Bertho Boman

Ball bearing & spring loaded pressure plate for uniform feed force regardless of filament thickness for Ultimaker 1

3D printer parts and enhancements

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Included in the zip file are:
.par =Solid Edge
For detailed instructions see:

The bearing can be found here for $7.41:
It is a Dynaroll SMR128ZZ A5

The spring OD is 7.72mm, has 8 turns of 1.14mm wire, and a free length of 20.9mm. Sorry, I do not have any part number since it came from my big junk box...

Since I needed to measure the spring used for the Ultimaker Upgrade I documented the steps both for a high accuracy measurement procedure and a simplified one.

Note, the spring for the upgrade is not critical. There is a tremendous adjustment range.

I added a section on Extruder Drive Force Measurements:

The long screw is 50mm.
The shaft screw needs to be 20mm since the yoke is 18mm.

Materials and methods

See below


  • Placeholder
    Berthos Ultimaker Extruder Drive Upgrade
    ZIP  –  1.4 mb
    Version 1 - Aug 04, 2014


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Ba2dfb12d93b502c89b217fbec54a300?default=blank&size=40perlguy added this to the Ultimaker collection ago
Mini 20070707 121041 2Bertho Boman published this design ago