An easy magnetic ball solution.

[Flateric]

Some are having trouble with the whole jbweld adhesion thing. Or having inconsistent results which are critical for a delta printer.

Was at the hobby store the other day and picked up some of these just for testing and because I would like to have a few different effectors on the side with different hotends in them ready to go.

They are made by "TRAXXAS" part # 4933. You get 4 for 5 bucks cdn. You also get some nice plastic cups for them to ride in that you may or may not be able to use in your arms themselves.

Here is a pic!

traxxas balls

As you can see they also have a nice allen key tip for tightening.

[Eaglezsoar]

Some are having trouble with the whole jbweld adhesion thing. Or having inconsistent results which are critical for a delta printer.

Was at the hobby store the other day and picked up some of these just for testing and because I would like to have a few different effectors on the side with different hotends in them ready to go.

They are made by "TRAXXAS" part # 4933. You get 4 for 5 bucks cdn. You also get some nice plastic cups for them to ride in that you may or may not be able to use in your arms themselves.

Here is a pic!

effector.JPG

As you can see they also have a nice allen key tip for tightening.

What is the diameter on the balls?
Edit: The balls appear to be 11mm in diameter which is 0.43307in. Since the cups on the Xnaron arms were designed for 1/2" balls wouldn't these
require a redesign of the printed cups?
Edit 2: The balls are supposed to be 3/8", not 1/2" so the balls listed above are a little too large.

[daftscience]

That looks like it would be much easier to assemble. What are they made out of? All the ones I'm finding are made out of aluminum.

[Tinyhead]

This is awesome. I've been pulling bearings apart at work trying to find 3/8 balls (Eaglezsoar I didn't realize the mag arms actually called for 1/2in) but with these traxxas joints, it might be a lot easier. Even redesigning the cups would be simple, but the length of the arms would need to change with the smaller balls in order to keep the geometry/scaling in check... I would think anyway...

[bubbasnow]

That looks like it would be much easier to assemble. What are they made out of? All the ones I'm finding are made out of aluminum.

4933 is both steel and alum pivot balls

http://www.rcparts.eu/traxxas-revo-pivo ... -4933.html

here too
http://www3.towerhobbies.com/cgi-bin/wti0001p?&I=LXSP31

[Eric]

Quick research says they sell the product in both materials. #4933 is steel, #4933x is aluminum.

I'm waiting to hear if they work as well as ball bearings with magnets.

[Flateric]

These balls are 10.9mm in diameter, the same size I have always been using since day one to be honest. Before this I was using pachinko (sp?) bearings from an old chinese style machine.

They are made out of VERY magnetic iron of some type and chrome coated.

As I say though, they also are accompanied by cups for each one that with a little modding can be made to work well with the magnetic arms. They fit nice a deeply within the cup. But the back half of the cup needs sanding away for the magnets to be as close as possible.

Overall they provide a much more consistent ball mount (height and being dead on straight), far more durable since these are one piece, and quick and easy alternative.

[Flateric]

I've been using them on my rig for about 9 months now TBH. They work great. Mine were all steel.

[Tinyhead]

These balls are 10.9mm in diameter, the same size I have always been using since day one to be honest. Before this I was using pachinko (sp?) bearings from an old chinese style machine.

Did you use this size using the stock xnaron cups? And if so, did you have to modify anything else to maintain proper part scaling?

That effector you posted looks awesome by the way. I'd like to try that with the e3d.

[whaleboy]

These look like an easier solution than JB weld. I wonder though if the flats from the Allen socket will cause issues with the magnetic attraction changing at different angles, and therefore different tensions. Also possible extra wear on the cups from the edge?

Or do you think these are these non issues?

What do you guys think of the Trick Laser arms? I'm guessing better than stock but not as good as a well done magnetic setup?

Thanks

-David

[Eaglezsoar]

This is awesome. I've been pulling bearings apart at work trying to find 3/8 balls (Eaglezsoar I didn't realize the mag arms actually called for 1/2in) but with these traxxas joints, it might be a lot easier. Even redesigning the cups would be simple, but the length of the arms would need to change with the smaller balls in order to keep the geometry/scaling in check... I would think anyway...

My error, they are supposed to be 3/8".

[Eaglezsoar]

These balls are 10.9mm in diameter, the same size I have always been using since day one to be honest. Before this I was using pachinko (sp?) bearings from an old chinese style machine.

They are made out of VERY magnetic iron of some type and chrome coated.

As I say though, they also are accompanied by cups for each one that with a little modding can be made to work well with the magnetic arms. They fit nice a deeply within the cup. But the back half of the cup needs sanding away for the magnets to be as close as possible.

Overall they provide a much more consistent ball mount (height and being dead on straight), far more durable since these are one piece, and quick and easy alternative.

In your opinion, will these work with the original Xnaron cups? The Xnaron cups are designed to use 3/8" balls.

[lordbinky]

These look like an easier solution than JB weld. I wonder though if the flats from the Allen socket will cause issues with the magnetic attraction changing at different angles, and therefore different tensions. Also possible extra wear on the cups from the edge?

Or do you think these are these non issues?

What do you guys think of the Trick Laser arms? I'm guessing better than stock but not as good as a well done magnetic setup?

Thanks

-David

Offhand, I would wager that having the balls being dead center (or closer to than typical assemblies) will produce better results than any error introduced by the difference in attraction with the holes.* It isn't ideal, but for practicality it is likely to be trivial. Trick laser arms are good, but magnetic setups have features a fixed solution does not. For a fix it and forget it solution (for older style arms, you may see little if any difference with the latest stock arms), the trick laser arms are fantastic.

