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Solving the motor gearbox backlash problem.

PostPosted:Sun Jan 15, 2017 7:57 pm
by Pratyeka
Here it is people, my fix for the motor gearbox backlash problem. when completed and installed, I observed that when holding the Tiko right side up and pushing up on the head, I could see the motors moving up slightly before I could feel the resistance of the rotors. Then when I release the head, everything moves down under the weight until all the slack of the gears is caught-up, meaning that ideal weight is pulling down and no more backlash in the gears. So now there is no delays when reversing direction in any of the motors. This along Teflon tape around the motor carriage clips and lithium grease on the guide tracks makes this printer as good as it can get.
Total weight added to each motors: 82 ~ 85 grams. I have added 20 gr to each motors, so total is ~105 gr each
These picture are self explanatory. I use a hot melt glue gun, epoxy would do too.
20170115_113913.jpg

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Re: Solving the motor gearbox backlash problem.

PostPosted:Sun Jan 15, 2017 8:00 pm
by Pratyeka
funny, can't attach more than 3 pics...
continuing:
20170115_124521.jpg

Once everything is in place, leave the Tiko on it's side and power it on. Observe how the motor do the homing motion. If nothing is in the way, they will move to the top, stop, go down, then return to the top and stop.
If something is blocking the homing motion, you will hear one or more motor strain and shake, eventually it will stop and flash the SOS. Locate which motor(s) is hitting what (probably on of the ribs at the very top), take it out and trim out the part that hits the obstacle. Put everything back in and try again.

Here is the STL of the gyzmo:
https://drive.google.com/open?id=0B8KTvsTIxS2jaUNhbmQyTnlsSGc

Re: Solving the motor gearbox backlash problem.

PostPosted:Sun Jan 15, 2017 10:03 pm
by Pratyeka
Here's how my Tiko looks like after weeks of tinkering...
Bowden tube: drilled a hole in the side so it comes out almost straight out of the extruder, minimal curve.
Two holes near the top; I needed a clear view of what is going on when the motors move to the home position.
Hole in clear plastic, near the base: clear, no distorsion view, access during print, able to use paper during manual calibration to feel tip contact.
Presently printing my own torture test. It looks perfect. The round parts are actually round, not difformed like before the backlash correction. Using this profile:http://forum.tiko3d.com/viewtopic.php?f=23&t=1199#p5536
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Re: Solving the motor gearbox backlash problem.

PostPosted:Sun Jan 15, 2017 11:10 pm
by Pratyeka
Test print completed, all dimensions are within -0 +.12mm
20170115_174902.jpg

Re: Solving the motor gearbox backlash problem.

PostPosted:Mon Jan 16, 2017 1:35 am
by FritzToch
Well, the Frankenstein's monster of a TIko you have is a little intimidating, but the results are amazing.

Re: Solving the motor gearbox backlash problem.

PostPosted:Mon Jan 16, 2017 11:52 am
by Mhammack
Impressive! Now if I can get mine to extrude I'll be one small step in the right direction :)

Re: Solving the motor gearbox backlash problem.

PostPosted:Mon Jan 16, 2017 4:40 pm
by Sixline
So do you find that you no longer need the carbon fiber tubes to stiffen the arms?

Where did you source the weights from?

Re: Solving the motor gearbox backlash problem.

PostPosted:Mon Jan 16, 2017 5:06 pm
by Pratyeka
Sixline wrote:So do you find that you no longer need the carbon fiber tubes to stiffen the arms?

Where did you source the weights from?


I don't know if stiffening the rods with carbon fibre tube will make any difference, it might. I will be able to test since I have ordered a set of rods and connecting rods.

I cut the weights from a steel bar, 20mm X 20mm, about 15mm long. But it would be possible to use pellets, bearings or any heavy granular material and mix with epoxy to fill the cavities.
I was lucky to evaluate the required weight for my Tiko, but it might be different with other.

Re: Solving the motor gearbox backlash problem.

PostPosted:Mon Jan 16, 2017 5:49 pm
by FuShiLu
Excellent! I'll start making some weights.

Re: Solving the motor gearbox backlash problem.

PostPosted:Tue Jan 17, 2017 2:59 am
by Jltx
Nice work!

Your original weight was 85 g (nut) and that seemed to work for you. But now you need 3x that weight? Did I read that right?