90 ton 1/14 metal excavator scratch build w/embedded PC

[liftmys10]

Awesome job!! I love the fact that you provide a link to all these materials. That's a first that I've seen. Keep up the great work.
I used to have a 1/16 scale CAT 390D. So a 1/14 scale would do some serious digging. You can look mine up for ideas on here.

[RCTech9]

Looks like a great start.

[SteinHDan]

Thanks!

I bought the chain in a local shop, but I see that you can buy the same on Amazon by the meter:
- 1M 08B K1 attachments: http://amzn.to/1W71CaA


Stein :-)

[crusher]

Probably the best presentation of a build I have ever seen, also great work on the project, have you considered drawing up plans for your build and selling them? I for one would definitely be interested in purchase.
Terry

[SteinHDan]

Hi Crusher!

Thanks!

No, no plans to sell, but you can have it for free:
- http://d1t2tbzmskak12.cloudfront.net...e_4%20v122.f3d (5MB)

Just download the free Autodesk Fusion 360 and then upload this file into that program. Then you can export any part to STL (for 3D printing) or I've also added the CAM setup for CNC cuts of some of the parts. And you can export the parts to other formats.

See the Autodesk Fusion 360 tutorials on YouTube for more info on how to use the program.

Don't pay any attention to the parts above the undercarriage. They are just placeholders for now.


Stein :-)

[SteinHDan]

I wanted to create a very simple swing mechanism, but ended up with something not that simple. I tried various types of bearings, and I was very close to just stack 5 of these on top of each other, but it didn't roll very well:
- http://www.ebay.com/itm/262008651254
Also it would have had to be machined and the tolerance was very low.

So I ended up with two tapered bearings facing each other. It is very sturdy.

Here are the parts:



All of the milled parts are from 6mm aluminum. The slip ring is not the one I'm going to use, but the same size. There is also a slip ring mount printed in ABS (50% infill) that both hold the slip ring in position but also helps align everything before the different parts are bolted in place.

Ebay links:
- Slip ring that I will use: http://www.ebay.com/itm/141778017008
- Slip ring from picture: http://www.ebay.com/itm/371343809973
- Bearing: 30212 http://www.ebay.com/itm/160994544123

The bolts are countersunk M6 80mm and countersunk M4 50mm.
The M4 nuts are locking nuts.

First, the slip ring is mounted inside the slip ring mount:





It's important that the M6 bolts are countersunk, because they are rotating and the wires are not, and I don't want the bolt heads to catch or damage the wires when rotating.








The static part is made up of 6 rings. If I should do it again, I would make the two similar pieces above and below the bearing mount plate into just one piece each of 12mm aluminum instead of two pieces of 6mm aluminum.


















And then the previous assembly goes in from the bottom:




Underneath, the wires from the drive motor meet up with the slip ring wires:

[SteinHDan]

The swing drive consists of a drive motor, a milled bevel gear and a set screw:



The drive motor is a 12V 50RPM gear motor. The set screw is M4. I'm going to use one that is slightly longer in the final version (10mm long).

Ebay links:
- Motor: http://www.ebay.com/itm/321622024429

The gear is milled from a 12mm aluminum sheet, where 6mm is the gear and the other 6mm is the part where the set screw sits. The set screw hole was drilled with a 3.5 mm drill and the tapped to M4 thread.




I 3D printed a test plate to find the right fit for the gears before milling the real bottom plate of the excavator:

[SteinHDan]

Milling the main bevel gear:
- https://youtu.be/_9gfQj9GZf4

[crusher]

Thank you for your offer re plans, I have downloaded Autodesk Fusion 360, now have to figure out how to download your drawings, not very computer literate. The pictures of your turntable look great.
Terry

[SteinHDan]

Hi Crusher,

Just click on the link and then save to your computer. Then start fusion 360 and select Upload and select the file you downloaded.

To create a drawing from the design, you can do as in these tutorials:
- https://www.youtube.com/watch?v=d4SY7RaL3K4
- http://knowledge.autodesk.com/suppor...4E837-htm.html


Best regards,
Stein :-)

[crusher]

Thank you for your reply and help, I will give it another try. As I said earlier I am not good at using the computer so appreciate your help.
Terry

[Marquez81]

I consider the project whatyou doing, a spectacular job Stein !

I am monitoring the project these to show.

You will put the various phases of the project complete the excavator ?

Best regards!

[SteinHDan]

Hi Marquez81,


Thanks!

I'm not sure if I understood you correctly, but if you ask if I plan to do the same as this for the rest of the components of the excavator, then the answer is yes. (even if I'm in that phase of the project where it dawns on you just how much work that is left... ;-). Just got to make sure to have a little bit of progress every day, and it will get done eventually. )


Best regards,
Stein :-)

[Rakthi]

That will be one impressive machine once finished! Interesting/brilliant way of doing the bucket. Gives you the possibility to easily make various widths.

Personally, I do not think the bucket is too wide at all.

[SteinHDan]

Thanks, Thuangs!

I'll upload some videos as soon as I have the excavator running again.

I guess I'll make a hydraulic version too at some point. Do you have any pointers to good cylinders that I can use?

The sizes I need:

- Boom stroke: 106,50 mm (4,19 inches)
- Boom total: 300,00 mm (11,81 inches)

- Stick stroke: 142,50 mm (5,61 inches)
- Stick total: 345,00 mm (13,58 inches)

- Bucket stroke: 102,00 mm (4,02 inches)
- Bucket total: 247,50 mm (9,74 inches)


Stein :-)

[Lil Giants]

Fumotec offers unassembled cylinder kits so you can make any length cylinder you want. Just specify desired diameter when ordering.

http://www.funktionsmodellbau-brueck...mplate=generic


With this electric version of yours, how will you regulate its digging power so it doesn't destroy itself?

[SteinHDan]

Hi Lil Giants!

I love your threads and builds!

Thanks for the link to the Fumotec cylinders. Those look very nice and very suitable for this model.

I'm going to control the force of the electric motors by current limiting. I'm using the Monster Motor Shield for Arduino (a cheap way to get the same driver chips as the Pololu quik controller), and I'm planning on doing it mostly the same way that this guy does:
- https://www.youtube.com/watch?v=7sr93cD--tg

Lots of options on the behavior. Cut off right away, exponential backoff, constant current (force), or more advanced like keep the current for a while and then back off. We'll see what works better.


Stein :-)

[Lil Giants]

I think I found a similar video with English... it's interesting how the motor shield works, is it possible to adjust reaction time from a stall? I'll look forward to seeing how well you're able to make it perform Stein.

You might need two set screws on every part? ...maybe three?

[SteinHDan]

Originally Posted by Lil Giants

I think I found a similar video with English... it's interesting how the motor shield works, is it possible to adjust reaction time from a stall? I'll look forward to seeing how well you're able to make it perform Stein.

You might need two set screws on every part? ...maybe three?

Yes, or four ;-) I think the biggest problem will be too much backlash in the gears. But we'll see.

For the motor shield, you can program any behavior you want. The motor shield just makes available the current measurement output from the driver chip out to the attached Arduino. You can add the logic of what to do either on the Arduino or even further out if you have something else that controls the Arduino.


Stein :-)

[Fired up]

Very nice work. Interesting system.