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:Long Thumb Screws Hexagon Socket Self Tapping
Materials:Stainless Steel
Surface treatment:Plain
Head Type:Cap Head
Drive:Knurled head and hexagon socket
Thread:Self-tapping, thread forming
Point:Sharp, tapered
Forming:Multi-station heading
Size:M1 M2 M3 M4 M5 M6 M7 M8 M9 M10 M14
Number:190
We make long thumb screws in passivated A2 stainless with a knurled cap head, a hexagon socket, a long shank and a self-tapping point, quoting them from M1 to M14. Knurl, socket depth, threaded length, point and grade come from your drawing, and the first article is driven in your material with the key.
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.
Long thumb screws are hand-adjustable fasteners with a knurled cap head, a hexagon socket, a long shank and a self-tapping point, made here in passivated A2 stainless and quoted from M1 to M14 with Number 190. The knurl is for setting the screw by hand once the thread is formed; the socket is for driving it the first time.
Knurled cap head. A straight-knurled cylinder that gives fingers something to grip for adjustment.
Hexagon socket. A socket in the top of the head, so the same part can be driven with a key when the joint needs torque.
Self-tapping point. A sharp thread-forming point that cuts or forms its own thread in the material it enters.
Passivated stainless. A2 grade, uncoated, so the knurl, the socket and the thread are as made.
Long thumb screws are used where the adjustment sits out of reach: a stop inside a housing, a cover at the back of a machine, a screw that has to pass through a spacer before its thread starts. The length is the reason for the part, and the two drives are what make the length usable.
A short thumb screw can be turned by hand because the thread is short and the torque is small. A long thumb screw cannot: the thread is at the far end of a long shank, and forming that thread in the material takes torque that fingers on a knurl cannot supply. That is why these parts carry both a knurl and a socket, and the two are used at different times.
The socket does the first assembly. It drives the self-tapping point into the pilot hole, forming the thread along the length that will engage, and it is the only drive that can apply enough torque through a long shank to do that without damaging the head. The knurl does the adjustments afterwards, when the thread is already formed and the screw only has to be turned in and out against a light load.
Length changes the torque that reaches the point. A long shank is a torsion spring: part of what the key applies goes into twisting the shank rather than turning the thread, and the longer the screw the more of it does. On a long self-tapping part that is why the driver has to be steady rather than strong, and why the pilot hole has to be right — an oversized hole makes the thread form with less torque, and an undersized one can stall the screw before the thread is formed.
The knurl has to survive that first assembly. A knurled head that folds over at the crests during driving loses the grip it was made for, and the part can no longer be adjusted by hand; the same caution as any knurled head applies, and on a long screw the temptation to grip the knurl with pliers is higher because the screw is awkward to hold.
What the length gives is reach. A long thumb screw adjusts something that is deep inside a housing or behind another part, where a short screw could not be reached and a tool could not be fitted. The self-tapping point removes the need for a tapped boss at that depth, which is often the reason the part exists at all.
The recorded range is M1 to M14, with long lengths made to the drawing. Custom lengths up to 2,000 mm are subject to DFM review after drawing submission. For long thumb screws the quotation carries the head diameter and height, knurl form, socket size and depth, overall length, threaded length and point.
| Item | How it is defined | What we control |
|---|---|---|
| Head | Knurled cap head | Head diameter, height and knurl |
| Socket | Internal hexagon | Across flats, depth and corners |
| Shank | Long plain or partly threaded body | Diameter and length |
| Thread | Self-tapping | Thread form, threaded length and crest |
| Point | Sharp, tapered | Point length and concentricity |
| Material | A2 stainless | Grade and heat number on the certificate |
| Finish | Passivated | Surface condition and knurl crests |
Threaded length is the number to agree on a long thumb screw. A screw that is threaded along most of its length forms a thread through everything it passes, which is wrong when it has to slide through a clearance hole first; one that is threaded only at the tip needs a plain shank sized to the hole it passes.
Overall length and threaded length together define the part; neither alone is enough. The point length is the third: it sets how far the screw enters before the thread starts, and on a long part it is easy to have a point that is short relative to the shank and therefore slow to start.
Three features define the part: the knurled head, the socket and the self-tapping point. The first is the hand drive, the second is the assembly drive, and the third is what removes the need for a tapped hole.
| Feature | What it gives | What it costs |
|---|---|---|
| Knurl | Hand adjustment without a tool | Wears if used to drive |
| Hex socket | Enough torque to form the thread | Key access needed at assembly |
| Long shank | Reach into a deep position | Twists under driving torque |
| Self-tapping point | No tapped boss needed | Pilot hole must be right |
| Passivated A2 | No build in socket or knurl | Softer than steel; galls dry |
The two drives are the reason the part works at all. A long knurled screw without a socket is a part that either cannot be installed or is installed with pliers, and the plier marks stay on the head for the life of the machine.
The cost is that the long shank has to be respected during assembly. The key should be applied steadily, the pilot hole should be checked, and the screw should not be used to pull two misaligned parts together.
