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:Extra Long Socket Screws
Materials:Stainless Steel
Surface treatment:Plain
Head Type:Cap Head
Drive:Hexagon socket (Allen)
Thread:Machine thread, half thread
Point:Plain, chamfered
Forming:Single Die Heading
Size:M1 M2 M3 M4 M5 M6 M7 M8 M9 M10
Number:577
We make extra long socket screws in plain A2 stainless with a cap head, a hexagon socket and a half thread, quoted from M1 to M10 to the length on your drawing. Thread start, shank diameter and overall length are agreed before the first part, and the first article is assembled through your own stack.
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.
Extra long socket screws are cap head machine screws with a hexagonal socket and a shank long enough to reach through a stack of parts. These are plain A2 stainless, half threaded, quoted from M1 to M10 with Number 577 and made to length on the drawing. The head is cylindrical with the hexagon in the centre, and the thread runs over the end portion with a plain shank under the head.
Cap head. A cylindrical head with a flat top and a hexagon cut into it, tightened with an Allen key.
Hexagon socket. The drive sits inside the head, so no wrench clearance is needed around the head.
Half thread. The thread covers the end portion, and the plain shank under the head carries the clamp.
Long shank. Made to the length on the drawing, reaching through spacers, housings or panels.
Plain stainless. A2 grade, passivated, with no coating to be rubbed off along a long shank.
Extra long socket screws are used where a joint is deep rather than wide: through-bolts in housings, clamps that span a stack of plates, furniture frames, and any assembly where a standard length stops short and a spacer would be the alternative.
Lengthening a screw changes three things, and only one of them is obvious. The obvious one is reach: the shank has to pass through everything between the head and the thread, and the thread has to end where the tapped part begins. The other two are the thread position and the way torque travels down the shank.
Thread position is a dimension, not a consequence. On a half-thread screw the plain shank is what seats in the clearance hole and what carries the clamp, while the thread engages at the far end. If the thread starts a few millimetres early it enters the clearance hole and the joint loses its bearing length; if it starts late, the engaged thread is short and the joint cannot take the preload.
Torque is the second. A long shank twists as it is driven, and the twist has to be taken out before the head starts to pull the joint together. In practice the driver shows torque at the head while the far end is still catching up, which is why a long screw needs to be driven in stages rather than in one pull of the trigger.
The third is handling. A long, thin shank behaves like a rod: it bends under its own weight when it is picked up, it marks when it rubs against another, and it can take a set if it is stored in a bundle. Parts are made, washed and packed so that the shank is supported rather than cantilevered, and that is a production decision as much as a packaging one.
Stainless makes the first two easier and the third harder. There is no coating to be damaged along the shank, so a mark is only cosmetic; but stainless work-hardens, and a shank that is bent in handling cannot be bent back without leaving a hardened kink that will not pass through a close clearance hole.
The recorded range is M1 to M10, with lengths made to the drawing. Custom lengths up to 2,000 mm are subject to DFM review after drawing submission. For extra long socket screws the quotation carries the head diameter and height, socket size and depth, the shank diameter and length, the thread length and where it starts, and the length overall.
| Item | How it is defined | What we control |
|---|---|---|
| Head | Cap head, cylindrical | Head diameter and height, top edge |
| Socket | Hexagon in the head | Across flats and depth |
| Shank | Plain, under the head | Diameter and length to the first thread |
| Thread | Half thread, machine | Length, start position and pitch |
| Length | Overall, head included | Length tolerance over the full length |
| Material | A2 stainless | Grade and heat number on the certificate |
| Finish | Passivated, plain | Surface condition along the shank |
The distance from the underside of the head to the first full thread is the number that matters most, and it is the one most often missing from a drawing. It defines how much plain shank sits in the clearance hole, and therefore how the joint behaves when it is tightened.
Overall length is measured over the head, and the tolerance applies to the whole length rather than to the shank alone. On a long part the tolerance is not tightened by making the blank longer; it comes from cutting and from the way the part is held during the operation.
Four features carry extra long socket screws, and each one costs something in production or in assembly:
| Feature | What it gives | What it costs |
|---|---|---|
| Long shank | Reaches through a deep stack | Bends in handling; harder to feed |
| Half thread | Clamp carried by the plain shank | Thread start is a critical dimension |
| Hexagon socket | No wrench clearance needed | Socket depth limits driving torque |
| Plain stainless | No coating to rub off at length | Work-hardens if bent |
| Cap head | High clamp on a small footprint | Head must clear the surrounding part |
The socket drive is what makes a long screw practical. A cross recess at the end of a long shank would release early and leave the joint partly closed, while an internal hexagon takes the torque and keeps the key engaged until the joint is seated.
The half thread is what makes it accurate. Where the shank passes through a close clearance hole, the plain section locates the screw and keeps the joint aligned while the thread pulls it together; a fully threaded long screw would thread its way into the clearance hole and lose that alignment.
