New Gears for an O Scale Rivarossi F9 Revisited

Back in February of 2015 I shared with you my 3D printed replacement gears for the Rivarossi O Gauge F9, you can read the post here.  Since producing the gears we have picked up a few anomalies in the different Rivarossi locomotives, mainly caused by a large manufacturing tolerance, that causes an issue with the gears.  In this post I will be showing you the new updated gears.

Although the 3D printed gears are vertically identical to the original Rivarossi ones they have been coming out at about 0.3mm to 0.5mm larger in diameter than anticipated.  For the majority of the Rivarossi O Gauge F9s that were fitted with the new gears, this had no impact as there was room for this.  But a few seemed to bind up.  The problem was traced to the 3D printed gear teeth hitting the corresponding gears root.  The root is the bottom of the gap between the gear teeth.

To solve this the 3D printed gears teeth where reduced in length by a fraction each reducing the overall diameter of the gear.

Below is an image with all three gears.  On the left is one of the first run of 3D print gears, in the middle is the original injection molded gear and on the right is the new 3D printed gear.

Rivarossi o Scale Gears 1

Although it is hard to see, as the difference is small, the teeth on the new gear are slightly shorter than on the first run.  This will make the new gears mesh perfectly with all the existing Rivarossi gears even if the drive gear position is a bit out of tolerance thus eliminating the problem that arose with a few models.

All the gear pack in my shop have been updated to the new versions and you can get them here.

Mike Dobson is the fellow modeler who first asked me to 3D print the gears to repair his locomotives and below you can see the new gears fitted to a chassis under a Great Northern GP7 shell.

Rivarossi F9 (O Scale Gears 6 (Mike Dobson)

As you can see below Mike has several sets of axles already repaired with the new gears ready to be fitted to his locos.

Rivarossi F9 (O Scale Gears 7 (Mike Dobson)

Rivarossi F9 (O Scale Gears 8 (Mike Dobson)

With the locomotive reassembled, it was time for a test run.  Mike storage yard is above his layout in the roof and there is a fair climb up to it.  This is a great test for the gears.

Rivarossi F9 (O Scale Gears 9 (Mike Dobson)

And finally we have a video of his repaired GN GP7 running on Mike’s layout.

And that ‘wraps up’ my last post before Christmas, but not wanting to leave you with out a gift, the nice people at Shapeways are having 15 days of deals to close out 2015, and today’s deal is $10 off all Frosted Detail Plastic orders of $30 or more!  As all the gears and my locomotive shells and detail parts are printed in Frosted Detail Plastics this could be useful.  Simply enter the code FROSTY2015 at the checkout.  This offer ends at 11:59PM Pacific Time on the 21 December 2015.

Happy Christmas