An easy magnetic ball solution.

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Flateric
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Re: An easy magnetic ball solution.

Post by Flateric »

I'm using them, have been for over 6 months atleast likely more, what do you need to know?
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Eaglezsoar
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Re: An easy magnetic ball solution.

Post by Eaglezsoar »

Flateric wrote:I'm using them, have been for over 6 months atleast likely more, what do you need to know?
Which effector are you using, are the rod ends different because the balls are larger the standard 3/8", are your arms the standard 269mm?
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Flateric
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Re: An easy magnetic ball solution.

Post by Flateric »

The effector is not critical really, keeping in mind this...

The rods should be measured from the center of the pivot point on each end for total length.

Meaning the center of the ball that the rod pivots on, whatever that may be.

I did my arms with this in mind. Yes, my arm length from pivot to pivot is 269mm. But even if this were not the case I could make the adjustment in any of the firmware to compensate for variations. What is gained more easily by using the premade ones is the consistency between each of the will be exact. Leaving the only remaining variable up to your mounting consistency. Oh, they don't come apart easy or at all either.

Keep the above rules and advice true for your effector and adjust values for them if different and you'll be fine.

Oh one thing as well, be sure your effector and your cheapskate arm spacing are identical. You do not want different spacing on each pair of arms relative to it's mate.
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Re: An easy magnetic ball solution.

Post by bdjohns1 »

Ok, after printing my earlier design, I decided the arms had too much flex in them, plus I wanted to modify the design to bring the studs in closer to the center so that you could have the horizontal offset parameter be less than/equal to the the stock effector.

So, here's what I came up with:

[img]http://i.imgur.com/vfFjBq2.png[/img]

The outer face of the mounting holes is 24mm from the centerline of the effector. The stock effector's offset is 32mm. Eyeballing the Traxxas studs, if you screw them in to the end of the threads, the horizontal distance to the center of the ball is another 8mm. So, this should perform.

I'll print one up this week - still need to draw up a ball-end adapter for my rods.
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Sturdy Effector.stl
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Eaglezsoar
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Re: An easy magnetic ball solution.

Post by Eaglezsoar »

Thanks for posting this. I still think that the cups that go on the ends of the rods will need to be enlarged to fit the larger Traxxas balls.
Is that what you are talking about when you say you need to redesign the ball end adapter? Slowly but surely we will do away with the glue, the welding, etc.
I have already received the Traxxas balls and with you designing the parts we need, it is beginning to happen.
Again I thank you for taking the time to design the components, it is appreciated.
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Re: An easy magnetic ball solution.

Post by bdjohns1 »

Eaglezsoar wrote:Thanks for posting this. I still think that the cups that go on the ends of the rods will need to be enlarged to fit the larger Traxxas balls.
Is that what you are talking about when you say you need to redesign the ball end adapter? Slowly but surely we will do away with the glue, the welding, etc.
I have already received the Traxxas balls and with you designing the parts we need, it is beginning to happen.
Again I thank you for taking the time to design the components, it is appreciated.
No problem. It's been a good learning experience in 3d CAD.

The rods ends will need to be redone. The new ball is about 10.8mm diameter vs 9.5mm for the 3/8 balls.

Might also need a modified cheapskate mount, or cut down the threads on the studs.

My first prototype this afternoon was too small, and #2 is printing.
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Re: An easy magnetic ball solution.

Post by Eaglezsoar »

bdjohns1 wrote:
Eaglezsoar wrote:Thanks for posting this. I still think that the cups that go on the ends of the rods will need to be enlarged to fit the larger Traxxas balls.
Is that what you are talking about when you say you need to redesign the ball end adapter? Slowly but surely we will do away with the glue, the welding, etc.
I have already received the Traxxas balls and with you designing the parts we need, it is beginning to happen.
Again I thank you for taking the time to design the components, it is appreciated.
No problem. It's been a good learning experience in 3d CAD.

The rods ends will need to be redone. The new ball is about 10.8mm diameter vs 9.5mm for the 3/8 balls.

Might also need a modified cheapskate mount, or cut down the threads on the studs.

My first prototype this afternoon was too small, and #2 is printing.
Your efforts are appreciated!
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Re: An easy magnetic ball solution.

Post by bdjohns1 »

Ok, I finally actually printed the sturdier effector design, and it looks pretty good - just need to tap it for the M5 thread on the studs. I've also got a decent ball end adapter now - STL attached. I sized the rod pocket so that if it's sliced at 0.2mm, you should end up with 1 layer bridging between the ball and the magnet, so there's no direct contact between the two.

The fit's not super-tight on the 3/8" rods, so you can get some glue in / around the rods for a secure fit.

Now, just need to do a modified part for the cheapskate, a jig part for setting identical rod lengths, and we should be in business.

