CE Declaration of Incorporation for Duet Boards?

  • Discussing the requirements for regulatory compliance for supplied kits and built printers on the reprap forums and have identified a few directives that are applicable to 3D Printers:

    Low Voltage, EMC, Machinery Directive, & ROSH. ...exact titles and spellings may vary! 😉

    Where is the declaration of incorporation information for the Duet boards?

  • administrators

    Tony deals with the certification paperwork, so I'll leave it for him to provide the details. I don't believe the Machinery Directive applies to a component such as the Duet, but it may apply to a complete printer.

    I personally did the EMC testing at a facility near me. We made a number of changes between revisions 1.02 and 1.04a in order to make it possible for our customers to meet the EMC directive without necessarily having to enclose the Duet in a metal case.

  • Thanks! That's posative. I'm scoping out how significant a body of work it is to get to the point of an appropriately backed up CE marked machine. I'm not under the illusion I can do it on my own and am aware that CE marking on many machines is likely to ne dubious, partly due to the self certification and the documents not being inspected until after an incident or by rare request.

    Difficult to judge at this stage whether it would be home appliance or fall under machinery directive. I'm guessing unless you are using serious stepper motors or reduction boxes the main risk would be from fire, rather than moving parts, crush, entanglement etc.

    My reseach will now go through documentation from Up!, Makerbot, Ultimaker, 3D Systems, and Prusa to see what they say their prebuilt systems comply with.

    Have your recent experiences with EMC investgated grounded steppers vs shielded cables? I did wonder whether shielded cables were as necessary if the stepper was grounded. The Ormerod's shielding of the connector, shielded cabelling, and grounded case may have just been providing the required ground link?

  • ...and yes, you couldn't CE mark the board, but would normally supply some details of how it would need to be used in a machine that was CE compliant, and to say that all parts comply with the materials regs - eg mo lead solder.

  • @doctrucker


    You might find this old RepRap thread interesting https://reprap.org/forum/read.php?1,182481. Lots of posts from "nophead" who used to make and sell an excellent Mendel variant (in kit form I believe).

    BTW there is an identical "CE" mark that is often used but which has nothing to do with any regulatory requirement. It stands for "Chinese Export" ☺

  • Thanks Ian, I'd been reading that and another google group chat that dc42 participated in in jis pre duet days!

  • This was the other thread that I was refering to:


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    @doctrucker, I only did limited EMC testing with a stepper motor attached, and only one motor. But the test passed, using ordinary 4-wire unshielded cable, with the cores loosely twisted around each other. BTW we added some capacitors at version 1.03 to slow down the signal rise time, in order to reduce EMI.

    I suggest you use two twisted pair cable, one pair for each phase. If you can afford to run the tests twice, try with unshielded cable first. It's advisable to ground the stepper motor bodies anyway, to guard against static discharge.

  • As I'm mainly working in the RF area, shielding of anything that could affect my other work is really important. Initially I had an eShapeOko as CNC machine. And I have built it as cheaply as possible. The NO end-stops were a nightmare to keep under control (falsely triggering in most inappropriate moments!), and I had twisted pair cables for all motors!

    The first step was to replace the stepper cables with properly shielded, really flexible cables. While not cheap, 4 core LAPP Kabel CY Flex 4G0,5 (https://lapplimited.lappgroup.com/products/cy-cables.html) proved to be very effective. The shield was connected only toward the controller, GRBL back then, with the end by the stepper left open.

    When building the WorkBee I have used the same type of cables for the steppers, leaving less than 10cm of cable without shielding near the stepper. Also, I have used a similar cables with just one twisted pair for the switches (homing and limits). The only false alarms since that have occurred only when one of the steppers missed some steps or I have touched one of the switches by mistake.

    Also, bear in mind that the CE logo applies to the whole product! The Duet might be CE compliant by itself, but improperly connecting a lot of steppers and switches to it might make the final build totally non-compliant. While temperature range, humidity etc. might be easily decided upon the least capable item in the build, EMI is a really tricky job!

    As a side note, even is enclosing the Duet board into a proper metal box will not insure the final machine will be meeting the CE requirements! While the Duet will be properly screened, the cables to the steppers may be a source of "electric storm", from an RF point of view.

  • Thanks for the advice to be honest I expect the client to run when I go back with estimates on effort/time alone to get to the point where the everything is ready for the external paid for tests.

    From a personal standpoint I would like to get to the point where I can demonstrate that the risk the axis present on a standard machine means the interlocking requirements are minimal for the axis and concentrate on overtemp trips. That would at least be helpful for my other machines.

