Early Planning stages for GUS build

Re: Early Planning stages for GUS build

Postby ajiau » Wed Dec 17, 2014 11:37 pm

Did the stringing last night, and got first movement!! At first I thought the stringing was going to be easy, then I realised I'd done it wrong and had to redo all over. :-/. After first movement, I noticed some of the strings are overlapping in a weird way. I need to restring again. Will get it right eventually!!!.

This is only the "prototype arm". I plan to play with it until I'm happy that I understand all the issues with friction, hysteresis etc before moving onto the next step.

I'm thinking of getting a micrometer to test repeatability, linearity etc too.

All-in-all a good night last night. :-)

Will follow up with assembled pics later.
ajiau
 
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Re: Early Planning stages for GUS build

Postby ajiau » Mon Dec 22, 2014 5:57 am

I'll see what I can do on my arm to get friction as low as possible.

On hysteresis. The Marlin firmware has the ability to handle hysteresis correction in software, but I assume this is only of limited use due to the fact GUS is a 'delta style' printer?
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Re: Early Planning stages for GUS build

Postby ajiau » Tue Dec 23, 2014 8:39 am

Assembled Arm after 3rd stringing attempt. ;-)
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Re: Early Planning stages for GUS build

Postby timrwilliams » Tue Dec 23, 2014 10:13 am

Thats impressive.

It looks as if you are running Spectra over threaded M8 studding. Thats interesting. I have just been trying it out on a spare bit of studding. It seems to work quite well, especially if you can clean up the studding thread first. I guess its then a trade-off between stopping lateral drift in the Spectra and friction of the threaded studding.
It also looks as if you have kept the tensioning simple. I used zip ties in a trial arm. It sounds and looks crude, but its very easy to adjust and cheap and easy to replace.

Regards
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Re: Early Planning stages for GUS build

Postby ajiau » Tue Dec 23, 2014 12:24 pm

Yes it's running on thread at the top but normal shaft at the bottom. That's mainly because of the things I had on hand at the time. I think using v grooge bearings is the way to go ideally but make the build cost higher and more complex. I like the idea of the PTFE bushing. Might try it but need to find the right size bush. I also noticed the spectra rubs on the inside of the motor arm, and catches on itself when spooling. Perhaps the spool should have a threaded groove to guide the line into place?
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