Gantry Crane – Part II

The Trucks
I figure that’s as good a name as any.

There are two ‘trucks’ mounted under the connecting/frame H-Beam. Each truck is made up of two 3/16″ channel and bits and pieces

Let’s take a closer look at a single truck.

It is made up as I said, from two pieces of channel. A shorter piece of channel at either end along with appropriate angle and rivets make up the truck body.

In the drawing to the left I have dropped one wheel/bearing assembly down so we can get a better view.

Finally, let’s zoom in to that wheel/bearing assembly.

The assembly was designed so that ‘hopefully’ I can actually put this together. While it is easy enough to create parts virtually .. it’s often harder (usually a lot harder) to re-create them for real. The biggest problem here is simply the small size of everything. With that in mind I tried using ‘off the shelf’ components to build it.

The complete bearing assembly is at (A). It consists of a thick plate (B) with two ‘wings’ on either side (C). This is ‘bolted’ to the inside of the channel (D). Running through the center is the actual bearing.The bearing itself that the N-scale axle set rides in is made up of two sizes of Evergreen tubing. I cemented the .093″ dia tube (F) inside the .156″ dia tube (E) and then notched it after the cement had set up. Everything else is stock Evergreen Styrene except for the bearing cap (G). That’s the pupil from a ‘wiggly eye’. You can buy them at Walmart or Michaels .. you get a good selection of round plastic pieces for projects.

  • B – Evergreen #147 .040″ x .156″
  • C – Evergreen #124 .020″ x .080″
  • D – Tichy #8142 2″ Washer 1.25″ Nut
  • E – Evergreen #225 .156″ O.D. x .100 I.D.
  • F – Evergreen #223 .093″ O.D. x .039″ I.D.
  • G – Pupil from Wiggly Eye
Interim progress: 8:58 AM – 06 Aug 2012
The channels were easy enough as I set up my NWSL Chopper to do that (I really would like a way to add a micrometer adjustment to the stop. That would be SO helpful). I glued the smaller tubing inside the larger, let that set up and then used my Proxxon mini-mill to cut the notch in the end. That required making the tubing quite a bit longer so I could hold it in the vice .. call it ‘Sacrifice Styrene’. The .156″ sq. bits .. the large ‘plate’ are a pain as trying to hold that and file a slight taper on the back top and bottom edges (the inner faces of the top and bottom of the channel have a slight taper). Funny – I’ve been quietly griping about my Proxxon mini-mill being TOO mini. Then I come to things like this .. and it’s TOO BIG!! 🙂

Currently .. I am slowly filing the plates as needed to fit the channel profile and cementing them in place. I’m using the depth rod on my dial-calipers to set this precisely.

Version 1: 8:37 AM – 09 Aug 2012
There’s really something to ‘taking note’ of what you did wrong and then correcting it next time. Hopefully.

I’m going to call this ‘Version 1’ of my trucks. Looking back I – I was concerned too much with trying to make the ‘bits and pieces’ regular and ‘looking right’ .. and did not think though the alignment issues. Either those ‘T-Pin’ axles should have been used to align everything prior to cementing together .. or (and probably a better idea) the tubing should have been on piece, aligned, cemented and after letting set up the bit in the middle removed.

Version 2 – I will be using several jigs to FORCE alignment of everything. The tubing/bearings .. instead of trying to align two small lengths of tubing .. leave as one long tube. That center section of the truck can then be milled out after the truck sets up (hopefully. If the cement welds everything together nicely that is)

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