I’ve been experimenting for the last month or so with creating my own version of the magnetic arms for the Rostock Max printer. I started with a few goals.
- Print as many of the parts as possible.
- Incorporate part and PEEK fans.
- Add support for LED strips.
- Help manage all the wires going to the hot end.
- No firmware changes.
- Any hardware changes can be easily reversed.
Initially I wanted to use magnets on both sides of the chrome balls. The effector had holes in it to place the magnets and so did the connection plates. So that means I was printing the mounts for the chrome balls instead of gluing them to screws that are then screwed into effector and connection plates. I’ll show the general progress of the effector design while skipping over all the smaller tweaks and printing/warping/curling issues.
You can also see the squares for mounting some 25mm fans. The magnets bothered the fans a lot in these locations and I could never get enough of a magnetic attraction along with the range of motion needed with the magnets stuck inside the effector. So I decided to try gluing the chrome balls to the effector instead.
Here I also moved the fan holes to a spot in-between the ball mounts. With the next itteration I moved the part fans a little further out and indented them into the surface of the effector.
And here it is with the balls and fake fans in place.
The mounts for the chrome balls were a lot fatter than they needed and limited the range-of-motion for big prints so I made them a little skinnier in the next version.
I also experimented with printing the effector in two different colors. I wanted to put white on the bottom to help reflect the light from the LEDs so I’d start out the print in white and then after a few layers, pause the print and put in black. Here are a couple versions of the idea. You could control how bright the white was by how many layers were printed. The black really wanted to show through and you ended up needing at least 6 layers to cover up the black.
I kept on getting slight curling and warping problems with ABS so I switched to PLA and was able to get a good unwarped print of the effector.
This one is all assembled and I was printing with it for a few days. Unfortunately I discovered that PLA isn’t appropriate for an effector. It isn’t because the hot end gets too hot. I don’t think the hot end heat is much of a problem, especially with the PEEK fan blowing. The problem is the heated bed. The large surface area of the effector hovering over the heated bed soaks up all the heat and after printing for a while, it starts waving like a flag as the arms push and pull on it.
Here’s the bottom showing the LED strips. I made it so I could put two sets of 3 LEDs on each side.
I used this effector to print a nylon one and that is where I’m at now.
It stands up to the heat well but probably isn’t ridged enough. The bottom of it also got a little torn up when I tried removing it from the grid I printed it on. And YES!, those chrome balls are superglued to nylon. It can be done. I just scuffed up the ball a little, put the ball in the indention with some glue and put a clamp on it for a few hours. I haven’t had any come loose while printing so far. The magnetic attraction will probably fail much sooner than the glue will. Even though, I’ll probably try printing in ABS for the next iteration.
You can get the latest version of it from Thingiverse.