FreeCAD News

4 responses to “WIP Wednesday, 7 January 2026”

1. 

   Usuario

   January 9, 2026

   Fil­let tool allows invalid radius when applied to mul­ti­ple con­nect­ed edges
   Description
   While test­ing FreeCAD 1.2.0 (devel­op­ment ver­sion), I observed unex­pect­ed behav­ior when using the Fil­let tool with mul­ti­ple con­nect­ed edges.
   When a fil­let is applied simul­ta­ne­ous­ly to two edges that are both con­nect­ed to the same adja­cent edge, and the spec­i­fied fil­let radius exceeds the max­i­mum geo­met­ri­cal­ly pos­si­ble val­ue, FreeCAD enters an incon­sis­tent or unclear state instead of prop­er­ly han­dling the invalid input.
   From a geo­met­ric stand­point, such a fil­let can­not be con­struct­ed with the giv­en radius. How­ev­er, the tool does not clear­ly reject the oper­a­tion, nor does it pro­vide an under­stand­able error mes­sage explain­ing the limitation.
   ________________________________________
   Steps to reproduce
   1. Cre­ate a sol­id with three con­nect­ed edges, where two edges share the same adja­cent edge.
   2. Select the two edges that meet at the same segment.
   3. Acti­vate the Fil­let tool.
   4. Set a fil­let radius larg­er than what the geom­e­try allows.
   5. Con­firm the operation.
   ________________________________________
   Expect­ed behavior
   FreeCAD should han­dle this sit­u­a­tion more explic­it­ly, for exam­ple by:
   • Reject­ing the oper­a­tion and dis­play­ing a clear error mes­sage, or
   • Auto­mat­i­cal­ly lim­it­ing the radius to the max­i­mum valid val­ue, or
   • Pro­vid­ing feed­back explain­ing why the request­ed fil­let can­not be created.
   ________________________________________
   Actu­al behavior
   The fil­let oper­a­tion fails or behaves unex­pect­ed­ly, with­out clear feed­back indi­cat­ing that the fail­ure is caused by a geo­met­ric lim­i­ta­tion of the select­ed edges.
   ________________________________________
   Addi­tion­al information
   This behav­ior can be con­fus­ing for users, espe­cial­ly when apply­ing fil­lets to mul­ti­ple edges at once. The lim­i­ta­tion is pure­ly geo­met­ric, but it is not clear­ly com­mu­ni­cat­ed by the tool.
   The same behav­ior is also present in FreeCAD 1.1 RC2.
   ________________________________________
   Ref­er­ences / Visuals
   • Fil­let tool, radius = 9.99
   https://imgur.com/ghPryKI
   • Fil­let tool, radius = 11.00
   https://imgur.com/MG2s4zI
   • Visu­al expla­na­tion of the geo­met­ric limitation
   https://imgur.com/fT05PCR
   • Max­i­mum pos­si­ble radius definition
   https://imgur.com/73ClvYl
   • Edge selec­tion examples
   https://imgur.com/cblv0ss
   https://imgur.com/G7xdR0r
   ________________________________________
   I have sev­er­al pic­tures that clear­ly show the sit­u­a­tion, but unfor­tu­nate­ly this blog does not allow image uploads.

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   1. 

      Aleksandr Prokudin

      January 9, 2026

      Thank you for tak­ing the time to report this. How­ev­er, this is a well-known issue with­out an obvi­ous solution.

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      1. 

         Blaise Pascal

         January 10, 2026

         Hel­lo,
         I am not a devel­op­er, but I believe that in this case more could be done to address the errat­ic behav­ior of the Fil­let tool.

         In par­tic­u­lar, it may be worth review­ing the imple­men­ta­tion of Fil­let when it is applied simul­ta­ne­ous­ly to two edges that are con­nect­ed by a third, com­mon edge. In the usu­al case, when the fil­let radii pro­duce tan­gent cir­cles whose cen­ters lie on the same side of the com­mon edge, the algo­rithm appears to work correctly.

         How­ev­er, when a con­fig­u­ra­tion occurs in which the fil­lets have their cir­cle cen­ters on oppo­site sides of the com­mon tan­gent edge, the tool fails, even though the result­ing geom­e­try appears to be well defined from a geo­met­ric point of view.

         It is pos­si­ble that the approach used for the case where the cen­ters lie on the same side is already imple­ment­ed and works cor­rect­ly, but that this same log­ic is not applied—or does not work properly—when the cen­ters are locat­ed on both sides of the com­mon edge. Review­ing whether this approach can be extend­ed or adapt­ed to this sec­ond case could help improve the robust­ness of the fil­let algorithm.

         This imple­men­ta­tion works well.

         https://imgur.com/fDUNNJu

         This imple­men­ta­tion does not work well.

         https://imgur.com/rx66YPD

         Thank you for your attention.

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2. 

   Michael Mulligan

   January 10, 2026

   The addi­tion of diam­e­ter mea­sure­ment (PR#24853) may seem like a small thing, but it will save me much effort. Thank You.

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