Printing below 50 degrees

Hi All,

My Robot lives in the garage.  An unheated garage in Seattle.  This is the first winter where I’ve kept the robot in the Garage, and man, is it a painful thing!  Once the temperature drops below 50F ( say 12C or so ), the printer is pretty much useless.

Problem — The filament can no longer be fed through the hot end.  The filament becomes cold and brittle, and the Wade’s hobbed bolt just strips it when trying to feed it.  It also has much higher friction characteristics — it needs a lot more pressure and heat to flow and output anything.  I have a Ron’s extruder as well — the Ron is a direct-drive extruder, using a planetary gear for torque.  It doesn’t work in these conditions, either.  While the MakerBot style spur gear does a much better job of gripping filament, and provides the needed grip to feed without stripping, the motor isn’t powerful enough to feed in those conditions.  So, the Wade’s doesn’t have the grip, and the Ron’s doesn’t have the power.

So, what to do?  I can either move it back in the house ( something the wife hates ), or I can design a new extruder ( which is a waste of time — I’m not selling EasyMaker, so designing new parts for EasyMaker won’t yield a return. ).  If I must design a new extruder, then I’ll have to make it compatible with the next design ( I’m not going to do the work, only to have a design I can’t run ).  I’m leaning towards a design that hybrids Ron’s and Wade’s design, and is meant for vertical mounting.  This would allow all three extruders ( yes, three.  I want a triple extruder system ) to fit in the same line.   Mass will become a problem with three motors mounted on a moving carriage.  I think a Bowden may be required at this point, if I want a triple-extruder design — regardless of how much power I put behind it.



2 thoughts on “Printing below 50 degrees

    • Possibly. I’ve thought about it, but haven’t fully investigated the right solution. A pre-heater could work. I don’t know how the plastic filament transfers heat form outside to inside. Does heating it with a pre-heater cause the outer layers to want to delaminate from the inner ones? I noticed that the MakerBot feed gear used in Ron’s design still has the grip to feed, even in the cold — Ron’s fails because the motor isn’t strong enough. So, an obvious solution is to modify wade’s extruder to use the MakerBot feed gear. But then I got into thinking about Mass. I want EM.Next to have 3 extruders — skin, infill, and support. Using Ron’s design would have worked if I could get more power out of the geared motor. Using Wade’s might work, but be less optimal. So, I’m now thinking through the solution. My current hunch is to integrate the extruder into the frame, then drive via bowden cables. But that’s just a hunch right now. I’ll have to do some experiments to find out. Running in a cold, wet, garage has been a very high-stress environment for the robot. I’ve identified issues most printer designs don’t take into account, and would cause eventual failures. The extruder, how bearings “leak” in the cold( axial loads cause degreasing of 608 bearings in 608zz bearings, due to the seals contracting too much from the weather ), how filament ages, how press-fit mounts loosen, how hot-beds cool in cold air, how PLA curls in cold air, etc… Running in the garage and lugging it around has been a great stress test, and I’ve been finding issues and designing fixes into the robot. All of that knowledge and design moves forward into the next robot.

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