Sanjay Mortimer  Check this out,

3D Printing
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1

@Sanjay_Mortimer Check this out, I roughed up both the ball and bolt head using a Dremel, and glued with metal Epoxy. It seems to be a strong enough bond.

I plan on putting just 3 balls on the effector plate, similar to the SpiderBot v1.2
http://www.qualup.com/spiderbot.eu/index.php?option=com_virtuemart&view=productdetails&virtuemart_product_id=44&virtuemart_category_id=13&Itemid=622

EDIT: I can’t break the bond with just my hands, try as I might. Definitely strong enough.
https://www.dropbox.com/s/zf2a9svyvkd7t7x/20130921_090549.jpg

2

Good idea but how do you know it the ball is centred to the tread as if it isn’t your geometry will be off.

3

The bolt has a socket, the ball actually sits nicely in it, helping you with centering.

4

Looks awesome. Are you designing in some flex or tensioning? Or just having the balls tight in the socket?

Calling in @Joshua_Rowley on this one too.

Thanks for sharing - I really think this concept of using balls in plain printed sockets has a lot of potential. Should decrease complexity, reduce vitamins, lower cost, and is more RepRap-able

5

I first designed the sockets as just a way to hold the ball (and avoid welding) and connect the rods using magnets. You could use the socket as the joint itself, and pop in a ball-bolt. That would work but it wont be detachable. You need a heat gun to insert/remove and there is only so many times you can do that without deforming it to death.

So my plan is - Printed sockets on the carriages, with ball-bolts heatgun inserted, and a magnet setup on the plate for easy removal.

6

Are you sure your design has enough range of movement? The socket + glued bolt design doesn’t have a 90 degrees range. I need to try with a smaller bolt.

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Tip: The epoxy box might say 5-minute - That’s a lie. Wait at least 6 hours before you apply any pressure to it.

8

@Shachar_Weis its not a lie, its a work time or gel time if you want. Every epoxy on this planet is labeled the same. If you buy 30min one it will give you 30 minutes to work with until it starts to work. Generally this time is given on quantity of 100 grams of mixture. Curing time can wary a lot, but for sure you can expect full properties advertised by manufacturer only in several days. It can take weeks with slow epoxies. You can speed up the cycle by curing it with heat :wink:

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Epoxy paint glues are all things that need time to cure especially if there water based general rule of thumb is 7 days for full strength.