*this doesn't apply to setups that use a magnetic ball, shifting the ferromagnetic material around the ball's magnetic pole is a much more significant diffference in attractive force that deserves more caution.

[Tinyhead]

Flateric, would you have the .stl for that effector plate you've got there?

[Flateric]

The effector pictured has been canned. While looking very nice and some of the design ideas behind it are great the overall issues it created are not acceptable.

The effector offset required to be put into the frmware was 64mm. So very substantial, it also introduced a bunch of play because of this large offset. The leveraging was too much if that makes any sense to you. I don't recommend it and won't use mine again after a few hours of playing with it.

The flats on the balls have been a none issue for our setups due to the small area of flat and angle of the arm contact point. I think they would work fine with the xnaron stl files but i cannot say I have used the original files for about a year atleast. I didnt like the small variances introduced with mounting and the fit of contact point between ball and plastic. I made my own hybrid steel and aluminium rod end and cup mounts long ago just for precision and consistency. I\ll post some pic of them here in a bit.

[Eaglezsoar]

The effector pictured has been canned. While looking very nice and some of the design ideas behind it are great the overall issues it created are not acceptable.

The effector offset required to be put into the frmware was 64mm. So very substantial, it also introduced a bunch of play because of this large offset. The leveraging was too much if that makes any sense to you. I don't recommend it and won't use mine again after a few hours of playing with it.

The flats on the balls have been a none issue for our setups due to the small area of flat and angle of the arm contact point. I think they would work fine with the xnaron stl files but i cannot say I have used the original files for about a year atleast. I didnt like the small variances introduced with mounting and the fit of contact point between ball and plastic. I made my own hybrid steel and aluminium rod end and cup mounts long ago just for precision and consistency. I\ll post some pic of them here in a bit.

Which effector does work and where do we get it?

[bdjohns1]

I can't say this one will work for sure, but here's what I'm working on. If someone wants to be a guinea pig before I print, it's got a decent shot at working based on flateric's learning about the effector offset.

[img]http://i.imgur.com/XqjWPZOl.png[/img]

[img]http://i.imgur.com/Xj4B5tJl.png[/img]

I designed this with an e3d hotend in mind - the groove-mount adapter can sit right on top of the effector, with the legs hanging down roughly to the bottom of the heatsink. The fan should fit in between legs. The holes are 5mm to match the studs on these Traxxas balls. I did the legs going down for what I'm guessing is the same reason flateric did it - to avoid losing z-height.

If you look at the picture below where I stuck the stock effector platform together with my part, the mounting holes are a bit inside where the axle of the stock effector sits. Mounting the Traxxas balls at a 45-degree angle, it's just under 10mm from the center of the ball to the face of the leg. So, when it's all said and done, you should only need to bump END_EFFECTOR_HORIZONTAL_OFFSET up by 7-8mm. I might flip the legs around so the reinforcement ribs are outside - that would knock the increase down to +5 mm - the Traxxas studs have an unthreaded portion below the ball.

[img]http://i.imgur.com/F5dDh2Zl.png[/img]

Thoughts? STL and STEP attached. (apparently, the board doesn't like STP as an extension, so it's unnecessarily zipped)

[Tinyhead]

I can't say this one will work for sure, but here's what I'm working on. If someone wants to be a guinea pig before I print, it's got a decent shot at working based on flateric's learning about the effector offset.

Aren't those offset issues going to remain a problem even with the design change? In my head it would still inherit the same issues that flateric was having.

[bdjohns1]

They should be less. I think the stock has an offset of 30-35 mm (it's the distance from the pivot points to a line through the effector center parallel to the pivot points). Flateric's was 64mm as he noted. Xnaron's is in the 30-35ish range. Mine should be in the mid-30s. The long edges of the platform are 31mm from the center point right now, as a reference. I could cut the design down further (at the expense of only having three holes 120 degrees apart for the mount, which is really all you need.

The next barrier to getting smaller would be the rod spacing itself (currently 50mm center to center). Intuitively, I feel like narrower would affect stability negatively though...

[Tinyhead]

Like a dummy I wasn't even considering the standoffs on the stock hot end. That makes sense. Is this designed to work with any ball rod ends? Or just flateric's Traxxas ball mod?

[bdjohns1]

Well, I sized the holes for M5 studs. I think most of the other ones out there right now are sized for M3. If you haven't already glued up your balls, then it should work fine with M5s as well. Bigger head to glue the ball to.

The standoffs on the stock hot end only affect things in the Z direction - they have nothing to do with the horizontal offset parameters. The issue with flateric's design was, as he implied with his "leverage" comment, that he had the legs angled out from the platform. That's what increased his offset. I just made the legs vertical and the holes bored through at 45 degrees. My guess (I'm too lazy to do the math) is that you want your delta arms long, and your effector small.

[Flateric]

My favorite effector design is actually old hard drive platters with the correct hole spacing for mounting the balls to. The old platters are heat proof, don't warp, don't flex and have a nice sized hole in the middle perfect! Can only fit one hotend through em though.

[Tinyhead]

My favorite effector design is actually old hard drive platters with the correct hole spacing for mounting the balls to. The old platters are heat proof, don't warp, don't flex and have a nice sized hole in the middle perfect! Can only fit one hotend through em though.

How would you drill that? Aren't they glass? Or are we talking really old platters?

[Flateric]

I have yet to find a glass one but they do exist.

[Eaglezsoar]

I have the Traxxas balls with the threaded studs. Is there anyone who actually has these working?
We would need the specs on the effector, the rod ends, the length of the arms etc. I am beginning to wonder if
anyone is actually using these great studded balls or they are too shy to share the specs.