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Re: Cat 340D Excavator build
Got a chance to wire up the motor and reassemble them boom, to give it a first motion test. This test was done with a 98 rpm gearmotor, I have faster and slower ones to let me dial in the max movement speed. After testing, I dont think I'd want it any slower (its on a speed control on the radio so it will do slower speeds depending on the joystick movement).
https://youtu.be/_X8LaI4TmHg The intermittant clunking noise when the stick is coming in is the flex cable just rubbing on the edge of the slot in the boom - need to grind back the slot end just a little more. Also, I checked the force it gives, and that seems reasonable (didnt have enough hands to do that on camera, did not have the tripod handy). Overall, happy with it for a first run! Work will continue on the bucket linkages and that cylinder, also need to rig up some limit switches on the movement to keep from over-running the ends of the leadscrew. A little insulation in the boom should knock down the motor noise some too. :) |
Re: Cat 340D Excavator build
That’s absolutely amazing ! Can’t believe the progress your making and now I feel like I’m slacking 😂
Are you going to swap the motors out for faster ones and test ? Looking really good |
Re: Cat 340D Excavator build
Hi Rob,
For the stick I am tempted to leave that motor in place, have been online looking at videos of real excavators at work, and the stick speed is about like that. If I go faster, it wont be by much. The bucket speed may need the faster motor. Guess I'll find out when more is together, and see how it all looks working as a system. I need to open the side of the boom up again anyway (sure it wont be the last time! ) to fix the cable rubbing issue and do the limit switch work. Six screws and the side panel will pop off, so that is easy (glad its not painted yet). There is enough room in the boom that I may go up a level on the gearmotor to a stronger one, I think that I have to stick with this size for the bucket motor, the stronger ones wont fit there. Chris |
Re: Cat 340D Excavator build
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Re: Cat 340D Excavator build
Started in on the mechanisms in the stick, got the motor mounted - tight fit...
https://i.postimg.cc/qgfYVy3m/IMG-6839a.jpg the opening for the drive cable from the motor to the cylinder: https://i.postimg.cc/QNBdDD75/IMG-6841a.jpg and also drilled for the bushings at the bucket end for the linkages: https://i.postimg.cc/brSMB3sD/IMG-6840a.jpg |
Re: Cat 340D Excavator build
Some more work done on the excavator - working on the linkages from the cylinder to the bucket. The side links were milled from flat bar stock on the rotary table:
https://i.postimg.cc/RVy82TZm/IMG-6859a.jpg The solid link from there to the bucket is being pieced up from a thicker piece of flat bar and two round bars with slots milled in. They will be silver soldered together and then more shaping done. https://i.postimg.cc/KvRw9WFQ/IMG-6860a.jpg |
Re: Cat 340D Excavator build
Got the bearings and rods for the bucket links made...
https://i.postimg.cc/xjMck9XV/IMG-6862a.jpg and silver soldered up the blank for the end link, ready for further shaping: https://i.postimg.cc/bNPdk4nD/IMG-6864a.jpg |
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Re: Cat 340D Excavator build
This morning got the pivot rods threaded and nuts made, and installed the motor in the stick. Here is a quick video of the motion test for the bucket linkage - better get started on the bucket!
https://youtu.be/qg6FHjgabfc |
Re: Cat 340D Excavator build
Been a bit since I've made any progress on this build, it is still happening, but I've been focussed on the final parts for my Stanley engine model, should be back on the excavator next week. I got some steel plate for the bucket, need to make up a bending form for the curved center section, then will trace the actual part to cut the sides out. Most likely it will be all silver soldered together since I do not have equipment or the know-how to weld it.
