Western Star 4900 SB - Bridge Inspection Truck

[BK9300]

22 hours ago, Scott Eriksen said:

I've seen Cat-track  material somewhere ...I think R/C stuff ,,,might be worth an innerweb search

I did have a look around at what's available for cable carriers that might work.  The searches quickly led to several kinds of carriers, or drag chains, for CNC routers and 3D printers, but the smallest turned out to be too big.  I may be leaning towards 4 mm, Wave springs as a possible solution.  An unsolved problem at the moment!

Paint booth still down for a day or two, so, until I'm back at the plow truck, more puttering with ideas about how to start in some of the Snooper's fabrication.  Like for the plow truck sander, I did an 'exploded' view of the main tower's upper section. 

 

Exploded view - counter weight assembly, tower support frame, slew drive motor, Boom 1, parallel levelling arms for tower 2 and the upper portion of tower 2, at the end of Boom 1 -

 

Can't say enough about how much help the 3D model will be to me, for figuring out a path forward.  Itching to get started! 

Edited August 4 by BK9300
typo

[Randy D]

WOW!!  this is going to be an epic build Brian.  So many  cool parts to create!

 

Randy

[BK9300]

16 hours ago, Randy D said:

WOW!!  this is going to be an epic build Brian.  So many  cool parts to create!

 

Randy

Thanks, Randy - no shortage of fabricating required here!

[BK9300]

Still don't have my paint booth operational yet, so, did some work refining the slew drive bearings for the two towers on the Snooper.  The outer ring gear that I had test printed needed to be modified, to include the inner portion of the bearing, so I could attempt to make the tower(s) rotate and be posable.  My version of a drive bearing is not like the real deal, but should allow me to seat the outer ring between two halves of the inner ring and end up with a unit that rotates (manually!)

 

Main tower drive on 3D model -

 

Sample, real slew drive bearing -

 

I plan to make the inner portion of the bearing in two halves, out of styrene, and glue (bolt?) them together around the resin, outer ring gear.  For now, @Bren is test printing everything in this modified design, to see if it is workable -

 

 

Still testing out other ideas in the 3D model, working out more 'how to' stuff.  Should be back to the plow truck later this week!

 

 

Edited August 9 by BK9300
typo

[Biggu]

Another world class build coming ....................  I'm sitting quietly in the front row..... eyes wide open....

[BK9300]

9 hours ago, Biggu said:

Another world class build coming ....................  I'm sitting quietly in the front row..... eyes wide open....

Thanks, Jeff - should be able to start in on it, in about a month!

[BK9300]

Earlier, I made some changes to the slew drive assembly design, and asked @Bren for another round of test prints.  I received the latest version yesterday!  I am satisfied with the external ring gear portion, and still plan to make the inner portion from styrene.  Because I want to be able to pose the boom sections, I started having some worries about the strength of the resin ring gears, given I need to drill numerous bolt holes around the circumference of the gears.  So, I started looking for alternatives or backups, just in case some testing down the road breaks a gear (or both).

Latest test print - external ring gear, drive motor gear (pinion?) and the two, inner ring pieces to sandwich the ring gear between -

 

After a bit of cleanup, and sanding the inner sections to fit inside the ring gear, I found the sections would move over each other, and that confirmed the workability of the design concept.  But, in this state of finish, there was considerable resistance to smooth movement.  That's partly what I hope to overcome with inner portions being made from styrene -

 

Was at the hobby store today, and came across some spur gears for R/C vehicles and picked up a couple.  One was 78 teeth and the other was 68 teeth, and the drive gears each had the same number of teeth.  My biggest resin gear has 120 teeth and the smaller one has 100 (maybe).  Each of the plastic spur gears are slightly bigger in diameter, with less teeth than their resin counterparts, but would definitely solve the strength concerns I was having - 

 

The plastic spur gears and the resin ring gears are the same height -

 

Perhaps all I need to do is make the slightly bigger, phantom version of the PM-260, say, a PM-262, to allow for the slightly bigger spur gear diameters (and change the logo on the main boom!).  I laid out the two spur gears on the overhead shot of the inspection unit and I don't think I would need to make too many changes to make the gears fit in - slightly bigger main, and secondary towers, slightly longer boom sections and all would be good.  Still going to consider the resin gears, and I'm going to test their durability, but I thankfully have a backup plan -

 

Oh, and Bren also sent along some coffee to the fab shop! -

 

Some things being worked out, so that's a good thing!

 

Edited 19 hours ago by BK9300

[Biggu]

Another magnificent build in the offing…. This is mechanical engineering stuff. And will become a viable working model. I am fully set in the front row with my new thermos and coffee mug  and maybe a bag of popcorn. 

[BK9300]

15 minutes ago, Biggu said:

Another magnificent build in the offing…. This is mechanical engineering stuff. And will become a viable working model. I am fully set in the front row with my new thermos and coffee mug  and maybe a bag of popcorn. 

Thanks, Jeff - lots to work out yet!  When I actually get started on this, I want to build it a bit more conventionally - frame, suspension, engine, cab,  hood and then the deck and the Snooper unit.  The rotating towers were the biggest concern and might be on my way to having them solved, so, that’s a big relief!  And those little thermos/coffee cups sets are pretty special - need a scale shop bench to set them on!

Edited 18 hours ago by BK9300

[Jürgen M.]

This is going to be another hi-complexity build! I'll be following curiously! 

Good thing you got enough coffee! 

[BK9300]

10 hours ago, Jürgen M. said:

This is going to be another hi-complexity build! I'll be following curiously! 

Good thing you got enough coffee! 

Thanks, Jürgen - will be relying on the Sketchup model a lot, to guide me along - pretty sure I wouldn't have attempted it just from the pictures I took!