3D Printing PLA on a flexible metal build plate

3D Printing PLA on a flexible metal build plate

By D. Scott Williamson

I love 3D printing.  I’ve designed and printed hundreds of models on the Replicator 2 and have developed many useful skills and techniques. The Replicator 2 has a non heated polycarbonate build plate with MakerBot emblems laser cut into one side and the other side is frosted.

I don’t care for having the MakerBot logo in relief on the bottom of my prints so I print on the frosted side of the platform.

These are rafts but I don’t like having the MakerBot logo embossed on my work.

This worked well for hundreds of prints but eventually, scraping the prints off the platform smoothed the rough surface and parts started sticking harder and harder to the build plate.  Ultimately they stuck so hard that the force required to get a spatula or razor under a part started cutting grooves into the build plate.

Two of the most common 3D printing problems are related first layer adhesion to the build platform…

If the first layer does not bond well enough it can result in corners lifting especially for broad parts on unheated platforms.  In the worst cases the part breaks completely free from the platform partway through a print leading to a stringy mess, wasted time and filament, and in rare cases the PLA can stick to and damage the insulation on the print head.

Catastrophe! Lifted corner, parts broke free, filament everywhere, and damaged thermal insulation on the print head.

If the first layer bonds too well to the build platform the part or platform may be damaged when removing the part.  When using blue tape, it may not be possible to completely remove the tape from the part.

I started using blue painters tape and Aqua Net hairspray on the build plate.  I found this combination to work well with PLA, though I’m not sure how necessary the hairspray is.  The problems are that the tape is damaged when removing most prints so needs to be reapplied frequently and can be difficult or impossible to remove from the bottom of finished parts.

Blue tape stuck to part.

Sometimes it’s impossible to remove all the tape residue.

Blue tape doesn’t last long and requires sticky messy maintenance.

I considered a heated build plate, and glass or metal build plates when the idea occurred to me to try to use a flexible metal build plate. I conducted several experiments using a cable chain model that is challenging to print due to fine detail and thin parts that need to bond well in the first layer.

Experiments

Experiment #1: Aluminum flashing with 2 coats of hairspray dried with heat gun and held by binder clips

First I tried aluminum flashing with hairspray.

  1. Measured and cut the aluminum on a paper cutter and nibbler to perfectly fit the build plate

    Aluminum flashing on roll with Replicator 2 build plate

    Rough cut aluminum.  Use gloves, sheet metal is sharp.

    Cut aluminum to size on the paper cutter.

  2. Rolled flat

    Thin sheet aluminum was curled and needed to be flattened.

    Rolling the thin rolled sheet aluminum flat with pipe on foam.  A towel could have also been used underneath the material.

  3. Cleaned with alcohol to remove oils/grease

    Cleaned the sheet aluminum with ammonia and alcohol.

  4. Coated one side with a thin film of hairspray, let it dry, and applied a thicker coat of hairspray

    Two coats of Aqua Net hairspray applied.

  5. Dried the hairspray with heat gun

    Used heat gun to rapidly dry the hairspray.

  6. Clipped aluminum to build plate with binder clips at the edge

    Aluminum plate clamped to build platform.  (The clip in the upper right corner is about to get knocked off.)

  7. Leveled the build plate to account for the thickness of the aluminum plate
  8. Printed a test

    The PLA bonded weakly to the platform and the parts detached easily in the second layer.

    The upper right and lower left clamps had to be moved because the print head knocked them off.

The nozzle interfered with some of the clips and knocked them off.  The PLA did not adhere to the build plate.  Failure.

Experiment #2: Aluminum flashing with wet hair spray and binder clips

Aluminum flashing with wet hairspray yielded the same results.  Failure.

Experiment #3: Aluminum flashing with glue stick held by clips

Using the back side of the same build plate I used a generous layer of glue stick.

