DIN 7979 Extractable Dowel Pins
Extractable dowel pins carry an internal thread in one end so the pin can be drawn back out of a blind hole. DIN 7979 covers two types, both with the extraction thread - type D in hardened and ground steel and type C in A1 stainless steel. We supply both, available across a range of metric and inch sizes.
Also known as: extractable dowel pin, internal thread dowel pin, threaded dowel pin, pull-out dowel, din 7979, bs 1804 dowel.
DIN 7979 (BS 1804 Pt 3) dimensions
| Nominal diameter | Extraction thread |
|---|---|
| 4mm | M2.5 |
| 5mm | M3 |
| 6mm | M4 |
| 8mm | M5 |
| 10mm | M6 |
| 12mm | M8 |
| 16mm | M10 |
| 20mm | M12 |
Materials & strength
Internal extraction thread
A tapped hole in the exposed end accepts a puller or extraction screw, so the dowel can be drawn back out of a blind hole without access to the far side.
Air-release flats
Flats are provided as standard on this pattern, releasing the air trapped when the pin is pressed into a blind interference hole and preventing pressure build-up behind it.
Type D and type C
DIN 7979 Type D pins are hardened and ground steel. Type C pins are stainless steel (1.4305/A1) and are not hardened. Both types carry the internal extraction thread in one end.
Related specificationsWhen is an extractable dowel needed?
Whenever the dowel sits in a blind hole and the assembly is expected to come apart again. A plain dowel in a blind hole has nothing to drive against; the internal thread gives a purchase for withdrawal.
How is the pin extracted?
A screw, stud or slide-hammer adaptor is wound into the internal thread and the pin is drawn straight out. No heat or drilling is involved, so the hole is preserved for the replacement pin.
What thread does each diameter carry?
The extraction thread steps up with the pin diameter - from M2.5 in the 4mm pin to M12 in the 20mm pin. The table on this page lists the pairing for each metric size.
How do these relate to BS 1804 extractable dowels?
Metric extractable dowel pins are commonly supplied to DIN 7979 dimensions; where BS 1804 conformance is required, confirm with us.
Need DIN 7979 (BS 1804 Pt 3) in a non-standard size or material?
Send us your drawing — specials quoted within 24 hours.