Cat 340D Excavator build

[Zabco]

Originally Posted by crueby

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

Thanks very much for info. I have a Sherline mill also and really like it but the one accessory they make that I really don't care for is their boring head for the reason you stated. I will have to look into getting one like yours. Keep up the great work, I really enjoy following your builds.

[crueby]

Got enough wired up to do some testing - the bucket and stick motors working well, the motor that drives the two cylinders on the main boom does need an upgrade though - with the weight of the booms and bucket extended out, it is really struggling. So, I need to either add some more gear reduction or swap out to a different motor with some more oomph. Still need to wire up the cab rotation motor and test that one...

[crueby]

Got enough of the wiring done to test things out, and swapped the main boom motor for a slower/stronger one which is pretty close but could be a little faster. Here is a short video testing the different functions out, moving slow so I didn't whack anything on the table and so I could learn which stick did what!


https://youtu.be/xkGL3TcqJPY

[crueby]

Another major assembly almost done - got the track frames/tracks assembled this afternoon, moving quite well. Still some more trim panels and brackets to go on, and need to pull the tracks off one more time to install the drive chains and sprockets on the inside. The chain sprocket on the center of the track drive sprocket is there, but there is another one in the center of the frame that still needs to be fitted. The drive motors will sit on the inside edge of the track frames, under the middle of the cab (one per track). As mentioned early on in the build, these are NOT true scale tracks for this machine, but are re-purposed from a RC Tiger tank model - getting me running a lot sooner, to see how the whole thing functions. They can be replaced later with better scale tracks if I get the time for it.

[crueby]

More done on the tracks - got the frames painted, chain drives installed, and fit to the frame. Here is a test assembly of the whole thing, will pull the cab/booms off again to turn the track assembly upside down to fit the motors to the bottom. It definitely is more stable now with the extra width and length to the footprint.

[crueby]

Got the motors mounted to the track undercarriage, ready to wire things in...

[frizzen]

I like it on those tracks on it, looks kinda like it's set up for extra stability or lower ground pressure

Are the motors running track from center, or does it chain drive to and end sprocket?

[crueby]

Hi Frizzen, there is a chain drive inside the tracks, with a 1/4" pitch bike style chain. Sprocket on the shaft with the motor, chain up to another sprocket on the track drive wheel. The drive wheels were two part castings, so I trimmed one side to make room for the sprocket in the center of the hub. That way the chain is not visible without looking inside. Having the chain inside made for some trade-off with the design of the track road wheels down the length, had to make them a little larger so things would clear.

[crueby]

Got the bigger/stronger gearmotor installed for the main boom raise/lowering, had to rearrange a few things to get it to fit in the cab. It works much better, the original one was barely able to raise the boom assembly. This one could be just a little faster, may swap up to the next rpm range on it (they come in a series of gear ratios). This one is quite a bit longer, so it has to sit sideways in the cab, and have a bevel gear set to attach it.









The shop elves are measuring things up to make a rack to hold all the speed controls, they are just temp wired in using some terminal blocks to test things out, want to have them all in a row and the wires neatened up from the current rats nest.









I was able to test out the crawler track motors, went for a long trip of about 6 inches back and forth on the bench. Looks good there too.

[Originalrob]

Looking great ! your progressing very well and will be digging soon !

keep up the good work

[crueby]

Thanks Rob!


I was taking a look at the travel on the bucket, it is not opening up as far as it should, looks like I need to adjust the positions of the links and cylinder a little bit to get the proper travel. The cylinder needs to move up the stick about 1/2", and the pivot hole for the bucket at the end of the stick is a little too far out the bucket, which messes up the geometry somewhat. That hole can be re-drilled farther in towards the upper lip of the bucket and the old hold trimmed off, so that will be easy. The cylinder moving will just need moving the mount holes for the upper brackets, and shortening the flex shaft to the motor. The joys of scaling up from such a small die-cast model!

[ddmckee54]

Chris:

If you move the cylinder are you still going to get the curl on the bucket that you need in the other direction? Don't want to be dropping bits out of the bucket when trying to stack the dirt on top of a tall pile.

I warned you those Shop Elves would weasel their way into this site, told you they were just like germs and that they would spread.

Just don't tell anybody on this site where you've hidden the elves' explosives, or their booze, and you should be OK.

Don

[crueby]

Originally Posted by ddmckee54

Chris:

If you move the cylinder are you still going to get the curl on the bucket that you need in the other direction? Don't want to be dropping bits out of the bucket when trying to stack the dirt on top of a tall pile.

I warned you those Shop Elves would weasel their way into this site, told you they were just like germs and that they would spread.

Just don't tell anybody on this site where you've hidden the elves' explosives, or their booze, and you should be OK.