    Edit: Catalin - wrote the above before I read your post.

  • Mind sharing how much one round of EMC testing cost?

    I appreciate that testing a whole machine would be more involved and it'd be sensible to budget for at least two rounds of testing.

  • As an aside I built a Core XY for a previous employer and decided at one point to share a comon ground for the limit switches and that seemed to tip it over the edge into false trips on my limits and reset/e-stop button. The latter wasn't a fully compliant e-stop system just something designed to be better than nothing, reliable, and with obvious user fault checking.

  • Hi Guys,

    would you please PM me which test houses you use for CE and other approvals.

    Always on the look out for somewhere decent, knowledgeable and not fully booked for the next 12 months.


  • @doctrucker There are a lot of "rule of thumb" things to be followed when dealing with EMI. While there might be some shortcuts reducing costs, those are insignificant when compared to the extra time that might be needed to track them down and fix them. From my point of view the "hobby CNC" domain (be it additive or subtractive) is very well covered by a lot of offers, from a huge number of companies. Considering that, the difference in the near future will be in the overall quality of the products.

    In order not to be misunderstood, I will try to make a comparison with another well known area... laser printers! About 20 years ago every laser printer had large cartridges with photosensitive cylinder, developer (a heavy iron oxide, slightly magnetic) and toner (a fine carbon dust, not to be inhaled), and those lasted for about 25-30.000 pages (for big ones, small ones limits were usually 10 times less). But back then the fight was over printing performance. Nowadays, when the printing performance limits within reasonable costs have been reached by all manufacturers, the fight is over reliability and, more important, TCO. So you get for reasonable prices printers that can handle 250-300.000 pages before requiring a major servicing (or a replacement for cheaper ones), with toner only cartridges and minimum waste. That comes with "casualties" as well - most of the companies that made fortunes 10 years ago with spare parts and maintenance for the big office machines - but we gain a lot, overall.

    The Duet is a pretty much disruptive product right now, with the potential to make some dent into the profits of long established companies. And it is cheap enough for the capabilities that spending some extra money on some quality wiring should not be a problem for equipment manufacturers as the final costs are pretty similar - if the wiring costs are relatively high to the machine costs, that machine is not worth considering from my point of view.

  • @catalin_ro said in CE Declaration of Incorporation for Duet Boards?:

    And it is cheap enough for the capabilities that spending some extra money on some quality wiring should not be a problem for equipment manufacturers as the final costs are pretty similar - if the wiring costs are relatively high to the machine costs, that machine is not worth considering from my point of view.

    I do not think I see read comment above as you intended.

    You don't like a significant proportion of machine cost in wiring?

    It appears to me that a significant number of issues are wiring related on these forums and of of the (thankfully rare and not read one on here otjer than re-tellings) true fire horror stories wiring has often played a major part.

    So I thought wiring quality (on the whole rather than just CSA choice) is a significant area where suppliers can differentiate themselves and optimise quality when function level capabilities are predetermined by the board which is open to all?

    ...or are you saying that when wiring is done right it the total costs are such that you may as well spend more on the rest of the machine?

  • Thanks all for keeping this so amicable. Discussion on safety and regulations often get soured before the topics fruiting information because people get angry too quick.

    Thanks again.

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    @jujudelta said in CE Declaration of Incorporation for Duet Boards?:

    Hi Guys,

    would you please PM me which test houses you use for CE and other approvals.

    Always on the look out for somewhere decent, knowledgeable and not fully booked for the next 12 months.


    We use Eurofins York, the facility close to Bristol because it is convenient for me. They charge around £500 per half day plus VAT. For this you get the raw data plots but not a test report. If you want them to prepare a formal test report, they charge extra for it.

    There are 3 aspects to CE EMC testing: emissions up to 1GHz, emissions above 1GHz (needed for the Duet WiFi but not AFAIR for the Duet Ethernet), and immunity to radiation over a wide frequency range. We spent a lot of time testing emissions under 1GHz because that is where all the problems were. A full scan takes about 20 minutes, but if it is going to fail badly then you will usually see that within a few minutes, so you can stop the test, make some changes (e.g. use shielded cables, add ferrite beads, or disconnect something), and try again.

    The major issues we had were with the 5V switching regulator and the WiFi module. At one point we prototyped 3 variations of the 5V regulator to see which one had the lowest emissions. The ESP WiFi modules produce a ton of spurious frequencies on the I/O and power lines (despite the module having a CE certificate) and we had to iterate the layout a few times to get one that contained them.