The recorded finish is passivation with no coating on A2 stainless. On a part with a knurl and a socket that matters twice: a coating rounds the knurl crests so they no longer grip, and narrows the socket so the key does not seat. Passivation leaves both as made.
| Option | How it protects | Effect on knurl and socket | Typical use |
|---|---|---|---|
| A2 stainless, passivated | Passive chromium oxide film | Knurl and socket as made | Instrument and machine adjustment |
| A4 stainless, passivated | Passive film with molybdenum | Knurl and socket as made | Marine and medical |
| Steel, black oxide | Conversion film, oiled | No measurable build | Internal mechanisms |
| Steel, zinc plated | Sacrificial zinc | Socket narrowed; re-checked | Indoor general work |
| Aluminium, anodised | Grown oxide, coloured | Rounds knurl crests slightly | Lightweight adjustment knobs |
Where the part is adjusted often, stainless keeps the knurl biting for longer, because there is no soft deposit to wear off the crests. Where the joint is wet, A4 is the grade and the socket is the surface that matters, since a seized socket is a screw that cannot be removed.
Where a coloured finish is wanted on the head, the answer is anodising on an aluminium part or a thin PVD film on stainless. Plating is the wrong choice on a knurl: it fills the grooves that make the grip.
Three assemblies where long thumb screws are the fixing:
| Where it sits | The screw adjusts a component that sits deep inside a housing, reached through a long shank and set by hand once the thread is formed. |
| When it goes wrong | A knurl used to drive the screw folds, and the part can no longer be adjusted by hand. |
| Why it happens | The position is deep, the thread is self-tapping, and the head is small. |
| What we control | Socket depth and knurl depth checked; first article driven with the key. |
| Where it sits | The screw holds a cover at a distance where a tool cannot reach, and releases by hand for service. |
| When it goes wrong | A long shank twists under the key, and the point stalls before the thread is formed. |
| Why it happens | The joint is long, the access is awkward, and the thread is formed in sheet or plastic. |
| What we control | Pilot hole agreed; driving tested on the first article. |
| Where it sits | The screw sets a position by hand and holds it, with the self-tapping end anchored in a plastic or light-alloy part. |
| When it goes wrong | The thread strips in the plastic, and the stop no longer holds its setting. |
| Why it happens | The joint is adjusted often, the anchor is soft, and the load is light. |
| What we control | Thread form and pilot hole matched to the material; first article cycled. |
Four reasons that matter on a long, hand-adjusted part, each tied to what the drawing has to prove:
|
Both drives and the length agreed
Knurl, socket depth, threaded length and overall length are agreed as a set, because on long thumb screws the drive and the reach both depend on them. Basis: Drives and length agreed. |
Formed, knurled, socketed in one route
The knurled head is formed, the socket cut, the long shank sized and the self-tapping thread rolled within one route. Basis: One route from wire to passivated screw. |
|
Socket and knurl checked
The socket is measured for depth and the knurl for crest condition, because both are drive surfaces that wear or fill. Basis: Socket and knurl checked. |
Pilot hole recorded
The pilot hole and the driving torque are recorded from the first article, so a repeat order forms the same thread. Basis: Pilot hole and torque recorded. |
Shi Shi Tong forms long thumb screws on multi-station headers that upset the knurled cap head and cut the hexagon socket, then size the long shank, roll the self-tapping thread and grind the point before passivating the parts. The first part of every run is measured on head diameter, socket depth, knurl, shank length and thread before the batch continues.
|
|
On a long part the shank is as much of a problem as the head. A long blank deflects while the thread is rolled and while the point is ground, and a shank that has been pushed around in both operations carries a set that shows up as a screw that does not run true in its hole; the head and the thread can both be perfect.
What decides whether long thumb screws pass is the socket, the knurl, the shank, the thread and the point. The inspection agreement covers those, and the criteria come from the drawing.
Head and socket on the projector |
Thread and point checked |
Hardness checked on the wire |
Coating proved by salt spray |
The socket is checked for across flats and depth, the knurl for pitch, depth and crest condition, and the shank for diameter and length. The thread is gauged and the point checked for length and for being concentric with the thread and the shank.
The first article is driven into the customer material with the key and the driving torque recorded. A long thumb screw that needs more than the assembly station can supply will stall in production, and only that test shows it.
Every shipment of long thumb 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. The documents carry the drawing revision and the batch number, so a repeat order keeps the same knurl, socket and threaded 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 long thumb screws the first article is driven into the customer material with the key, because the thread is formed there and nowhere else. 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 point grinding station 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 |
The socket drives the self-tapping thread the first time; the knurl is for adjusting by hand afterwards, when the thread is already formed.
Not into a new hole. The knurl would fold or the head would be gripped with pliers, and the marks stay.
A long shank twists under torque, so part of what the key applies is lost before it reaches the thread. Steady driving and a correct pilot hole matter more than force.
Yes. The screw forms its own thread, and the pilot hole sets how much material it displaces.
Overall length plus threaded length; the plain shank is what passes through the clearance hole.
Head diameter and height, knurl, socket size and depth, overall length, threaded length, point and the grade.
How a long thumb screw project runs from drawing to repeat delivery:
|
1
Send the drawing and the material it enters
|
→ |
2
Knurl, socket, threaded length and point agreed
|
→ |
3
First article driven with the key
|
→ |
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, knurl, socket size and depth, overall length, threaded length, point and the grade.
|
Head diameter
|
Knurl
|
Socket
|
|
Overall length
|
Threaded length
|
Point
|
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
