• BoB gets a new body to go with his shoes.

    HappyFox • 02/13/2015 at 06:18 • 0 comments

    BoB's body had to be completely redesigned for his new heavier servos.

    I choose to keep closer to the classic BoB shape. I hope this will put less stress on the servos, especially on the ankles.

    I also modified the design so the front and back panels can be easily removed and changed. Note the "box" towards the bottom of the body.

    This means the front and back can be removed, which allows you to work on the components mounted to them without the body falling apart. It also provides cable management of the servo cables.

    I completely redesigned the legs in 6 mm ply to give them some more strength. I also originally designed the legs to have two side panels, as you can see from the tab cut outs. However that limited the range of motion for the "ankle" so I left one side off.

    The heavy duty servo horns from Servocity worked well. They gave the legs much more rigidity and strength, so no more swaying in light breezes!

    I am pretty happy with this as a starting point, now off to do the electronics!

    More pictures of the current state of BoB:


  • BoB needs some new shoes !

    HappyFox • 01/23/2015 at 04:43 • 0 comments

    Originally my BoB was going to be a much shorter and smaller bot. However as I was starting to build it, I was given an Intel Edison by the nice fellows at Metrix Create:Space. Obviously an Edison is massively more powerful than what is needed for a BoB, but the absurdity of using it in such a project tickled my nature. This means that my BoB is now much larger than originally planned.

    The original servos were 9 gram micro servos that most BoB's use. However the increase in height and weight means that the servo horns are not strong enough to support his new girth. As seen in the video below:

    So I decided to upgrade to standard servos, I went with Hitech HS-425BB as they were cheap with dual ball bearings. This should be enough to move the added girth and support the added weight. I also grabbed some heavy duty horns from Servocity.

    Of course this means that I had to redesign and rebuild the feet and legs.

    So the original legs and feet:

    Feet

    And the new feet:

    As I was doing this I realized that I would need to upgrade the hips as well. This will mean a redesign of the body. But I would rather do that now than later. So I have ordered 2 more servos and horns. When they arrive I will rebuild the body and legs.

    I do have a concern that the legs will get too long, causing the bot to tip more even when lifting his foot slightly. I have made the foot wider to handle this, but we will have to see when it is all together.