Magnetic arms with printed mounts

[jetpad]

I've been experimenting for the last month or so with creating my own version of the magnetic arms. 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.

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.

[img]http://bitsintoatoms.files.wordpress.com/2013/06/img_2300.jpg?w=300[/img] [img]http://bitsintoatoms.files.wordpress.com/2013/06/img_2297.jpg?w=300[/img]

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.

[img]http://bitsintoatoms.files.wordpress.com/2013/06/img_2298.jpg?w=300[/img]

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.

[img]http://bitsintoatoms.files.wordpress.com/2013/06/img_2299.jpg?w=300[/img]

And here it is with the balls and fake fans in place.

[img]http://bitsintoatoms.files.wordpress.com/2013/06/img_2228.jpg?w=300[/img]

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.

[img]http://bitsintoatoms.files.wordpress.com/2013/06/img_2315.jpg?w=300[/img]

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.

[img]http://bitsintoatoms.files.wordpress.com/2013/06/img_2308.jpg?w=300[/img]

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.

[img]http://bitsintoatoms.files.wordpress.com/2013/06/img_2306.jpg?w=225[/img]

I used this effector to print a nylon one and that is where I'm at now.

[img]http://bitsintoatoms.files.wordpress.com/2013/06/img_2311.jpg?w=300[/img]

It holds 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.

[img]http://bitsintoatoms.files.wordpress.com/2013/06/img_2318.jpg?w=300[/img]

[img]http://bitsintoatoms.files.wordpress.com/2013/06/img_2317.jpg?w=300[/img]

[JohnStack]

Fantastic! Are you going to share your design with the community or on Thingiverse? I'd love to try it out.

[Eaglezsoar]

A Very interesting post, please keep us updated on your progress.

[barnett]

I like your integrated downward facing fan mounts. Neat & tidy.

I'm imagining repeatedly adjusting firmware & calibration for all those effector/arm/carriage mount combos.

[jetpad]

Fantastic! Are you going to share your design with the community or on Thingiverse? I'd love to try it out.

Yes, as soon as I finish my tweaks to them I'll get them in shape to put them on Thingiverse. It's still quite traumatic switching all the arms out and I don't want anyone to have to do it more than once.

[jetpad]

I'm still messing with the files but I've posted the latest versions of the effector and the arm plate mounts on Thingiverse.

http://www.thingiverse.com/thing:94724

This doesn't include the files for the actual magnetic arms or instructions for creating them. I hope I'll have those ready in the next couple days.

[Broose]

Jetpad- Are you using the same 3/8" dia magnets that Xnaron uses in his arms, but with the 1/2" dia balls?

[jetpad]

Jetpad- Are you using the same 3/8" dia magnets that Xnaron uses in his arms, but with the 1/2" dia balls?

I'm using different magnets with the 1/2" balls. They are 10mm in diameter by 3mm. I stick four of them on each side of an arm and it ends up using 48 of them.

Magnets
http://cgi.ebay.com/ws/eBayISAPI.dll?Vi ... 0717855827

Ball Bearings
http://r.ebay.com/9t3vOI

[cambo3d]

nice work indeed,

maybe you could also angle the fans to point toward the nozzle tip, instead of straight down??

[jetpad]

nice work indeed,

maybe you could also angle the fans to point toward the nozzle tip, instead of straight down??

Good idea. I could probably get it at least a little more directed toward the tip.

[jetpad]

Here's an update to it I've been working on. I've got all the fans pointed right in the center now. I wonder what kind-of breeze it'll actually make or if they'll cancel each other out. I need to try printing it.

[jetpad]

I've just posted on Thingiverse, the files to make the magnetic arms that go with the effector. They look really simple but it was really weeks of tinkering. I wish I had something that could accurately measure the sizes of the arms I created so i'd know how close I got them to each other.

http://www.thingiverse.com/thing:107208

[lordbinky]

I'm using a modified version of Jetpad's effector platform on my magnetic arms setup. I recently printed another platform in black abs to mount the hotend above the platform instead of having the E3D hang below it.

To protect the effector I put a coating of silicone on the bottom. I then took a piece of vector/prototype board (the plain perforated circuit board material) that I cut out to match the platform and pressed that into the silicone.Another layer of silicone went on top of that to smooth it all out, and then I covered the bottom in an aluminum foil tape. The inside of the effector had a liberal amount of silicone applied to it for insulation, and the foil wrapped around that up to the top of the platform.

So far I've printed a few hours of nylon with no detectable issues in the platform. The platform has stayed cool to the touch top and bottom with the hotend at temperature, even the inner ring next to the heater block (yes, my curiousity is > my intelligence).

Is it insulation overkill? Probably, but I'm not going to spend time to find out which is the critical piece.

I'll post picture tonight hopefully.

[jetpad]

The insulating layers are a good idea. I wonder which part had the biggest effect? I'd guess the circuit board material probably helped the most.