Front Beam and Pilot Part

Revised:  8/16/2012          Subject to Revisions

The author decided to design the front beam of the locomotive to compensate for the rounding of the platform on the front chassis section that sits over the pilot truck.  On a previous blog post the rounding of the front chassis section was discussed.  Rather that reprint the part it appears easier to design the pilot beam with angled extensions and use the Sherline mill to modify the front platform to match.  The pilot or cow catcher portion of the front beam assembly is rather complicated having many small bars including angled bars that brace the pilot.  The design file on the Alibre CAD is one of my larger efforts.

The above part design may be printable on the 3D printer.  If so it will prove the real worth of the machine by building complex parts with many design features.  This design has 50 features with may faces (568), edges (1541) and vertices (1051).  This is the most complex part designed to date.  It will be bonded to the front of the existing front chassis section.

The very front of the front platform that sits behind the pilot beam is curved due to part shrinkage during printing.  The curves are outside the two main frame sections.  Between the frame sections the front platform is straight.  The design of the front beam and pilot part has the mating portions of the platform angled at about 9 degrees.  The front of the front frame portion (not yet attached to the main frame) will be milled to matching angles so that when the two are mated they will line up.  The milling will proceed after printing the pilot beam part in case further modifications will be needed.

The front beam and pilot part bottom rear view is shown above to more clearly show the angle straps that support the pilot and front steps.  It also shows the hollowed out portions of the beam.  Slight engineering changes were made to facilitate 3D printing.  These were done in a fashion that would meet prototype design principles.

After 13hrs and 2 minutes the front beam and pilot part was finally finished as shown above.  The part was configured by the Axon software with extensive support material, the green ABS in the above pix.  The black ABS is the part embedded in the support material.  The composite print had no discernable problems, no separations, no warpage.

A view of the rear of the print composite shows the greatest portion of the green support ABS.  Any color could be use, I used green because much was on hand and no other print project called for that color. 

The front view of the composite print shows the pilot (cow catcher) and the pilot beam above.  All else is covered with support material.  Because of the rather thin sections of the pilot and steps to the side and their braces at the back removal of the support will need care and patience.

As material was removed the step on the fireman side of the part was broken.  It will be glued in place using super glue after the part is fully removed.  Some of the support material adheared to the foot of the step triggering the breakage when removed.  It is quite difficult to remove support from in and around such thin parts.

Needle nose pliers and side small cutter tools were used to grab and cut the material away.  Much cutting was used around the pilot and other step to eliminate forces being applied to the thin sections.

Above pix shows the part after support material removal and prior to gluing on the broken step, step sheet and back brace and removal of the green support residue on various portions.

The front portion of the frame has the front platform.  It was noticeably warped at the front.  It will be modified slightly using the Sherline model 2000 milling machine to straighten the two rounded sides to an angle that matches the newly made front beam and pilot part.  The angle is 7.89 degrees. 

Above pix shows the finished front beam and pilot part and the modified front frame part ready for glueing. 

After glueing the front beam and pilot become a portion of the front frame and pilot spreader section, the spreader is below the previously warped platform. 

Above is a trial fit of the front frame with pilot beam and pilot on the overall locomotive.  It looks real good. 

The next item on my list will be the side rods so the drivers can be coupled.