Lulzbot Mini 1 and Taz 5

I’m a public librarian working on a shoestring budget. When I took this position 3 years ago I inherited 3 Lulzbot Mini 1s and a Taz 5 that we purchased with grant money. Until now I’ve been able to upgrade, operate and maintain them well enough but it seems like my one of my Minis has a shorted RAMBO and my Taz has a torn thermistor wire. Can I put the head from the Mini on Taz 5? They look similar enough to me but I’m not an engineer. Any thoughts?

I know it’s shoestring, but 100k thermistors are under $1 each -

The two printers use different mounts, so a direct swap wouldn’t work. You could potentially move the hexagon hot end and the rest of the parts to the Taz 5 mount though, but $10 for a pack of thermistors should be the better option.

For the mini with the shorted board, check the fuses. You may be lucky and have another sub-$1 fix on your hands. They’re standard automotive-style blade fuses. A visual check should be enough to tell if one of them is blown.

The thermistor is not a problem to replace. I’m worried about the cost of replacing the RAMBO. I checked my fuses and they’re all still complete. I don’t see scorching or any other indication of a short.

Ultimately what made me think it was a short in the RAMBO is that it’s starting prints in mid-air. It touches all the washers and wipes the nozzle and then starts the print like 2 inches above the bed. I’ve tried to flash firmware and played around with the g-code but it makes me worried I’m gonna brick it or something.

If it’s wiping the nozzle after touching any washer, it is failing to get a signal from the last washer it tried to touch. The way the washers are attached makes it unlikely it’s a failure at a washer, and more likely a failing wire for the common zero sense wire. It could be on the printhead itself, or the wire from the bed. Connect your multimeter to one of the washers and one to the ZMIN ground pin. Move the bed back and forth several times and ensure there’s continuous connectivity. It sounds like it’s a repeatable problem, so it should show up fairly easy. If the bed to ZMIN connectivity is good, check between the nozzle and the other side of the ZMIN plug while moving the printhead left and right.

I’m not sure why this type of failure would let it continue to where it would start printing midair though, but I haven’t had an original mini to do any sort of experimentation with, just a Mini2, which uses entirely different electronics.

From my point of view out of the two I would say the Lulzbot mini though I am waiting for the mini 3