BIT 1.36 V2 Building Blog (Part2: Assembling) English Version
After finish designing the robot, we started to buy all the parts. Standard parts (like bearings and screws) can be ordered from Taobao, All the CNC metal parts and WEDM parts are ordered from Team Scrapiron (he gave an extra frame to me). All the electronics are from the last robot I built.
Since most of the work is just tighting the screws and soldering the wires, I will pick some interesting work to talk about.
Many of the armors on the robot is 3d printed. Normally armors made of PLA or ABS does not hold up very well in beetle weight fights. TPU armors of the same weight is much more durable than those made of PLA or ABS. But TPU filaments are tricky to print, for they are so soft that they may get stuck into the gap between the extruding gear and the heat break, causing print failures. Even it didn't get stuck, the gap may also effect the extruding pricision, causing some ugly bands. The ender3 v2 I have does not have direct drive extruder, and it is only capable of print some small TPU parts. It is very likely to fail when printing big parts like armors. I upgraded the printer twice and I will talk about some of the upgrades in the next post. The upgrades improved the overall printing quality a lot.
And about the stiffness of the TPU filaments, most of the filaments sell online have a stiffness of 95a, which is bit too soft for armor, and is also harder to print. Of course you can get pretty strong armors out of it as long as they have a relatively higher infill and wall thickness. At first I used 95a TPU filaments as well, but I found that the robot has exceeded the weight limit, and the armor will be too soft if I decrease the infill, so I decided to buy some filaments with a stiffness of 64d, which is much stiffer. Since the filament is harder, it is easier to print as well, and the print quality is much better than before.
The stiffness of the silica gel is 35 degrees, the trick of pouring the silica gel into mould is to be slow and pour it round by round and make sure that the gel has flowed to the the bottom of the mould. There will be some bubbles more or less on the top, probably because of the hardener. I found that most of the bubbles are on the top, I poke them with toothpicks as many as possible. Someone uses vacuum machine to suck the bubble out, but I don't have one. So I found an alternative solution, which is using a vacuum cleaner to suck them out. The result turns out to be okay. There is a small amount of bubbles that I can do nothing about them. I just leave them there since they don't really effect anything. You can see it as a method to reduce weight.
It is important to make sure that the bearing is pressed into the pulley perpendicularly, otherwise it may effect the cocentricity a lot, leading the weapon to spinner unsmoothly. Remember to have something placed between the bearing and hammer to act like a cushion if you are trying to hammer it in, so that the bearing will not be damaged.
The robot is actually a little over the weight limit at first, so I replaced some of the screws with titanium screws. Titanium parts are usually expensive but since they are only screws the price was okay. Most of the titanium screws are on the edge of the robot, like the screws for the 3d printed armors, since they do not require much strength.
The robot was 2wd at first, but I found out later that the center of gravity is too far away from the wheel to the front, so the wheels don't really have much grip. I have to use one of the screws in the front which was a part of the armor act like a shaft for the front wheels and use an extra set of PU belt for power transmission.
That is pretty much all about this machine, the rest of the work is just improve the color scheme and the look, I have posted a video on Bilibili and here is the link: https://www.bilibili.com/video/BV1wP4y1Y7qq?spm_id_from=333.999.0.0
Comments
Post a Comment