Don

Yes - I took the bucket off, and held it to the side of the stick and moved the cylinder piston to both ends to figure out how much to change the pivot points, so it SHOULD be good now. I hope.... Before, the bucket was reaching the furthest-curl-in point with the cylinder only partway out, and would not go to the furthest-open point at all, stopping when the piston bottomed out - this should re-center things. Also, the distance between the pivot holes on the plates attached to the bucket were too far apart, moved them in so that the travel angle is higher. This should make it match the real machine closer, I had mis-measured things initially and did not understand the geometry of how the movement worked.


I have the changes made, and the parts have been given a respray to coat the new cut edges. Tomorrow will be able to reassemble and test the movement again. In the meantime, started making the rack that will hold all the speed controllers for the motors in a neat row. The rack is plywood, with notches cut in on the sides for the ESC's to slide into. The sides are glued up on a baseboard, when that sets up I can drill mounting holes to screw it to the cab floor plate and start the wiring.

[crueby]

Some more progress to show - the wiring is pretty much done, still want to bundle up some of them but all is functional. Re-tensioned the tracks, since it was fine when the drive wheel was pulling the tracks from underneath, but going in the other direction where it was pulling the tracks over the top, the plates were bunching up as they went under the track rollers - just needed another 1/8" of movement outwards on the idler wheels. Also started in on the cab - making it out of a thin ply skin and shaped wood formers for where it angles in at the top, plus ply frames around the back:





Next steps will be to add the inner walls and top panels, then can start on the operators cab.




On the background project, have gotten a lot done on the Mann Steam Wagon - 3D CAD model is pretty much done, and I've decided on a 1:8 scale for that build, with a 3" diameter gas fired boiler. The 3D model was done at full-size dimensions, will make a copy of it and scale it down to 1/8, then start generating the 2D drawings for the parts. Here is a screen capture from Fusion:

[ddmckee54]

How do you work that fast in Fusion? Is it practice, practice, practice? Fusion still feels slow and confusing to me, but then I really haven't logged that many hours in it yet - only a few.

I'm used to Autocad 2D, and most of the 3D work that I do is in Designspark3D. At the time I was first learning 3D CAD, that was easier to understand than Fusion 360. Still is, but I know it's not nearly as powerful as Fusion 360.

Don

[crueby]

Originally Posted by ddmckee54

How do you work that fast in Fusion? Is it practice, practice, practice? Fusion still feels slow and confusing to me, but then I really haven't logged that many hours in it yet - only a few.

I'm used to Autocad 2D, and most of the 3D work that I do is in Designspark3D. At the time I was first learning 3D CAD, that was easier to understand than Fusion 360. Still is, but I know it's not nearly as powerful as Fusion 360.

Don

Hi Don,

Yes, I have been getting a lot of practice in Fusion, first started using it a few years ago for my Lombard log hauler model, then for the Marion steam shovel which was a huge project, plus several rc submarine and small engines. I never used any CAD programs before, which may have helped with nothing to unlearn on other workflows. I only use it for modeling and drawing, don't use any of the other functions. With all the practice it does feel intuitive now, at first was very confused till I watched some of thier tutorials. Doing as much as possible in sketches then extruding or rotating helps a lot since changes to the sketch get propogated forward to the parts. I still run into problems now and then, some bugs, but overall I really like it.

[skeeter]

Great job with the excavator. The steam truck will be phenomenal when you get it finished!

[crueby]

Originally Posted by skeeter

Great job with the excavator. The steam truck will be phenomenal when you get it finished!

Thanks Skeeter! Between sessions of gluing/waiting for glue to dry/painting/waiting for paint to dry/repeat on the excavator cab, I've started generating the 2D drawings from the 3D CAD model of the Mann truck. LOTS of sheets, LOTS of dimensions to place. Once that model starts the build log will be over on the Model Engine Maker forum, where I've done most of my other steam models.


More to show soon on the excavator, as the cab comes together. I'd be playing with it in a pile of sand by now, but I am waiting on some electrical bits for the radio system. Turns out that having this many ESC's on one receiver is an issue - there is some interference and possibly ground looping between them. Found out this is a known issue with the Mtroniks ESC units, they have made an opto-isolator unit for them, which plugs inline with the radio lead, that goes from electrical wire/signal to an optical signal and back again, that both boosts and isolates the signals and eliminates the cross talk. What I was seeing was once I had at least four ESC's all plugged in there motors would start glitching, even if only one was turning at a time. Any three ESC's in any three channels, no problem at all. Tried different radios (different brands too), same thing. So, got a handful of those on order, but it may take a little while since they are coming from England to the US. Will continue on the cab for now...

Chris

[avel]

I love these self built machines. Always amazed at what people can build at home. Looking good.

[crueby]

Going to call this one just about done, and start playing with it! Got the last of the wiring bundled up and out of the way so the cab would go on, and set up the radio. Just need a lot more practise to train myself which lever does what in which direction. Here is a video of the first digging run, using a mortar mixing tub and some 'scale gravel' (AKA kitty litter - NEW, assuming the shop elves didnt do anything nasty in it).


https://youtu.be/oimbHLx2Kkk


And a couple photos of where it stands:










Elfric at the controls: