SDS CSK Head Screws
Countersunk head that finishes flush
CSK means countersunk. The head is cone-shaped, so it sinks into the material and finishes level with the surface.
Stocked in Bengaluru · Special sizes made to order · Bulk rates available
Available sizes
Dia × Length (mm)
- 6 x 13
- 6 x 16
- 6 x 19
- 6 x 25
- 7 x 13
- 7 x 16
- 7 x 19
- 7 x 25
- 8 x 13
- 8 x 16
- 8 x 19
- 8 x 25
- 8 x 32
- 8 x 38
- 8 x 50
- 8 x 60
- 8 x 75
- 10 x 25
- 10 x 32
- 10 x 38
- 10 x 50
- 10 x 60
- 10 x 75
Widest size range in our self drilling family — 6, 7, 8 and 10 gauge. Other sizes made to order.
Available sizes for SDS CSK Head Screws: 6 x 13, 6 x 16, 6 x 19, 6 x 25, 7 x 13, 7 x 16, 7 x 19, 7 x 25, 8 x 13, 8 x 16, 8 x 19, 8 x 25, 8 x 32, 8 x 38, 8 x 50, 8 x 60, 8 x 75, 10 x 25, 10 x 32, 10 x 38, 10 x 50, 10 x 60, 10 x 75.
What it is used for
Use this screw when the head must finish flat with the surface and not stick out.
Board on metal frame
Fixing cement, calcium silicate and gypsum board onto steel studs.
Door and window frames
Frame fixing where hinges and beading must sit flat over the screw.
Under a second layer
Anywhere another board or panel goes on top of the fixing.
Walkways and worktops
Surfaces people walk on or slide material across, where nothing can stick up.
Overview
That leaves nothing sticking up to catch on. It is the right screw wherever something has to sit flat on top of the fixing, or where people or materials move across the surface.
Our CSK screws have small cutting ribs under the head. These cut a neat seat as the screw goes in, instead of tearing the board.
Finishes flush
The cone head sinks level with the surface, so panels lie flat over it.
Cuts its own seat
Ribs under the head cut a clean recess instead of tearing the board.
Nothing to catch on
Important on door frames, worktops and any surface in use.
Widest size range
6, 7, 8 and 10 gauge, from 13 mm to 75 mm long.
Specifications
Standard stock configuration. Non-standard sizes, drives and coatings are made to order — ask us.
| Head | Countersunk cone with cutting ribs |
|---|---|
| Material | Case-hardened carbon steel |
| Finish | Zinc plated / black phosphate |
| Drive | Phillips PH2 / Pozidriv PZ2 |
| Diameter range | 6, 7, 8 and 10 gauge |
| Length range | 13 mm to 75 mm |
| Drill point | #1, #2, #3 — up to 5 mm base steel |
| Head angle | 82 degrees |
| Best for | Cement board, calcium silicate, gypsum, light sheet, timber |
| Packing | 250 / 500 / 1000 piece boxes |
Technical documentation
Exact specifications vary between manufacturers and production batches. Tell us the job and we will confirm the specification before despatch, and send the manufacturer’s datasheet or test certificate for the batch if you need it for a submittal.
Section 1 — Installation
How to fit it
Everything depends on sinking the head level without going too far. In board, the difference between a clean finish and a broken hole is about a quarter turn.
Drawing made for Modern Fastening Solution. Shown for guidance — check against your own job before ordering.
- 1
Support the board behind the fixing
A cone head pushes outwards as it sinks. Unsupported board will flex, then crack.
- 2
Start slow and straight
Let the tip find its centre before speeding up. A crooked start makes an oval recess that never sits flat.
- 3
Let the ribs do the cutting
As the head reaches the surface, hold a steady speed. Pushing harder just tears the board.
- 4
Stop at flush
Level with the surface is the target. Use a depth stop if you are fixing a lot of board.
- 5
Fill and finish
For a painted finish, fill the small recesses and sand once dry.
Section 2 — Applications
Where it is used
Anywhere the surface has to stay flat and clear.
Metal roofing and decking
Decking and sheet where the fixing has to finish flush with the surface.
Steel framing
Light steel framing and girt connections in fabrication work.
Ducting and HVAC
Duct and fitting assembly where a raised head would catch.
Panel fixing
Board and panel fixed to steel studs, ready for finishing over the top.
Electrical panels
Enclosure and control panel assembly needing a flush, clean face.
Signage and fascia
Sign faces and fascia panels where nothing can be left proud.
SDS CSK Head — questions we get asked
Do I need to countersink the hole first?
No. The ribs under the head cut their own recess as the screw goes in. That is the point of this design.
Can I use CSK screws on a metal roof?
No. They cannot take a rubber washer, and sinking the head makes a dip in the sheet where water collects. Use hex head screws for roofing.
Which size is most commonly used?
8 x 25 mm and 8 x 32 mm move fastest for board on steel framing. We stock 6, 7, 8 and 10 gauge.
What drive should I use for a lot of board fixing?
Pozidriv PZ2 with a depth-stop nose cone. It grips much better than Phillips over long runs and gives the same depth every time.
Request a price for SDS CSK Head
Send us the sizes and quantities and we will come back with a price, usually the same working day. Not sure of the size? Describe the job and we will work it out.
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View specificationsTell us what you need
Send us the sizes and quantities, a photo, or just a description of the job. Most quotations go out the same working day.
Monday – Saturday, 9:30 AM – 7:00 PM · Delivery across Bengaluru, Karnataka and all India