Printer Upgrade Part 2

Last we left our printer saga, everything was quite broken, and I was waiting on parts.  The 625z bearings came in and I put the extruder motor back together.  When I could easily turn it by hand, I knew my extruder problems were solved.  Sure enough, I can extrude PETG at high speeds and no jams.  The hot end was not to blame.  I did develop a new problem though.

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That is the status of my end stops.  The printer thinks the inductive sensor is touching the bed even though it is nowhere close.  I had an occasional issue with the inductive sensor reading poorly.  That has become constant now, all my messing with the cables finished off my probe.  I can’t start a print without that probe.  I massaged the cable and found a spot that flipped the 1 to a 0.  Time to troubleshoot.

Ok, so the cable is pretty well shot.  I opened the jacket where the issues was, but couldn’t figure out the exact problem.  They used very thin wire, it could be a break within the jacket.  I just cut most of the cable and redid the wiring.  That got me back up and running.  I printed everything I needed for the upgrade plus spares in both PETG and PLA.


I double checked all the instructions to make sure I wasn’t missing anything and started with the tear down.  On the plus side I am really good at disassembling the whole hot end/extruder!  It looks so naked.

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I only ran into one small snag.  The part that holds the x-belt wasn’t accepting the belt on the right hand side.  I printed 3 different versions, and they all had the same issue.  I took that part off and worked around the groove with a hobby knife.  It eventually relented and let the belt seat fully.

After that, the extruder assembly was pretty straight forward.

The bed assembly was a breeze.  I like most of the changes they made to the cable management, and think this will be more robust.  How the rats nest gets handled in the controller box could be a little better though.  Maybe just a bigger box.

I went through the calibration wizard, did some nozzle height testing, then printed a smart looking benchy.  Dimensionally it is great, but course settings mean it isn’t cosmetically the best.

I am thrilled to be over the failures, and proud of myself for solving all the issues.  Given that is almost exactly the 1 year anniversary of getting this printer, I decided to share a few stats.

Printer Stats:

  • 380 successful prints (more than a few failures, especially these last 2 weeks)
  • 44.7 days spent printing (12% of its life)
  • 6.3km of filament

 

Prusa Spool Upgrade

When I got my current 3D printer, I quickly upgraded the spool holder.  The original worked ok, but was a pain to load and adjust in width.  Every spool manufacturer has different widths to their spool.  The spool support I found on thingiverse was easy to adjust and load.  Eventually it had issues though.  The black threaded shafts that held the bearings in place started breaking off.  I installed 5/16″ bolts as a replacement.  Left photo was the original installation, right photo shows my bolt mod.

As those shafts failed they caused a lot of rolling resistance on the spool, and it ended up failing a few prints before I diagnosed the issue.  The bolts help, but there is a fundamental issue.  They hold the spool at the outer edge.  Any force imparted is a long distance from the axis of rotation.  If it were held in the center, then it would take a lot more resistance to induce the same torque.  That is how the original supports worked, so maybe they were on to something.  A diagram might help.

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The extruder will pull at roughly the same angle and with the same force in either setup.  A full spool will be heavier and require more force to spin, but the filament will be at the outside edge, far away from the axis of rotation (red cross hairs).  This produces higher torque.  Think of putting a pipe on a wrench, you can push further away from the axis of rotation, which makes more torque.  My old setup (left) held the spool at the outside edge (orange dots), far from the axis of rotation.  My newly devised holder (right) runs through the middle.  Even if it doesn’t spin well, it can’t impart that much torque on the spool.


I heard Adam Savage give a good talk about how everything you try involves a lot of failure and trying again.  He was suggesting maker spaces nail to the wall (literally) the progression of projects to show that it takes effort and that nobody gets it right the first time.  I wanted to show some of my work on this one.

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First I needed a way to hold the spools.  I decided a center hub (for reasons explained above) was best.  After measuring all my spools I set the outer lip just small enough to pass through the hubs, then made the center area a little smaller so the spool can’t walk off the hub.  Pressed in bearings mean it spins really effortlessly.  I had a bunch of red filament, so I started with that.  It was simple and worked right the first time.  So much for showing progression!  The next task took an extra try or 4.  I used jam nuts to hold the two spool halves (they are identical) together.  Don’t tighten the nuts against the hub, the bearings spin better without side loading.  To make handling easier I printed a handle with internal 5/16″ threads.  The first one was too short for my hand, so I cooked up a longer one.  The threaded rod goes 2.5″ into the handle.

This hub system will need some kind of support to keep it up high on the printer.  I took some measurements of the printer frame and started with a thick test piece to make sure it would clip on and be secure (far left).  I thought it was good enough and went forward with a full spool support (second from left).