The recorded finish is passivation on A2 stainless with no coating. On a long part that is an advantage: there is no plated layer to be scuffed along the shank when the screw is pushed through a stack of plates, and nothing to flake inside a housing that has to stay clean.
| Option | How it protects | Effect along a long shank | Typical use |
|---|---|---|---|
| A2 stainless, passivated | Passive chromium oxide film | No build; shank as formed | Housings and frames |
| A4 stainless, passivated | Passive film with molybdenum | No build; shank as formed | Marine and washdown |
| Steel, black oxide | Conversion film, oiled | No measurable build; oil carries | Internal mechanisms |
| Steel, zinc plated | Sacrificial zinc | Thin build; marks show as grey | Indoor general work |
| Steel, Dacromet | Inorganic zinc-aluminium layer | Build noticeable; thread re-checked | Outdoor and wet joints |
Where the joint is outdoors, the finish question changes with length: a coated long screw has far more surface to protect, and any scratch along the shank becomes a rust line that runs down the whole part. On those joints stainless is the simpler answer.
Where a coating is specified, the build is checked at the thread rather than at the shank, because the thread is the only place where a few micrometres change the fit. The shank is measured for diameter, and marks that do not change the diameter are accepted.
Three assemblies where length, not diameter, is the specification:
| Where it sits | The screw passes through a housing and a spacer to a tapped plate at the far end, where the stack is deeper than any standard length. |
| When it goes wrong | The thread starts inside the clearance hole and the joint never seats. |
| Why it happens | The stack is deep, the thread is at the far end, and the head sits in a recess. |
| What we control | Thread start and overall length checked; first article assembled through the stack. |
| Where it sits | The screw spans a series of plates where the clamp has to be carried by the plain shank rather than by the thread. |
| When it goes wrong | The shank bends as it is driven and the joint pulls to one side. |
| Why it happens | The span is long, the clearance is close, and the drive is by key. |
| What we control | Shank diameter and thread start checked; first article fitted to the frame. |
| Where it sits | The screw reaches through a post into a threaded insert where the head has to stay below the surface line. |
| When it goes wrong | The thread engages too deep and the post crushes before the joint is tight. |
| Why it happens | The part is long, visible at the head, and the joint is tightened on site. |
| What we control | Thread length and head checked; first article fitted in a sample post. |
Four reasons that matter at length, each tied to something the drawing has to prove:
|
Thread start quoted as a number
The distance from the head to the first full thread is agreed as a dimension, because on a half-thread long screw it decides where the clamp sits. Basis: Thread start quoted as a dimension. |
Headed, threaded and handled as one route
The head and socket are formed, the thread is rolled to position, and the parts are washed and packed so the shank is supported. Basis: One route from wire to packed part. |
|
Length and thread measured on the part
Overall length and thread start are measured on the finished part, because both can shift during handling and finishing. Basis: Length and thread start measured. |
First article assembled through your stack
The first article is assembled through the customer stack, because reach and thread position are only proven in the joint. Basis: First article assembled through the stack. |
These screws are headed on machines that form the cap head and the hexagon socket, then rolled with the thread at the position the drawing sets and cut to overall length. The parts are cleaned and passivated as a batch, and each step is planned around handling, because a long shank gains and keeps damage from the way it is moved.
|
|
Rolling the thread at a defined position is the step that separates a working long screw from a part that measures correctly. The thread has to start at the distance the drawing gives and finish before the end of the blank; a roll that runs a little long eats into the plain shank under the head and the joint loses its bearing length, while one that stops short reduces the engaged thread at the far end.
Handling after the thread is rolled matters as much as the forming. Long parts are kept in carriers and moved in small groups, and they are packed so that the shank is supported along its length rather than held at the head. A mark on a stainless shank is cosmetic; a bend is not, because it work-hardens and cannot be corrected.
What decides whether extra long socket screws pass is the overall length, the thread start, the head and the thread itself. The inspection agreement covers those four, and the criteria come from the drawing.
Head and socket on the projector |
Thread and start position checked |
Core hardness checked |
Salt-spray testing of the grade |
Overall length is measured with the part supported along its whole length, and the thread start is measured from the underside of the head, because that is the datum the joint uses. The head is checked for diameter, height and socket depth, and the socket is proved with the production key.
A sample from every batch is assembled through a stack that matches the customer’s clearance hole and thread engagement, and then removed. On a long screw that check is the one that matters: the part can pass every dimension and still bind on a clearance hole that is a few hundredths tight.
Every batch 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 dimensions 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 thread start and the same 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 extra long socket screws the first article is assembled through the customer’s own stack, because reach and thread position are proven only in the joint. Buyers visit during the process to review samples.
|
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 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 |
Custom lengths up to 2,000 mm are subject to DFM review after drawing submission. The length follows your drawing and the stack it has to pass through.
The plain shank sits in the clearance hole and carries the clamp. If the thread starts early, it enters the clearance hole and the joint loses its bearing length.
The shank twists as it is loaded, so the torque at the head arrives before the far end has taken it up. Staged driving keeps the joint even.
Yes, usually. A cross recess releases early and the joint ends up partly closed, while a key stays engaged to the end.
Stainless work-hardens, so a corrected bend leaves a hard kink that will not pass a close hole. Parts are made and packed to avoid it.
Head diameter and height, socket size and depth, shank diameter, thread length and its start position, and overall length.
How an extra long socket screw project runs from drawing to repeat delivery:
|
1
Send the drawing and the stack
|
→ |
2
Thread start and length agreed
|
→ |
3
First article assembled through the stack
|
→ |
4
Batch production and repeat orders
|
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, socket size and depth, shank diameter, thread length and start, and overall length.
|
Head size
|
Socket
|
Shank diameter
|
|
Thread start
|
Thread length
|
Overall length
|
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
