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MKIII Drives
#11
I was going to re-use the V2 omni's, but after seeing how good the MKIII versions work, I decided to upgrade those also.

Printed/assembled the tires and cores for the omni wheels.

[Image: attachment.php?aid=1500]

Secret to the tires on the hub is heat. I put the tires in a 200C oven for about 5 minutes - they slide right on the core (no tools) - throw in the freezer for a couple minutes and they lock right on.

You also want to make sure you're putting the core in the tire the correct way. On one side of the tire, the internal edge is chamfered, the other is straight - same with the hub. You want to insert the smaller (un chamfered) end of the hub into the chamfered end of the tire and push it through.


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#12
(02-15-2019, 06:43 PM)LarryJ Wrote: Been away for a while - haven't even touched the printer since before xmas.

Michael released his new drives and it started the itch back up again.

Here's the main frame in PLA - probably going to re-do it in PETG. It's pretty strong, but after I finished it I realized I did the last ones in PETG and they have held up great, why mess with a good thing. By offsetting the holes in the cross brackets, Michael made it real easy figuring out which parts go where.



Here are all the drive train pieces, these are all printed in PETG [6 shells (top/bottom/sides) - 30% fill]. The pieces on the left are printed axles - I'll most likely replace these with metal equivalents.



When installing the gears, install the middle one from inside the motor cage - and then move it left/right into position - fought with this one for a bit.



The rest is pretty straight forward.

  

I printed the tire with Ninjaflex Cheetah [ 3 shells - 20% infill ] - the lower infill gives the tire a little bit of flex. I lubed the edge of wheel with some Super Lube and positioned the tire on as far as I could by hand - a couple whacks with a rubber mallet and it popped right on - MUCH easier than V2.



Still waiting for some hardware and I still need to print the upper part of the assembly (ankle) before putting it together to test it out.


Nice photos . Thanks


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#13
LarryJ  Here are all the drive train pieces, these are all printed in PETG [6 shells (top/bottom/sides) - 30% fill Wrote:. The pieces on the left are printed axles - I'll most likely replace these with metal equivalents. pid='3268' dateline='1550252600']
I was wondering if any bearings were used in the construction for the drive systems?  I haven't seen any and figured not but thought I would ask. 

 I am currently working on the foot shells now.  Trying to get everything printed that will need to be sanded and painted before summer hits here in North Carolina.  
I am then going to start on the inside parts for drive and movement after I figured out more about it.  My legs, body and dome are printed at this point and are mostly assembled.  I am printing the V2 because of the size of my Ender 3.  Still haven't figured out what to do about the shoulder mounts because I want a 2-3-2.  So I haven't printed those parts yet.  Wife will let me print at night only so it has been a long 7 months lol.

Thanks for all your photo and post LarryJ  they have helped out quit a bit.
Andy
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#14
(03-16-2019, 06:24 AM)LarryJ Wrote: I was going to re-use the V2 omni's, but after seeing how good the MKIII versions work, I decided to upgrade those also.

Printed/assembled the tires and cores for the omni wheels.

[Image: attachment.php?aid=1500]

Secret to the tires on the hub is heat. I put the tires in a 200C oven for about 5 minutes - they slide right on the core (no tools) - throw in the freezer for a couple minutes and they lock right on.

You also want to make sure you're putting the core in the tire the correct way. On one side of the tire, the internal edge is chamfered, the other is straight - same with the hub. You want to insert the smaller (un chamfered) end of the hub into the chamfered end of the tire and push it through.

I second this heat trick.  I just did it with my new V3 omnis, and it worked like a charm!  A couple suggestions.  First, I did 5 at a time because they cool pretty fast and that's as many hubs as I could get in before the tires shrank back to their original size.   And second, (this one learned the hard way) the tires are hot when you pull them out of the oven, so be sure to wear some gloves!
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#15
So when you say 200c, you mean a 400 deg F. oven? My ninjaflex skins started melting after just a minute. I tried dropping the temperature to half that but kept breaking the nylon cores.
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#16
I think I figured it out: 350 degrees F on broil (bake would melt the bottom), flip 'em half way and hope you get lucky for it to "pop" past that lip. Otherwise it either goes crooked or breaks. Hopefully, I have enough nylon and tpu to reprint 8 omnis
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