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
Place of Origin:Guangdong,China(Mainland)
Brand Name:Shi Shi Tong
Materials:Stainless Steel
Surface treatment:Natural colour, passivated
Head Type:Cylinder Head
Knurl:Diamond pattern, depth to the drawing
Drive:Knurled rim and slot
Thread:Machine thread
Point:Plain, chamfered
Size:M6*25mm,Diameter 15.5mm
Forming:Turned from stainless bar: head turned to diameter and height, knurl cut into the rim, slot cut in the top face, thread cut or rolled; cleaned and passivated
We turn stainless knurled head screws with a diamond pattern on the rim and a slot in the face, quoting head diameter, knurl depth and thread to the drawing. A hand can only give a couple of newton metres, so the head diameter is the lever and the knurl is the grip that has to last through the adjustments.
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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 knurled head screw has a patterned grip machined into the head so it can be turned between the fingers. This one is stainless steel with a 15.5 mm knurled cylinder head, a single slot and an M6 thread 25 mm long, supplied in its natural colour and quoted to the clearance around the head.
Knurled head. A diamond pattern on the rim, giving the fingers something to push against.
Slot. A single slot in the top face, so a blade can be used when fingers are not enough.
Stainless body. No coating, no rust, and a bright natural finish.
Machine thread. A fine thread for a tapped hole or a nut, with a plain chamfered point.
They are used on knobs, adjustment screws, equipment covers and instruments where the fixing is opened by hand and needs no tool at all, and where the joint is set by feel rather than by a torque value.
A knurled head screw is turned by hand, and a hand is a poor driver. Between finger and thumb most people can produce a couple of newton metres on a head this size, and that value falls as the fingers slip and the knurl smooths. The joint is therefore designed for what a hand can give, and the head diameter is the lever arm that produces it.
That is why the head on a knurled head screw is wide for its thread. A 15.5 mm head on an M6 body is not decoration: the knurl sits at the rim, so the torque is applied at the largest radius the part allows, and a wider head converts the same finger pressure into more turn.
The knurl itself has a life. Its teeth are small, and each turn wears the crests against a fingertip or a glove; over a few hundred cycles the pattern flattens and the grip drops. A knurled head screw that is turned often is a consumable part in that sense, and the pattern depth is what sets how long it lasts.
The slot is the back-up. When a knurled head screw has been tightened by hand and needs one more turn, or when the joint has been sitting for a year, a blade in the slot gives the extra torque the fingers no longer can. On a head this diameter the slot is also what a production line uses instead of bare hands.
Stainless suits the application because the part is handled, not just driven. There is no plating to wear off under fingers, the natural colour matches most equipment, and the head does not rust where a thumb rests on it.
So a knurled head screw is specified by the hand rather than by the tool: a head diameter for leverage, a knurl depth for grip and life, a slot for the last turn, and a thread that suits the joint it closes.
Knurled head screws are quoted by head diameter and height, knurl type and depth, slot width and depth, thread size and pitch, length, and finish. Custom lengths up to 2,000 mm, subject to DFM review after drawing submission. The quotation carries the material, the head, the knurl, the slot, the thread and the finish.
| Item | How it is defined | What we control |
|---|---|---|
| Body | Stainless steel | Grade and condition |
| Head | Cylindrical, knurled | Diameter and height |
| Knurl | Diamond pattern | Tooth pitch, depth and grip |
| Slot | Single slot | Width and depth |
| Thread | Machine thread | Size, pitch and length |
| Finish | Natural colour | Surface condition and burr |
The knurl depth is written as a dimension. It is the feature that does the work, and a pattern cut shallow looks right in a box and slips between dry fingers.
The head height is written with the slot depth, since the slot is cut into the same material. A head that is reduced for appearance takes the slot with it.
The thread is written for the joint. On a hand-tightened knurled head screw the thread is rarely near its limit, but galling in a stainless nut is, so the thread class and any lubricant belong on the drawing.
Four properties decide this part, and each carries a cost:
| Property | What it gives | What it costs |
|---|---|---|
| Knurled head | A fixing opened without a tool | Hand torque is only a couple of newton metres |
| Wide head | Leverage and a bearing face | Stands proud, and takes space |
| Slot | A way to add torque later | Another feature to cut and check |
| Stainless body | No plating to wear under handling | Galls in a stainless nut |
The value is a fixing that any user can open and close with their fingers, and that a technician can still tighten with a blade when the joint needs it.
The cost is a low torque ceiling and a knurl that wears smooth: the part suits adjustment and light clamping, and not a joint that has to hold a high preload, which is why it is rarely specified where the clamp load is the design driver.
The recorded finish is the natural colour of the stainless, cleaned and passivated. On a knurled head screw that is more than cosmetic: a plated rim would wear through at the knurl crests within weeks of handling, and the pattern would then look blunt even where it still grips.
| Option | How it protects | Effect on the knurl | Typical use |
|---|---|---|---|
| Natural stainless | Natural oxide | No build; teeth stay sharp | Instrument knobs |
| Passivated | Clean, thickened oxide | No build; free of free iron | Laboratory equipment |
| Black oxide | Conversion layer | Thin; matte pattern | Dark equipment |
| Coloured anodising (aluminium) | Grown oxide | No build; colour in the teeth | Lightweight knobs |
| Nickel plated steel | Hard barrier layer | Builds; teeth softened | Cost-driven parts |
On a plated version the knurl is the first place the coating fails, because it is the highest point and the one that is touched. That is why hand-turned parts are usually supplied in natural stainless or anodised aluminium rather than plated steel.
