MagBall Arms - 288mm PRINTED
Six carefully assembled and matched Magnetic Ball Arms are 288mm long +/- .3mm measured from the center of one ball to the center of another. Within a given set, the arms are marked with their lengths and are guaranteed to match one another within 0.10mm (100µm). Also included are 12 Ball Studs which have standard 3/8" diameter balls and 3mm diameter, 10mm long shanks. The magnets typically exert at least 1000g (1kg) of force on the balls.
Effector and carriage STLs are on GitHub/UltiBots/K250VS.
Rail carriage is available thanks to AdrianW http://www.thingiverse.com/thing:1264254. They have 45mm ball spacing and are untested by UltiBots.
NOTE: These arms are made by the MagBall guru Haydn.
Posted by Oleg on 22nd Sep 2016
Very strong magnets , so strong that my fan stoped working because of magnetic field . So i needed to redesign my effector to put the fan away from magnets.
Im using e3d cyclops hotend.
Now everything fine.
Posted by W3DRK on 15th Aug 2016
DYI'd my own Kossel 250 and purchased many of the parts from Ultibots including this arm kit.
Using the 43mm ball spacing carriages available on Github and a customized effector for an E3D V6 bowden setup with the same 43mm spacing worked out perfectly.
I would certainly recommend these to anyone building or upgrading their delta.
Posted by Chris M. on 19th Apr 2016
I bought these arms to retro-fit onto my SeeMeCNC Rostock Max v2 and they worked great. I custom designed the new effector and carriage and these arms work perfectly to prevent play and slop from ruining my print quality. I now get perfect prints both dimensionally and in surface quality. They came labeled with their exact lengths and all 6 were exactly the same. This made calibration and settings easy and quick. They were also very cheap compared to doing it myself. I highly suggest these arms for any printer upgrade.
Posted by Zach on 10th Aug 2015
I mounted these on my Kossel Clear from Blue Eagle Labs. After installation with some 6mm carriages, effector and a little calibration, my prints had noticeably tighter tolerances. My 20mm calibration cubes are +-.03mm on all sides and my infills and perimeters seem to overlap a little better.
This is a great upgrade for a Kossel printer. It holds tighter tolerances, won't wear out nearly as fast as the stock ball joints and looks great!
Posted by Unknown on 8th Mar 2015
These arms are pre-assembled and have the length marked accurate to 100th of a mm. All six varied no more than .02 mm maximum from any other, and all were .01 mm from the average length.
A second advantage of the magball arms are that they disengage if a head crash or other misfortunate thing occurs, saving the hardware from worse damage.
Posted by Jon on 6th Mar 2015
I bought this recommended upgrade with my Kossel 250 V kit, and boy, it was a good idea. During the "first movements" testing phase, I made more than a few poorly-advised movements, and sent my print head outside the print envelope. "Outside" means either into the bed, or into a column, or into space between columns that's physically fine but drives the Marlin math insane. When it crashed, a magball popped off; it was a total nonevent. It's cheap insurance to make your build less intimidating.
I've also popped the balls off just to service the effector head a couple times. Very convenient.
The only reason I can imagine to not buy this upgrade is because you like the idea of building everything from closer-to-raw parts.
Posted by Matt on 28th Dec 2014
These arms are very well-made and the action is very smooth and quiet once installed - no more spring noise.
It's nice to be able to yank the extruder so easily now; plus crashing the nozzle won't cause any damage as the arms just pop off. I know this because the new carriage, arm, effector geometry reduces the build height by about 24mm and I didn't measure the height difference ahead of time. ;) That said, the upside is that the new geometry does enable reaching the extreme edges of the build plate. This is not possible with the stock arm setup.
The new arm geometry resulted in an auto-calibrated marlin firmware delta radius (R) value of 172.5 for me and a build height (H) of about 232. These should be good places to start after install.
One gotcha I ran into is that the ball effector provided via the github link is thinner than stock (as of this review); I had to add a stack of washers on top of it to keep the extruder body screws from bottoming out.
*** UltiBots Added *** updated STL on GitHub for 7.5mm effector thickness
All prices are in USD.