Musings and Experiments on the Art and Science of 3D Printing


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New RRF, DWC and IAP, oh my!

By Michael Hackney → Saturday, March 19, 2016
Much good news! Christian Hammacher has made a lot of changes to the firmware, Duet Web Control and his IAP to eliminate the web disconnect issues, improve reliability, etc. I've tested the new DWC and firmware and have not had a single disconnect in over 6 days on my two test machines! That's progress! The IAP is much more robust and reliable too.

You can get these latest releases from Christian's github
If you've been using the IAP to update firmware then you can do the complete update without USB, bossac or removing the CF card! Here's how, it's as easy as 1, 2, 3:

From Settings->General in DWC:
  1. upload the DWC zip file. Note, Mac OS X automatically unzips after downloading so you may have to recompress the root folder.
  2. upload the IAP
  3. upload RRF
There are a few feature differences between ch and dc42 firmwares (comparing the latest versions).
  • ch has G-code interleaving, which means you can run G-codes from any input source at the same time like PanelDue, Serial USB, code quay, file and macro. There is a G-codequeue that insures codes like M106 are executed in time. These features are useful for cooling bridges, etc.
  • the current ch has the most recent fixes for the disconnect issues that affected many users.
  • otherwise, the overall functionality is basically the same.
Note that the latest dc42 firmware also supports the IAP and DWC 1.11

Duet In-application firmware updates!

By Michael Hackney → Sunday, March 13, 2016
I've been testing some new firmware and Duet Web Control code developed by Christian Hammacher. I initially contacted him with some DWC connection issues and provided some network logs to help out. He's made great progress on eradicating the disconnects but this post is about the great feature he's developed along the way - in-application firmware updates.

What's this all about? Basically, iap.bin (the name of the new utility) runs on the Duet and allows users to upload new firmware binaries from the Web interface and installs them! No more bossac, no more command line stuff, no more USB needed. Once installed, iap.bin installs any RRF release, including dc42, right from the DWC Settings page. You can install iap.bin the first time via the web interface too (I think you need to be using the absolute latest DWC though for this to work, otherwise you can simply transfer the file to the CF card). I've been switching back and forth painlessly as Christian has worked on the disconnect stuff. It is implemented as the new M997 code and the gcode wiki page has some info on it.

On top of this, Christian has implemented in-place config.g editing in DWC and the ability to upload zip packages. For instance, you can use the zip uploading to upload all of the Duet Web Control files to update DWC.

Here's a screen shot of the in-place config.g editing:

These new features now allow almost complete "hands-off" configuring and firmware updates via the web interface with no need to remove the CF card or hook up a USB cable.

This just in, David Crocker has just released an updated dc42 firmware that includes Christian's iap.bin! 

How to choose an SSR to drive your heated bed

By Michael Hackney → Tuesday, March 8, 2016
Many folks are driving their heated beds with and SSR in order to get better heater performance using higher amp and/or voltage power supplies. Unfortunately, not all SSRs are created equal and you could actually have a fire if you choose the wrong one. I know, it happened to me. Here's what I wrote back in 2014 when this happened:
I had been running for over a year with my 24V supply hooked directly to RAMBo and then to my Onyx. When I rewired my Rostock a couple of weeks ago top permanently use my Azteeg X3 Pro I decided to "do the right thing" and use an SSR to control the Onyx. It had been working for a couple of weeks and just now, I noticed that distinctive "magic smoke" smell. Then I heard sparks so I immediately unplugged everything. When I opened the bay the smell was bad and the Fotek SSR-25 DD was extremely hot - way too hot to touch. The wires in and out were cool but the SSR was melting down. I've not experienced this with an SSR before and I got the 25A version as I thought that was plenty, maybe not. 
It turns out that simply looking at the peak amperage the SSR can handle is not sufficient. The issue is many inexpensive DC-DC SSRS have a high voltage drop which results in them getting hot, VERY hot. Even a heat sink with a cooling fan is not always sufficient. So be safe and look for a DC-DC SSR with a low voltage drop. Luckily, a good, affordable option exists - the Auber 100A #MGR-1DD80D100.  Here is the product description:
This SSR is specifically designed for low voltage DC applications such as thermoelectric cooler (TEC or Peltier cooler), LED illumination and low voltage DC heater. A unique feature of the design is its extremely low on-resistance (only 0.006 ohm@ 70A, 10V). The main benefits of using this design are1) Low heat generation from the SSR. Removing the heat generated by the SSR itself can be a headache when high current is passed. 2) Low voltage drop. There will be negligible voltage drop at the SSR. In comparison, other DC SSRs may have 1 - 3 volt drop with a 12Vpower supply.  The voltage drop can become a significant issue when low voltage DC power source is used.3) Low cost. The price of this SSR is much lower than other same current rating DC SSR with higher voltage rating. In addition, you will also save the cost and space for a heat sink.The maximum working voltage is 80VDC.Since the heat generated by this SSR is about 10 to 100 times less than other DC SSRs with higher voltage ratings, there is no need to usea heat sink when load is a 12VDC 10A TEC or heater. When used with our HS25 heat sink, it can handle a 60A load. When used with our HS25ET (rated for 25A AC SSR) external heat sink, it can take a 80A load.  And when used with our HS40ET (rated for 40A AC SSR) external heat sink, it can handle a 100A load.  
I use these exclusively on all of my 3D printers and they have been performing very well. I do have them mounted on a heat sink (no fan) and they are not even warm to the touch.