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.
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.
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.
@Hestand any update on this? My printer just started having the same issue. The motor is definitely still trying to tension. Sometimes it gets there sometimes it doesn’t. Nothing mechanical looks problematic so kind of at a loss.
Hi, were you able to fix the tensioner?
I updated firmware on my printer and after reboot got “tank tensioner failure”. my Form 3 doesn’t print anymore, during boot initialization tensioner motor seems to be pulling the tank fine bit still returns error every time. To be honest it seems like it’s a software issue at this point. I tried to downgrade fw. didn’t help.
Unfortunately, I get this error on my Form 3L printer. In the e-mail we sent to the support team, we received a feedback that the tension motor should be replaced. I hope you can solve the problem.
Hestand do you have anymore images of the motor showing the label with all the specs on it. My printer has been out of action since early this year and I keep getting given the run around by our local reseller so I’m looking at sourcing a replacement myself and that information would be helpful as I haven’t pulled my machine apart yet.
I had been going through a “tensioning error” with my Form 3 a few months ago. I was given the response by the support team that it was usually a software issue and to turn it off and back on again. This worked for a while but then I was still getting failures even after rebooting several times. Support then washed their hands of me and said all I could do is buy a new machine. However, I SOLVED this problem by backdating the Preform Software AND the printer software. I had to go back to versions that were issued over a year ago before I was happy with the results. When I tried more recent versions of the software, I got cupping errors that I never had before. I am running Preform version 3.30.0 and Printer Firmware version 2.1.0 and having no issues now. I turned off the automatic updating in Preform and have to constantly tell the printer not to update, but I have no more failures.
After going through the tensioner assembly and ruling out each piece, I finally decided to look at the motor/gearbox, and for me the gearbox was the problem. The first issue was that the mounting screws weren’t very tight, which seemed to allow for the components inside to shift causing the gears to bind. Also, the grease inside the gearbox was gummy and made it difficult for the gears to turn even when properly aligned. I scrubbed the parts in a solvent bath to clean the entire gearbox assembly, then I reassembled everything and at that point all of the gears were spinning freely and easily. I applied a light lubricant to make sure it doesn’t “gum” up again, then I mounted the gearbox tightly to the motor being careful not to let any of the components become dislodged from their proper position. Once together, it took just a little torque to spin the shaft with my fingers, but there was no binding or sticking. If it doesn’t move smoothly, you may need to make sure nothing came loose during reassembly. Once everything was back together I turned it on and it started working again with no problems and has worked perfectly since then. Hopefully this is helpful to others who are being told there is no fix. Make sure to check the gears for signs of damage, such as broken teeth, while you have it apart. Also, be cautious about the solvent you use to clean the gears because there is one plastic gear that you don’t want to melt.
Thank you @bzcrawford for your explanation! You encouraged me to try to fix the tensioner motor as well for our Form 3B+.
It had the same tensioner failing error as everyone else. A college of mine found the Form 3L Tensioner Motor as a replacement, directly from Formlabs. I checked with customer support and they confirmed that it’s actually the very same motor as the Form 3/3+/3B+, just the wires are too short and need to be elongated. Also, the top black tensioner gear is too long and needs to be cut in half with a saw.
If you have a variable DC power supply, you can also check if your motor is broken first:
take it out, and insert ground (-) into the pin of the connector with the black wire and +24V into the pin with the red wire. You need JST pins or small needles for this. Limit the current to something like 500 mA and turn on the power. If the motor doesn’t turn, it’s broken. All other cables (blue, orange, etc) are hall sensor cables to tell the printer how much the motor turns, but they’re not needed to power the motor.
To extend the wires of the tensioner motor, you can just cut them and solder longer wires to them. Or if you don’t like soldering, you can use PAP-06V-s and B06B-PASK-1 connectors, wires and SPHD-002T-0.5 JST pins and crimp the cables.
The only tricky part is to get the motor out and back in again without removing the whole motherboard. It’s a bit finicky, because a JST connector is right in the way. I ended up filing away a bit of plastic of the hole where the gear goes through, but it’s not a big deal.
After replacing the motor, everything works again! For everyone who’s having the same problem, this is definitely worth a try. It’s just untrue that this motor is a “non-replaceable part”, the repair process is actually straightforward and not very hard. Even the spring in the tensioner system is easily removable with some pliers. You might break something, but there’s nothing to loose, the printer doesn’t work anyway.
I encourage everyone who’s comfortable to try this, I hope this will help someone too.
