Backlash compensation will be useful for those of us running ballscrews. I haven’t pulled the trigger on the duet WiFi, duex10, plus daughter board, extended thermistors yet however this will be an important feature if we continue moving forward with development of this printer using duet products. It has been difficult finding resources online with dozens of hours researching duet and the lack of overall descriptive content describing its capabilities however it does seem to be an overall good candidate for our servo based commercial printer using external drives. Even some self proclaimed industrial controllers do not have the features and potential this system has without going to a pc based controller.

@t3p3tony ,It would seem then if one just pauses and uses an external heater control you could simply shut the heater pod controls down for nozzle and bed and than resume later on. That way no dependency upon control board for bed and nozzle. Many already do something similar for the bed when using ssr’s and mains heaters. Other than needing to have a placement for a couple of paid controllers somewhere on the machine it eases the process and you can simply turn the heater back on, wait until temp desired achieved and hit resume. This is a nice feature and being able to pause and have the print head move to the side at a designated x/y/z would also allow for unique prints where you may want to embed an item or structural brace of another material like metal for customized applications. Just don’t knock the print out of place while adding foreign material.

@stoneking I messaged you to see if you had figured this out. I’ve had quite a bit of thought about your project. I’m not sure how you would use a fan output to control an Rc esc. From what I understand you will need a 50k digital potentiometer that accepts a 0-5v input connected to a ne555 or other triple 5 pulse timer which would control your esc. Plenty of manual controls available including a simple servo tester which utilizes the 555 but adapting to the duet adds further complication. We are still waiting for our boards to arrive here so I can’t answer if the duet or duex expansion boards have a controlled voltage output. I’m not familiar enough with fan 0 or fan 1 to know if these would be potential options. I suspect duet controls a 12v fan signal? Perhaps a moderator/developer could step in. There may be 12v digital potentiometers also available but I am not familiar with one in particular. It seems that this would be the way to go about properly controlling an esc. We do have an assortment of various electronics, chips, etc... arriving soon so we can hopefully find a solution for ease of digital control. These small bldc Rc Motors put out a fair amount of power (10k-15k watts) and would work excellent for a spindle motor keeping within a small 58mm x 98mm lightweight frame for those wanting to quickly change over to a mini mill for pcb boards. I’ve even seen others machining aluminum and brass. What I haven’t seen is any direct control from the duet they have all used manual potentiometers which I understand takes an element of automation away and adds additional controls that tend to ugly up your machinery and lose that professional feature most prefer from digital operations like this. Maybe someone better versed can elaborate on my suggestion rather than opening a new post so this one could be further elaborated upon.

I’m curious why the filastruder expansion breakout board and duex5 couldn’t be used together? Even if custom wiring had to be done why wouldn’t that suffice in his case. It seems you’re losing necessary features either way with duex5 Or 2 and that your hybrid made much more sense. Hardware seems to always be the limiting factor and it’s funny but it is a common theme among engineers. A good product is always sacrificing features somewhere that could make it potentially exceptional however hardware engineers are overly focused on a particular design and features. I’ve purchased every duet optional expansion and daughter board for the WiFi and waiting to receive everything yet because I too could not find the exact features we need in one particular setup so we decided to experiment. It may be we end up using a pc based system but it seems this has so much potential as a standalone product. There is the ioni drive that I’ve seen used with duet and it is supposed to work well for larger steppers, servos, and even runs BLDC motors. That like everything has its limitations which is the output voltage at 50v if I recall. For most printers that suffices. Any large format table printer or CNC machine it may not be enough. Curious how you guys configured your setup it is much like what we’re doing here. I fortunately have a business associate who is a programmer so we’re considering unusual configurations we may have to rewrite custom code to implement. Programming is above my pay grade but I imagine the right person can manipulate any number of custom hardware configurations.

