Wednesday 30 March 2016

3D Printing with Proto-pasta Magnetic Iron filament

Proto-pasta - Magnetic Iron PLA

This is part of a focus on 3D Printing materials series, I hope to cover as many materials as possible, from a wide range of manufacturers. From everyday to experimental filaments, print results and views on using them.

If you want to get involved, please feel free to contact me. (details at the bottom of this post).

I will be discussing all the Proto-pasta materials, first up is a rather special one, and it's my favourite material from Proto-pasta - Magnetic Iron. Making rusting stuff very, very cool again.

I you decide to try any of the Proto-Pasta materials, I would strongly recommend this one, it's really nice to print with and is so much fun to post process by allowing the printed parts to rust.

You can view my video on printing and rusting Proto-pasta Magnetic Iron filament below, or in HD on Youtube Here

I have tried both 1.75mm filament and 3mm (2.85mm) in various machines and drive systems - bowden feed and direct / geared. All operated correctly with only minimal adjustments over printing with standard PLA. Normally a little more retraction and slightly lower temperature - then check your flow rates and adjust +/- 5%

I was sent a roll for testing and feedback, so here is what I did with it - And I also need to thank Ben from Hawk3DProto for sorting me out with another roll when I rather quickly ran out.

You can get 500g of material on a standard sized roll, that's only around 42m in length for the 3mm filament (around 129m for 1.75mm). At the time of writing Proto-Pasta have some special offers for their Iron filament, so now is a great time to pick some up and experiment.

They also sell 125g samples and large 12" 2Kg spools if you are feeling adventurous.

The exceptional thing that Proto-Pasta seems to achieve very well, is that their composite filaments are easy to use. Wherever possible they try to make them as similar to using 'normal' PLA as they can. You are really going to appreciate this fact. It means you will waste less material getting it tuned in and you can be confident to print something almost straight away.

For the Magnetic Iron I found that dropping the temperature by about 9 degrees C (from 205 Degrees, to 196) was about right.
The other change was with flow rate -
  • On one RepRap machine running with the 1.75mm filament - Into a wade style geared extruder and a hardened spur drive, I had to lower the extruder flow by -3% to get perfect results.
  • On the BCN3D Sigma (Bowden) machine running with 3mm material I had to increase the extruder flow by +8% for perfect filling.
For choice of hot-end, I used E3D V6, and I tried both standard brass nozzles (0.6mm - with the 1.75mm filament) and hardened versions (0.8mm - with the 3mm material). Both work fine and showed no significant sign of wear after 500g of filament was used in each machine (1Kg in total).

Obviously when you use exotic or more costly material that's designed to be on show, you want to use as little as possible on a print. Here are a few tips I would recommend for minimizing material use.
  • Check what minimum level of infill you can use. Rectilinear will tend to use the least, and still provide some support for overhang and slopes. I typically use 6% in complex metal prints and for many vases, statue figures or busts you can use 0% and just have a single perimeter outline.
  • Select a slightly bigger nozzle - and then only do one outline. Using a 0.6mm or 0.8mm will print quickly, still show up all the detail you usually need in a metal print -considering that you will most likely post-process.
  • Don't print the bottom layers - in almost every metal print I do, I always leave off the bottom, it's almost always not going to be seen and I like to fill the object after printing, so it makes that process easier too.
  • Using minimal material means you may get a small hole or two occasionally, that's not the end of a print or a failure. Just melt a section of filament with a lighter, and drip or wipe into the hole, sand and post-process and you won't be able to tell it ever had a hole or defect. 
  • Fill with plaster for that added weight and feel.

With the Iron filament, you really want to be rusting it. It's not really possible to get a shine onto the Iron, so it's also not all that important to smooth or sand the object before rusting.

However if you do lightly sand or scrub areas of the print, then they will start to rust first, I have tried various methods of rusting, here are some good and bad options -

Don't fill your prints with cement or concrete! - That was the very first material I used and it done some serious damage to the structure and integrity of the printed model.

Plaster is not as aggressive and can be used as a filler for Magnetic Iron Filament (and other metal filled materials).

