thickness both come out of the length that has to be bought.
Three features define this part: the wide head, the gimlet point and the stainless body. The first two are a pair chosen for soft material, and the third is what makes it survive outdoors.
| Combination | What it gives | Where it fits | Where it fails |
|---|---|---|---|
| Truss, gimlet | Wide bearing, own start | Board, decking, soft polymers | Thin sheet without a pilot |
| Pan, gimlet | Lower profile, own start | General soft material | Wide or damaged holes |
| Truss, flat point | Wide bearing, prepared hole | Thin sheet, moulded bosses | Material that needs a start |
| Flat countersunk | Flush surface | Hard panels with a countersink | Soft material that cannot hold a cone |
The pair earns its place where a washer would otherwise be needed and a pilot hole would otherwise be required. On a deck board or a panel of MDF there is no clean hole to start in and a narrow head sinks; a truss head tapping screw starts itself and spreads the load across an inch of face instead of a few millimetres.
The limit is thin sheet. A gimlet point on a sheet edge skates and tears, and a stainless gimlet on stainless sheet polishes the surface before it does anything. Where the material is sheet, a flat point and a prepared hole is the combination, and the same truss head is then doing only half its job.
The recorded finish is plain, passivated stainless. There is no coating to chip at the head and nothing to bleed into the board, which matters because a timber or composite joint shows a rust stain for a long time after the screw has stopped being the problem.
| Option | How it protects | Effect on head and thread | Typical use |
|---|---|---|---|
| Stainless A2, plain | Passive chromium oxide film | None; gauged as formed | Outdoor board and trim |
| Stainless A4, plain | Passive film with molybdenum | None; gauged as formed | Coastal, marine and poolside |
| Zinc plated steel | Sacrificial zinc | A few microns; re-checked | Indoor board and fittings |
| Dacromet on steel | Zinc-aluminium flake layer | Film builds; thread re-checked | Outdoor steel and mixed assemblies |
| Black zinc on steel | Sacrificial zinc, dark passivation | A few microns; re-checked | Dark indoor panels |
Stainless into timber is not automatically the better choice. In hardwood the screw can split the board if there is no pilot, because stainless does not deform as easily as a plated steel screw; and a stainless screw driven too fast will gall against a stainless insert. Where the board is dense, a lead hole is still the right instruction.
The grade question is the same one that applies anywhere near water. A2 covers most outdoor work inland; A4 is for coastal, poolside and marine joints where chloride is present, and the difference shows at the thread long before it shows on the head.
Three assemblies where a truss head tapping screw belongs:
| Where it sits | The screw fixes a board or a trim to a frame where the material is soft, the head is seen, and the joint is exposed to weather. |
| When it goes wrong | A narrow head sinks into the board, and a plated screw leaves a rust stain that outlasts the fixing. |
| Why it happens | The material is timber or composite, the head is visible, and the joint is outdoors. |
| What we control | Head diameter and point lead checked, grade confirmed, parts driven into a sample board. |
| Where it sits | The screw fixes a panel or a bracket into MDF or a composite where the point has to start without a pilot and the head must not crush the face. |
| When it goes wrong | A pan head dimples the face, and a blunt point will not start in a soft board. |
| Why it happens | The board is soft, the face is finished, and the fixing repeats. |
| What we control | Point and thread checked, driving torque read on the customer’s board. |
| Where it sits | The screw fixes a trim strip or a fitting where salt water is present, the material is soft, and the head has to sit down onto it. |
| When it goes wrong | A stainless screw in a damp teak screw hole galls or seizes, and a steel one rusts the wood around it. |
| Why it happens | The joint is wet, the timber is soft, and the fixing is visible. |
| What we control | A4 grade where chloride is present, thread gauged, lubricant recommended. |
Four reasons that matter on a wide head with a gimlet point, each tied to what the drawing has to prove:
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Head, point and material reviewed together
The head diameter, the point lead and the material are reviewed as one set, so a head that would sink or a point that would skate is raised before the die is cut. Basis: Head, point and material reviewed as one set. |
Heading, rolling and pointing in one route
The truss head and the cross are formed in one stroke, the thread is rolled and the gimlet point is formed in the same route so the lead keeps its thread. Basis: Gimlet point formed with the thread, not after it. |
|
Point and thread checked on the part
The point angle and lead are checked on the projector, the recess is driven with the production bit, and the thread is driven into the customer material. Basis: First article driven into the customer material. |
First article fixes the setting
The first article fixes the wire heat, die set, roll and passivation; repeat orders are compared against that record. Basis: First article signed off before the batch is released. |
Shi Shi Tong heads these truss head tapping screws from stainless wire on single-die headers that form the wide head and the cross recess in one stroke, rolls the coarse thread and forms the gimlet point so the lead keeps its thread, then passivates the parts. The first part of every run is measured on the head, driven with the production bit and started in a sample of the customer’s board before the batch continues.
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The truss head is formed in one blow, and that is where a too-thin die shows: the rim comes out slightly rounded and the face slightly dished, and the head then bears on its edge and sinks into soft board exactly as a pan head would. The face is checked for flatness at the rim and the centre on the first article.
What decides whether truss head tapping screws pass is the head, the recess, the point, the thread and the alloy. The inspection agreement covers those, and the criteria come from the drawing.
Head and point on the projector |
Thread gauged per batch |
Hardness checked on the formed head |
Salt-spray testing of the stainless grade |
The head is checked for diameter, height and face flatness, and the recess for depth and width. On a truss head the diameter is the bearing area, and a head that is a millimetre under will sink in soft board even though every other dimension is correct.
The point is checked for angle and for the length of the threaded lead. A point that is sharp but has no thread on the lead will start and then stop, and in soft material the operator’s answer is pressure, which tears the surface.
The thread is gauged and driven into a sample of the customer’s board, with the driving torque recorded. In soft material the strip torque is what the joint has, and a screw that drives easily and strips early has too little thread in the material rather than a bad finish.
Every shipment of truss head tapping screws is traceable to the wire it was made from and to the passivation batch. The 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 grade or the passivation. 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 self tapping part the first article is also driven into the customer’s material, so the point and the thread are proved against the board rather than on a test plate. Buyers visit during the process to review samples and to see how the parts are formed.
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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 |
It is wide and shallow, so it spreads the load over a large face without a washer. On soft board or thin sheet that is what stops the head sinking.
It bites and starts its own hole in wood, board and soft polymers, and the threaded lead pulls the screw in. It is not a drill and it will not pierce sheet.
Not with a gimlet point. Sheet needs a flat point and a prepared hole; otherwise the point skates and tears.
It can, because it does not deform like a steel screw. A lead hole is still the right instruction in dense timber.
A2 inland, A4 where there is salt or chloride. The difference shows at the thread long before the head.
Head diameter and height, recess size, thread size and point lead, length and datum, and the stainless grade.
How a truss head tapping screw project runs from drawing to repeat delivery:
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1
Send the drawing or the board sample
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→ |
2
Head, point and thread review
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→ |
3
First article driven into your board
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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 height, the recess size, the thread size and point lead, the length and datum, and the stainless grade.
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Head diameter
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Head height
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Recess size
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Thread and point
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Length
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Stainless 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