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Re: Cat 340D Excavator build
Getting back on the excavator build finally - started with some 3/32" steel flat stock, and bent the center section of the bucket over a wood form. The side plates are rough cut. The parts will be silver soldered together once ready. Still a number of pieces to shape out...
https://i.postimg.cc/Kj3m7Xfp/IMG-6959a.jpg |
Re: Cat 340D Excavator build
Got the bucket shell silver soldered up today, and the extra metal on the outside ground off:
https://i.postimg.cc/5NHCyXtc/IMG-6972a.jpg Next will shape in the open part of the sides, and start adding the plates on the outside.... |
Re: Cat 340D Excavator build
the side plates going on too....
https://i.postimg.cc/qR2YXJwj/IMG-6974a.jpg Next up will be the plates on the top to link to the stick, and the plates for the teeth at the bottom... |
Re: Cat 340D Excavator build
That's a nice looking scratch built bucket!
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Re: Cat 340D Excavator build
Here is a shot of the boom/bucket assembly for the excavator all assembled and ready for the base bracket and lower cylinders.
https://i.postimg.cc/8c4d6h4m/IMG-6984a.jpg And a shot of it painted. The yellow is actually from rattle cans of Cat paint, they sell it for touchup and repairs, covers amazingly well for a yellow paint. This is one coat. The black is Duplicolor ceramic engine enamel. https://i.postimg.cc/L52B5yts/IMG-6985a.jpg Underneath the boom you can see the little die-cast model that I am scaling up from. Next parts are the steel plates that form the framework that the base of the boom attach to, rough cut plates are in the lower left of the photo. |
Re: Cat 340D Excavator build
I am getting the base for the booms pieced together - from the weight of the boom assembly, I am wondering if I'll be able to use the same gear motor for it as I did for inside the booms, given how heavy the parts are. Even with the two cylinders, I may need to go to a larger/more powerful motor for this last one, but fortunately there is plenty of room inside the cab block. May wind up with a car seat motor or something like that. Possible that just another gear set will do - the two cylinders need to be kept in sync, so will be driving both from one motor with a line of three gears, motor on the center one. That gear set could be a 2 or 3:1 combination.
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Re: Cat 340D Excavator build
Okay, catching up on this side project build - been busy setting up a new computer, and all the time that always takes! Will be better suited for all the CAD work I am doing these days, so well worth the time. Anyway, I got the part in to switch the cylinder pair that holds up the entire boom assembly over to single-start Acme threads vs the original 4-start threads, which were just too aggressive on the movements. Here is the base assembly:
https://i.postimg.cc/d3MrRf2v/IMG-6991a.jpg Each cylinder has its own drive shaft - in the picture the one on the right has a small drill chuck on it to make it easier to turn by hand. With the new leadscrews I can turn the shaft and lift/lower the booms with just one cylinder and a reasonable amount of force. Before, that was very difficult. The two shaftws will come back to a common drive gearmotor, have not decided if I'll do a gearbox to link them or use a small chain drive (leaning that way at the moment). Here is a picture showing the entire assembly, bucket lifted off the table - stays there now, before it could spin the leadscrews and lower itself back, which meant that it would have been putting constant strain on the motors. https://i.postimg.cc/xCNLzQbt/IMG-6990a.jpg Lots of spare shafts and couplers in the foreground from figuring out the whole thing. Here is a shot showing the part for holding and spinning the cab - there will be a lot of side force at times, so I wanted a strong way to connect things. Wound up with a spare set of tapered roller bearings from a trailer - figure it will be more than strong enough! The gear will be mounted to the track unit underneath, and a motor drive gear in the cab will engage it and turn the cab. There is a slip ring unit there to take the motor leads for the track drive motors down from the cab to the lower unit, but still allow the cab to turn as many full circles as it wants. The spindle will be home made, hollow unlike a normal car axle end to allow the wires through. https://i.postimg.cc/90GTLBb9/IMG-6992a.jpg |
Re: Cat 340D Excavator build
Got the sprocket assembly for the chain drive started - using some .250 pitch chain and sprockets from Servo City for these, nice fine chain for small spaces but plenty strong. They sell the master links and link pin removal tool too. I am going to use the same chain for the track drives too. So far have the sprockets on hubs, next will make up a support to hold the sprockets. The output of each shaft will go to one of the cylinders on the main boom via a shaft with universal joints. The input will be from a gear motor onto one of the shafts. So, one motor will frive both cylinders at a matched speed and direction.
https://i.postimg.cc/MGZ5S3d6/IMG-6994a.jpg |
Re: Cat 340D Excavator build
It's good to know I'm not the ONLY one that winds up with spare parts left over when doing a custom project!