    Ethernet is a different ball game altogether. We were warned that nobody with Ethernet kit ever achieves CE compliance without using shielded Ethernet cables, and this is indeed what we found. Of course nobody ever uses shielded Ethernet cables in practice, so this is an example of the regulations being over-strict. The grounding of the Ethernet socket shield is critical, so our recommendation to any manufacturer using the Duet Ethernet is to use a metal enclosure and ground the tag next to the Ethernet socket directly to it; or use a spring tab like they do on PCs.

    Seeing how strict the regulations are makes me wonder how powerline network adaptors can ever meet CE regulations. I'm guessing that they are tested using shielded twisted pair or similar, not real mains wiring.

    Eurofins also advised us on the Low Voltage Directive. It's because of that advice that we added the 7.5A fuse protecting the heater and stepper motor circuit. The bed heater fuse wasn't strictly needed to meet CE regs, but we figured that we'd be criticised by some of the review sites if we didn't include one.

  • This is the post on the RepRap forums where I began to discuss regulatory requirements:


    I was discussing there as it applies to all 3D Printers rather than just those using Duets.

    It appears that the main safety guides are contained within the following standard which I am trying to learn more about:

    BS EN 60950-1:2006+A2:2013

    I'm guessing this will be ensuring all components are working within specification (temperature and loading limits) as well as stating single fault tolerance before the tested item can fail into a dangerous state.

  • Is the often seen comment in user manuals; "For home use ONLY!" a result of the unit being CE marked as a home appliance rather than under the machinery directive?

    If used in the workplace environment outside of R&D does it have to be Machinery Directive compliant?

    I've not seen a decent guide as to when something is a home appliance and when it falls under Machinery Directive. I'm guessing this is largely down to manufacturers discretion.

  • @doctrucker Indeed, my idea is that a really cheap machine is not really worth considering. But building a decent machine as cheap as possible, taking advantage of all possible offers/bargains, without cutting too many corners, is a completely different idea!

    I bought good Lapp Kabel multi-core, screened cables from Farnell - 0.5sqmm/core (that is usually around 5A continuous current). The code 1891252 is for 4 cores cable, around 1.7EUR/m all included and 2499550 for 2 cores cable, around 0.85EUR/m. For my WorkBee I actually needed in the end cables costing about 15-20EUR in the end (I have used too much 2 cores cable!). If that is relatively expensive when considering the cost of the machine, then that is a really cheap machine. Again, when I mention "cost", I consider the actual value of the items used to build the machine - if you can get for free items values over 500EUR, that is a machine built cheaply and not a cheap machine!

    After one year of using the WorkBee, mostly for milling Aluminum and POM (Delrin), it needed new V-Slot wheels on the Y-axis. That is 28 OpenBuilds polycarbonate V-wheels, including some accessories - all values North of 200EUR. With 100USD I bought a set of SBR12 linear guides, thrown in some elbow grease and some clever machining (with the WorkBee already crippled!) and the end results is more rigid than the original. While being cheaper, again, it was not done "on the cheap"...

  • I've got no grumbles over your thoughts there.

    While the likelyhood of the project pretty much vanishes I do wonder about how we can effectively relay the information contained in relevant directives and standards to help people who are interested but can't (like most) spend £200-300 per standard then spend a week reading through the standard-speak looking for the take homes.

    We'd hugely benefit from someone open sourcing there CE compliance file, but that is unlikely to happen without community funding.

    One thing I have learnt is that an importer (anyone who orders from abroad on aliexpress/ebay?) is responsible for CE compliance documentation. So many of these super cheap imports with wiring and other issues were probably never compliant in the first place. This could be awkward (insurance?) for anyone who has used these in educational or Makerspaces.

    I suspected one of the biggest time drains would be going through a machine's bill of materials and making sure all of the kit list is RoHS/WEEE/Reach compliant as required.

    This all grates a little as this presents as a massive cost barrier for people who genuinely want to produce a decent product, but due to this all being self certified many less diligent people can just slap a CE mark on and carry on. I'd much rather see the standards and directives open access and the CE marks paid for with the documents registered in an independent body.

  • @dc42
    Thank's for the EuroFins York info.
    I'll give them a try for our next product approvals etc.
    York is a nice place to spend a couple of days in !
    (Better than the plastic cold damp unheated shed in the middle of some woods I currently use)



  • @jujudelta I used EuroFins York (aka York EMC) for the CE testing for 3 of my products (battery powered instruments using either Bluetooth or WiFi) and found them very good to work with. I have no experience of other companies to compare them to but I would certainly use them again.

  • @burtoogle
    Thanks for the recommendation.

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