Makerbot Mini

[Julien Bulliard]

Hi All,

I've bought a "used" makerbot mini and I have an issue :

When you start the print, the nozzle must hit the left side of the build plate support.

 

Then the extruder goes on the round metallic chip and goes down.

 

But, every time, the nozzle and is misaligned , it goes to hit the build plate and melted it !

 

Can you help me please ? I don’t find something about this problem on the internet.

Thanks in advance

[William Steele]

Welcome to the MakerBot Mini.  :-(

The Mini does not use traditional end stops, instead it relies on the motor controllers to detect the skipped steps when it hits the physical limits.  Make sure there is nothing preventing it from moving all the way to the edge.  Also make sure your smart extruder is actually letting the nozzle bounce... it's spring loaded and the tip will push up into the smart extruder, which triggers the "z endstop" portion of it.

You could also have a firmware/settings issue.  Try installing the lastest firmware or force an earlier version to install, if it is already up to date to get it to reset it's home offsets.

Bill

[Julien Bulliard]

Thanks for support, 

The moving is totally free, I've tried the firmware solution but the issue is the same.

Any one have another idea ?

Thanks in advance.

[Jetguy]

Honestly, there is almost nothing you can do as a user on the mini. All you can do is validate the gantry can move freely and that's a stretch, left to right is a linear bearing, front to back is molded plastic shoes riding in a specially coated aluminum rail. It's stiff to move front to back because there must be huge spring tension jamming the shoes into the rails to keep the gantry square and that same spring force causes the friction.

The only other known related problem to this is a belt clamp that comes loose from the gantry. MakerBot super glued the belt into the clamp on later models, but there is a slight chance that the clip can break a tab and thus not be well attached to the gantry.

There are no limit switches, homing is detected when the stepper slams the gantry into the mechanical ends of the motion travel. If friction or just a failing or shoddy mainboard cannot properly detect homing, then all coordinates after the fact are off.

This is why they are selling them so cheap, they are more expensive to repair than the machine is worth.

Makerbot is the only source of parts, this is likely a mainboard issue or mechanical issue, but since you cannot buy parts, the only fix is sending to MakerBot at extreme expense.