Core-XY based on Rat Rig V-Core and Duet 2 Ethernet

  • @deckingman and WOW again re the "floating" hotend. Just looked through the blog. Have you chosen the mechanical precision approach over lets say a piezo cause that's what you can do best or is there other considerations that stopped you from using a piezo probe ?


  • @snoozer I don't have spacers between the aluminium plate and the 2020 extrusion but if I was doing it again, I would use them. In fact, it's on my list of things to do. The reason is that the semi rigid insulation is slightly compressible, which means that if I don't tighten the fixing screws by the same amount, it is possible to distort the plate.

    I have no problems with belt stretch and that is with using standard 6mm GT2 timing belt. But I do use 1mm single start Lead screws so the torque requirement to drive them is low. Of course, you don't have to use 6mm wide belts, nor indeed do you need to use 2mm pitch belts. The steps per mm are determined by the lead of the screws and the step angle of the motor. So the interconnecting belt can be any size and pitch.

    Ref machining slots in aluminium - I have done this in the past using a wood working router and HSS (high speed steel) cutter. Paraffin is the best lubricant to use when machining aluminium IMO but if you take small cuts, you can do it without any coolant or lubricant.

  • @snoozer said in Core-XY based on Rat Rig V-Core and Duet 2 Ethernet:

    @deckingman and WOW again re the "floating" hotend. Just looked through the blog. Have you chosen the mechanical precision approach over lets say a piezo cause that's what you can do best or is there other considerations that stopped you from using a piezo probe ?


    Several reason really. Firstly, fitting a Piezo to a Diamond hot end is difficult to do. Secondly, a Peizo needs some sort of interface board whereas a simple switch does not. Lastly, the "mechanical approach" isn't a problem for me but I can see how it might be for a "non-mechanical engineer". Having said that, it's not hugely difficult - the mounts that take the bushes and dowels are both printed parts so it's not the ultimate in precision engineering.

  • @snoozer One other thing before I forget. When using a thick aluminium plate, mounting of the temperature sensor requires some thought. The "normal" method is to have the sensor built into the heater or sandwiched between the heater and the aluminium plate. This is problematic because when the heater comes on, the interface between the heater and the plate heats up quickly and so the heater turns off again (or the PWM value reduces). But it takes time for the heat to penetrate the plate and reach the upper surface. So if the heater is cycling on and off (or high and low) quite quickly due to the position of the temperature sensor, then it takes an inordinately long time for the top surface of the plate to reach print temperature. My solution was to drill a 3mm diameter hole in the edge of the plate, as deep as possible and as close to the top surface as possible without breaking through, and fit the temperature sensor in there. So the sensor "sees" the temperature close to the upper surface, rather than the temperature of the bottom surface. Of course, after a period of time, thermal conduction means that both surfaces will be more or less at the same temperature but during the warm up period, this is not the case.

  • @deckingman I know what you mean, in my original design I had a small slot and hole designed in my CAD model for the thermistor. So for my current plan I thought of either having a hole in the center from below or as you do from the side.


  • I have thought of redesigning my hotend/extruder mount to use less space and also to include a piezo probe. Someone else has done a pretty good looking design already.

    I have exported the design from OnShape to be able to work on it in Fusion 360. This should resolve my desire for a more compact mount including piezo probe. I share it once I am done.


    PS: I have abandoned the idea of a quick release tool holder for this printer. Maybe I look into that idea again on my next build.

  • Very frustrating day today...... the design above was evidently made around a clone Titan Aero, the original has issues fitting on the mount. I needed longer bolts for the stepper mount and the hotend is shorter apparently, I had to trim some of the part cooling duct off. The belt attachment is for ppl with a LOT of patience but I did get it done in the end. A nice baseline design but I will do that again from scratch and fix the issues I found. So far I can not recommend it for an original E3D Titan Aero. On the positive side, its very compact and gives a few mm more print area.


