sansthelight

3D Printing

In 3D Printing, Crafts on November 5, 2013 at 7:25 pm

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I recently bought a 3D printer kit.  I got the Prusa 8″ i3 from Makerfarm.  It is a kit that shows up in box and you have to assemble.  The assembly took me a few nights to get it finished.  The video instructions were not great.  He would list certain parts as being needed for each step and then he would use extras or not use all of them or use completely different parts.  Occasionally he would put something together and then tell you that you actually needed to do this later on during a different stage of assembly.  But of course it would not be mentioned when it should be done.  You get the idea.  I made it through but there was a lot of backtracking and taking things apart so that I could redo something or whatever.  Finally, I got it all assembled and it was time to print.   Or at least to start learning all of the software that was needed.  This was actually not too bad.  If all you want to do is print 3D models that have already been designed all you need is to ingest the file for that model into a slicer program.  The slicer program slices the model into a thin layers that the printer can handle.  Then you load that sliced file into the printer and tell it to print.  After a little calibration the printer was up and running.

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After a couple days the prints started to get really messy.  It took me a little while to discover a couple problems.  The first (and one I should have noticed right away) was that some bolts on the bottom of the print tray where hitting the frame of the printer as the tray moved back and forth.  This caused it jump a bit whenever the tray needed to move that far.  I fixed it by sanding down the frame to give the bolts a little more clearance.  The second problem was the many of the bolts on the printer were starting to loosen up.  The kit did come with locking nuts for some of the bolts.  I used them where ever I thought I was supposed to.  The instructions never really mentioned them though so it was a bit of guessing on my part as to where they should have been installed.  After making tightening up the bolts and using some locktite on them I was back to printing…. for about a day.

The next problem was constant jamming of the print media (in this case ABS plastic wire) in the print mechanism.  After a couple days of tinkering, I decided the problem was the print nozzle.  It was supposed to have an opening of .4 mm.  However I couldn’t even see the opening or get a guitar string (.3 mm) through the hole.  I decided to open it up a bit by grinding a tiny bit off of the end with a dremel.  That went about as well as you would think.  I went from almost no opening to almost 1 mm pretty much instantly.  So I got online and ordered another nozzle.

After a couple days the new nozzle showed up and I discovered that I ordered the wrong one.  The one I needed should have had a female connector on it where as the one I ordered had a male screw connector.  I decided to just get a whole new hotend (the bit that melts the plastic wire and attaches to the nozzle).  The hotend I had would not do PLA (a lower melting temp plastic).  PLA is probably the most common material for people starting with 3D printing.  I ordered a new hotend that would handle PLA and ABS.

A few more days pass and the new hotend arrives.  I get everything hooked up mechanically.  The electrical hookups take a couple more days though as the wiring and connectors that came with the new hotend are just a little different from the old one and I needed a trip to Radioshack to get it all sorted.  I get everything hooked back up and turn it on.  And it won’t heat up to the temperatures needed for ABS.  I test all of the electrical to make sure I’ve hooked everything up correctly and the correct amount of voltage is going to the heater and the temp sensor is working, etc, etc.  Everything is fine.  It turns out that despite the product description saying this hotend could handle ABS the ceramic heater it comes with isn’t capable of reaching those temps.  So I swapped it out for the one that came with the original hotend and tried again.  I was still coming up a little short. By turning the cooling fan so that it pulled air across the nozzle rather than pushing air across it I was able to get the last 10 degrees I need for ABS printing.  So it was time to try again.  Same problem, it won’t feed the wire through the hotend and nozzle.  The gear that is supposed to push the wire through just grinds a hole in the wire.  I clean everything out (the dust and debris from a few jams like this really make a mess and gum up the works) and inspect everything.  I suspect that some of the dust has gotten in the bearing that applies pressure on the wire to hold it against the feed gear.  The bearing isn’t spinning as easily as I like.  I order a new bearing and sit down to wait a couple more days.

The new bearing is hear and it spins exactly the same as the old one.  So that isn’t the problem.  I’m not really sure what to try now.  I think I will get a spool of PLA wire and see if it has the same problems.  Some hotends just don’t deal with different materials no matter what you think they should do.  It may be this one just doesn’t like ABS.  I know the description said it did on the website but I’ve already discovered that it wasn’t capable of the temperatures needed so maybe the whole bit was wrong.  Some hotends need the cooling in different places as well.  Some need the cooling directed right on the nozzle and some need the barrel of the feed tube cooled.  My fan assembly directs the air at the feed tube.  Printing a fan mount and nozzle to direct air at the print nozzle would be an easy solution if i could get the printer to work long enough for a print job.  But I think I will probably have to order one of those assemblies along with the PLA wire.  Then I can test it with both types of print media.

To be continued…

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