Linear Stage Replacement

As I discovered earlier, my X axis stage had hidden damage that was not obvious in normal use but was subtly affecting print quality.  Rebuilding the stage appeared to have fixed the problem so I did not originally intend to replace the X axis stage, but a good opportunity presented itself on eBay and I decided to jump on it.

The replacement is missing its cable assembly, but that is not a problem as I will be reusing the cables that are already in place.  A hundred bucks for a replacement stage is fair, and it will be comforting to have a functional replacement stage available should the need arise.

Replacing the stage was quite simple as the MX80L cables are highly modular.

I carefully disconnected the four internal connectors and then unscrewed and removed the complete cable harness before performing the reverse procedure with the new stage.

Any time a new stage is installed the printer must be re-aligned.  I've done this process so many times that it is starting to become rather tedious, but at least the jig I printed makes it easy.

I finally decided to apply some finishing touches to the electronics and attach the back panel.  At this point I am confident everything is working correctly and no longer expect to be making major changes to the printer.

The Smoothieboard is located rather deep within the printer, so I needed to break out its USB connection with a panel-mount extension cord.  I use these quite often as they add a nice touch of polish to a project.

Although the replacement stage looked fine, I still ran a full set of tests and verified that all the sensors and features were working correctly within Parker's configuration software.

The panel cutouts will eventually be covered by dust filters and acrylic windows as appropriate, but the printer already looks quite nice as-is.

This hopefully completes the mechanical and electrical portions of this printer, leaving only the extruder as a work in progress.


jbeck said...

Thanks for the new segment.
I have two questions.
On the new linear stage can you feel any amount of cogging when you move it manually (when unconnected)?
Did the print quality improve?

Ryan said...

All three stages I have purchased have some degree of cogging. In my experience most iron-core motors cog to some degree, even those with a skewed stator.

There is no obvious change in print quality when comparing the new servo to the rebuilt servo. Under magnification both prints show room for improvement, but I've measured the performance of the stages with test indicators and suspect other errors are starting to dominate.

I will need to print dozens of tests under different conditions before I can start to understand what variables influence surface finish at low layer heights.

Servo gains, temperature variation, filament variation, and especially play in the extruder assembly (which is currently 100% printed plastic until I can machine replacement parts from aluminum) are the likely culprits.

jbeck said...

Just as a heads-up: I am using the same Chimera nozzle as you do (probably for the same reasons). I have had some trouble with jamming nozzles and such. In the end, it turned out that it was not able to keep the cold end of the heat break cold enough and after a few minutes of flawless printing filament jammed up in there. I switched to an E3dv6 and the problem went away.

Apparently, I am not the only one with these heat creep problems. At E3D's website, one of the reviews mentions it as well.

Hope this helps save you some time.

Ryan said...

I've read similar experiences. The Chimera arguably has less cooling than a single V6 but supports two simultaneous hot ends, so I suppose overheating should not be surprising.

I expect my design to be okay because I have considerably more cooling than the typical Chimera setup. I am using a 40mm fan in place of the stock 30mm fan, but the primary improvement is that my Chimera is bolted to a large aluminum plate so I can dissapate a massive amount of heat.

My final design channels the layer fan through the mounting plate so the Chimera is actually being cooled on both sides. I'll be posting it shortly, it took a while to build because I needed to bring my CNC mill back online to machine the parts.



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