I figure if the robot/AI uprising is inevitable as so many seem to speculate then I may as well start making sure they know I'm on their side. So...why not welcome another bot into my house!
I've already got the 3D printer and MPCNC as well as the eggbot I built this past spring. Not to mention the mini CNC I started with. Oh, and the robot arm I made:
So...what's next? What other new and interesting kind of 'bot can I welcome into our home...
A polar bot! I've wanted to build one of these for a long time. In fact I almost built one as my first bot since I figured it would be one of the quickest/cheapest to build. But it wasn't until I got the 3D printer and gained the ability to manufacture custom parts that I really dug in on building things.
Rather than start from scratch I'm jumping on some good old giant shoulders and using existing work. The same guy who designed the arm I printed also designed a polar bot so I started with his design: https://www.thingiverse.com/thing:798076
Turned out to be a fairly easy print, one evening and I had everything except the motor mounts printed:
There are fancier designs that use bearings to help the supports rotate...but those are fairly large and expensive bearings which I didn't have on hand. I also decided to do this about a week ago in hopes of having it done for an art show at our office tomorrow...so waiting for mail order parts wasn't much of an option. This design is simple and seems to "just work".
I stole the RAMPS board I used on the eggbot, along with the steppers from the eggbot. Eventually I'd like to have a few more steppers and spare electronics so I can keep both bots going at the same time...but since the eggbot is rather seasonal I don't mind borrowing from it for now. Oh, I also stole the servo from the eggbot but that was due to me being too lazy to walk out to my shop and grab another. Eggy doesn't need it right now anyway
The one problem I had with the prints was that the D cell batteries I had on hand don't quite fit the weight holders. I haven't had time to adjust them so I just kind of forced one to fit and the other two I just taped to the chains. It's not pretty...but it works.
Like, really - it works:
Well, ok. It's got a few issues still.
I haven't fully calibrated everything, I just took some "educated" guesses at the steps per degree and got it in the ballpark. And the speeds still need a lot of work. I'm using the Makeangelo firmware/software to control it: http://www.makelangelo.com/ It should be able to handle "normal" gcode but I haven't tried that yet because I haven't got the LCD/SDCard working yet. And the Makeangelo software for control doesn't seem to give a lot of control over speeds. So I've been modifying the hardcoded max speeds in the firmware and reflashing to find what works.
Drawing the built in generative "art" routines of the software it goes WAY too fast and the pen jumps all over. This causes the chain to jump in the sprockets and things get ugly quick.
On the other hand when I loaded up an SVG of the FT logo and ran it it (as in the video) it slowed down and actually didn't do that terrible:
Though as you can see I did still have some chain skips that resulted in things going out of alignment. The problem is the pulleys don't quite match the chain I found at my local hardware store. I either need to find better chain or modify the pulleys. I'll probably try modifying the pulleys tonight because I can't find better chain in town. (These setups seem to work better with chain that has fewer but larger beads - like that used on some kinds of vertical blinds. Which I can order off Amazon or ebay but not in time for tomorrow!)
The other big issue I have is my stepper motors are too short. It fits this 24"x24" chunk of wood (that some of you may recognize as the original base of my MPCNC and which now serves as my waste board - the other side is UGLY) but just barely. But at the office I want to hang it on a big white board so it can draw with dry erase markers - so I'll need to extend the stepper wires.
I had one other issue at first where it was slipping like crazy...pulling on the cords one side would always slip while the other held fairly well. I thought it was the current on the steppers - but they're set almost identical. So I was going crazy trying to figure out what was wrong...then I remembered. I didn't add the set screws to the pulleys - one fit snug but the other was rotating on the motor shaft. Adding those set screws helped a LOT!
Oh - and so far none of those photos showed the pen up/down servo connected:
Nothing fancy, just a few servo extensions dangling there. May need to add one or two more if I put it on the big dry erase board.
