Wobble

[Bryan Ross]

Hello,

 

My students are finally far enough along in SolidWorks this year that we would like to start printing again.  Ever since we started using the MakerBot, it has had a wobble.  We tried the re-alignment of top gears, shimming the bottom bearings (as they wiggle around in the bottom slot (not a lot, but it is noticeable)), printed anti-wobblers, etc... it still wobbles.  I think it wobbles more now, then it did when we first started printing with it.  I have found a lot of sites where the users have replaced the threaded rod with ACME theaded rod.  I have found these being sold on eBay for $75/$85.  Do these work?  Is it worth the investment?  This is an awesome tool for my students, and with a little wobble, we were able to print some stuff off.  But, now that it has a lot of wobble, our prints are no where near what they should and probably could be.

 

Any suggestions??

Thanks!!

Bryan

 

[Owen M Collins]

Which model of Makerbot do you have? Cupcakes are the ones with wobble issues, so I assume it is one of those. There are items on thingiverse that can help:

"wobble arrestor" http://www.thingiverse.com/search?q=wobble+arrestor&sa=Search

"wobble" http://www.thingiverse.com/search?q=wobble


O.

[Bryan Ross]

Hello, thanks for the reply. Yes, it is the cupcake. And, we have tried the first one on the first link, nd the one in the second link. Neither of them really corrected the wobbling... The second one actually made it worse :(

It almost looks like the gears that drive the screws up and down are not really on center, which might be part of the issue... With the ACME screws it looks like the makers turn down the ends, so the bearings and cogs are sitting on a flat surface rather then threads. But, for $85, I'd like to know if those really do solve the underlying issue, or if it is a waste of time/money.

Thanks again for your input and ideas!!

Bryan

[ddurant]

I wouldn't do ACME screws - they're overkill..

 

For the wobble arrestors, you REALLY don't want to have more than 2 installed unless you have the full arrestor kit, which involves installing 2 smooth rods to guide the platform on x/y while the original threaded rods guide z and are floating on x/y.

 

If you install more than 2 of the floating bits on the threaded rods without installing the smooth rods to guide x/y, you end up with little or no guidance on x/y and the wobble will get worse.

[Benucds]

Hi Bryan

I might have some spare parts for a cupcake if things look worn. We could swap out some parts and see if that solves any of the issues. We have two cupcakes( that aren't getting much use because we got a new replicator). I also have a load of 3mm filament if you are interested. Let me know. I work at a small school in the university district in Seattle. If its convenient you could meet me at the school.

Ben

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[Bryan Ross]

Hello,

 

Thank you for your reply and offer!  We are from Michigan, so that would be quite a drive for us!  Otherwise, I would take you up on your offers :)

 

Bryan

[Bryan Ross]

We have tried two wobble arrestors, you are very correct in saying that the result is worse.  It looks like the actual threaded rods may be bent?  But, the threads are not tight in the bearings and the belt cogs are not 'centered' when the set screw it tightened.  For those reasons, it looked like the ACME screws like this one: http://www.ebay.com/itm/Makerbot-Cupcake-CNC-z-wobble-eliminator-ACME-rods-/130661755008?pt=LH_DefaultDomain_0&hash=item1e6c0c2880 looked promising... as the bearing and the cog sit on 'smooth' surfaces. 

 

The X/Y slides are pretty true and good... there is no wobble on the build area.  All of our wobble is in the clear plexiglass platform that the extruder sits on.

 

Thanks again for your time and input!! I really appreciate it!

 

Bryan

[Owen M Collins]

That (off center thing ) has been mentioned before in the group. I think it was a set screw issue. I never had to worry about it, but others did. Can you check the google group past posts from 2010 or so?

O.