Archive | October, 2013

Heated Build Platform update

26 Oct

Heated Build Platform update

Since I published how I built my Heated Build Platform, it's been by far the most read article on this blog. According to Google, it's had more than 13.000 unique page views up until today and I regularily get emails regarding it. Time for an update!

Since the orginal article was published, I've changed the setup several times and I now have what I think is a pretty optimal solution. I should add that Ultimaker is also working on an official Heated Bed for the Ultimaker 1, but there's no date yet for when it's ready for sale. So - here's my updated version on how to create a heated build platform for your Ultimaker.

My current setup

The main change from my first setup is a more powerful Power Supply and an Aluminium build surface.

  • 21 x 21 cm of 4mm Aluminium sheet ($60)
  • Standard Prusa MK1 heated bed ($50)
  • 100k Thermistor ($2.75)
  • 4.7k resistor ($0.1)
  • Relay + relay socket with cables, just as in the original setup. ($10.50)
  • 12V / 360 watt industrial power  supply ($40)
  • wooden plate for mouning the MK1 onto

Mounting the Aluminium sheet was easy. I cover the aluminium with kapton tape, just as I did when I used a glass surface. 4mm appears to be the thinnest you can use without getting warping problems. 6mm is actually better and there's little difference in how fast it heats up, so get that if you can.

I tried different power supplies before ending on the 12V/360w. These industrial types are much more efficient than an ATX supply and at $40 from ebay it's also hard to beat the price. Finding one that would fit beneath the Ultimaker was the most difficult. I ended up just printing some extra feet to increase the distance, so the PSU had good clearing.

This is how the build surface setup looks:

Note that the leveling screws (B) are at the bottom of the bed, making it easy to tweak the platform height while a print is running. This takes about 1.5 cm off the maximum height, but it's easily worth it. A stop-bolt and a wing-bolt is attached to the bottom of the levelling screws for easy adjustment. The screws that attach the aluminium and PCB to the plywood (A) are counter-sunk into the aluminium, so there is nothing that the print head may hit.

At the bottom of the printer it looks like this. 

As you can see, the PSU mounts nicely towards the front of the Ultimaker. It takes 220v AC straight in, but I've added a strain relief to the cable to ensure it stays put even if someone stumbles on the cord. The 12V output goes through the relay to the heated bed, and it's turned on/off by the Ultimakers heated bed output on the main PCB. This is pretty much the same as in my original setup, apart from the new PSU.

Since I now have a beefy PSU, I had to use some of all that power. I picked up some NeoPixels from Adafruit and pimped it up!

Now I have work-light when I need it and some bling when I don't wink

The only improvement I plan to this setup is to replace the Automotive relay with a Solid State Relay. All that'll do is to remove the clicking sound when the relay turns on/off. It's not much noise compared to the machine itself, but anything that can reduce the noise is worth a try.

Aluminium or glass?

Initially, I went the usual route and used a glass plate beneath the PCB heater. A architect friend of mine pointed out that glass actually resists heat and that's why they use it for insulation. Good point, right? How about using aluminium instead he suggested? 

How on earth am I going to get hold of aluminium was my first thought, but it turned out that all I needed to do was to call up a local metal shop. The price wasn't too bad so I was seriously considering using Aluminium instead of glass. In the end I didn't use the metal shop. A fellow Ultimaker user in Oslo was making an Alu plate for his own printer and he made a few extras so I could have one.

Here's some of the things in favor for using an Alu sheet:

  • I have fastened the 4mm alu with screws that are sunk into the surface. When you use a glass plate, you'll need some sort of clips on the edges to hold it in place. The print head will sometimes hit these clips and it's just annoying.
  • Aluminium heats up MUCH faster than glass and more even heat distribution. Also - aluminium does not break like glass does wink
  • The Alu sheet can be slightly bigger than the PCB, so that you can still use the full 21x21cm that your Ultimaker provides. With glass, it MUST be the same size as the PCB (20x20cm) so it heats evenly. If not, it'll break from the tension caused by the heat difference (since it resists it). I cracked two glass pieces due to this.