@dc42 .., I am also interested in backlash compensation. I was unaware, my fault overlooked when our company purchased the boards that it was unavailable or to be honest I would’ve had to go a different route. If any plans, or not yet, please let me know so we can decide how to proceed with these control boards. I believe that the majority of printer consumers probably use their printer more so as a weekend hobby so they haven’t seen the difference in print quality to desire backlash compensation as a priority and are happy with prints just being a usable part or printable idea. I’m sure only a small percentage actually want to use these controls in a commercial assembled platform that prints with precision or may not have equipment that benefits from a more precise control. Perhaps those unknowing would share a different perception if they knew it was available and made BL adjustments to their printers. Please keep us posted and Thank you.

Fantastic discussion gentleman. I enjoyed reading this post and the thoughtful responses. I spent 1 year of my college time spent on electronics and computer repair. The information I learned was only the sugar in the cake. Without the remaining ingredients it only left me with basic electronics skills which in many cases is much more than the average person and I was able to take those skills along with automotive computer programming and apply it in years of custom building fuel injected hot rods and diagnosing them. Those years along with self taught fabrication led me to own a machine shop today. It’s hands on and yet I feel so lost in many ways with all these different motor applications. I can look at 4 photos of motors that look identical and everyone of them operates completely differently. How frustrating is that? .,And to further expand with hundreds of hours online studying I feel I barely grasp essential concepts. I too would love to delve into the use of bldc motors and I think that they do have some applications where they would be useful including direct drive spindle motors for various CNC operations. It’s been done, it’s being accomplished and even in 3D printing there are many using it for their x/y axis and yet very few discussions that make me comfortable in delving into experimentation. Almost as though it’s a secret recipe. Perhaps as much it is. I would like to utilize a bldc motor for a quick change mini mill, engraving spindle for a 3D printer project here but I fear I would delay completion of the project delving into learning what circuits, programming, and processes are required to successfully implement it besides I lack all the time necessary to experiment so not having a tried and true plug and play option is very discouraging. I agree that if you have the motors, they are free, and you have the time than why not experiment and see what you accomplish? And if so.., please share with the rest of us.

I agree with this assessment your looking to get more speed you either need to spec the motors appropriately or consider other option. Example running a motor rated at 50v on a 24v circuit isn’t going to suffice for proper speeds. Many of the issues come from properly choosing the components you need. If you want to run external drivers simply utilize driver motor combinations designed for each other. One of the easiest ways to go about driver choice is to learn the specifications of your steppers and consider what drivers are used in conjunction with them. Many of the chines steppers rum poorly at lower rated voltages. For example using a 80v max rated motor with a 36v driver which is commonly seen when purchasing package motor driver combinations. Many of those 36v drivers also have a rating of 24v - 50v max so running a 48v power supply is often more productive. That said you can not overcome the limiting factor of majority of steppers. Most cannot operate at higher than 1000 rpm at max voltage. Also consider are you using a belted drive, ballscrews, or leadscrews? There is a common misconception that a larger stepper will provide more speed and that is simply untrue. In fact I would further suggest that oversizing should have other purposes unrelated to overall speed where speed may be an equivalent option between choice of motors. In other words you’re likely increasing torque and not total rpm which is inherently unnecessary in 3D printers. We have a project currently underway to build a high speed moderately large format printer (380x380x500). To get higher speeds a simple choice to utilize integrated driver servos with a speed of 3000rpm and max unloaded speed of 4200rpm. The x and y will maintain a Nema 17 sized (40mm) Motor so we are not oversizing and cranking up the torque where a gantry is light weight and torque unnecessary. These servos will operate off external drives and expansion board. For the z axis we chose a high speed Nema 23 to integrate a single operation versus dual motors. We also chose high speed and relatively low 2nm or .57nm max rpm torque. With the oversized 1/2” milled Precision bed and 4 linear rails and blocks to maintain rigidity the overall mass had been increased therefore requiring the need for a Nema 23 sized frame where a typical over the counter printer would not need this size motor as the beds and guides in general are lightweight. These are factors you should consider as well the good advice in reconsidering your build specifications. You may also want to reconsider the heatbed depending what your intentions I’m printing are as stated it is either a relatively small printer or undersized heater. Larger heaters can heat up faster and maintain better consistency so as long as your not reaching temps that could warp your print bed. The other question you need to ask is what speeds are you trying to achieve and what your existing design is that perhaps some negligible changes could resolve your issue. If you have high voltage motors than use external drivers on those motors and operate them at 80% efficiency. One of our CNC machines utilizes Nema 34 framed Motors. It came factory with a 60v system and 80v drivers to find out that the max voltage of the motors is slightly over 105v suggesting they are clearly under rated and explained the issues we had in speed and step loss why it was under performing. Raising voltage to 75v was the natural choice without changing drivers still only running over 70% efficiency the improvement was night and day as a 15v increase made an entire different piece of equipment. I know this post is older however for future builders I wanted to elaborate and empathize additional research is necessary in a case like this and that typically larger steppers will have very little improvement on overall speed where force and load isn’t issue and additional torque unnecessary. Summary: properly matched hardware/voltage/drivers/motors is key in peak performance of your 3D printer.

