Jeremy's ORD Bot Build

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Re: Jeremy's ORD Bot Build

Postby JeremyBP » Sat Mar 03, 2012 10:45 pm

Nice. Added to my print queue.
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Re: Jeremy's ORD Bot Build

Postby JeremyBP » Sun Mar 04, 2012 6:45 pm

Alright, so here's the squirrel. There are some small striations, and I'm having a hard time figuring out where they come from. I'm pretty sure it's not from belt stretch, so I think I may need to tweak the infill settings a bit and see if they go away. Then again, this squirrel is only a smidge over 1" tall as printed, so the rough bits are almost not noticeable.
CIMG2567.png
Squirrel!

In conclusion, D'awwwwwww......
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Squirrel

Postby bdring » Sun Mar 04, 2012 6:59 pm

I have one of Jeremy's squirrels. It does have some minor striations. They are on a period of about 0.05" which is the same as the pitch of the Z lead screw. You should check the straightness and perpendicularity of the lead screw. In an earlier photo, it looked like the screws were not perfectly vertical.

If the lead screw imparts a wobble to the system, the acrylic may flex a little and it could so up in the print. I would look at that. If you rapid the Z you might be able to see it in real time.

BTW: Jeremy is using only 0.2mm layer height. The squirrel is quite small.
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Re: Jeremy's ORD Bot Build

Postby JeremyBP » Sun Mar 04, 2012 7:02 pm

Hm. I assumed that the makerslide would cancel that out, but that is a good point about the flex in the acrylic. I'll check out the screws.
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Squirrel

Postby bdring » Sun Mar 04, 2012 7:23 pm

Here is a photo of the one he gave me with a quarter to show the scale.

sq_01.JPG
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Re: Jeremy's ORD Bot Build

Postby Gijs » Sun Mar 04, 2012 7:25 pm

Yes, I noticed that in the ORD motion video you posted on page 2 of this thread, that the left z-axis was wobbling visibly, it was audible too.

I am sure you will find the cause, apart from that issue, the print looks very clean, thanks for posting!
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Re: Jeremy's ORD Bot Build

Postby JeremyBP » Sun Mar 04, 2012 7:32 pm

So after failing to cancel the z-axis wobble despite my best efforts, I decided to pull out the screws. My screws aren't very straight (the fact that I used them as a jig during assembly didn't help with that), so I will be making some new ones. That should do it.
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Re: Jeremy's ORD Bot Build

Postby JeremyBP » Sun Mar 04, 2012 11:00 pm

So after some tinkering, I've managed to reduce the wobble a bit. At this point you don't notice it unless you're really looking, so I'm going to call that good. I'm doing some long, complex prints to try to really push the bot, and it's just taking whatever I throw at it without even breaking a sweat.
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Re: Jeremy's ORD Bot Build

Postby IPvFletch » Mon Mar 05, 2012 12:32 am

Gee, I hope it doesn't break a sweat, that would be horrible!! :o

Seriously though, I'm glad you figured some things out and I'm glad that it has such amazing quality after only a few days of tweaking it. This is all new ground and uncharted territory, but the preliminary results look great!! :D

So, were you saying the Z screw alignment could impact quality - or would you say that is not related, just visible and that is it? I would think that the Makerslide Z rails would and eccentrics on the wheels would dictate Z alignment. Also, I was thinking are there 3 eccentrics for each carriage? On the Z, couldn't some weird combination of eccentric spacers cause the carriage to be uneven from the bed? Also each Z motor likely has to be in the exact same spot, right? Can you just align those with the carriage laying on the bed flat?

Are you using like a .5 or .4mm nozzle right now?
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Re: Jeremy's ORD Bot Build

Postby bdring » Mon Mar 05, 2012 12:43 am

Each carriage only has eccentrics on one side, so the fixed side does all the registration. In general the fixed wheels should be on the side that has no slot on the rail surface. That is the stiffer side.

If the screw is bent or bowed it imparts a stress to the carriage plate. Even if the MakeSlide and Wheels never move, they could act as a hinge point for the stress and the other side could move. The heat treated 60612-T6 aluminum plates will be quite a bit stiffer than the Acrylic and should bend less. Even the aluminum will move if the screw is way off by being bent or off center. The trick is to remove all possible stresses.
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