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  • Author Author: dubbie
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DC Motors Mobile Robot : Adding the Battery Container

dubbie

The next step in my DC Motor Mobile Robot is to add the battery container. This is a 3D printer box that a slightly smaller 4 x AA battery holder fits into. I decided to use a smaller battery holder as the original one did not leave any room for putting some sides onto it. The downside of the smaller battery holder is that it doesn't have an ON/OFF switch but that should not really matter, once I have the controller added.

 

The battery holder fitted perfectly so what was needed next was a lid for it so that I have a flat surface on which to attach the rotating dome part. Again I have gone for an interference fit for the lid as it is the easiest approach. I have made the lip deeper than I usually use at 3.5 mm, to ensure it is stable when something else is added to the top.

 

 

Everything is still working, as after all, currently it is only four DC motors connected directly to a battery so there is little to go wrong. My next step will be to design and 3D print a dome that will fit on top of the battery lid. I have put a hole in the battery lid that is the same size as the arm parts of a micro step motor as I will be using this to rotate the dome. It does mean that the dome will only be able to move through an angle of 180 degrees, but that should be enough. In order to minimise the height of the entire mobile robot I will put the micro servo motor into the dome itself. Hopefully there will also be room for the Arduino controller as well. I have not always included routing points for all the wires that will need to connect from the DC motors to the dome, so I will have to fix them nicely on the outside, maybe with some small 3D printer covers to make everything look nice.

 

There will be some design issues as the current body of the DC motor Mobile Robot is rectangular but the dome will be circular. It might look OK. There is also the issue that the dome part may become too big to be made in one piece on my 3D printer. I might have to make it in two or more pieces, which will be tricky, or maybe go for some other curved surface, perhaps a segment or something. I will also need to ensure that the completed mobile robot does not become top heavy.

 

Dubbie

  • in reply to genebren

    Gene,

     

    Thanks for this comment. I'll have to look at levelling the print bed and see if that helps.

     

    Dubbie

  • in reply to dubbie

    Dubbie,

     

    Tuning your 3D printing process can be a full time job.  It seems like I get everything dialed in and 'bang' something else changes.  When I was printing parts for my 'Walky' robot, I started getting some of my larger prints to lift in the corners.  At that point, I more frequently and more carefully leveled the bed prior to each print.  Weeks later the problem got worse and no amount of leveling would help.  I then started using blue painters tape on the bed to help with adhesion.  Later I noticed that I could improve on this by cleaning the tape surface with alcohol prior to each print. (Note: not all blue tape is the same. I switched tape, same 3M brand but a slightly different surface finish, and things would not stick).

     

    The constant creep in print quality is troubling. I wonder if the the temperature (bed and/or extruder) is shifting due to aging or some other reason.  Lately I have been getting a lot of stringy prints, where excess plastic is coming off the extruder as in is moving between depositing material.  Too hot? Too cold?  Or is it an issue with the filament?  I need to do some experimenting.

     

    Keep on printing.

    Gene

  • in reply to genebren

    Gene,

     

    I quite agree, it is great fun. It would be more fun if I didn't keep stabbing myself with the scraper I use to remove the raft from the printed model. It is very sharp. I haven't quite worked out why for some prints the raft comes away quite easily, while for other, especially the larger ones, it seems to be welded to the part. I also still get a little bit of lifting on one corner of larger prints.

     

    Dubbie

  • Looking good!  Being able to print parts is such a boom to the robotics hobby.  I have had some luck in machining parts in plastic (mill/drill/lathe/saw/file), but printing them is so much more fun and precise (in my case).

     

    Keep up the good work!

     

    Gene