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Agricultural and Industrial Equipment A place for your agricultural, industrial, and other heavy equipment builds!


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  #76  
Old 04-14-2016, 02:00 PM
SteinHDan SteinHDan is offline
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Hi, Dallas!

Yes, it sure could be autonomous. I'm already planning to add angle sensors to the joints (for a different reason) so then it could run by itself.

Best regards,
Stein :-)
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  #77  
Old 04-14-2016, 04:06 PM
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Prop Shaft Prop Shaft is offline
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Quote:
Originally Posted by SteinHDan View Post
Thanks, Prop Shaft!

Yes, the boom cylinders are not exactly wide enough to be to scale. But the length, stroke and force is what it should be. Another thing is the width of the boom itself. It is a bit wide, even for this LME version (Mass Excavation, shorter and stronger boom). That is because I needed to fit the gear motor at the end and it looked weird if I changed the shape, so I just widened it. Those two things combined, the smaller cylinders and the larger boom isn't the best match, even if each of them by itself isn't that much off from the real scale.

But it all looks much better from the front than from this angle.

Best regards,
Stein :-)
Ahh I see. I probably wouldnt have noticed is it was one or the other. Waiting on updates.
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  #78  
Old 04-15-2016, 06:59 AM
Larsra Larsra is offline
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Once again, what an impressive build Stein! The motor compartment is so clean and nice when you use those electronic cards insted of hydraulic. Would love to see this beast with a quality hyd.system though. Keep up the good work I guess you work with cnc, or is it all self learned?
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  #79  
Old 04-15-2016, 02:52 PM
SteinHDan SteinHDan is offline
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Thanks, Lars!

I guess I have to make a hydraulic version at some point, but I'll complete this all-electric version first. :-)

I'm a computer programmer by trade and the only thing I knew about CNCs before I got one was that I wanted one! ;-) The one I have is no longer sold, but I think there are some good alternatives, like this one:
- CNC 6040Z 3-axis, 1500W VFD spindle, 110V/220V

I've not tried it, but the spec looks ok. 1500w spindle is good for aluminum. Ball screws are good. There is probably lots of reviews on YouTube. I saw these two:
- Review: https://youtu.be/DeRuMZKCiy8
- Cutting aluminum: https://youtu.be/kTIYiZFGcRE

I guess the most important things I've learned about cutting aluminum is:
- I'm cutting only 0.3 - 0.4 mm each pass
- Run quite fast, to avoid milling the aluminum to dust (generates heat). Should be small chips, not dust. Full spindle speed. As fast movement speed as you can without breaking the bit.
- Use a solid carbide end mill made for aluminum, e.g. Amana Tool 51474, 51454, 51402 or similar.


You can use the free Autodesk Fusion 360 to model and generate the G-code.
Not much more to it. :-)

Best regards,
Stein :-)
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  #80  
Old 04-19-2016, 06:04 AM
Larsra Larsra is offline
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I guess I have the same "thought", the only thing I know about CNC is that I want one I've seen a used StepCraft for sale at the norwegian forum rclastebil, but at this moment I'm nearly finished with my studies so the next priorities are unfortunatly not this hobby. Don't think it's much room for an excpensive CNC machine in the nearest future, but I will definetly consider it when the economi is in place.

I've tried a bit autocad for practice and fun, will try out the Autodesk for sure.

Thanks!
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  #81  
Old 04-23-2016, 01:51 PM
SteinHDan SteinHDan is offline
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First test digging dirt!




https://youtu.be/YNJewdL_CPk

Last edited by SteinHDan : 04-23-2016 at 02:21 PM.
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  #82  
Old 04-26-2016, 08:10 AM
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RCJEEPBUILDER RCJEEPBUILDER is offline
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Bravo!!
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5 ton of fun
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  #83  
Old 04-29-2016, 05:42 PM
SteinHDan SteinHDan is offline
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Thanks, RCJEEPBUILDER! :-)
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  #84  
Old 04-29-2016, 05:43 PM
SteinHDan SteinHDan is offline
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Added a simple mount for the brain (CPU) of the excavator. At the same time I replaced the Raspberry Pi 2 with the version 3. It's mostly the same, but a little bit quicker and has WiFi and BlueTooth built in.

- Raspberry Pi 3


The mount is very simple. Four self-tapping screws to hold the PCB and then two nylon M4 bolts to hold the mount on the base plate.








The audio (engine sound) has its output through that 90-degree 3.5mm jack on the top.

