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+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:Very Long Screws Hex Head Machine Screws
Materials:Steel
Surface treatment:White Zinc Plated
Head Type:Hex Head
Drive:External hex
Thread:Machine thread, full thread
Point:Blunt
Forming:Two-die heading
Size:M1 M2 M3 M4 M5 M6 M7 M8 M9 M10 M14
Number:001
We make very long screws in white zinc plated steel with a hex head and a full thread along the shank, quoting them from M1 to M14. Across flats, head height, overall length, thread type and finish come from your drawing, and the first article is assembled through your stack.
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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.
Very long screws are fasteners whose shank is several times their diameter, used where a joint spans a gap or where a bolt has to pass through everything it joins. This one has a hex head, a full thread over the whole shank and a white zinc finish over steel, quoted from M1 to M14 with Number 001.
Hex head. Six flats with a flat bearing face, driven with a wrench and clamped without a recess.
Full thread. The thread runs the whole length of the shank, so the screw can hold at any depth along it.
Long shank. A slender body that passes through the assembly rather than stopping in it.
White zinc. A bright sacrificial zinc deposit over steel, the general-purpose finish for indoor assemblies.
Very long screws are the family behind most deep assemblies: a through-bolted frame, a stack of plates with a nut on the far side, a plastic housing that is driven to whatever depth the material will take. The length is the point of the part, and the thread type decides how the joint behaves.
On a long screw the choice between full and half thread is the main design decision. A full thread lets the screw hold at any point along its length, which is what a through-bolted joint or a connection into plastic or wood needs: the screw can be driven to whatever depth the material will take, and the engaged length is whatever has entered the material.
The cost of full thread is that it cuts into everything it passes. Where a long screw goes through clearance holes in several parts and threads into the last, a full thread will score the bores of the parts in between and hold them, so the joint no longer comes apart cleanly. That is why half-threaded long screws exist, and why the choice is made from the joint rather than from the catalogue.
Full thread also changes how the screw is made. Thread rolling a very long blank requires the blank to be supported along its length while the rolls work, and any movement shows as a thread that changes pitch part way along. The result is a screw whose first threads and last threads gauge correctly and whose middle does not.
The hex head suits that length. A wrench on six flats delivers a steady torque without a recess to wear out, and the flat bearing face lands on the part with a full ring of contact. On a very long screw the drive is the part that has to be trusted, because the shank absorbs some of the torque before it reaches the thread.
White zinc is the finish that goes with the head. It is bright, sacrificial and thin enough to keep the thread usable, and it is gauged after plating so the thread the customer runs a nut onto is the thread they receive. It is the general-purpose choice for an indoor fastener, and its limits show out of doors.
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 very long screws the quotation carries the across flats and head height, overall length, thread type and the finish.
| Item | How it is defined | What we control |
|---|---|---|
| Head | Hex head | Across flats, height and face flatness |
| Shank | Long body, fully threaded here | Diameter and thread along the length |
| Thread | Full thread, or half on request | Pitch, form and gauging |
| End | Blunt, chamfered | Chamfer and thread start |
| Material | Carbon steel | Grade and heat number on the certificate |
| Finish | White zinc plated | Thickness and gauging after plating |
| Standard | GB | Dimensioning of head and thread |
Thread type belongs on the drawing as a word, not a convention. A very long screw quoted as full thread and supplied half threaded is a part that does not reach the nut; one quoted half thread and supplied full is a part that will not pass a clearance bore.
On a full-threaded very long screw the thread is what the joint slides on, so its diameter and pitch are both functional. A thread that is on the large side of its tolerance binds in a clearance hole that was cut to nominal.
Three features define the part: the full thread, the long shank and the hex head. The first lets it hold at any depth, the second gives the reach, and the third gives the torque.
| Feature | What it gives | What it costs |
|---|---|---|
| Full thread | Holds at any depth along the shank | Scores clearance holes it passes |
| Long shank | Passes through the assembly | Twists under driving torque |
| Hex head | Wrench drive, full bearing face | Head stands above the surface |
| White zinc | Bright sacrificial protection | Thin; wears at the thread |
| GB dimensioning | Familiar head and thread sizes | Limits to the standard’s options |
The full thread is the reason the part is chosen for through-bolted and plastic joints. A nut can be run to any point, the screw can be driven to whatever depth the material takes, and the engagement is set by the joint rather than by the screw.
The cost is paid at the clearance holes. Anywhere the screw passes a part that has to slide, a full thread will cut or score it, so a joint that needs to come apart repeatedly should specify a half thread instead.
