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Magnetic Joint Delta

PostPosted: Wed Apr 03, 2013 8:18 pm
by bdring
Check out the BerryBot3D printer. It uses magnetic balls as the universal joints, which appears to be an awesome inspiration. There are a lot of out great features, like the hot end.

It appears to use makerslide and my qu-bd drive lever

Re: Magnetic Joint Delta

PostPosted: Thu Apr 04, 2013 4:36 pm
by k4mg
Speaking of your qu-bd drive lever, I can't find it in your store, do you still sell it?


Re: Magnetic Joint Delta

PostPosted: Thu Apr 04, 2013 5:10 pm
by bdring
I added a few back in. I was taking a break from making them. ... x&cPath=12

Re: Magnetic Joint Delta

PostPosted: Fri Apr 05, 2013 7:21 am
by Digitalmagic
I find the hotend too bulky.
In a bowden extruder like this , the motor is on the frame, and the huge cold part, above real hot end, is bringing too much mass, (printing speed).
The extruder stepper seems to be a Kysan with gear (42BYGH243-5 5:1 probably)

Is magnetic joint a good idea? Advantage? don't know.
Detach-ability? At high speed, I hope it won't detach, representing a potential hazard..

But the concept is appealing, and this guy luves magnets!

Re: Magnetic Joint Delta

PostPosted: Fri Apr 05, 2013 2:42 pm
by Cre8ivdsgn
The cold fin portion might look heavy, but I bet its pretty light. Plus with the main platform made from a tiny piece of 0.125" 6061 al, I bet its not bad.
As far as separation goes, those magnets can be brutally strong, and having six points to distribute the forces through... well, just looking at the video I'm going to take a WAG and say the magnetic forces are at least an order of magnitude greater than the forces that could be generated by the NEMA 17 or even NEMA 23 motors. He'd have to smack the head against something to run the risk of separation.
My only gripe with the design is that the ball and socket joint need to be kept pristine. Those ball magnets - if they are rare earth - are composed of a powdered metal in binder, but then chrome plated. Its possible for the chrome plating to delaminate. And whether the surface is chrome or simple steel, debris will inevitably cause wear. It would be cool to have either the ball or screw have a wear surface of Rulon or something like, but it would have to be thin considering how rapidly the magnetic field strength drops off.
Andbody got any spare, artificial knee joints laying around?
Berry's joint strikes me as original and his idea of magnetic mounts is nifty. I like all the work he did with the 1/8" plate too - making the carriages and the main platform with that material.
Just a thought - in a past life I would shrink a small hole by setting a 1/2" steel ball over the hole and smacking the ball with a hammer. I did this to make a very fine laser aperature. But what I recall is that you could get a good sized dimple. What if he drilled a larger hole, smacked a ball to form th edges of the hole, and then epoxied the ball from the back end? Hmmm... I know I'm not that good with a hammer, but maybe with an arbor press?

Re: Magnetic Joint Delta

PostPosted: Fri Apr 05, 2013 6:01 pm
by cvoinescu
That was what I thought, too. Then I went further: just drill a hole a bit smaller than the ball, and glue the ball there. No fuss. If you're doing this on a CNC machine, you can even mill a blind hole, or a recess shaped to fit the ball. Put some epoxy in, drop the ball in there, done. No hammer, no press. Put another magnet, or a piece of steel, on the back of the plate, and the ball, being a magnet, will hold itself down too -- look, ma, no clamps.

Re: Magnetic Joint Delta

PostPosted: Sat Apr 06, 2013 1:31 pm
by Cre8ivdsgn
I used to make three-ball-array fixtures which would have a vacuum cup in the center and three balls and this would work great for flat objects that had to be held for various manufacturing processes. The balls would be steel, plastic, or whatever the job required. But to fixture those balls (usually 1/2" diameter) I would drill and tap the ball for a 6-32 screw (or was it 4-40... can't remember) and use a 1/2" ball mill to make the pocket. This might work for magnetic balls, but I'm not sure. Rare earth magnet balls I don't think could be drilled and tapped.
To drill and tap the ball, I would use a 5C 1/2" collet with end stop to hold the ball. This was pretty easy and fast.

Also, Loctite makes a super glue (CA - cyannoacrylate) that has rubber powder in it or something like that. It used to be called Black Max and I think they sell a variation at Home Depot. This stuff is great for holding metal balls in sockets. Its impossible to get them out without either a blow torch or BA hammer. :roll: