What are Dynabolts or Sleeve Anchors?

close up shot of a dynabolt or sleeve anchor expansion fastener


What are Dynabolts or Sleeve Anchors?


Firstly it's important to get the naming conventions resolved. Sleeve anchors are a type of expansion bolt for masonry and concrete whilst dynabolt is a brand name.

Dynabolt is a brand of sleeve anchor made by Ramset in Australia and the name has taken on every marketeers dream of becoming synonymous with all expandinganchor bolts. The technical term though is 'sleeve anchor'.

Of course everyone will ask for dynabolts as this is now the most common term when referring to a sleeve anchor but unless the retailer is specifically selling or promoting the ramset own brand (dynabolt) of sleeve anchor they will generally sell it and promote it as a 'sleeve anchor'.

Not that this matters much but I thought it'd be good to clear that up first.


So what is a sleeve anchor?


Sleeve anchors are what we call mechanical expansion fasteners.

They fasten into concrete, blockwork or other masonry substrates by way of expansion.

They are a medium duty fastener, capable of fixing loads up into the 100s of kilos and are one of the most commonly used masonry and concrete fastener on the market.


Sleeve Anchor Bolts get their name from the way they are made - at the core a centre bolt with an expansion cone on the end, surrounded by a full length sleeve and a hex nut on top.

Heres a picture of a sleeve anchor disassembled so you get an idea of the components


sleeve anchor disassembled into parts


When you tighten the hex nut it pulls the centre bolt and expansion cone up through the sleeve and expands the sleeve.

The expansion cone is always wider than the sleeve.

Here is a sleeve anchor not tightened at all:


not tightened sleeve anchor base including expanding cone


Half tightened (around 3 full turns)


half tightened sleeve anchor bolt fastener


And heres a sleeve anchor fully tightened. This will likely never happen when fixing into masonry as you would always drill the pilot hole the same diameter as the sleeve but we thought we'd over exaggerate it slightly so its a little easier to visualise.


fully expanded sleeve anchor fastener


Thats pretty much all there is too it.

  • Drill a hole the same diameter as the sleeve.
  • Hammer in the sleeve anchor through the item you'd like to fix into the base substrate (mostly concrete)
  • Tighten up until tight 

There will be slight differences in installation process depending on what brand your using or what the manufacturers specifications are. This is just a super brief overview on the basics, how they work, how to install etc

If you'd like any more information on any fasteners at all be sure to check out our fasteners page here: Fasteners


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The Scrooz Fasteners Team