Backlash compensation will be useful for those of us running ballscrews. I haven’t pulled the trigger on the duet WiFi, duex10, plus daughter board, extended thermistors yet however this will be an important feature if we continue moving forward with development of this printer using duet products. It has been difficult finding resources online with dozens of hours researching duet and the lack of overall descriptive content describing its capabilities however it does seem to be an overall good candidate for our servo based commercial printer using external drives. Even some self proclaimed industrial controllers do not have the features and potential this system has without going to a pc based controller.

@djdemond

For others reading this I’d run separate drivers through duex5 and 3000rpm servos and it will fly with fine pitch screws setup direct drive or 1:1. I have a CNC mill with 10mm pitch and very large servos that can run 1200ipm. Off top of head that is in 30,000mm/m and extremely fast I can’t imagine a 3D printer keeping up. At 10mm pitch I have 2.5 tpi and a 5mm pitch at approx 5tpi would potentially cut the speed in half. That’s still faster than you need so consider a 4mm or 2mm pitch. Ultimately you can go many of ways and use gear reduction if needed. The accuracy and positional feedback would be a huge improvement over belts if setup right. If using a course pitch to attempt industrial speeds you will have other challenges including z axis holding. I would in that case be sure the z axis servo had a built in off power brake. You can run steppers for extruders and servos for your axis. Presuming you want to spend $240 per axis. Personally I would do it and not waste my money again on steppers. Once you’ve changed you have a difficult time ever looking back. Everyone will say steppers are fine, blah, blah, and I’d be willing to bet it comes down to their own williness to spend the money on quality products. After all for most it’s a weekend hobby and nothing more. For others it’s the future and the sky is the limit. For myself I won’t even say what I’ve spent on this current project. Good thing I’m not married

Re: DIY 3D Printer with duet wifi

Reading another post it appears that this is a feasible solution. We have a project prototype here that will need 9 drivers total including several extruders. The question is in using a duet WiFi with the duex5 the thought is that the extruders can remain on the internal drivers using standard steppers and the axis can be run using external steppers as the size and current drawn would exceed internal drivers turning ball screws. We intend to use closed loop steppers despite the board itself is not closed loop for positional feedback and higher accuracy between motor and driver. Most are familiar with these products and that they connect to any standard open loop motion board. Using an external heat bed so we only need to switch an SSR for controlling temps. SSR is rated at 3-32v input and 120v switching for a 1300watt aluminum heat bed. Since this is not an open source project we’re doing I cannot elaborate much more about it here in the forums however the concern was the ability to relabel internal drivers from external drivers in the software so there isn’t any conflict. I presume like smoothieboard this is ok? Finding a control board to use these intended features in a 32 bit control has been daunting. While seeking an industrial solution we had no luck finding anything beyond Avante though there is no support forums or contact that can collaborate with us through development. If anyone here is affiliated with duet3d and interested in working with our company please consider contacting me for further discussion we would love to know more about the product, add on solutions, etc.. as well if our intended use is not just feasible but complete with commeircial level performance. Thank you for your time and any responses.