  1. Using the back of the cut aluminum plate from Experiment #1
  2. Coated the plate with glue stick
  3. Clipped aluminum to build plate with binder clips at the edge where the nozzle would be less likely to interfere with them

The PLA adhered wonderfully and the print turned out great.
When done I removed the aluminum plate and was able to remove the print by bending the plate – Success!
But the aluminum does not lay flat and the part left dimples in soft thin aluminum plate before letting go.  I need a stronger material.

Experiment #4: Steel sheet with glue stick held by clips

I scrounged around and found a stiffer steel plate salvaged from a magnetic children’s book many years ago.  I did not try to cut the steel plate to fit the platform because I don’t have a shear and did not want to dull my paper cutter cutting steel.  I can cut the steel on the metal shear at Workshop 88.

  1. Using paper towels, I cleaned the steel plate with ammonia to be sure to remove oil or grease, then with alcohol, and finally with tap water
  2. Coated the plate with glue stick
  3. Clipped steel plate to build plate with binder clips at the edge where the nozzle would not interfere with them
  4. Leveled the build plate to account for the difference in thickness between the aluminum and steel plate
  5. Printed another test

The print turned out great!

But the plastic clips that hold the build plate to the printer are raised causing the plate to be irregular and warped and not flat against the polycarbonate platform beneath it.

If you remove a print by flexing the steel it pops right off but it is still possible to dimple the steel this way.  The dimples can easily be gently pounded out with a broad hammer with the steel on a flexible surface like a neoprene mouse mat or a towel.  Parts firmly attached to the steel are easily removed using a spatula and/or a razor so dimpling turned out to be a non-issue.

Experiment #5: Steel sheet with glue stick held by magnetic sheet

To get the platform to lay flat on the platform I attached a sheet of flexible rubbery plastic “refrigerator magnet” material originally intended to be a furnace vent cover to the platform with double sided tape.

  1. Cut magnet to size
  2. Attached magnet to build plate using double sided tape and pressed it flat using a rubber roller
  3. Aligned the steel plate with the platform and when laid flat the magnet holds it firmly and flat
  4. Leveled the build plate to account for the additional thickness of the magnet layer
  5. Coated the plate with glue stick
  6. Printed another test

Best results yet!

Excellent first layer adhesion with fine detail.

The build plate is flat and level, firmly attached to the platform in the center without using clips which makes it very easy to insert into and remove the plate from the printer.  The finish on the bottom of every part is smooth and shiny, far better even than when printing with a raft.

Even though others reported using a coating of glue stick up to a dozen times, I found reused glue stick not to adhere well.  Adding layers of glue builds up, so every couple of prints I wipe the plate down with a wet paper towel before adding a new layer.

I’ve added alignment markings to the build plate to help install the plate consistently, to help center parts, and to help apply glue only where it’s needed for each print.

 Examples:

Markings help guide application of glue and placement of parts in MakerWare software.

Printed right where expected, with a beautiful first layer and finish quality on the bottom without a raft.

Extremely challenging pinhole lens print

This pinhole lens is .2mm thick and each hole is printed separately with 2 shells then the rest is filled in, if any pop off the build plate it will stick to the hot end and gather the rest into a blob of plastic.

This folding phone/tablet stand (http://www.thingiverse.com/thing:692523) is a favorite model in my house.  It’s a hinged phone/tablet stand that prints fully assembled. If you look carefully you can see that there is some slight curling. The plastic is pulling upward at the corners and even though it has not detached from the build plate it is deflecting it slightly up off the magnet.

The finish quality of the base is comparable to printing on glass.

Not every print has been perfect though, this is another phone/tablet stand that started to curl. The print head caught one corner and moved the entire build plate on the magnet. You can see it continued to print offset before I stopped it. It is impressive that it moved the whole build plate without detaching from the platform. I was able to reprint this model successfully. Only a heated bed or chamber can really prevent this issue entirely, but a stronger magnet may require more force to move.

