First Conversion: Bruder Delta Loader

[RobotArms24]

So this will be my first attempt at converting a toy to R/C. I have spent some time researching other peoples conversion and have come up with a game plan. I chose a skid steer because they are pretty simple and I always wanted a skid steer.

I saw on another forum someone had used an embedded computer to control his skid steer, and this idea intrigued me. I decided the extra cost for the microcomputer was not worth it tough, and my programming knowledge is very limited because I haven't done any programming since I was in high school.

So the plan for now is to use gear motors and the sabertooth motor controller. Hobby King has some cheap receivers and transmitters that I will use to control the loader.

I have already ordered my loader and ripped it apart. We have all seen pictures of them so I wont post any. I did break most of the tabs when disassembling, and I have no idea how anyone can disassemble these toys without breaking them...

Here is a short parts list I have going:


The lift servo is a servo I have lying around already so I figured I will give it a shot. It's almost 15kg/cm so it should be more than strong enough.

The bucket servo is a "robotics" servo that should be able to do 180 degrees, and should have lots of power. I saw on the other forum that one guy had a full size servo on his bucket and had made a 3D printed mount for it, that anyone can buy, so I will try that.

I drew up a wiring diagram:


I have two BEC's on there, but I don't know if it is necessary.... The motors are I believe 800 mA stall and I can't find specs on the servo's, does anyone know roughly how much power a servo will draw? I might end up just getting a single larger BEC to control everything, it would probably make less interference that way as well.

These are the motors I plan to use:
https://www.pololu.com/product/1594


According to my measurements they should fit great. They are the slowest RPM they make in that style at 80rpm@4.5V, and I will run them at 6V so I hope they aren't too fast.

They make nice looking motor mounts for these motors.



I have been working on some 3D models for drive hubs. I can send them to get 3D printed in Nylon for really cheap. I had test printed my first design at a local printing hub and they turned out not too great, the local printer was very low resolution.


I have a newer model I will get printed by shapeways. I have seen pictures of their prints and they are much higher quality and still afforable. The problem with shapeways is the looong wait time, something like 30 days to print.

Here is what I have so far:

The recess in the back is for the shaft adapter.

This is what the real thing looks like, I tried to make it realistic looking.



This is my progess so far, and it will probably be a bit of a long project, work is slow so r/c money is limited.

Any thoughts/suggestion would be greatly appreciated!

Thanks for looking!
-Kyle

[RobotArms24]

I got most of my parts in last week, so I did a bench test of the electronics and they work great. I had an oops though, I accidentally ordered my drive hubs in orange instead of yellow, so I will have to paint them. I am also waiting for another cheapo towardpro servo to use instead of the savox.



A quick test video:

https://youtu.be/JM0Lu6t7n-Y

My video skills need some work.

[gmmiller06]

Nice! Love the work so far! I'm subscribed!

[RobotArms24]

Some progress finally!

Big mess from trimming plastic!


Motors are mounted to a piece of 1/4" aluminum. I drilled and tapped the plate to bolt the motor mounts, and sabertooth on to.














Test video on the floor, hauling around a 6000mah 2cell lipo.
https://www.youtube.com/watch?v=BSA80z1AVHs

It's a little slow in my opinion... Maybe I will try the higher RPM motor down the road... For now, it's on to modifying and mounting servos!

[Kingcam2]

Looking good so far Kyle,

Like you I have never converted anything to Rc before, at the moment I am trying build a Kat ex but I keep finding new problems with or that I am missing part that I didn't know I needed for it.

I have a Bruder dozer the one with the rubber tracks, sitting my Rc shelf waiting to be convert to Rc.

Thanks for the Idea on the drive motors, I get some from the same site but in a bigger rpm.

Regards Cameron.

[Rvjimd]

I don't think it is too slow. I would run it that way once you get it all done, for a while before you change the motors. I think a lot of RC stuff is run way too fast and it kills the scale look. Good job so far, keep at it!

Jim

[RobotArms24]

I had last week off from work for a staycation, so I had some time to work on this finally. It is about 90% done now, needs a couple touch ups and some paint. Here is what I have done now:

I modified the transmitter and took out the spring mechanism on the one stick.


I modified the bucket curl servo to get more travel. It runs about 160 degrees now. I soldered in two 2.2k resistors, one on each side of the potentiometer. I also moved the wire to the side of the case.



Video of servo travel. You can see where I marked the cardboard stock and the new travel.
https://youtu.be/ZPzTH3JKpzY


I was able to keep the engine cover by mounting the servo low, and cutting it out for the servo arm and linkage.


I mounted the lift arm servo to the model with 1/4" aluminum blocks, they are drilled and tapped to mount to the servo, and on the side to mount to the model.

The bucket servo is mounted with SteinHDan's 3d printed mount I ordered from ShapeWays. I modified a small servo arm to fit on the bucket mount, then drill and tapped the arm for a 4-40 screw. I drilled the pivot point for the bucket so I could screw an m3 screw into the servo gear.




I mounted the receiver under the cab and had to cut out a bit of the seat to get it to fit.

The BEC is mounted behind the cab in the main compartment above the motors.

I had a hard time finding a battery that would fit because I mounted the servo pretty low. I ended up with 2 x 450mah 2-cell li-po batteries, wired in parrallel.




How it sits now, almost done.


Video of it running:
https://youtu.be/Ye79_dS8ZME

It seems to be very stable, I don't think I will have to worry bout it tipping.

I may try to get a little bit more travel out of the lift servo, I feel like it is not lifting all the way up.

Thanks for looking.
-Kyle

[Rvjimd]

Kyle,

In your last video the bucket and boom works really fast. Is it possible to slow that down on your transmitter programming or is it just the way the geometry of the servos and attachments to the machine? I have always thought one of these would be a fun little project. Good job!

Jim

[RobotArms24]

Hi Jim,

My transmitter is the cheapest one I could find from HobbyKing, it was like 30 bucks. It does not have any fancy features that would allow me to slow it down. I would expect some of their better ones with screens, or other name brand transmitters would have features to do it, maybe an exponential would do it.

Also hitech servo programmers seem to be able to program their servos so that you can slow it down as well. Again I bought super cheap servo's from hobbyking that are not programmable.

If you are a computer nerd you could put in a micro-controller and set the speed in the software programming. I have seen this done on this model, on another forum, and it was very cool. You can even program it to auto-level the bucket.

Thanks,

Kyle

[Themonty73]

Great job keep up the good work...