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  #85  
Old 04-30-2016, 02:53 PM
SteinHDan SteinHDan is offline
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Bolting together the arm

The arm sandwich of 3mm aluminum sheets with 3D-printed ABS in the middle is held together by 34 M4 countersunk stainless steel bolts and sleeve nuts.

There are different length bolts used throughout the arm:
- 23 x 50mm (for the main part)
- 5 x 75mm (80mm cut to length) for the stick hub
- 4 x 80mm for the stick mount
- 2 x 55mm for the stick angle sensor mount

Ebay links:
- Bolts: http://www.ebay.com/itm/231787670429
- Sleeve nuts: http://www.ebay.com/itm/191771467782



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  #86  
Old 04-30-2016, 03:15 PM
SteinHDan SteinHDan is offline
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I added a gas spring from the boom to the stick. I only found the correct length, stroke and force on Aliexpress:

- 6kg (60N) gas spring: http://www.aliexpress.com/snapshot/7601366858.html

The sleeves and spacers are cut from 8mm and 12mm stainless steel tubes. The pin is also gotten from Ebay:

- 8mm (ID 4mm) tube cut to 13mm length: http://www.ebay.com/itm/121600172085
- 12mm (ID 8mm) tube cut to 4mm legnth: http://www.ebay.com/itm/121762512929
- 8x30mm pin: http://www.ebay.co.uk/itm/121851516316







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  #87  
Old 05-01-2016, 06:02 AM
SteinHDan SteinHDan is offline
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I also added a gas spring to the bucket, mostly for the visual appearance as the bucket is already way more powerful than it needs to be.

The spacers are made the same way as previously, cut tube to length.

Ebay links:
- 8mm (ID 6mm) tube cut to 4mm length: http://www.ebay.com/itm/121762445745
- 12mm (ID 8mm) tube cut to 4mm legnth: http://www.ebay.com/itm/121762512929
- 6x30mm pin: http://www.ebay.co.uk/itm/121868709865
- 8x80mm pin: http://www.ebay.com/itm/291511678072
- Eyelets: http://www.ebay.com/itm/151838223022

The lower eyelet is drilled out to 8mm to fit the 8mm pin in the bucket linkage.









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  #88  
Old 05-01-2016, 01:53 PM
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very cool man. Absolutely love it!
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  #89  
Old 05-02-2016, 04:07 PM
SteinHDan SteinHDan is offline
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Thanks, Lilsami87! :-)
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  #90  
Old 05-02-2016, 04:10 PM
SteinHDan SteinHDan is offline
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I've had one issue with the operation, and that is that I need some way to stop the motors at the end of travel. I could have done this with limit switches like I did for my MAN truck build:
- http://www.scale4x4rc.org/forums/showthread.php?t=80393

An alternative is to use angle sensors in each joint, and I've selected this method for this build because it also allows for a host of other cool applications and features:

- End stops
- Stall detection
- Recording of movement
- Replay of movement
- Full servo capability at the joint
- Alternative control modes (e.g. for beginners), like absolute bucket movement forward/backward and up/down, not angle control
- Automatic bucket leveling
- Automatic grading
- GPS assisted digging
- GPS controlled digging
- .. and probably more.

So I've started to add some angle sensors to the arm. First the stick and the bucket. (This approach could also very well be used on hydraulic arms, btw.)

I'm reading the sensor on the corresponding motor controller. That way, the control of the motor based on the angle sensor can be completely controlled on the controller without having to bother the main CPU.

As I was already modifying the motor controller, I added some heat sinks for good measure, but those are most likely not required at all.

Ebay link:
- 18x18x13.5mm heat sink: http://www.ebay.com/itm/361352931009




To read the sensor, I'm using the unused analog inputs 4 and 5 on the Arduino. I've added longer pins to these positions so that I can attach wires on the front side. I did the same for GND and 5V.




The angle sensor itself is just a 10k Ohm linear potetiometer. I'm using a thumb wheel version to get it as flat as possible. I bought these ones at SparkFun:

- Thumbwheel potentiometer, 10k linear: https://www.sparkfun.com/products/retired/11173




The potentiometer attaches to the hub adapter using one very small self-tapping screw.






The hub adapter has a D-shape that fits exactly onto the D-shape of the gear motor axle:






I've printed a part that mocks up a stick mount that has two purposes:
- Cover and hold the angle sensor
- Be a base when running the control an power lines to the stick.





The sensor connector has three pins, that connect to the Arduino cable from the first step:
- Pin1: GND
- Pin2: Sensor output (0-5V)
- Pin3: 5V





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