Build a Fourth Set of Tender Wheels - One Side Insulated

Last Revised:  1/14/2014          Subject To Revisions

New Direction - Insulated Wheels

Decided that I should make the locomotive capable of running on a G scale layout with conventional DC power applied.  Although the project will be powered with a novel internal DC motor driven air compressor powered by rechargeable batteries and radio controlled, it should be able to run on a layout without interference with normal track power.  Indeed, the track power could be used to recharge the batteries.  At this moment, the batteries and charger will be mounted in the tender with the compressor and drive motor in the locomotive.   The radio receiver and servos have yet to be located, but they are generally very small.

To accomplish this, two varieties of tender wheel are needed.  The wheel on one side is directly attached to the axle while the other side is separated by a plastic insulator, probably Delrin.  I redesigned the wheel to obtain one that provides for the addition of an insulated wheel spacer.  Both wheels will be pressed on the axle as was done before with the previous uninsulated design. 

At the moment, electrical contact for the battery charger will be obtained by placing the insulated side of the tender on one rail and the insulated side of the locomotive on the other.  Diodes will be used so that polarity will not be an issue for the battery charger.  Only the charger will be powered by track power, all else will come from the batteries in the tender. 

Building Wheel Disc Blanks

Using my horizontal band saw, eight pieces of 1.25" 6061 T6 aluminum bar stock were cut to about 1/2".  These are the starting point for both the insulated and uninsulated tender wheels.

Eight New Aluminum Blanks Cut From 1-1/2" Bar Stock With Prior Uninsulated Wheel Set

Each part was mounted in the lathe three jaw chuck spaced 1/4" from the chuck face and a G-code program used that trimmed the outside diameter and face cut the part.  The overall thickness of the blank will be trimmed using the mill which can trim the thickness faster than the lathe. 

Wheel Disc Blank Being Turned in The Lathe to Get A Controlled Diameter and Flat Face

All parts were drilled to a little over 1/4" using my 1/4" drill bit and four were then four were bored to 0.2535" diameter center holes for the insulating spacers.  Each part was marked so I wouldn't mix them up during subsequent operations.

Disc Blanks Marked With Center Hole Diameters

 

Now that the Holiday's are over and winter has set in I hope to make more rapid progress with the tender wheel sets.  In a forthcoming revision I will show the wheel disc holding tool being made to thin the wheel blanks down to a bit more than required for milling the outside and inside contours and the tire contours.  They are much to thick for those steps now, nearly double what is need for my existing G-codes for those operations.  The Insulated wheels will require either a manual narrowing of the region around the axle hole to allow for the insulator flanges or modification of the G-codes.  I'll be looking into how much it will take for the G-code modifications vs simply trimming down the center regions around the axle holes manually.