The only real drawback of aluminium are that it's a little harder to find. The "hardness" is basically that you're not used to visit hardware shops in your neighbourhood, but have a look. There should be one nearby as there's metalworkers in pretty much every town.

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Heated Build Chamber for Ultimaker

25 Oct

Heated Build Chamber for Ultimaker

No - I'm not giving my Ultimaker away as a fancy wrapped gift in the image above. I'm just working around the most stupid patent ever granted in regards to 3D printing. Printing with ABS has one core problem - it shrinks when cooled down by almost one percent. This will cause all printed objects to have clearly visible cracks along the edges where the tension is the highest. It is very easy to solve the problem, but not without breaking a patent that should never have been granted.

Working around the Heated Build Chamber patent

It's incredibly easy to make a heated build chamber on the cheap. In my case, I used cheap oven bags from my local convenince store as suggested by Andrey on the Ultimaker forums. You just unwrap the backs, cover open surfaces and tape it in place. It takes some time to cover it all up, but it creates a fully working Heated Build Chamber. The oven bags are flexible enough to not break and they have no problem withstanding the heat.

Heated Build Chamber solves ABS cracking in 3D printing

I have now printed several ABS models using this method and I get no cracks in the surface at all. I also measured the inside temperature and without overdoing the tape along the oven bags, I can easily maintain 60C inside the printer - enough to prevent cracks. It is also important to let the object cool slowly after printing, so I just let the machine stand there until it's cooled to about 30C. Works like a charm and given that we have had ABS plastic since the 1950's - it should be fairly common knowledge that ABS needs to be cooled uniformly and slowly to prevent cracking and warping.

The patent and the problem with it

In June 2000, the company Stratasys was granted a patent that covers pretty much any way you can think of to cover your 3D printer to maintain a constant temperature as the object is built up. This idea did clearly not originate from Stratsys. It was common knowledge in the polymer business. However - Stratasys applied for a patent on this in regards to their already patented FDM printing process and they got it. The biggest problem with this patent is that it prevents you from doing what is obvious. It should not be possible to patent something obvious, but Stratasys managed to do so anyway.

So, patent US 6722872 effectively prevents ANY other firm from creating a printer with an enclosure around the printer that prevents ABS plastic from cracking up. They can of course contact Stratasys to license this or any of the 900+ patents that Stratasys holds. I do not know what terms a small scale 3D printer manufacturer would get, but I doubt it will be interesting to them. Just looking at the list of patents that Stratasys holds makes you cringe. These ideas won't be available to the general public until the patent expires in 20 years.

Why is that a problem then? My best illustration for how patents PREVENT innovation is looking at the RepRap family tree. The original FDM patent was filed by S. Scott Crump in 1989. Before the patent expired, there were only the Stratasys models as well as a few licensees. Just look at what happens in terms of diversity as soon as the patent expires! There's now more than 500 different 3D printers based on FDM out there. Now there's REAL innovation happening where crazy ideas are being tried out that Stratasys never persued like delta-printers and even more excotic ideas. That's not the biggest though. The price has come down from several hundred thousand dollars to below $300 for a machine that produces comparable quality. That alone should tell you quite a bit about how Stratasys has been milking the original patent.

Despite the patent having expired, we still cannot use the term FDM (Fused Deposition Manufacturing) since this is a trademark of Stratasys. Due to this, the RepRap project has come up with the definition FFF (Fused Filament Fabrication). Other patents are also attached to the FDM patent, preventing the full potential of 3D printing to be realized.

Can I break the patent?

Yes, but you cannot make a business out of it. In Europe, anyone is free to break patents like this as long as it is for personal use. In other words - you can break the patent, but you cannot sell a kit that allows you or others to break it. This previous weekend I was told that this is not the case in the US, but I have not been able to find good info on it. Please post links in the comments if you know more about US patent litigation and enforcement against individuals.