Future work

  • Cut the build plate(s) to size on the shear at Workshop 88. The build plate is still larger than the platform and must bend to go over at least one of the platform holding clips.
  • Cover the entire platform with magnetic material.  The current magnetic material does not cover the entire platform, it is what I had on hand.
  • Find stronger magnets.  The print quality is wonderful but it is still possible for corners of large parts to lift the platform off the magnetic base while staying attached to the platform.
  • After I started printing on steel I found PRINTinZ’s flexible build plates.  I haven’t used them but check them out! http://www.printinz.com/printinz-3d-printer-plates/

Thanks for reading, and good luck with your 3D prints!

D. Scott Williamson
Compulsively Creative

Last minute gift ideas for makers!

Here’s some ideas for the maker, tinkerer, builder on your Christmas list. (Following these links and buying from Amazon will support Workshop 88.) Most of these items are still available to be shipped before Christmas!

Hard to go wrong with an arduino uno – even if your maker already has one, it’s always nice to have a spare.
This kit comes with all the parts needed to get started making with arduino.
10 NRF24L01+ 2.4GHz Wireless RF Transceiver Modules compatible with arduinos. Very cool way to quickly experiment with wireless communication between arduino projects.
This book is a great introduction to learning how to make with the arduino microcontrollers.
This kit includes everything needed to get going with the Raspberry Pi.
Have a Raspberry Pi already? Here’s a handy case to help protect it.
Add a camera to your Raspberry Pi!
Every maker doing electronics needs a multimeter. Here’s a fully featured one at a decent price.
If your maker is new to 3D printing, you may want to consider this accessory kit.
A fun filament to print with is glow-in-the dark plastic. This might be a filament that someone may not choose to buy on their own, making it a nice gift. 

Recently at Workshop 88!

Last Thursday evening we had the pleasure of having a group from the Society Of Women Engineers tour our makerspace and ask questions on the many aspects of being a maker and what we were working on. They were a mix of female Engineers from different fields of engineering; chemical engineers, mechanical engineers, electrical engineers,and civil engineers. Really great night having them here with us. Are you, or do you have a group of people interested in makerspaces or hackerspaces? Come visit us on any Thursday evenings from 7-10 pm @ workshop88.

from Workshop 88’s Facebook page

Last Thursday night @ Workshop 88

biff-setting-up-the-radio-jim-working-andrew-watching-scaled
Last Thursday we had quite a bit going on at the weekly open house:

Ray connected the chassis of a motorized wheelchair to a remote control unit and was able to drive it around the front room.  Here’s a video:

The laser cutter was being used extensively to cut out some tesselating lizards and geckos, as well as to make stencils for an ammo box intended to hold plastic eggs. The project is called “Hen Grenades”.

Later in the evening Rachel came in and showed off her new LEGO compatible circuit boards – they are really awesome!  We were having so much fun playing with them that no one remembered to take photos.  Come in next week and ask her about them!

Mathematica on the raspberry-pi – a library class

I really like teaching classes through Workshop 88 at the libraries.  Over the summer, I had a chance to teach a few of the classes Workshop 88 offers at some of the local libraries. One library that we like going to wanted a class to introduce their teens and preteens to the Raspberry Pi.

I recruited a few helpers and we gathered up several Raspberry Pis, keyboards, mouses, and power supplies to have enough supplies that the kids would be working in pairs or at their own Raspberry Pi.  We set up before the kids arrived and had everything ready to go. At the start of class we talked about the idea of the Raspberry Pi as a low-cost single board computer and we pointed out all the hardware features of the Pi.  Then we showed off all of the distributions that we had brought examples of.

That took all of 25 minutes for a 90 minute class. Oops.

So, I asked how many of the kids were familar with Scratch, and it turned out that more than half of them had already used Scratch in school.  I decided that they should get a chance to work with Mathematica, so that they would be exposed to something new.

There is a pretty good introduction to Mathematica for the Raspberry Pi on the Raspberry Pi Foundation website. (The actual Mathematica tutorial starts here.)

