Replicator 2 Platform wobble - less drastic fix than aluminium arm upgrade?

[James Avery]

Hey!

We have had our Replicator 2 for some time now and it has been in near constant use since that time. Im not sure if it has got worse over time, or if it just showing up with the extremely large prints we are doing these days, but the build platform does seem to be wobbling excessively causing some problems in our builds. The platform has over a mm of play on the linear bearings on the Z axis, in other words, we can rock the platform up and down quite a lot, which would suggest the bearings are starting to wear. 

So my question is - has anyone found a solution to stiffen the arms and fix the bearing without having to spend $150 and more importantly wait for a month for aluminium arms? 

Cheers,

James

[Christopher M.]

Hi James,

some people buy this arm upgrade while waiting for the full aluminum upgrade: http://www.ebay.com/itm/Platform-Support-Shelf-for-MakerBot-Replicator-1-1-dual-3D-Printer-GOLD-color-/271375851207?pt=LH_DefaultDomain_0&hash=item3f2f42dec7 

I don't own one myself but it should reduce the wobble you are getting.

Most of the time the shaking comes from roundish shapes. 

If you don't want to spent any money you could reduce the speed to 30-40 mm/s 

Hope that this answers your question ;) 

[Eighty]

Have you checked the 4 screws that hold the Z leadnut to the platform? My platform always had some up/down play until I discovered that those screws were loose. Tightening them up made a big difference.

[andre]

Actually, loosening those screws reduced my wobble.  Simply put, the less confined you are with the Z-rod, the less wobble gets transferred to the platform.  I am creating a ball-socket connector which will give the lead screw nut a few degrees of movement in any direction whilst reducing translation into axial motion on the platform.  That should greatly reduce wobble.

[Greg Fisk]

Couldn't we print some sort of thick 'over-arms' to stiffen the plastic arms? Cheap and accessible to everyone? Just to beef them up a bit?

[Jetguy]

A bit of not so common sense.

The arms warp because they are injection molded and the plastic flows and cools in the mold with varying pressure buit into the plastic.

The hot and cold cycles of the heated bed print after print cause the arms to heat cycle and release that built in stress so the arms warp and bend to find thier natural stress position.

 

Prints parts DO the EXACT SAME THING. The very nature of FDM printing layr by layer means the previous layer is cooled and shrinks before the next layer it printed on top and bonds, but then it too shrinks creating shear stress across the layer bonds.

So printing a part and putting in the same hot/ cold cycle enviroment just will cause stress cracks and warping in the part.

 

Ultimately, you may make the problem worse, not better.

[Jetguy]

I was trying to find the printed arm upgrade someone came up with that also used aluminum extrusions

Ultimately, I have serious doubts that it would do anything to counteract the warping forces.

 

The only thing that will likely work is real metal.

[James Avery]

Thanks for the idea! Slowing it down might be our interim fix, although we are doing some pretty big prints at the moment - the last one was 2 days. So slowing it down doesn't fill me with joy!

[James Avery]

We dont have a heated build platform so I would hope that there isnt too much of a heat cycle on our arms, but I certainly take your point that injection molded plastic is prone to these sorts of changes over time. I was more thinking it was caused by battering by less than delicate undergrads!

[James Avery]

FUN TWIST

The retaining clip which holds the acrylic build plate onto the build platform has broken so it is not able to hold the build plate on properly anymore. So I guess the wobbling arms are a problem for another day as we try and fix this first.

Cheers for all you help!

[Greg Fisk]

Please let me know how you fix your broken clip.

Also, I don't have a heated bed, I just notice the arms are pretty 'wobbly'. I figure beefing them up would stabilise things a bit, with minimal effort....