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This worked but was a little too thin and wobbly.  The odd rounded rectangle cutout is for my LED strip.  It was too close to where the spool will be.  I couldn’t have the light and spool installed at the same time.  Next I made a few minor adjustments to the frame clip and printed another test (middle).  That was more snug.  I moved the LED strip to a reasonable location and tried again (second from right).  I ran with this one for a week or two and liked the results.  The only changes to the last version was to increase the thickness for slightly less wobble, and an extension of the hub shaft holder.  My current spools fit, but a future spool might be larger in diameter.  The final design was printed in Prusa orange (right).

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Everything fits together nicely.  The large flange on the handle keeps it from sliding up your hand, and aids in alignment.  My LED strip slides in its slot with a little wiggle room.  The uprights can move if need be, but are in a good place.  The center hub is wide enough to accommodate a large range of spools.  I think this will be a great holder for a long while (until 5 minutes after this post when I run into an issue with it!).

This should be compatible with any of the Prusa i3s.  I think the MK1, 2, and 3s all have the same size and shape frame.  If I am wrong on that, then this only works for the MK2.  I uploaded it all to thingiverse.


As a bonus, it is holiday time, and that calls for cookies.  Cookies that come in fancy shapes taste better than normal ones.  True fact!  Add some pizzazz to your holiday gathering.

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June 2017 3D Prints

Lots of good prints this month.  I have got the new printer pretty well figured out and have ventured out into new materials and longer prints.  First up is a cool blade guard I made.  I picked up this nice boning knife for bbq goodness.  It is crazy sharp but came with no guard.  I printed a two piece guard with magnets set into the one half.  The two bits glue together.  It keeps the edge and my fingers safe and fits snuggly.

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Porch Cup Holder

I have some Adirondack chairs on the back porch.  They are reasonably comfortable, but have a distinct lack of cup holders.  I fashioned some a while back out of wood, but the sizing was all wrong.  These are perfect.  They hold coffee cups, large tumblers and small glasses alike.  The RTIC’s blue handle was printed back in September and is still alive after daily use.  Thingiverse Link


Thermocouple Kickstand

I got a cheap thermocouple reader for reasons beyond my obsession with measurements… I swear.  It works well, but didn’t come with a kickstand.  I am used to all my multimeters having some way to sit themselves upright.  This one clips together, then slides on snugly.  It doesn’t add too much bulk and stands steady.


PETG

I have a few high temperature projects, so it is time to venture beyond the safety of PLA.  It is a great material to print with, but loses strength quickly when things get hot.  Enter PETG.  It is higher temp and strength like ABS, but less toxic, and lower warping.  One of my firsts was the Franken-Cooler.  Not without issue, but largely a success.

Next I made a small clip to keep the USB cables in my car in order.  They always get pinched in the lid when I close my center console.  This will keep them in the pass through.  Simple but effective.  I needed the higher temp material because cars get hot in Florida.

I made some mods to the camera setup on my prusa.  Someone made a decent set of parts to attach a common webcam to the Y stage.  The only problem is their main bracket was a bit loose.  I started with PLA because that was all I had.  It sits up against the underside of the heated bed.  If I need higher bed temps the part could fail.  I designed a lighter tighter fitting version with speed holes to help cord wrangling.  The PETG part will not fail due to excessive bed heating.

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While I was at it I found a lens adapter that could replace the original webcam lens with a very wide angle one.

The new lens give a much better view of the print bed.  I can see the whole thing instead of just the middle third.

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Finally I can take time lapse videos that don’t look terrible.  Behold the birth of a baby groot.

Prusa I3 MK2s Build

I finally got my new printer.  Nearly 2 months after purchasing it shows up the day after my birthday!  That is one serious adventure in a cardboard box.

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I rolled out some paper onto the dinner table and got rocking.  I couldn’t help but setup my gopro and get a time-lapse of the assembly.

The total build time was between 5 and 6 hours plus some tweak and tune time.  The first print had to be the prusa logo in honor of the great maker.

Print baby print

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With it up and running I got to bootstrapping.  The kit comes very complete, and really is a wonderful printer.  That having been said, the little knob they included to run the interface isn’t great.  It rubs and is awkward to use.  Print a new one!

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A lot of my filament is from when I first bought the monoprice back last summer.  It spent a lot of time sitting out collecting dust.  Someone made a nice clip in dust filter that goes right on top of the extruder.

Next came a replacement for the spool holder.  The one included works, but you have to sort of bend it out of the way to get a new spool on.  Plus something with bearings would DSC_0832roll a lot smoother.  Any catches or resistance in the spool rolling could cause Z banding as the extruder fights to pull in filament.  Thingiverse had a great assembly that sits on top.  It included a printable threaded nut and bolt that turned out gorgeous!  Skate bearings pressed into the rollers so the spool rolls with little resistance.  A filament guide keeps it running true.

