FreeCAD News

We’ve fea­tured a few projects under the “Forged In FreeCAD” title but what caught our eye with this one is that FreeCAD was used to not only cre­ate an inno­v­a­tive solu­tion, but also was used to then help oper­ate the cre­at­ed machine. 

Project cre­ator Jor­dan Poles had a bur­geon­ing inter­est in lath­es and want­ed to make an engraved brass ring. The lathe aspects were cov­ered as Jor­dan owned a small 7×14 style lathe and so turn­ing a ring blank from a piece of brass bar stock was no problem.

For the engrav­ing side of the project Jor­dan want­ed to utilise their CNC3018 machine. If you don’t know the CNC3018 it is an afford­able entry point for desk­top small form fac­tor CNC rout­ing. They are small and, whilst there are lot of big­ger and bet­ter options, it has enough capa­bil­i­ties for those new­er to CNC to do lots of projects. As such it’s not uncom­mon to see hacks and mod­i­fi­ca­tions car­ried out on them.

Jordan’s mod was to cre­ate a 4^th axis which could also be referred to as a rotary axis. The design con­sists of a NEMA 17 step­per motor in an enclo­sure that allows it to be bolt­ed to the bed of the small CNC router. Attached to the out­put shaft of the NEMA 17 is a work hold­ing sec­tion designed to receive the blank stock ring. It’s sort of a man­drel work hold­er with the ring insert­ed over a flex­i­ble jawed sec­tion with the jaws pushed out with a wedge device. The end of the work hold­ing sec­tion is sup­port­ed on a “tail stock” of sorts which con­sists of some rollers in a 3D print­ed enclo­sure again bolt­ed to the bed of the CNC. This allows the part to be machined with min­i­mal deflec­tion as both ends of the man­drel are sup­port­ed. FreeCAD has been used for all of this design and the files can be found over on the project Thin­gi­verse page.

For the engrav­ing process Jor­dan has cre­at­ed a design as an SVG file which is then import­ed into the Draft work­bench in FreeCAD. Mov­ing to the CAM work­bench, Jor­dan then cre­ates the tool paths as if the object is a flat piece of work and not cylin­dri­cal. The CNC3018 is con­trolled by a board run­ning GRBL and the rotary axis assem­bly is actu­al­ly con­nect­ed to and replaces the Y axis of the machine. This means that if the X and Z axis are posi­tioned care­ful­ly and accu­rate­ly above the ring in the rotary attach­ment then the work under­neath the tool bit is the same as a flat piece of stock as the ring rotates. 

It’s excel­lent to see FreeCAD being used in this mul­ti-func­tion­al way. There’s lots more detail over on Jordan’s blog and some videos of the set­up in use.