Expanding gap-filling polyurethane foam works very well, obviously not adding all that much weight, but great to help with strength - especially with 0% infill objects.

I have now settled on filling most hollow objects with dry sand and sealing with a plaster cap. This provided good weight and causes no damage to the Iron material.

You can use many different chemicals to generate rusting - ( just be careful and don't mix things if you don't understand what they will do together - Chemical reactions and gases can be very nasty )

Whatever rusting method you decide to try, I strongly recommend that you do not submerge the object or add substantial amount of fluid at any one time.

Proto-Pasta also have various tips for rusting here, and other people use soaked cloth or tissue for different and selective rusting.

Below is what I used - I'm not recommending any particular method, do this at your own risk.

I originally wanted to make a gel type solution I could paint on, but after much experimentation with various gels and substances, I reverted back to a known method. I'll attempt the gel idea again at some point in the future.

I like using a 100% saturated salt solution - That's 500ml of water at room temperature with as much table salt dissolved as you can. Stop when salt crystals remain and won't dissolve.
Then I added 100ml of white vinegar.
And 20g of oxy-action laundry stain remover.

Mix all this up and put into a spray bottle. - If you can warm up the liquid and ideally the printed objects it will help with the rusting process.

Wear protective glasses and gloves, then in a ventilated area spray onto the Printed object, leave to stand, or for accelerated rusting put in a warm place, spray again as required - usually after 4-5 hours and again 10+ hours. You should end up with a nice level of rusting in any area that has been lightly sanded. If you continue to spray and keep the part lightly coated, you will get more and more rust.

 Place in a plastic tray.

 Lightly spray with rusting solution.

 About 5+ hours later you should start to see rusting. Add more spray as you like.

Some salt crystals may form, these can be washed off after rusting.

I like to allow more rusting fluid to sit in pockets or gaps, then scrub, sand or polish off some of the other areas of rust, for a really nice old looking finish.

The longer you keep Magnetic Iron printed objects damp, rust will continue to form and grow.

Why would you not want a rusted old skull?. My only wish was that I printed it even bigger... Maybe next time.

Support structure works well with the Iron filament, it's strong and takes a little more effort to remove, but it breaks away cleanly.

I have much more to come in the materials series - (Continuing with Proto-Pasta, then looking at many other filaments - I'm also open to suggestion of whatever other materials you would like to see used and tested, just let me know.) -

Proto-Pasta Stainless steel filament requires a lot more work to get a pleasing shiny finish, I will take a look at that in the next blog post and video.

Proto-Pasta Carbon fibre (V1 and V2) material is strong and also really nice to use - look out for my thoughts on using that and where if can be a good option over other materials.

High temperature PLA (including the coffee material).

And finally I will be also looking at their conductive material (not tested yet). - And as a note on this - I have tested so many 'conductive' filaments in the past and still am yet to find a really good one.) < Yes, that's laying down a challenge to any filament manufacturer - We want real conductive, not just high-resistance / 'anti-static' and/or brittle carbon loaded materials that don't really work well as a conductor in an electronic circuit.

I will leave you with an extended collection of images and links to the 3D design files - from the Magnetic Iron printing and rusting experiments (October 2015 to March 2016).

Thanks again to all of the Proto-pasta team Over in the US. And Ben at Hawk3DProto in the UK.

Thanks for reading. Please leave a comment, subscribe to me on Youtube and if you want to get in contact -

Twitter - @Richrap3d
Google+ - RichardHorne_RichRap3D

Until next time, happy printing.


The EasterEgg Generator from 2015 - by Richard Swika -

Another set of great models by David Mussaffi - Bottle and screw cap 41 -

Above is the fantastic Skull keychain (printed bigger) By Paul Badeuille

The Celtic Skull is an essential print in any material, especially good in Rusted Iron - by -

 The fantastic terracotta warrior - Great model by Lolita kuma -

One of my favourite designers designed this amazing shaped vase - Bump vase 1 by David Mussaffi -

Pirates of the Caribbean Coin 1 piece -  by cyclone -

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