WEINIG MACHINERY FAQs: Serrated knives & your Powermat
- PWT
- 6 days ago
- 3 min read
When customers transition from a conventional spindle-type moulder to a Weinig HSK Powermat-type machine, the emotive subject of tooling always comes up. With some exceptions, most conventional blocks will no longer be needed. In reality, however, it’s the profile knife that’s the valuable asset – not the cutterblock itself
Q: Can I use my existing serrated knives in new Weinig PowerLock cutterblocks?
A: Yes, it’s possible to use existing profile knives in new PowerLock cutterblocks if the serrations are set at 60°.Examine the serrations carefully – there’s two methods of producing them: grinding or rolling. Grinding is the more accurate method, ensuring matched pairs. This is important because the knife steel is harder than the cutterblock steel and can cause irreparable damage if the serrations don’t match perfectly.
Balance is the other critical factor, which is why Weinig always refer to matched pairs. Opposing knives in a cutterblock that weigh differently cause exponentially increasing vibration as the cutterblock speed increases. Vibration negatively affects finish quality, bearing life and safety.
Q: Can you explain what ‘matched pairs’ means?
A: With Weinig PowerLock tools running at up to 12,000rpm, you’re dealing with precision engineering where balance and centrifugal forces are significant. Knives should only be purchased as matched pairs from your supplier, arriving in sealed packaging, with each knife’s weight matching within 0.1g.
Always verify this with a reliable set of electronic scales when opening a new pack. Knives should also be weighed again after rough profiling. Steel density can vary – especially in cheaper knives – and material removal can lead to an imbalance. You might detect this during grinding, when the wheel moves across hard and soft spots – this is a common sign of poor-quality steel.
Q: What knife lengths are available?
A: First, match the profile dimensions to the knife length. Weinig supplies balanced, matched pairs from 40mm to 322mm. It’s strongly recommended to match the knife length to that of the cutterblock, which ensures balance, optimal finish and extended bearing life.
Q: What knife depths are available?
A: There are three depths of 8mm-thick serrated knives, depending on profile depth:
50mm depth for profiles up to 15mm
60mm depth for profiles up to 25mm
70mm depth for profiles up to 35mm
Always ensure at least 15mm of the knife is clamped by the wedge.
Q: Can I use a knife that’s longer than the cutterblock?
A: Very simple answer: definitely not. Match the knife length to the profile, then to the cutterblock.
Q: Can I use a short knife in a longer cutterblock?
A: This practice isn’t recommended but is feasible with caution. Never leave part of the cutterblock pocket empty – use blanking pieces of the exact same thickness as the knife, so the wedge secures both parts evenly. These blanking pieces must also be matched pairs.Finish issues can occur in this setup due to the increased number of components needing balance: profile knives, blanking pieces, wedges and screws. Each might be slightly off and those small imbalances can add up to cause tool vibration.
Q: What’s the best method for setting knives in the cutterblock?
A: Once you’ve selected the correct knife length and depth, and verified they’re a balanced pair, Weinig recommends using a swivel, bench-mounted HSK stand. This safely secures the cutterblock, giving you both hands free to mount the knives precisely, using an HSK setting disc for accurate alignment.
Q: All serrated knives are the same, so does it just come down to price?
A: If your decisions are based solely on the lowest purchase price, we’re surprised you have a Powermat! It should never be just about cost – best moulder + cheap tooling = finish issues, just as cheap moulder + best tooling = finish issues. What you’re being sold might look the same, but is it really?
FURTHER INFORMATION
Michael Weinig (UK) Limited
T: 01235 557 600
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