The recorded finish is white zinc plating over carbon steel. On a very long screw the coating is doing all of the corrosion work over a long surface, and it has to survive being run through holes and turned in a nut; white zinc is thin enough for that, and sacrificial enough that a scratch does not become a rust spot immediately.
| Option | How it protects | Effect on thread and head | Typical use |
|---|---|---|---|
| White zinc plated | Sacrificial zinc, bright | Thin build; gauged after plating | Indoor general assemblies |
| Blue zinc plated | Sacrificial zinc, blue tint | Same as white zinc in practice | Indoor machinery |
| Black zinc plated | Sacrificial zinc, dark | Thin build; wear visible | Dark housings and frames |
| Dacromet | Inorganic zinc-aluminium layer | Thick; thread allowances needed | Wet and outdoor joints |
| Stainless alternative | Passive film, no build | Thread as made | Wet and food service |
Where the joint is outdoors, white zinc is a short-lived choice on a long screw: the thread is the surface that corrodes first, because it is the thinnest part of the coating and the part that is turned in a nut. Dacromet or a stainless body is the specification that changes the outcome.
Where the screw is in a dry interior, white zinc is the economical answer, and the head is worth checking after plating. A rough deposit on the bearing face marks the part it clamps.
Three assemblies where very long screws are the fixing:
| Where it sits | The screw passes through several members and takes a nut at the far end, with the length set by the stack. |
| When it goes wrong | A half thread that does not reach the nut leaves the joint short of engagement. |
| Why it happens | The joint is a through bolt, the stack is deep, and the nut is on the far face. |
| What we control | Thread type and overall length checked; first article assembled through the stack. |
| Where it sits | The screw is driven to a depth set by the material, where a full thread holds wherever it stops. |
| When it goes wrong | A thread that is too fine for the material strips, or a shank that binds before the head seats. |
| Why it happens | The material is soft, the depth varies, and the joint is assembled by hand. |
| What we control | Thread form and length agreed; first article driven into a sample. |
| Where it sits | The screw holds frame members together where a wrench can reach the head and the length is structural. |
| When it goes wrong | A long shank twists under the wrench, and the joint never seats. |
| Why it happens | The joint is structural, the access is by wrench, and the head is visible. |
| What we control | Thread type and shank checked; driving tested on the first article. |
Four reasons that matter on a long part, each tied to what the drawing has to prove:
|
Thread type and length agreed
Full or half thread, overall length, across flats and finish are agreed as a set, because on very long screws the thread type decides whether the joint assembles. Basis: Thread type and length agreed. |
Two-die heading and rolled thread
A two-die header supports the long blank while the head is formed, then the thread is rolled along the length and the parts plated within one route. Basis: Two-die heading for long blanks. |
|
Thread gauged at both ends
The thread is gauged along the shank, because a long rolled thread can read differently at its ends and its middle. Basis: Thread gauged along the shank. |
Packing fixed by the first article
Packing is agreed with the first article, because on a very long part the transit is part of the process. Basis: Packing agreed at first article. |
Shi Shi Tong makes very long screws on two-die headers that form the hex head and cut nothing in the top face, then support the long blank while the thread is rolled along the shank and the parts are white zinc plated. The first part of every run is measured on across flats, head height, overall length and thread before the batch continues.
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A long blank is the hardest thing on a heading line. It has to be held over most of its length while the head is formed at one end, and any misalignment in the grip shows as a head that runs off the axis; the screw then measures correctly and will not pass a close hole.
What decides whether very long screws pass is the head, the thread along the shank and the overall length. The inspection agreement covers those, and the criteria come from the drawing.
Head and thread on the projector |
Thread gauged along the shank |
Hardness checked on the wire |
Coating proved by salt spray |
The head is checked for across flats, height and face flatness, the shank for diameter and length, and the thread for pitch and form along its length. The coating is checked for thickness, and the thread is gauged again after plating.
The first article is assembled through the customer stack with the nut it will use. A screw that threads correctly in a gauge and will not accept a nut at the far end of a deep stack is still a part that fails, and only the assembly shows it.
Every shipment of very long screws is traceable to the wire it was made from and to the plating 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 coating. The documents carry the drawing revision and the batch number, so a repeat order keeps the same thread type and overall 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 very long screws the first article is assembled through the customer stack, because the thread and the length are both proved there. Buyers visit during the process to review samples.
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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 two-die headers and the plating 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 |
Full thread holds at any depth and suits through-bolted joints and plastic; half thread keeps the clearance holes smooth. The joint decides.
The shank absorbs part of the torque, so the thread turns less than the wrench. Steady driving and a clean thread matter more than force.
It is thin and sacrificial, which is right indoors. Outdoors the thread corrodes first because it is the thinnest coating on a turned surface.
Yes. The parts are packed so the length is not loaded, and the joint should not be used to pull misaligned parts together.
This family is dimensioned to GB sizes for head and thread, which is what the drawing should state.
Across flats and head height, overall length, thread type and pitch, the grade and the finish.
How a very long screw project runs from drawing to repeat delivery:
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1
Send the drawing and the stack it passes
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→ |
2
Thread type, length and head agreed
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→ |
3
First article assembled through your joint
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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 across flats and head height, overall length, thread type and pitch, the grade and the finish.
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Head A/F
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Head height
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Overall length
|
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Thread type
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Grade
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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