Where the part is opened often, a dry film lubricant on the thread is worth more than any finish: it keeps the stainless from galling so the hand-tightened joint can be undone by hand.
Three products where the fixing is turned by hand:
| Where it sits | The screw sets a position and is turned in small increments by the user. |
| When it goes wrong | The knurl smooths and the adjuster slips, or the screw creeps. |
| Why it happens | The knurl depth is too shallow and the thread is too loose for hand setting. |
| What we control | Knurl depth and thread class agreed; sample turned by hand through a cycle. |
| Where it sits | The cover is opened for access without a tool, and closed again by hand. |
| When it goes wrong | The screw cannot be turned by hand, or it works loose in service. |
| Why it happens | The head is too small for the fingers, and there is no lock in the joint. |
| What we control | Head diameter and knurl set for fingers; sample opened and closed. |
| Where it sits | The screw locks a sliding or tilting element that is adjusted on set. |
| When it goes wrong | The head catches on a case, or the screw marks the rail. |
| Why it happens | The head is too wide for the clearance, and the face is not flat. |
| What we control | Head diameter and clearance checked; sample adjusted in place. |
Four points that decide whether a hand-turned screw stays usable:
|
Knurl and head written as dimensions
The drawing gives the knurl depth and the head diameter, because those two are the grip and the leverage. Basis: Grip and leverage fixed. |
Head turned, knurl cut
The knurl is cut into the finished head, so the teeth sit on the diameter the drawing calls for. Basis: Teeth on the finished head. |
|
Turned by hand
The first article is turned between dry fingers and with a blade, the way the part will be used. Basis: Grip proved by hand. |
Same pattern every lot
Knurl depth, head diameter and thread are recorded with the drawing revision, so a repeat lot feels the same. Basis: Same feel across lots. |
A knurled head screw is bought for a feel rather than a number. These four points turn that feel into something that can be repeated from one batch to the next.
These screws are turned from stainless bar: the head is turned to diameter and height, the knurl is cut into the rim, the slot is cut in the top face, and the thread is cut or rolled before cleaning and passivation. The first piece of every run is measured on head, knurl, slot, thread and length.
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The knurl is cut with a fine tool and checked by hand as well as on the projector. A pattern that is a little shallow measures close to nominal and still slips, so the hand test is part of the first-article approval rather than an optional extra.
The slot is cut after the knurl so the two are centred on the same axis. An off-centre slot makes the blade pull the screw sideways, which on a hand-turned part shows as a wobble when the joint is adjusted.
Stainless work-hardens at the cut, so the knurl and the slot are finished with light passes. A torn tooth on a knurled rim is felt immediately, because it is exactly where the fingers sit.
What decides whether a batch of knurled head screws passes is the grip the knurl gives, the slot that backs it up and the thread that holds the setting. The inspection agreement covers all three.
Head and knurl on the projector |
Thread checked with gauges |
Material checked |
Salt-spray testing where required |
The knurl is measured for tooth pitch and depth and then turned between dry fingers. That test is subjective, which is why it is written into the sample approval: two inspectors should agree on the same feel before a batch is accepted.
The slot is measured and driven with the blade at the torque the joint needs. On a hand-tightened part the slot is the only way to add torque, so a shallow slot removes the back-up as well as the drive.
The thread is gauged and run into its nut by hand. On a knurled head screw the joint is turned by fingers in service, so a thread that needs a tool to run down is the wrong thread for the part.
Every batch of knurled head screws is traceable to the bar it was made from. The material certificate states the grade, the heat number, the chemistry and the mechanical properties, and the inspection record carries the head, knurl, slot and thread against the drawing.
ISO 9001:2015 |
RoHS test report |
Registered trademark |
Patent: security screw and driver |
With each shipment we supply the material certificate and the inspection record for the head, knurl, slot and thread. The records carry the batch number, so a repeat order can be compared with the first on the knurl depth that decides the grip.
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 hand-turned part the first article is turned by hand rather than measured only, because grip is part of the specification. Buyers visit during the process to review samples.
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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 turning cells 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 |
A couple of newton metres on a head this size, falling as the fingers slip. It is a hand-tight part by design.
The slot. A blade gives more than fingers, which is why the slot is cut into the face.
The teeth wear. The pattern depth sets how many cycles it survives.
It is the lever. A wider head turns the same finger pressure into more torque and gives a larger bearing face.
Stainless can gall in a stainless nut. A dry film lubricant keeps a hand-tightened joint undoable by hand.
Head diameter and height, knurl type and depth, slot width and depth, thread, length, finish and the clearance around the head.
How a knurled head screw project runs from drawing to repeat delivery:
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1
Send the drawing and the clearance around the head
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→ |
2
Head, knurl and thread agreed
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→ |
3
First article turned by hand
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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 used for the first article is what repeat orders are checked against.
For a quotation, send the drawing with the head diameter and height, knurl type and depth, slot width and depth, thread and length, and the finish.
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Head dia
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Knurl
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Slot
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Thread
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Length
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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
