Replacement rotor holder for the PWH 2800 B2 roller shredder

With older machines, it’s common for the manufacturer to no longer supply spare parts. When such a part breaks, the owner has nowhere to buy a replacement and has to work out how to keep the machine running.

Key information

• Customer: A private customer from Petřvald
• Scope: Replacement rotor holder for the Parkside PWH 2800 B2 roller shredder

Customer requirements

The customer contacted us about a replacement rotor holder for the PWH 2800 B2 roller shredder. The machine’s manufacturer does not offer an official spare part, so there is nowhere to get one.

The customer gave us the damaged part with a slipping bearing. We measured it and produced a detailed 3D replica, which we then printed in a suitable material.

Since we saw potential in the part beyond this single job right from the start, we decided to combine developing the model for the customer with offering the part to service centres that work with these machines.

Design and choice of material

We modelled the part from the original in the CAD software Fusion 360. We then printed a PLA prototype to verify the design.

After the customer approved the design, we printed the model in two different materials, Nylon and PC Blend CF (a polycarbonate blend with carbon fibres). We put these prototypes through load and temperature tests. Based on the analysis, PC Blend CF was chosen for the final product.

As this is a heavily loaded part, we also adapted the print data for this purpose. We chose 5 outer perimeters and 35% gyroid infill. This combination of a strong outer shell and an organic inner structure gives the part much greater strength than printing with 100% infill. According to our measurements, this combination of material and inner structure is in many respects even stronger than the original injection-moulded parts.

Tolerances and precise dimensions

With technical parts like this one, dimensional accuracy is also important. While a millimetre or two usually doesn’t matter for design parts, here it can mean the difference between a correctly seated bearing and a hole that’s too small for it.

That’s why we always precisely calibrate all the materials we use, ensuring both the best possible appearance and dimensional stability. For example, for the material chosen here we have measured a shrinkage of 0.83%, and we account for it already when preparing the print data so that the part has exact dimensions after printing and cooling.

Although this is a technical part, surface quality is always a priority for us. That’s why we used HIPS as the interface layer between the support structures and the part itself, which ensures easy support removal and a perfect finish on overhangs.

Technical data

• Material used: PC Blend CF (a polycarbonate blend with carbon fibres)
• Key parameters: strength, dimensional accuracy
• Number of outer perimeters: 5
• Infill: gyroid 35%
• Production volume: 40 spare parts
• Lead time: 7 days from brief to dispatch of the complete set

Future use

We have archived all the print data, so the customer can order a new spare part from us at any time. We have also offered the part to service centres in the Czech Republic and Germany that work with these machines. These service centres have currently ordered 40 of these holders.

The advantage of a 3D-printed solution is that spare parts don’t have to be ordered for stock. Their quantity can therefore be optimised according to current demand.

Result for the customer

• A spare part that was otherwise impossible to obtain
• A part made from durable PC Blend CF
• An attractive unit price
• Assured availability of the part without having to order for stock

Do you have an older machine for which the manufacturer no longer supplies spare parts? Get in touch.

We can create a spare part from the original or from a damaged piece — and if only a broken-off fragment remains, we’ll complete the model from photos and drawings.