Sculpfun S9 Expansion Kit Woes

Has anyone else had success with the Sculpfun S9 Expansion kit? I am having serious y-axis positioning issues to the point where I can’t make accurate cuts.
I am wondering if the belts need to be extra tight, or if there is something else I am missing.

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How about some pictures and better explanation of the problem to narrow down the possibilities?
And since not everyone knows what a “Sculpfun S9 Expansion Kit” is, you might provide a link or something to explain otherwise the only people who might be able to help you will be those with your exact kit and not many problems are kit specific.s

Good points Doug.
The expansion kit basically doubles the y-axis length. I did some more testing with multiple passes and was able to measure the offset happening in the Y-axis. The offset was the same size as the pitch of the belt teeth. I ended up tightening the belts, which solved the problem for now, but I am concerned how tight the belts are now. I will keep testing to see if:

  • The tightened belt continues to remove the y-axis inaccuracy
  • How long will the very tight belts last.

if the belts are too tight they will kill the bearings on the stepper motor too. You should find lots of videos on how tight the belts should be. They should hardly sing when plucked.

Yeah, if it skips a tooth it’s definitely too loose. But if it is just barely tight enough not to skip a tooth, it still might not be accurate; you do want the belt teeth to be fully engaged with the pulley. The proof of the pudding is in the eating. If you do bidirectional engraving on that axis, and you get ghosting, the belt is probably too loose.

If it is too tight, not only can you kill bearings, but also you can get a slight repeating pattern with the same pitch as the belt, as you squeeze each individual tooth enough into the tooth form in the pulley to distort the shape. This is probably easier to see in 3D printing than in most laser engraving, though. I think. :relaxed: