Cat 340D Excavator build

[skeeter]

It's good to know I'm not the ONLY one that winds up with spare parts left over when doing a custom project!

[crueby]

Originally Posted by skeeter

It's good to know I'm not the ONLY one that winds up with spare parts left over when doing a custom project!

Got a bunch from this one, lots of experiments. Ones that are not reusable wind up as ballast in rc boats.

[crueby]

Few more parts - got the linkages from the ends of the lower cylinders back to the chain drive sprockets made, including a guide rail in the center to keep the u-joints from flopping around. This will only run at slow speeds, running the main boom up and down. Next need to make the holder for the shafts on the chain sprockets and the motor mount...

[crueby]

Some more done on the excavator - cut out the outline of the cab floor plate on some aluminum sheet stock, and made up the shafts/holders for the lower boom cylinder drive. While laying things out, realized that I should do the holes for the cab spindle (whatever that is called, the thing the cab spins on over the track assembly) at the same time, save some assembly/disassembly rounds. Here is the floor plate with the parts set on top:





So, back to Fusion 360 to model up the spindle parts. I bought a trailer wheel bearing kit with 1-1/16" center hole size to use, knowing that regular whel bearings are set up to handle all the side/twisting loads. These should be MORE than strong enough for this purpose! Using the measurements of those parts as a starting point, modeled up the assembly. In all these screen grabs, we are looking at the bottom side of things - the square grey background is the bottom of the floor plate, the track assembly will bolt to the flange at the top of the darker grey 'hub'.





Now, to show things better, some more shots with parts peeled away. Here it is with the hub removed, showing the two bearing races/cups inside. The red spindle is hollow to hold the slip ring for the track drive motors. Sides are smooth, end threaded for the spindle nut.





Spindle with bearings removed:





And the hub itself - the step in the center on the inside goes between the bearings, holding the bearing cups apart.





This is all laid out just like the trailer axle/hub would be, just slightly different shapes to bolt to the cab floor and the track frame. Should work, as long as I didn't forget some important part...

[crueby]

Been some 'boring' days lately, boring out and turning the spindle and hub for the cab rotation bearing assembly. The spindle/hub are steel, the washer and nut are brass (just since I had some offcuts the right size, otherwise would have been steel too). The gear was bored out as well to fit the hub, there will be a gear motor inside the cab by the boom base driving a spur gear against the big gear. The big gear and hub stay stationary with respect to the track frame, and the spindle/cab spin around on that. All fits well, and the hub spins freely without play - no grease in the roller bearings yet, just since it will be handled so much for a while. Here are some pics of the top/bottom of the assembly.


Bottom view, the end with the nut will face downwards in the final assembly.




Top view - the inner spindle will bolt to the cab floor.



With these parts done, now I can lay out and start drilling the patterns of holes in the cab floor for the spindle as well as the boom base and its drive motor....

[crueby]

Getting the floor plate drilled for the mounting screws, and test fitting the parts....


Bottom view:





Top:





Need to open up one hole for the base frame, missed that one by a little bit. Then get the spacer block under the motor drilled/installed, and add the angle-aluminum around the rim to hold the cab shell on. The cab is most likely going to be a wood frame clad in thin plywood, set down over the top.

[crueby]

Got some more done on the floor plate, riveted on the angle pieces around the edge to hold the cab in place, and bolted down the motor and boom base parts.





closer look:





The vertical motor at the lower right of the boom base frame is to turn the cab around on the track base. It will drive this spur gear (once I make the shaft to connect it) against the large gear on the hub. The hub and the large gear will be bolted to the track base.

[crueby]

Started in on the framework for the undercariage - this will hold the spindle/hub for the cab on the top, and the tracks out at the lower arms.





lots of drilling/tapping later...





Still more holes to go to get the lower arms on...

[skeeter]

How come you went with motors, rather than hydraulics to for this excavator? It's still an AWESOME scratch build, but I was curious.

[Mikem]

Skeeter that’s because he is a steam guy and couldn’t find any steam powered hydraulics !

[crueby]

Mike is sorta right, not enough room to fit the boiler in the cab!




Actually, its a combination of cost and mess - having seen what happens when a hydraulic line leaks, and I want to be able to run this one around in the house. Also wanted to see if it could be done - kind of a middle ground between the pure hydraulic machines and the plastic-geared 'toy' ones. The gearmotors and leadscrews are an interesting combination, seen them used in some of the builds here (especially in truck dump beds). It seems to have enough power in initial tests, but it could always be converted to hydraulics later on if need be.

[crueby]

More done on the undercarriage - getting it skinned with aluminum sheet. All are roughed in, ready to do final trimming/blending on the edges.





The spindle unit is sitting on top - need to bore a large hole in the top sheet so it will sit down on the top sheet.

[crueby]

Bored out the hole for the spindle assembly:





and test fit in the base:

[Originalrob]

Looking absolutely amazing !
Really impressed with the speed of the build too
Keep up the great work ����

[Zabco]

Very nice work as usual! What is the boring head you are using on your Sherline mill?

[crueby]

Originally Posted by Originalrob

Looking absolutely amazing !
Really impressed with the speed of the build too
Keep up the great work ����

Thanks Rob! Got some paint drying on the base parts, hope to start assembling it to the boom tomorrow, then can start wiring up the motors to the speed controls and do some full motion tests, see how the twin cylinders at the base handle the weight of the boom assembly.

[crueby]

Originally Posted by Zabco

Very nice work as usual! What is the boring head you are using on your Sherline mill?

Hi Zabco,


That is an APT boring head - it takes the same 3/8" boring bits as the Sherline, but is a much more rigid and accurate head. The Sherline one just pushes on the moving portion of the head in one direction, so its easy for things to slip when tightening it down. The APT dial moves the head both directions, and there are adjusting screws on the dovetail to tension it all - I've had much better luck with it. They do not make it to match the Sherline headstock threads, so I had to turn down an adapter and mount it in a mill cutter blank holder with a 1/2" hole. Taller than the stock one, but I think it works better. I do have the taller column on the mill, so it can handle the extra height for most parts.


Chris

[skeeter]

Originally Posted by Mikem

Skeeter that’s because he is a steam guy and couldn’t find any steam powered hydraulics !

LOL!

[skeeter]

Originally Posted by crueby

Mike is sorta right, not enough room to fit the boiler in the cab!




Actually, its a combination of cost and mess - having seen what happens when a hydraulic line leaks, and I want to be able to run this one around in the house. Also wanted to see if it could be done - kind of a middle ground between the pure hydraulic machines and the plastic-geared 'toy' ones. The gearmotors and leadscrews are an interesting combination, seen them used in some of the builds here (especially in truck dump beds). It seems to have enough power in initial tests, but it could always be converted to hydraulics later on if need be.

Very true! The hydraulic machines DO get messy! I believe the operating system you went with is far less expensive than a hydraulic system. For indoor operations, I too wouldn't want a hydraulic machine.

[crueby]

Got the cab/boom assembly bolted onto the track base this morning:




As expected, needs some counterwieght at the back of the cab to balance out the booms. The cab rotation drive gear meshes okay:




Good place to park the die-cast model:





Next up is to do a bunch of wiring for the radio/speed controls, and I can do some testing!