We did a bunch of things that I think worked really well:

1.) Showed basic math operations
2.) Showed how to make graphs
(One of the kids said at this point that Mathematica is basically just a less powerful calculator. That’s when we kicked it up a notch.)
3.) Kids explored how many digits of pi they could get out of Mathematica.
4.) Kids played with displaying 3D shapes using the Graphics3D function. Examples: Graphics3D[{PolyhedronData[{Antiprism, 4}, “Faces”]}]
Graphics3D[{Opacity[.4], Glow[RGBColor[1, 0, .5]],
PolyhedronData[“JessensOrthogonalIcosahedron”, “Faces”]}]
5.) Kids played with 2D shapes.  Examples: Graphics[Polygon[{pentagon, 1 + .5 pentagon, 1.5 + .2 pentagon}]]
hexagon = Table[{Sin[2 Pi n/6], Cos[2 Pi n/6]}, {n, 6}]
Graphics[Polygon[hexagon]]

Lastly, we tried to generate some sound files with Mathematica, but it didn’t seem to work too well on the Raspberry Pis.

Overall, I think the kids had a great time playing with Mathematica and trying out a bunch of things that they had no idea a $35 computer could do.

 

A member review

A member of the Workshop 88 mailing list posted a review of a new sewing machine she recently acquired.  With her permission, we’re posting it here:


Sewing Machine Review

Janome /  New Home Derby 1/2 Size, 10 basic stitches
I purchased this as a second machine, because it is simple, small, and very light — the opposite of my complex computerized full-size heavy motor Elna 9000 machine.
     Don’t get me wrong, I still love the Elna.  Truly.  But the idea of an ultra portable machine, that I could take along when I’m meeting up with other crafters had a lot of appeal.  And then I saw the Derby models online at Amazon, in 10 beautiful color choices, and it was time to save up my coins to get one.
     What’s in the box?  The sewing machine itself, user manual,and a small plastic bag containing the foot pedal, power brick/cord, 2 spare bobbins, 1 spare needle, and a needle threader.
     Setup:  It took only about 5 minutes to unpack, plug in, thread up the machine to wind a bottom full of thread, load the bobbin into the machine, and rethread the machine for sewing.  The threading diagrams were clear and instructions straight forward.
     Sewing:  Ok, the machine was ready, and it was time to sew.  I started with a piece of polarfleece.  I was turning the raw edges of the fleece over to give a stadium blanket a nice solid hem, so I was using the largest zig zag stitch, stitching through 2 layers of polar fleece.  I left the upper and lower tension on the factory presets. Unlike most machines, the foot pedal does not control sewing speed; it’s more of an on-off switch. There is only one speed. This feels a little weird when you’re used to speed control, but isn’t bothersome once you’ve sewn for 10 minutes or so.  Overall, the machine was smooth and even, and less noisy than I expected from a primarily plastic machine.  The machine had no problem sewing the polar fleece, and the feed dogs advanced the fleece evenly.
     Switching to cotton fabric, the machine breezed through a a simple seam. Next I sewed in a zipper.  The machine has no zipper foot, but it does have one stitch that moves the needle to the far left position so you can sew alongside the zipper coil.  It was old school sewing, but it got the job done.
     Next I sewed a cotton panel onto a sturdy canvas bag. It required sewing through the tough canvas (multiple layers) and seams. It required using the reverse stitch, straight stitch, and using the free arm to sew “into” the bag. (The cotton band creates a set of organizer pockets on the outside of the bag, and the fabric adds a nice accent.)  I was concerned that the small size of the machine would make it hard to sew things that are complex shapes (not flat) and that need to be stitched “inside”.  The machine passed with flying colors!  Janome / New Home did a good job designing the machine so that there is ample clearance, so you can sew things like cuffs, collars, and other items that are dimensional. The machine handled the medium weight canvas well, even up to 3 layers.  But I would not recommend the machine for sewing heavier materials than that, because of the power limitations of the machine.
     Pluses:  The machine is really cute, and very light.  It sews well.  It meets all expectations.
     Minuses:  There is no built in light, so you might want a portable lamp to help see during needle threading.  The machine has only one speed, which takes a little getting used to.
     Overall: 4.5/5.0  Would recommend as a second machine, or a starter machine.