Product Guides

Chain Breaker Guide: Breaking & Rejoining Roller Chain

Shortening a roller chain, replacing a worn section, or fitting a new drive chain all come down to the same job: disconnecting the chain cleanly, then rejoining it without damaging the plates or the pin. A dedicated chain breaker — also sold as a chain puller — does this by pressing the connecting pin out of the link rather than hammering or grinding it blind, the difference between a clean job and a chain that's now unusable. This guide covers how a chain breaker (chain puller) works, what actually goes wrong when it doesn't, and the pitch range AIMS stocks it for. What AIMS Stocks — Chain Breaker & Chain Puller Range AIMS stocks genuine chain breaker and chain puller tools across two pitch ranges, covering both the ASA and BS numbering systems used on Australian industrial and agricultural chain: Tool ASA pitch BS pitch Suits No.1 Chain Breaker / Chain Puller 25 to 60 06B to 12B (1/4" to 3/4") Light-to-medium chain — common conveyor and ag drive sizes No.2 Chain Breaker / Chain Puller 60 to 100 12B to 20B (3/4" to 1-1/4") Medium-to-heavy industrial chain The two ranges overlap at ASA 60 / BS 12B — chain at that size can be handled by either tool, which is normal hand-tool jaw capacity overlap, not an error. Working with a larger industrial or mining-grade chain? Contact the AIMS team — we can talk through the right option for your chain size. Using a Chain Breaker or Chain Puller — And What Actually Goes Wrong The tool works by winding a pin down against the chain roller until it presses the connecting pin out through the far side plate, separating the link. Rejoining is the same process in reverse, pressing the pin back through. Whichever name you know it by — chain breaker or chain puller — the mechanism is the same. Before starting, check how your chain is riveted. Centre-sink riveted chain can go straight onto the tool with no preparation. Double or quad-stake riveted chain needs the rivet heads ground back with an angle grinder first — skipping this step on stake-riveted chain is the single biggest cause of a pin punching through the far plate instead of breaking cleanly, rather than any fault in the tool itself. The tool must be firmly secured — bench-mounted or clamped over solid support — before you apply pressure. It has to react against real force to push the pin through, and an unsecured tool will bounce or slip rather than break the link. Wear safety glasses; the pin can shear or the chain can shift under load. Other points that came up repeatedly across independent trade sources: Match the tool and punch size to the chain pitch — an undersized punch on a bigger pitch chain is a common cause of a failed or off-centre push For a one-off job on chain outside your current tool range, several experienced tradespeople note that grinding the rivet head and driving it out with a hammer and punch over solid support is a genuine, widely-used method Stainless steel chain is noticeably harder to rivet back together than standard carbon steel chain A connecting (master) link is the practical alternative to re-pinning altogether where one is available for the chain size — it avoids the rejoining step entirely. Clip-style master links can be fiddly to fit: opening the retaining clip with a screwdriver and rotating it into the groove, rather than forcing it straight on, is the standard technique, and the closed end of the clip should face the direction of chain travel ASA vs BS Pitch — Quick Note AIMS's chain breaker and chain puller range is specified to cover both ASA and BS pitch numbering, and BS is the more common standard in the Australian market. For the full pitch and breaking-load cross-reference between the two systems, see the numbering section of the Roller Chain Guide — no need to repeat that table here. Related Guides Roller Chain Guide — chain identification, ANSI/ISO-BS numbering, and sprocket selection Chain Lube Guide — the other half of routine chain maintenance Chain Tensioner Guide — keeping chain at correct working tension and the 3% replacement rule Frequently Asked Questions What's the difference between a chain breaker and a chain puller? In practice, very little — both terms describe the same type of tool that presses the connecting pin out of a roller chain link to disconnect it. AIMS stocks products under both names; check the pitch range rather than the name when choosing. What chain sizes does the AIMS chain breaker / chain puller range cover? Two tool sizes covering ASA 25 to 100 pitch (BS 06B to 20B) between them: the No.1 tool covers ASA 25–60 (BS 06B–12B), and the No.2 covers ASA 60–100 (BS 12B–20B) — between them, the great majority of industrial and agricultural roller chain in use in Australia. For anything larger, contact the AIMS team. My chain breaker pushed the pin through the other side instead of breaking the link cleanly — what went wrong? This is the most commonly reported issue, and it's almost always down to preparation and support rather than a faulty tool. Check your rivet style first: double or quad-stake riveted chain needs the rivet heads ground back before you start; centre-sink riveted chain doesn't. Either way, the tool needs to be firmly secured to solid support to react against the pushing force — an unsecured setup is the other common cause. Do I need to grind the chain before using a chain breaker? Only if it's double or quad-stake riveted — grind those rivet heads back with an angle grinder first. Centre-sink riveted chain can go straight onto the breaker with no grinding needed. Can I break roller chain without a dedicated tool? For a one-off job on chain outside your current tool range, yes — grinding the rivet head and driving the pin out with a hammer and punch over solid support is a genuine, widely-used trade method. For regular use, a dedicated chain breaker or chain puller is faster and lowers the risk of damaging the side plates. What do I do if my chain is bigger than what a hand-held chain breaker covers? Contact the AIMS team — we can talk through the right option for larger industrial or mining-grade chain. Is BS or ASA pitch more common in Australia? BS is the more common standard in the Australian market, though ASA-pitch chain and equipment (particularly imported machinery) is also widely used. AIMS's chain breaker and chain puller range covers both. Can I reuse a chain pin after breaking the link, or do I need a new connecting link? A pin that's been ground and pressed out can usually be reused if it isn't damaged, but a purpose-made connecting (master) link is the more reliable option where one is available for your chain size and pitch — it avoids re-riveting altogether. Why won't the clip go on my connecting (master) link? Clip-style retaining clips are tight by design. Rather than forcing it straight on, open the clip slightly with a screwdriver, seat one end in its groove, then rotate the clip into place and press the other end down. The closed end of the clip should face the direction the chain travels. Is stainless steel chain harder to break and rejoin than standard chain? Yes — stainless chain is noticeably harder to rivet back together than standard carbon steel chain, so allow extra time and expect more resistance when rejoining. Is it safe to use a chain breaker without clamping it down? No — the tool needs to react against real force to push the pin through, so it must be bench-mounted or clamped over solid support before use. An unsecured tool will bounce or slip rather than break the link cleanly, and increases the risk of the pin shearing. Wear safety glasses.