1 Topic by dsmith1912

  • dsmith1912
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  • Registered: 2015-04-23
  • Posts: 1

Topic: Y-Axis- Issues and solution(s)

Hi all,
I'm a new Solidoodle Apprentice owner and yes, it had problems (locking up, very out of round circles, skipping steps, etc)  with the Y-axis right out of the box.  Sound familiar?  I came this these conclusions after examining the design:
1.   There is WAY too much friction in the belt/pulley/bearing system in the Y-axis.  The excess friction results from the amount of belt tension required to eliminate/limit backlash.  This tension increases the load on the plain bearings increasing the frictional losses greatly.
2.   The middle bearing on the jackshaft is not and can not be aligned with the outer two bearings.  This bows the jackshaft adding to the friction problem.
3.  The long belt tensioning pulleys are not synchronized.    This allows the y-axis to become misaligned on the linear bearing which adds yet more friction.
4.  The wiring service loops add considerable resistance to the y-axis motion when moving towards the rear of the machine.  This taxes the y-axis even further.
5.  The mass and resulting inertia of the extruders/fans/x-axis is considerable and all the losses mentioned previously rob the y-axis of the power needed to move this mass smoothly, without errors.

My solution gets rid of the excess belt tension, bearing misalignment, plain bearings and lack of synchronicity in the two long y-axis belts by doing the following.
1.  Couple the y-axis motor to the end of the jackshaft with a beam coupling.  This eliminates the need for the middle, problematic bearing AND there is NO frictional loss from the short, very tight belt.
2.  Replace the main jackshaft bearings with self aligning ball bearings.  This greatly reduces losses from friction.  I designed special brackets to hold the bearings.
3.  Replace the belt tensioners with another jackshaft running on ball bearings.  Clamp the two pulleys to this jackshaft and they will always be synchronized.  I designed special bearing holders/belt tensioners making belt adjustment a snap.

Theses fixes resulted in greatly improved print quality.  The machine NEVER misses steps or locks up.  I never fiddle with the belts and round printed features are truly round.  All the off-the-shelf parts cost approximately $100 but I think a smart shopper could do it for about $50.  The custom brackets were all printed.

If anyone is interested I can post pictures.

2 Reply by mdrVB6

  • mdrVB6
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  • Registered: 2013-12-18
  • Posts: 717

Re: Y-Axis- Issues and solution(s)

Nice work.  Your mods sound similar to what many of us have done to our SD2 and 3's.  There are several threads on here about people dealing with Y axis skipping issues.  It's a shame they did not up their quality control on the press/ workbench apprentice/ workbench models.

I've got my Y axis on my SD2 working well for the moment but if I ever tear it down again I will be installing an 8mm shaft to replace the stock 6mm.  It would provide additional rigidity.

SD4 w/ RUMBA, E3D Volcano, all bearings, glass bed