Form 3 Tensioner Failing

Have a Form 3 at the University makerspace I work at as a student employee. Had the tensioner error begin appearing late last spring. Worked through support with a few potential fixes but no avail. The tensioner sounds like trying and physical moves the bed ( though abit more aggressive than the other 3 we have?)

Ultimately always fails to tension tank whether it be error 148 or now just explicitly says it fails to tension tank.

We have since replaced with a new Form 3+ (as the 1300$ refurb honestly just seems like a a scummy money grab considering the printer is only 2 years old and has 1/2 the print time (LPU on time) then the other 3 units we have).

Since this unit is ultimately just destined for scraps or trash, we have decided to go a bit more into the printer and see if any obvious issues are visible. Obviously there’s a reason the tensioner is “non user serviceable” as it’s a pretty hefty spring.

Have successfully opened up the tensioning systems and found a few things, and thoughts of what to try.

Gear on the motor appears damaged to a small extent. Thinking it could be worth out sourcing a new one or seeing if it’s available anywhere as potentially this could be causing the issue even though the system is clearly moving.





Found the board the “interlock connector” goes to. Wondering if maybe board is bad so going to try taking a closer look at the components.


Other thoughts are to replacement the motor and/or gearbox with a new one of same or lower RPM (higher torque). Not sure if the current draw is measured from the motor to determine health of system or only what appears to be the Hall effect tension sensor. If it only cares about positioning, if it’s only slightly slower it hopefully doesn’t time out too fast.

Any advice or additional experience in this issue would be greatly apprecited. Whether that be from community or if anyone from formlabs can give some at my only risk/liability advice. This seems like something that’s very doable to fix. I’ll try to update my findings and things I try as I go.

Hi @Hestand,

Thank you for getting in touch and for sharing those photos! As you mentioned, from a support perspective, we are unable to advise on this kind of repair due to liability reasons. With that said, other users can certainly advise if they’ve tackled this previously. Please keep us posted if you are able to successfully resolve the issue.

I had a similar issue. I took mine apart and put it together and I’m pretty sure that cleaning the magnet on the underside of the long black plastic piece that the goes directly over the tensioner sensor board did the trick. It appeared that some of the lubricant used by the motor had covered it so the sensor couldn’t pick it up. It’s amazing that Formlabs wanted us to purchase a new printer for such a small issue.

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