The thread on these studs might be a little long for the close-quarters mounting we're doing, so I'm going to look at sawing them down a little bit. Pro-tip - put a nut on the stud before sawing - that way you can twist it off to chase the threads clean after cutting.
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Rod End 5.8 5.3.stl
(1.65 MiB) Downloaded 217 times
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Re: An easy magnetic ball solution.

Post by enggmaug »

I bought these, printed a new effector with M5 holes for the screws.

I did not change my arms or adaptors in any way, and it works very well.

I realized that most of my geometry problems were coming from that the BB were not perfectly aligned with the screws.

Now I have these, I reset all the delta radius and tower rotations to the default values, and the calibration is nearly perfect.
I still have one tower lifting a bit, but it probably comes from that the distance between screw holes is not consistent enough.
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Re: An easy magnetic ball solution.

Post by Eaglezsoar »

bdjohns1 wrote:Ok, I finally actually printed the sturdier effector design, and it looks pretty good - just need to tap it for the M5 thread on the studs. I've also got a decent ball end adapter now - STL attached. I sized the rod pocket so that if it's sliced at 0.2mm, you should end up with 1 layer bridging between the ball and the magnet, so there's no direct contact between the two.

The fit's not super-tight on the 3/8" rods, so you can get some glue in / around the rods for a secure fit.

Now, just need to do a modified part for the cheapskate, a jig part for setting identical rod lengths, and we should be in business.

The thread on these studs might be a little long for the close-quarters mounting we're doing, so I'm going to look at sawing them down a little bit. Pro-tip - put a nut on the stud before sawing - that way you can twist it off to chase the threads clean after cutting.
Thank you for posting the effector and the Ball Ends. It is appreciated.
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Re: An easy magnetic ball solution.

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Ok, I think I've finally reached the point that these parts are actually good to go.

Changes from the prior versions of parts posted:

1) I made the mounting arms on the effector thicker and shrank the holes 0.1mm. Decided the ball studs weren't fitting tight enough. These should be good enough to just drive them in without needing a nut on the back.
2) Rod ends - no change. I posted two versions. One's got the radius of the ball socket at 5.7mm, and the rod hole at 5.3mm, the other at 5.7/5.25. Depends how close your printer hits the inner diameter of holes. I'm using the 5.7/5.3 one. Slicing at 0.2mm layers should give you one layer of extrusion separating the ball from the magnet.
3) Cheapskate adapters. New. Like xnaron's, these use the holes just to the outside of the stock cheapskate U-mounts.
4) Rod sizing jig. New. Sized for some 10d nails I had laying around. Use it a little differently than the other jigs - just take a pair of the cheapskate adapters, mount 1 to the board, and secure the other using this part and some nails.

I did the parts in Alibre/Geomagic, so I've got .ad_prt files available as well for tweaking if you want them.
Attachments
Sturdy Effector.stl
(507.7 KiB) Downloaded 222 times
Assembly Jig.stl
(101.84 KiB) Downloaded 226 times
Cheapskate Adapter.stl
(402.04 KiB) Downloaded 215 times
Rod End 5.8 5.3.stl
(1.65 MiB) Downloaded 218 times
Rod End 5.7 5.3.stl
(1.65 MiB) Downloaded 205 times
Last edited by bdjohns1 on Sun Apr 27, 2014 2:54 pm, edited 1 time in total.
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Re: An easy magnetic ball solution.

Post by Eaglezsoar »

bdjohns1 wrote:Ok, I think I've finally reached the point that these parts are actually good to go.

Changes from the prior versions of parts posted:

1) I made the mounting arms on the effector thicker and shrank the holes 0.1mm. Decided the ball studs weren't fitting tight enough. These should be good enough to just drive them in without needing a nut on the back.
2) Rod ends - no change. I posted two versions. One's got the radius of the ball socket at 5.7mm, and the rod hole at 5.3mm, the other at 5.7/5.25. Depends how close your printer hits the inner diameter of holes. I'm using the 5.7/5.3 one. Slicing at 0.2mm layers should give you one layer of extrusion separating the ball from the magnet.
3) Cheapskate adapters. New. Like xnaron's, these use the holes just to the outside of the stock cheapskate U-mounts.
4) Rod sizing jig. New. Sized for some 10d nails I had laying around. Use it a little differently than the other jigs - just take a pair of the cheapskate adapters, mount 1 to the board, and secure the other using this part and some nails.

I did the parts in Alibre/Geomagic, so I've got .ad_prt files available as well for tweaking if you want them.
With the jig, does the other cheapskate adapter just fit in the slot of the jig?
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Re: An easy magnetic ball solution.

Post by bdjohns1 »

Yes, it's basically just a hold-down so you can get the rods in position, then secure it while your glue cures.

Also, if you downloaded the new effector before 1:50pm Central, redownload it - I discovered I missed one feature (one of the holes) when doing the STL export.
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Re: An easy magnetic ball solution.

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bdjohns1 wrote:Yes, it's basically just a hold-down so you can get the rods in position, then secure it while your glue cures.

Also, if you downloaded the new effector before 1:50pm Central, redownload it - I discovered I missed one feature (one of the holes) when doing the STL export.
Just one more question, what or who was the source for your rods?
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Re: An easy magnetic ball solution.

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Eaglezsoar wrote:
Just one more question, what or who was the source for your rods?
http://dragonplate.com/ecart/categories.asp?cID=18" onclick="window.open(this.href);return false;
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Re: An easy magnetic ball solution.

Post by Eaglezsoar »

Thanks for the link, those rods look like the best solution because I know that the carbon fiber is strong.
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Re: An easy magnetic ball solution.

Post by Renha »

Will (or do) you sell magnetic-ball-solution kit for Rostock (if it matters, v2) owners?
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Re: An easy magnetic ball solution.

Post by Eaglezsoar »

After printing the two Rod Ends. A couple of comments.
Printed with Cura with ABS at 230c, bed temp at 90c
The one at the rear is shorter than the one in the front.
The shorter one is the Rod End 5.7 5.3.stl
After printing these I question if maybe the cup end should be toward the glass for better quality of the cup.
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GEDC0100.JPG
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Re: An easy magnetic ball solution.

Post by joecnc2006 »

The originals have the ball end down.
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Re: An easy magnetic ball solution.

Post by Eaglezsoar »

joecnc2006 wrote:The originals have the ball end down.
I know that Joe, but I usually go with the default position provided by the creator. This time though I wish I had turned them 90 degrees so the cups were
on the bottom and I have no idea why the one was significantly shorter than the other. On the plus side, the ID on the parts were excellent and slightly smaller then 3/8".
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Re: An easy magnetic ball solution.

Post by bdjohns1 »

At some point as I was making revs, I think I did extend the length of the rod end adapters, which is probably why one of them is shorter. I must've forgot about that revision. :oops:

Your ABS looks awfully bubbly - I wonder if that has anything to do with the quality of the bridging.

You're right that the original design has the cups printed down. For some reason, slic3r originally decided to lay mine down the other way (even though I drew it cup-down in Alibre).

Just for laughs, I tried it, and I actually decided I like it better that way - at least on my printer, I tend to see a "flare" on the first layer or two, and I felt like it would be better not to deal with that on the ball end. Here's a couple of photos, top and bottom:

[img]http://i.imgur.com/2uslQpYl.jpg[/img]

[img]http://i.imgur.com/0x9wmEGl.jpg[/img]
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Re: An easy magnetic ball solution.

Post by bdjohns1 »

Renha wrote:Will (or do) you sell magnetic-ball-solution kit for Rostock (if it matters, v2) owners?
I don't. I think Traxxas has resellers over in Europe, so you might have luck finding the ball studs there.
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Re: An easy magnetic ball solution.

Post by Eaglezsoar »

bdjohns1 wrote:At some point as I was making revs, I think I did extend the length of the rod end adapters, which is probably why one of them is shorter. I must've forgot about that revision. :oops:

Your ABS looks awfully bubbly - I wonder if that has anything to do with the quality of the bridging.

You're right that the original design has the cups printed down. For some reason, slic3r originally decided to lay mine down the other way (even though I drew it cup-down in Alibre).

Just for laughs, I tried it, and I actually decided I like it better that way - at least on my printer, I tend to see a "flare" on the first layer or two, and I felt like it would be better not to deal with that on the ball end. Here's a couple of photos, top and bottom:
Yeah, Cura is my goto Slicer but not so good on the Rod ends. The outside of the cylinders feel like 80 grit sandpaper. I will reslice with Slic3r and see if I
can get better results. This is the first time where Cura has failed me. I will try adjusting some settings also, I will not give up on Cura! Of course if I wanted a real person's slicer I would plunk down $140 for Simplify 3D. NOT IN THIS LIFETIME!
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Re: An easy magnetic ball solution.

Post by bdjohns1 »

I got good results on the rod ends both with slic3r 1.0.0 and with KISSlicer.

The bubbles might be an effect of your filament picking up moisture from the air. Might be time for your spool to spend the night in a 170F oven. Either that, extruding too hot, or too fast?
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Re: An easy magnetic ball solution.

Post by Eaglezsoar »

bdjohns1 wrote:I got good results on the rod ends both with slic3r 1.0.0 and with KISSlicer.

The bubbles might be an effect of your filament picking up moisture from the air. Might be time for your spool to spend the night in a 170F oven. Either that, extruding too hot, or too fast?
Thanks for the ideas, I think a little too hot at 230c I will retry at 210c.
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