Haydn Huntley’s MagBalls and MagBallArms for Delta/Kossel 3D Printers

My adapters for the Predator effector, printed on a Photon.
https://www.thingiverse.com/thing:3880977
Photo and print courtesy of Tai Hromnak

My Kumu-3D printer.
An unusually rigid machine.

Photo Gallery

Note: NdFeB magnet prices have doubled during the past year.
First Class postage has tracking only within the US.
Priority Mail is faster and includes tracking, even outside of the US.
UPS Worldwide is currently the best option for outside the US.
One way to save on international shipping is by ordering together with a friend.
Another way is by using a freight forwarding service such as USA2You.nl or Polar Express.

Description	Examples	Price	US First Class Mail (inexpensive)	US Priority Mail (faster)	International First Class (no tracking)	UPS Worldwide (fast, with tracking)	International Priority Mail (no longer recommended)
High-precision MagBalls	for a 3D printer	12 for $18	$5	$8	$17	$40	$45-$55
High-precision MagBalls	for kinematic coupling	6 for $10	$5	$8	$17	$40	$45-$55
CNC’d Delrin rod ends		12 for $15	$5	$8	$17	$40	$45-$55
N52 NdFeB magnets		$2 each	N/A	$8	$25	$40	$45-$55
215mm set of arms	Mini-Kossel w/170-190mm bed	$90	$7	$10	$25	$40	$45-$55
288mm set of arms:	Kossel w/225-240mm bed	$90	$7	$10	$25	$40	$45-$55
304mm set of arms:	Kossel w/250mm bed	$90	$7	$10	$25	$40	$45-$55
360mm set of arms	Kossel w/300mm bed DC42’s Precision Kossel Kumu-3D Ultibots D300VS	$95	$7	$10	$25	$40	$45-$55
400mm set of arms	TEVO Little Monster w/340mm bed	$120	$7	$10	$25	$40	$45-$55
440mm set of arms	Anycubic Predator w/370mm bed	$120	$7	$10	$25	$40	$45-$55
Custom length set of arms up to 600mm		$120	-	$15	-	$40	$45-$55
10mm pultruded CF tubing instead of 6mm		extra $60	-	$15	-	$40	$45-$55

A handy rule of thumb is that the arms need to be about 120% of the bed’s diameter, so a 300mm diameter bed needs 360mm length arms to easily reach the edges.

Email haydn.huntley@gmail.com for MagBalls, magnets, and carefully assembled, precisely measured carbon fiber arms.
I test and measure each set of arms. The magnets in the joints have a tested holding strength on a MagBall of at least 1.5kg.
The arms in a set match lengths within 50µ, according to my calipers, and typically they match within 30µ.

All sets of arms include MagBalls, N52 magnets, pultruded carbon fiber tubing, and CNC’d Delrin ends.

Lubrication: I’ve heard that the best is SuperLube PTFE, which I now include a small tube of.
I’ve also had good results with bicycle chain lube, which is waxy enough to stay in place, such as White Lightning Easy Lube

John Giardino wrote up a guide on converting the Anycubic Predator to use MagBall arms, using the stock effector and controller and my printed adapters, however it results in printing objects scaled incorrectly, so now I recommend the following technique:
It produces correct scaling and uses the stock controller. Here is an easy, 4-step guide here. Paul Schulyer was the first to let me know about this improved technique.
Many people have also done it using either an SKR or Duet controller, which is straightforward.