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Re: Cat 340D Excavator build
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...
https://i.postimg.cc/3NKMyTKV/IMG-6996a.jpg |
Re: Cat 340D Excavator build
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:
https://i.postimg.cc/jShWdVbn/IMG-6998a.jpg 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'. https://i.postimg.cc/5t76Lwjx/Spindle1.jpg 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. https://i.postimg.cc/sxSXkqmX/Spindle3.jpg Spindle with bearings removed: https://i.postimg.cc/KzCjsxnw/Spindle4.jpg And the hub itself - the step in the center on the inside goes between the bearings, holding the bearing cups apart. https://i.postimg.cc/hGPXXCDy/Spindle5.jpg 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... |
Re: Cat 340D Excavator build
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. https://i.postimg.cc/1zjZyJh2/IMG-7001a.jpg Top view - the inner spindle will bolt to the cab floor. https://i.postimg.cc/nz9frBnz/IMG-7002a.jpg 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.... |
Re: Cat 340D Excavator build
Getting the floor plate drilled for the mounting screws, and test fitting the parts....
Bottom view: https://i.postimg.cc/DzQwFZ1R/IMG-7004a.jpg Top: https://i.postimg.cc/pT2XdHZr/IMG-7005a.jpg 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. |
Re: Cat 340D Excavator build
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.
https://i.postimg.cc/W32PD56S/IMG-7007a.jpg closer look: https://i.postimg.cc/GttwK9fy/IMG-7008a.jpg 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. https://i.postimg.cc/hjpRVV2n/IMG-7010a.jpg |
Re: Cat 340D Excavator build
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.
https://i.postimg.cc/CLpWWJdc/IMG-7011a.jpg lots of drilling/tapping later... https://i.postimg.cc/mkCKP1p3/IMG-7012a.jpg Still more holes to go to get the lower arms on... |
Re: Cat 340D Excavator build
How come you went with motors, rather than hydraulics to for this excavator? It's still an AWESOME scratch build, but I was curious.
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Re: Cat 340D Excavator build
Skeeter that’s because he is a steam guy and couldn’t find any steam powered hydraulics !
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Re: Cat 340D Excavator build
:lol:
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. |
Re: Cat 340D Excavator build
More done on the undercarriage - getting it skinned with aluminum sheet. All are roughed in, ready to do final trimming/blending on the edges.
https://i.postimg.cc/cJqFKwLk/IMG-7015a.jpg 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. |
Re: Cat 340D Excavator build
Bored out the hole for the spindle assembly:
https://i.postimg.cc/3JQf9W0D/IMG-7016a.jpg and test fit in the base: https://i.postimg.cc/8PdKYDLX/IMG-7017a.jpg |
Re: Cat 340D Excavator build
Looking absolutely amazing !
Really impressed with the speed of the build too Keep up the great work ���� |
Re: Cat 340D Excavator build
Very nice work as usual! What is the boring head you are using on your Sherline mill?
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Re: Cat 340D Excavator build
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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. |
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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 |
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Re: Cat 340D Excavator build
Got the cab/boom assembly bolted onto the track base this morning:
https://i.postimg.cc/8kWn44jH/IMG-7019a.jpg As expected, needs some counterwieght at the back of the cab to balance out the booms. The cab rotation drive gear meshes okay: https://i.postimg.cc/WbvYHZZP/IMG-7020a.jpg Good place to park the die-cast model: https://i.postimg.cc/kXvY35NR/IMG-7021a.jpg Next up is to do a bunch of wiring for the radio/speed controls, and I can do some testing! |
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