Tag Archives: stepper motor

ProfileMaker thoughts…

Posted on by

Looking at Dave’s Profileinator seems really well suited to a stepper extruder.  However, he also suggests adding a “Flow Fudge Factor.”  I just use this set to 1.0, so I’m not sure if I’m using it correctly.

Flow Fudge Factor: I have to enter 1.0 into the flow rate to get 2.0 RPMs on the extruder.. I got tired of doing this math so I added flow fudge factor and set it to 0.5. This doesn’t change the volume calculations – it just modifies the flow rate on the table. If you have a MK4/MK5 extruder with a DC motor, start this at 127.5 to get the PWM value to use

In any case, it looks like by multiplying it by 127.5 you can get the required flowrate for a DC motor.  In printing with a DC motor, I never wanted to drop the speed below 255, because the DC motor had such a small range of speeds.  I could print between about 230 – 255.  Given this, I can understand why so many others, probably using a DC motor, would rather pick their flowrate as 255 and then determine the proper feedrates.

More calibration

Posted on by

Calibration is proving to be a relatively slow process. As you can see from my prior post, my prints are drifting towards the back of the MakerBot. This appears to be due to either improper tension, the power being set too low for the Y stepper motor, and/or the Y axis rods not being smooth/oiled/straight enough. Given that the first few layers are spot on, I suspect it is a stepper board power issue. The Y axis motor is easily the first quietest of the three axes. As the X axis motor is the nosiest, I could probably dial it back without an effect on performance.

To do for tonight:

  1. In the hopes of diminishing the Y axis drift problem
    1. Oil the Y (and X and Z) axis rods
    2. Check the Y (and X) axis slides
    3. Dial up the Y axis power by turning the potentiometer on the Y axis stepper board clockwise
  2. In the hopes of diminishing operational noise
    1. Dial down the X axis motor slightly
    2. Dial down the Z axis motor slightly

My first hack

Posted on by

Seeing as how I already had the heater in pieces, I figured it couldn’t really cause that much harm to move the plastruder board.  I totally get why the MakerBot guys put the board on the extruder – that way all you had to do was swap out an extruder and you can roll with a totally new print head.

I don’t really intend to do printing beyond single color plastic.  This may very well change if we see a support material extruder being offered.  But for the foreseeable future, I am really looking forward to printing away with my giant coil of black ABS.

That said, I’m not attached to the idea of having totally modular heads. 1  On the right side of the MakerBot there’s a really large area above the motherboard and to the left of the three stepper motor boards.  The only things preventing the plastruder board from being mounted right there are (1) the motor wires are too short and (2) four holes in the body.

I had dissected a piece of ethernet cable for the wires running to the nichrome wire and thermistor, so I still had four wires left.  I used another two and a bit of solder to extend the wires to the extruder motor.

Sometimes when I need to drill a small hole through soft or thin material I don’t even bother with the drill.  I used a small drill bit with a rubber band wrapped around the non-drill-bitty-end to give it a grip and rotated it into the right panel of my MakerBot.  Bolt it on and…

Presto!  Now I can see all the way through the plastruder.  :)

  1. Sorry about the pun. [↩]

Adding the circuit boards

Posted on by

Once I had the opto-endstops all soldered up, I really wanted to keep going.  I made the Y-endstop cables, bolted the opto-endstops on, and bolted the motherboard and stepper motor boards to the MakerBot.  Clipped in the cables and it looks like a robot after all!  I’m going to need to organize those cables, but that will have to wait until all the other parts are in place.

An interesting side note – as I was moving the various axes someone noticed that little lights started flashing on the stepper motor boards!  Cool!  I presume moving the platform caused the motors to act like generators and pushing power to the boards, lighting up the LED’s.

Once the opto-endstops were done, I couldn’t resist bolting them on.  Once I started doing that, I wanted to make the Y-endstop cables, then the ribbon cables, and wire it all up.

If nothing else, it looks like a robot now!

Things I learned while assembling my MakerBot

Posted on by

I’ve assembled quite a lot of my MakerBot today.  This entailed assembling and putting together the X axis stage, Y axis stage, pulleys, putting gears on stepper motors, mounting gears, putting in the slider rods, Z axis threaded rods, bolting on the motors, and assembling the two “dinos.”

  • If you’ve got a Batch 9 MakerBot, definitely install the Z-axis after assembling the body of the MakerBot.
  • Put off adding the Z-stage/extruder-stage for as long as you can.  It will just be in the way.
  • Keep that sandpaper handy – you may need to sand down some tabs or widen slots or holes to make things fit, especially if you painted your MakerBot.
  • If the smooth slider rods are just a smidge too short, they will slide back and forth causing a little extra noise as your MakerBot operates.  I haven’t gotten mine running yet, but I have read this is the case.  I noticed that one of the slider rods for the X axis on my Batch 9 MakerBot was about 1mm too short.  When I put the caps on, I noticed that it still had some wiggle room.  I took a scrap of paper towel, folded it up so that it would push up against the end of the rod, and clamped it down.  There’s no wiggle room now, so hopefully that’s it.
  • Make sure the top bearing is just under the top edge of the top panel.  This is in the directions, but it’s really important to make sure everything spins freely.
  • Putting gears on the stepper motors is tough!  Even when you back the tightening screws on the gears out as much as you can, the fit is incredibly snug.  I eventually sanded the inside of the gear slightly, put the motor on cardboard, and then pushing downwards slowly and forcefully.
  • When you’re installing the geared belts, get them as level as you can manage.
    • For the top stage this will involve adding/subtracting washers/nuts from the printed pulleys as well as adjusting the gear’s placement on the stepper motor.
    • For the X and Y stages, the height would essentially be dictated by the height of the belt on the clamps.  The height of the belt on the clamp is essentially set, so the pulleys and gear on the stepper need to be matched to that.
  • When assembling the carriages with the plastic sliders, the instructions suggest you may need to sand the circular hole they fit into.  Just make a point of sanding them, if they’re tight they could affect the looseness of the stage on the rods.
  • Inspect your Y-stage pulley (this is the smallest printed pulley) to make sure the top is level and there are no protuberances.  Even a little bit of a nub will prevent it from rotating properly.
  • The easiest way to remove the itty-bitty sticky-paper protective acrylic cover is to use a razor blade or exacto-knife to pop them off.  You probably don’t need to, but it’s an aesthetic thing.