Another RC model side project

[crueby]

While I was back in the shop working on the Kearsarge engine, the elves snuck down the hall and got out a spool of kevlar kite string to rig up the boom on the Ruston shovel with some pulley shells they made for the sheaves. First they strung the tilt pulleys on the main boom. Here it is tilted up as far as it would be used on the shovel configuration (remember that this machine could be set up as a crane, dragline, shovel, etc with different booms).

and lowered back down to about 45 degrees (for changing configurations, they could lower it right down to the ground, but for the shovel setup this was enough)

Then to check for conflicts in the cabling, they set up the bucket hoist cable. The drum mechanism is not completely built yet, so the inboard end of the cable was just tied off after going around the motor shaft. Also, since the dipper stick is not made yet, the bucket is just hanging in midair! But, you get the idea of what its going to look like. There was one conflict on the cable routing found, so the inboard end of the tilt pulley was moved over one hole in the gantry crossbar, all clear now. In this picture, the boom tilt is in the middle of the excavator range of movement.


So far so good!  Pieces left to make: dipper stick and its pivot/slide assembly, spring and pull rope for the door latch, servo mount for the pull rope, two sets of cable drums with limit switches, battery holders, then after all is tested, adjusted, fixed, reworked as needed, will make the cab shell. Sounds easy!   

[cnr6400]

  With all that cable work , were there any elf cries of "let go the main sail" or "snug those beckets there, d'ye hear me now?" 

Looks great Chris! 

[crueby]

With all that cable work , were there any elf cries of "let go the main sail" or "snug those beckets there, d'ye hear me now?" 

Looks great Chris! 

As long as they don't buy another !@#ing parrot!!   

[Kim]

That's going to be a great looking shovel, Chris!   

Good to find the cable routing issues now while it's easier to adjust 

Kim

[crueby]

That's going to be a great looking shovel, Chris!   

Good to find the cable routing issues now while it's easier to adjust 

Kim

Thanks Kim!  The old manuals I have for the original shovels show the routing, but since I am not using the same locations for the winch drums as the original did, a couple minor tweaks needed. All was good out on the booms since that part matches the original. String is a LOT easier to move around than the original steel cables, I'm sure!

[crueby]

Oh, and there is a frame at the end of the boom with guides across the rim of the sheaves that prevent tge cable from being able to jump out of the groove. Need to make that too.

[crueby]

Got the bar for the dipper stick cut and fit at the end by the bucket. Holes drilled/tapped for the brackets to hold the brace bars that will go down to the door hinge pin. Here it is set in place against the main boom - the slide/tilt fitting in the center of the boom that holds the dipper will be a complex piece.

[Kim]

That's looking mighty cool, Chris! 

The latch mechanism for the bucket seems like it's going to be pretty complex too. When are you going to do that?  It wasn't made as part of the casting, was it?

Kim

[crueby]

That's looking mighty cool, Chris! 

The latch mechanism for the bucket seems like it's going to be pretty complex too. When are you going to do that?  It wasn't made as part of the casting, was it?

Kim

I'm going to  get to it about a week or so... ago! The latch itself is a simple sliding bar, looks a lot like a normal house door latch. Right now its dropped in place by gravity, but I  going to add a small helper spring dince its so light. There will be a rope to pull it back to let the door open. When the dipper stick is lowered down near vertical, the door self closes, the latch has an angled end like a house door does to push it back as the door swings shut, and then it slides down into the hole in the striker plate.


The casting didn't  have the holes for the bar, I  drilled and rotary tooled that in. It was originally  in the CAD model, but I  closed it when it  looked like I might have it CNCed. Forgot to open it again for the metal printing, whoops! Easy enough to drill through and use a diamond bur to shape it again.


I'll be  showing detail pics when the spring is added.


 

[cnr6400]

  Looking great Chris. 

[Kim]

The latch mechanism for the bucket seems like it's going to be pretty complex too. When are you going to do that?  It wasn't made as part of the casting, was it?

Kim

I'm going to  get to it about a week or so... ago!

Yikes!  Did I just sleep through that update?!?   

I'll be  showing detail pics when the spring is added.

OK, maybe I didn't blank out for your whole bucket latch update after all! 
Looking forward to that and the rest of the build! 
Kim 

[crueby]

No, you didnt blank out, I had not shown pics of the latch yet!   

This morning I made the spring to assist gravity on closing the latch. On the original shovel there is a spring on the end of the cable coming up from the cab to open the latch, but I think that is mainly to overcome the weight of the cable hanging down the main boom. If you look way way back at the Marion build, that door had a more complex latch/lever setup, but that was to overcome the higher weight of the big latch bar, since that bucket was several times the size of this one so the door was larger, more forces on it from the bucket contents.
It took me longer to remember which drawer I had put the several sizes of spring wire I had bought a few months ago than it did to make the spring! Here is a look at it, simple setup to give the bar a little push back into the stroker plate on the front edge of the bucket:

There will be a cable (yes, a string) running from the screw on the back end (right in the picture) of the latch bar, back up to the dipper stick, and out to the other end of the stick. The servo in the cab will have a line running up inside the boom to loop around that first cable, pulling it down (right angles to the length of the cable) to pull the latch open. That way it wont matter about the distance changes when the crowd action pushes the bucket in and out. On the original, they had a cable winding around the drum next to the crowd cable to compensate for the same distance change. This will do the same job.

[Kim]

Thanks for the details on the bucket latch mechanism, Chris.  Much simpler than the Marion bucket latch for sure.  It looks good! 
There sure are a lot of little details in a shovel like this, eh? 
Kim

[cnr6400]

  Spring is finally here!  (great looking latch Chris!)

[bent]

Wow, take a few days off to attend son #2 graduation, and the elves go nuts!

Hopefully you have plenty of that kevlar string handy, I'd not want to have to splice the stuff (though you'd probably just hand it off to the apprentice elf?)