Kodiak AEV 3 Armoured Excavation Vehicle

[wibblywobbly]

Spent the evening designing and printing prototype parts. Now have simulated hydraulic cylinders and push fit motor holders. The motors and the wiring are all concealed, and everything is pivoted to allow the arms to move naturally. When its all done I will reprint most of it at better quality. Seems that it is all working out ok after all.

Go to say though that the 3D printer, useful though it is, is only about 10% of what's involved. It's getting to grips with Openscad that is making it possible. It's weird how I always envied the engineering skills that others had, and never imagined that my years spent programming would ever come in useful when it came to building RC tanks??

RobG

[wibblywobbly]

Spent today getting the arm completed. I hope the pics show how I did this. The pivot at the back of each arm drives the arm in front of it. All the way up to the bucket.

Each hydraulic section is made of two parts, the rear part holds the motor, which has a 30mm M3 threaded gear driven shaft coming out of it. The motor is a secure push fit into the psuedo hydraulic cylinder, and the threaded section extends towards the next arm.

Coming back off the next arm is a hollow cylinder that has an M3 nut glued into a recess in the end.

When the motor turns it pushes/pulls the nut, and therefore the next arm goes up and down.

There are half-hexagon covers on the real thing, so when these are on all of the exposed motors and slots will be out of sight.

I gave the bucket a quick test and the cylinders slid backwards and forwards so that was a good sign, and I have been sanding everything to make sure that it all moves smoothly.

Next up is to get to Maplins and get hold of 3m of wire so that I can make a nice tidy job of threading it down through the arms, though before I can complete it all I have to do the brackets and mount for the lift mechanism on the underside of the arm, and rework the turntable so that I can bolt it down into the drive motor.

The good bit is that there is no glue, and that everything simply unclips to take it all apart.

[edpanzer]

Looks great I'm really impressed

[AlwynTurner]

Wow Rob, you must by now be an absolute whizz at Openscad judging by the results, it looks amazing. And NO GLUE! WOW!!! Great job. Alwyn

[wibblywobbly]

What you are seeing is the 'end result'. What it takes to get there is another thing altogether. lol.

The smaller items I have managed to design and print without any bother at all, though it does take a few hours to get them right on screen before I commit them to the printer. There are some tapers etc, and everything is separate parts, so they all have to be designed, and then rotated and angled to get them to line up perfectly, except that Openscad has a few foibles and does not like parts that just touch each other, or removing material from a surface and leaving an invisible wall. Eg a cube 4x4x4, and then remove a cube 4x4x4. This would confuse the program, and produce a messy print.

The actual arms have been a complete pain. The lift arm was printed 4 times, and it went bad every time. It is right on the limits of the print bed. In the end I cut it in half and printed it, but then one half went bad, so I cut that half in two, and printed that as two parts. One of those went bad, so I ended up with three parts making up the lift arm, which I then had to glue/weld together...followed by hours of sanding. I ran out of blue builders masking tape which is what I use to coat the print bed as parts stick to it very well.

I now have a lift arm that is how I designed it, and really need to try and get two decent prints of the other two arms. Each arm takes a few hours to print and wastes a whole load of filament when they go bad. so I am tempted to finish it and leave any attempt at reprinting until another day. They will work fine, they are just not as thick as they should be.

I have test threaded wiring through the arms, and tested the lift arm, and the turntable is back in action, I will continue this tomorrow, as you can see there is a lot of sanding and filling to do...

[AlwynTurner]

Looking great so far Rob, it might be irritating with all the little problems but it is incredibly impressive, and you will have a completely unique model at the end. Really amazing work well done! Alwyn

[wibblywobbly]

Looks like I am on the home run now. Need to shorten a few bolts, and complete the wiring - which is a bit of a challenge in itself as the turntable rotates - but everything clipped and slotted together ok. I will be so glad when I can actually paint the thing...jeez, this has been a long haul.

The lift motor works like a charm, much better than my old handcrafted version.

[wibblywobbly]

Quick update, everything now wired in, tested and it all works. Made custom trays to hold the IBU2 and the RX18/receiver, they just clip in.

Printed some smoke launchers to replace the styrene tube that I had on there before. Waiting for a speaker to arrive, that will have to go in the upper hull as there is no room left in the lower.

So just finishing off, paint and it will be good to go.

[mcevoyi]

Rob

This is such an epic build ..i really love what you have created ....I don't know how long it's take to
Print the arm ...but it seems so much like the way to go in so many ways ,,,i dont have the PC skill
To do that

..but just fantastic so far Rob

[wibblywobbly]

I didn't have any skill at all a few weeks ago, I had never been near a 3D printer in my life? Building the printer was like building a tank, quite easy really. Then came designing parts, and that was the difficult part as I had never used any sort of CAD software before. The one I am using is arguably the most difficult to use, but the most flexible (for me at any rate). I used to do programming, so I guess I wasn't afraid to give it a go. I have made numerous errors, had all sorts of mishaps with the printing, but each time something goes wrong I learn from it. I have also learnt from You Tube tutorials, online manuals, and trial and error (some of the YouTube techniques are not the best way to do things at all). I am now printing around 90% reliability.

This is what you don't see.... All completely useless, and scrap.