Monday, 3 October 2011

Current Status : Printing

  • Finish frame
  • Solder electronics
  • Test motors
  • Calibrate firmware
  • Print test pieces
  • Print some parts
  • Calibrate printer
  • ...
  • Profit
Ok, just kidding on that last point - who starts this hobby thinking it's going to be a serious money maker?

The good news is I'm printing.  Yay me! After suffering through multiple extruder jams, the pain of default skeinforge settings and the complete newb-like confusion that accompanies installation and use of PrintRun / SFACT on a fresh Ubuntu install - I was finally able churn out useable objects.

I'm still calibrating my machine - it doesn't print as fast as I think it should, I still have trouble getting the first layer to stick and I think there are some niggling issues with hardware alignment.  Specifically, holes are not round enough, a real issue because I want to start printing my own gears and a new accessible Wade's.

One of my early goals was to upgrade my machine, something proud to have already.  So far I've printed new z-couplers, a y-axis belt tensioner and a pulley idler for my x-axis.  I'm not sure the pulley idler helps as my circles are slightly skewed because of backlash and a possible mis-alignment in my x-y axes.

Top things I've learned so far:
  • Set your extruder motor current to stall so you don't strip the incoming filament.
  • Limiting motor current also helps to prevent extruder jams - forcing the filament into the extruder caused molten plastic to rise up out of the melt chamber.  It's nasty to get out the first time, just plain annoying every time after that.
  • Wing-nuts on the extruder springs.  I haven't done it yet, but after disassembling my extruder multiple times I can see how they would help.
  • A level print bed is essential.  I check the levelling and z-endstop before I start doing a print run.
  • Don't expect the speed you see on youtube videos.
  • Don't expect any sort of quality output.  Just be happy you got some plastic out in the general shape you were after.
  • Need help in a hurry?  Get onto IRC.  It's an amazing feeling to have the guy who wrote the software help you out personally. Not to mention the rest of the community who are so eager to help.
  • Expect to be calibrating for a looong time.  I've seen some amazing prints on the interwebs, and the people behind them are still on the forums discussing how to make them better.
I'd like to send a special thanks to Wildseyed for helping me out so much - I wouldn't be printing anything without his help.

Wednesday, 21 September 2011

Removing pulleys from motor shafts

My secondhand NEMA17 motors (purchased from ebay) came with metal pulleys attached.  No, not attached, they were on so tight they could have been welded there, or grown .  No amount of yanking could get them off.

I eventually made one of a gear / pully remover, but could still not budge it.  So I resorted to brute force - an anvil and chisel.  Big hammer + hard chisel + anvil + gear = split gear.  Yay!  Or so I thought.  The aggressive approach resulted in a bent shaft.  That, and half the pulley was still hanging on it.  I used the DIY gear puller to remove the remaining half pulley, which gave me an idea.

For the next motor, instead of dealing a full force blow to the pulley I instead tapped with a low - medium force 3 or 4 times at different locations.  The impact loosened the bond between the shaft and the pulley, allowing me to use the pulley remover to extract the pulley with minimal effort and zero damage to the shaft.

Lucky I had 8 motors - it took 3 tries to figure it out resulting in one completely destroyed motor and 2 very slightly bent shafts.  I only needed 5 for my Prusa, so all is good :-).

Monday, 19 September 2011

How to save yourself an hour when testing your RAMPS

Make sure you set the correct pins in the firmware before flashing.  I'd like to say stuff just magically works after that, but I think being clueless about the pin settings made me recheck all my wiring and connections so it just appeared to work after finally getting the pins right.

More testing tips:
  • Disable endstops in firmware. It'll freak you out when your motors only move in one direction.
  • Test controllers and steppers individually to avoid blowing up more than one thing at a time.
  • Here is the quick way of figuring out how to wire your stepper.
  • Make sure you order pins with your connecter housing (otherwise you'll be left scrounging for connectors in your computer cases).  My fingers still hurt from taking connectors apart.


Putting together my RAMPS 1.3 kit was mostly uneventful.  All soldering was of the through-hole variety and the components were well spaced.

The terminal strips were a bit of a challenge - making them sit up at 90 degrees to the board is something that tweaked my obsessive tendencies.  Getting all the pins upright also helps when attaching / detaching the Arduino and the controllers.   Following the assembly manual, I soldered a single pin of each terminal strip before adjusting the orientation of each strip.

The headers sitting in place, ready to solder.
I taped a piece of cardboard on top so I could...
... flip it over and do all the pins at once one pin on each header
before aligning pins and soldering the rest.
I had to file down this solder pad so it wouldn't hit the
Arduino power connector.
Complete RAMPS with micro SD reader.
Yes, that's red nail polish on my +ive terminals.
I also bought the SDRAMPS in kit form.  It was my first experience soldering surface mount components with a regular soldering iron and it was quite intense.  The though of screwing up $15 worth of kit was constantly in my mind.  Luckily it all worked out (after hunting down some unconnected pins on the SD socket).

This is really annoying me - my kit came with some heat transfer pads for the heatsinks.  They transfer heat really well, unfortunately they don't do a good job of fastening the heatsink to the stepper controllers so I ditched them.  Since then I've tried using a dab of thermal compound and spot of super glue in the corners.  Works great... for about a day then they start falling off again :-(.  Maybe it's time to get some thermal adhesive.

Tuesday, 13 September 2011


Erecting the frame was fun!  I suppose anything would have been a welcome change from the anxious wait for shipping.

While I was waiting for my packages to arrive I had managed to buy some rods and cut them to size.   Then I spent the next 2 weeks alternately staring at the tracking info on my packages and looking at the lonely row of unconnected rods on my workbench.  And of course the first package to arrive contained motors, not the most interactive of components...

Soon enough I got my printed parts and it was time to build.

Tools I used:

  • small pliers. (I didn't want to over tighten any nuts)
  • scalpel for cleaning parts
  • 8mm drill bit for reaming holes
  • a copy of the Prusa Mendel Visual Instructions by Gary Hodgson.  I viewed this on my iPad to save paper
  • an "object with precisely 290mm length" and an "object with precisely 234mm length".  Make these out of rod or anything else you have lying around.  I used a wooden ruler.
My ruler jig.  It's a little too flexible, lengths of smooth rod would be better.
Assembling the frame was straight forward.  In short - make a triangle, make another triangle, join them together, now adjust all the rods so the jig barely fits.  The last step takes a longer than you think as quite often one adjustment will affect other parts of the frame.

Triangle, triangle
Join and adjust.  Easy
I did come across one problem.  I was supplied with a bottom thicksheet that was slightly too big to fit between the bottom vertices.  To overcome this I had to completely loosen one side and move it approximately 10mm out.  I also had to make a new jig for this new measurement so everything would be in alignment again.

That's about as far as I've gotten with my frame so far.  My printable parts came with ABS bushings so I've been dragging my feet on doing any of the axes until I figured out what to do with them.  More on that in another post.

Element14 has blazingly fast shipping

Last night I ordered a package from at 5:55pm, barely making their 6pm cut off for next day delivery.  15hrs later I've got the package in hand.  Wow.