Lulzbot Mini Part Cooling Fan Current Limit

Does anyone know if the PWM outputs on the for the fans on the Rambo Mini are current limited? I printed the part in the thingiverse link below and installed the recommended blower (well I thought I bought the recommended fan, but now it’s linking to another product) from Digikey and the blower doesn’t turn on while printing PLA. I’ve tested the functionality of the fan using a 18v power supply and the it works fine, so everything after the extruder connector works well. Any thoughts, or are there any other tests that I can run to make double check this before I have to re-solder in the old fan?

Fans have a threshold PWM level. You should be able to find the level with M106 S<0-255>.
The setting it starts to run devided by 2.55 is your threshold in %. My Mini part cooling fan starts at S70 (27%).

I’ll test that out tonight. I asked a similar question on the thingiverse page and they had the same problem with the fan that they recommended during the “in development” phase of the project.

Using Cura on a Taz, you have to set the fan speed to around 30 to get it to start spinning.
Below that, it won’t run.


This is my dual duct design from thingiverse.

If you read the last update from december, the original blower was tested and will not work. We sourced a new blower which is now in the info page and it is confirmed to work from S35 to S255.

First line of the info page:

“UPDATED 12/11/16 - Linked to a new 15mm blower. The original one, for whatever reason, wouldn’t run at speeds below 100%. This new one has a much wider speed range. I’ve updated the STL files to match the new blower, which was slightly narrower than the original 15mm blower.”

and below the link to the new blower I give the minimum and maximum speed percentages over which the new blower works:

"Note: This particular blower operates on the mini between M106 S40 and M106 S255. Tranlation: in your slicer, zero blower speed is 16% or less and full blower speed is 100%. "

Buy the new blower and you will be golden. Don’t waste your time with the old blower. That was used during the “work in progress” phase. Sorry you got the older one. We were in the “work in progress things on this design might change” phase. The design is now finalized as of 12/11/16 and has been confirmed to work on multiple mini printers.

I’ve had two people build with the new blower and both have had success.

If you have any issues or problems, please feel free to contact me on this thread, DM me, or contact me on thingiverse comment page or DM me on twitter at @jimscuba2386. I’d be happy to help! :slight_smile:

Thanks for the follow up boss. Just incase anyone is interested, it looks like the fan connection is able to pump out around 140ma at 24v.