Speaking of spool holders, my one major disaster so far has been this print job.  Sometime over night the extruder actually pulled the spool off the holder.  Nothing broke except the filament guide (just print another).  It turns out the spool was wrapped poorly and kind of synched itself off.  Poor spool wrapping perhaps.

I monitor all my prints with a webcam and octoprint.  This works out well while on the other side of the house, or on the go.  The only trick is that I have to leave a light on after dark.  Instead of leaving the room lights on constantly I designed and printed some brackets for holding thin under-cabinet LED lights.  Serendipitously one light will fit in a slot the spool holder had.  Only a small printed wedge was needed to keep it secure.  The other two went on my bracket.  It clears the extruder at full height.

It is turning into a proper looking monster!  Let the print games begin.

 

Printing For The Printer

It seems like when you get a fancy new tool you end up spending a lot of time building stuff for the tool.  Ideally it can build most of its own upgrades.  Most of my first projects on the CNC mill involved making better parts for it, and the 3D printer is no exception.  Printing for the printer.  Bootstrapping at its finest!


Tools

3D printers end up needing a few extra tools to succeed.  You can’t do everything with a printer, a computer, and your bare hands.  Printing a few small tools can make life a lot easier.

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Holes often come out under-sized and may have a little overhang issue, especially if printed horizontally.  A small set of drill bits is a good thing to keep around.  The red handle attaches to bits with a 1/4″ hex base and makes opening up holes a breeze.

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You want prints to stick well to the bed during printing.  If they shift, the jig is up and the part is ruined.  The issue comes at the end when you want to pry the thing off a delicate print bed.  Careful work with a razor blade can coax them from the only home they have ever known.  The razor holder is not my design, but a popular choice on thingiverse.  The blade guard houses magnets and pops on easily to keep unwanted cuts to a minimum.  There are other designs available, but they needed magnets I didn’t have, so I made my own.  Thingiverse link.


Octoprint

Sneaker-netting a SD card between the computer and printer gets old, and all control of my printer has to come from the front knob.  Instead I grabbed a raspberry pi and installed the latest version of Octoprint.  It is amazing!  I can see what is going on and control things from any computer in my house, and even have it sending me updates via a messaging service.  I liked it so much I printed a little Octoprint statue in honor of the new service.

It was one of my first prints with support, and everything went really well.  The other fun thing it allows is a webcam to monitor the print visually.  You can even use it to take time lapse video of your prints.

Combine the fancy statue with a really nice pi cover and the print server has a proper home.

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Extruder Medallion

Last but not least, there has to be some decoration involved.  I saw that the extruder sits on top of my printer and spins slowly as the printer prints.  The extruder grabs the filament and slowly pushes it down into the hot end.  I figured it could use a little medallion.

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As you print the shaft spins and the rebel starbird goes round and round.  Enter another time lapse video.  Thingiverse Link to the medallion.

 

New 3D Printing

I broke down and finally bought a 3D printer.  The monoprice mini at only 200 dollars is basically the best value buy there is.  And here it is sitting on a messy desk full of printed parts and printer tools.  This thing is going to need a custom table soon.DSC_0489

I was so excited when I first fired it up that I shot a little video of its first print.

OMG OMG OMG it's alive!

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It worked really well out of the box, though I have been doing my best to monkey with settings and make everything go faster and smoother.  The major learning point has been that buildtak is a great surface to print on, and turning the bed heat down from 60°C to 45 really helped the prints come off without a jackhammer.


Printing for the Printer

The front knob on the tool is really annoying.  It is flush with the surface, and yet you have to spin it a lot.  It gives you bonus moves sometimes, which only makes things more frustrating.  Luckily, there is a print for that!  Some kind soul figured out how to pull the knob off and print an extension.

Getting a spool cracked open is fun, but dealing with an unwinding spool isn’t.  Luckily there are a number of great choices on Thingiverse for filament holding clips.  Why not print a few?  The loose filament goes through the small hole.

The downside to this printer is that it isn’t exactly open source, and they don’t sell replacement parts.  Luckily the 3D printing community is amazing, and they have a bracket you can use to put a COTS replacement on this puppy for the day when the hot end dies.  Better to print that now than be sorry later!

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Once I got the basics down it was time to tackle some of the settings.  I printed a 1 inch cube to check dimensional accuracy, and some benchy models that stress overhang, bridging and other fun 3D printing features.  The course setting did really well, but is kind of rough in places.  No surprise there.  The high quality setting looks awesome on most surfaces, but had some fuzzies on thin surfaces and didn’t handle the bridging as well.  So many settings, so little time.

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Lots more wacky prints to come in the very near future!