But...if I can't get the pulleys to play nicer tonight then I probably won't risk running it in public tomorrow.
I've already got the 3D printer and MPCNC as well as the eggbot I built this past spring. Not to mention the mini CNC I started with. Oh, and the robot arm I made:
So...what's next? What other new and interesting kind of 'bot can I welcome into our home...
A polar bot! I've wanted to build one of these for a long time. In fact I almost built one as my first bot since I figured it would be one of the quickest/cheapest to build. But it wasn't until I got the 3D printer and gained the ability to manufacture custom parts that I really dug in on building things.
Rather than start from scratch I'm jumping on some good old giant shoulders and using existing work. The same guy who designed the arm I printed also designed a polar bot so I started with his design: https://www.thingiverse.com/thing:798076
Turned out to be a fairly easy print, one evening and I had everything except the motor mounts printed:
There are fancier designs that use bearings to help the supports rotate...but those are fairly large and expensive bearings which I didn't have on hand. I also decided to do this about a week ago in hopes of having it done for an art show at our office tomorrow...so waiting for mail order parts wasn't much of an option. This design is simple and seems to "just work".
I stole the RAMPS board I used on the eggbot, along with the steppers from the eggbot. Eventually I'd like to have a few more steppers and spare electronics so I can keep both bots going at the same time...but since the eggbot is rather seasonal I don't mind borrowing from it for now. Oh, I also stole the servo from the eggbot but that was due to me being too lazy to walk out to my shop and grab another. Eggy doesn't need it right now anyway
The one problem I had with the prints was that the D cell batteries I had on hand don't quite fit the weight holders. I haven't had time to adjust them so I just kind of forced one to fit and the other two I just taped to the chains. It's not pretty...but it works.
Like, really - it works:
Well, ok. It's got a few issues still.
I haven't fully calibrated everything, I just took some "educated" guesses at the steps per degree and got it in the ballpark. And the speeds still need a lot of work. I'm using the Makeangelo firmware/software to control it: http://www.makelangelo.com/ It should be able to handle "normal" gcode but I haven't tried that yet because I haven't got the LCD/SDCard working yet. And the Makeangelo software for control doesn't seem to give a lot of control over speeds. So I've been modifying the hardcoded max speeds in the firmware and reflashing to find what works.
Drawing the built in generative "art" routines of the software it goes WAY too fast and the pen jumps all over. This causes the chain to jump in the sprockets and things get ugly quick.
On the other hand when I loaded up an SVG of the FT logo and ran it it (as in the video) it slowed down and actually didn't do that terrible:
Though as you can see I did still have some chain skips that resulted in things going out of alignment. The problem is the pulleys don't quite match the chain I found at my local hardware store. I either need to find better chain or modify the pulleys. I'll probably try modifying the pulleys tonight because I can't find better chain in town. (These setups seem to work better with chain that has fewer but larger beads - like that used on some kinds of vertical blinds. Which I can order off Amazon or ebay but not in time for tomorrow!)
The other big issue I have is my stepper motors are too short. It fits this 24"x24" chunk of wood (that some of you may recognize as the original base of my MPCNC and which now serves as my waste board - the other side is UGLY) but just barely. But at the office I want to hang it on a big white board so it can draw with dry erase markers - so I'll need to extend the stepper wires.
I had one other issue at first where it was slipping like crazy...pulling on the cords one side would always slip while the other held fairly well. I thought it was the current on the steppers - but they're set almost identical. So I was going crazy trying to figure out what was wrong...then I remembered. I didn't add the set screws to the pulleys - one fit snug but the other was rotating on the motor shaft. Adding those set screws helped a LOT!
Oh - and so far none of those photos showed the pen up/down servo connected:
Nothing fancy, just a few servo extensions dangling there. May need to add one or two more if I put it on the big dry erase board.
But...if I can't get the pulleys to play nicer tonight then I probably won't risk running it in public tomorrow.