  • Hello,

    I am finally getting somewhere. After resolving some of the issues with the Titan Clone Mount I spend some time getting Slic3rPE set-up. My approach to that was basically a mix of the Prusa settings and some input from the a Railcore II300 profile I found online. I can not claim that I would know all the details what each parameter actually does but so far I have a working printer setup and print setup for 0.2mm and 0.1mm layer height. One of the things I struggled with most was priming of the nozzle prior to the actual print. The way Prusa does it did not really work so I have taken that from a Railcore profile. I can run both print profiles at 100% with very nice looks and at 200% for a very fast print. I have speeds set to 60mm/s for perimeters 30mm/s for external perimeters and 80mm/s for infill and support, 20mm/s for the 1st layer. Some distortions are noticeable after sharp corners for example printing a cube. Printing it at 200% speed that obviously gets worse. It is in no way so bad that it would worry me for now but something that shows there is some unwanted vibration. I will look into that once I have my final bed finally on the printer.

    Another issue I ran into was heat in the wrong place of the hotend. I had the Titan Aero fan set to 70% to reduce noise. That was not a good idea, on an longer print I started missing steps on the extruder and it finally ground through the filament. The problem was the fan was to slow to provide enough cooling. So my heatbreak was clogged and I had to disassemble the Titan Aero to remove the blockage. This has not happen since I run at 100% fan speed.

    I have no good light here to take pictures of prints, I take them with me to the office and post pictures later today or tomorrow.

    Have FuN!

  • @deckingman, You mentioned 3DLAC as printing aid you use on your glass surface, I have been looking at it seems there are 2 versions, an aerosol can called 3DLAC and a pump spray called 3DLAC Plus. Which is the one you use successful ? I have ordered 4 float glass surfaces now 320x320x6mm at 27 Euro. I find that is dead cheap, really no point if wrecking my head over flex plates. With the machined aluminium its the first time I try my virtual UK shipping address provided by DPD. I hope that works out.

    Have FuN!

    PS: The glass comes from a local supplier, If I get a ride tomorrow I can pick it up. At that price I assume its measured with a measuring tape and hand cut. Probably have to find a way to make the edges less dangerous 😉

  • @snoozer 3DLac in an aerosol is the original. The pump action is a later addition to the range. I have used both with equal success. I suspect there isn't much difference in the actual product so go with whichever is most readily available or cheaper.

    On the subject of glass, I bought mine from a local supplier but asked them to polish the edges. It might be worth asking your supplier if they offer the same service.

  • I have to take a step back for a few days. I was spending way to many hours getting nowhere on Fusion 360 for my Titan Aero mount with piezo. Turns out to difficult to print or to bulky. Having the flue as well in the moment. I leave it rest for a few days. Still waiting for final deliveries for optical endstops, tooling plate, 230V AC heater etc......

    Be back soon

  • Hi,

    I really took some time off the printer and started from scratch with the Titan Aero mount including the piezo and having a detachable extruder from the base plate. Some preliminary work is shown below. Base plate and bolted on extruder mount with a flat part for the piezo, it can be seen slightly visible. A couple of guides for the PTFE tube and wiring. A bit of a support for a wire guide will bolt on to the back that's what the M3 nuts are for. On the side is also the mount for my (still) mechanical end stop. Playing with it in hand pushing down on a surface it is VERY sensitive but wont know for sure until its mounted.

    After all that I have to say I am not sure I would use a Titan Aero next time. I find the mount requires just to much asymmetric shapes and it is not easy to get the nozzle centered. Also what I have notices is yes, it is very compact vertically but its not ideal horizontally. Have been looking at the BMG M extruder now with Mosquito hotend, that looks way easier due to the symmetry of everything and yes its way more expensive...... next printer 😉


  • Moderator

    Have you considered using an underslung mount for the Aero? Like this?

    It rotates the Aero 90 degrees and has the motor riding under the rail.

  • @Phaedrux

    I would find that a waste of build height to be honest, That vertical compactness of the Titan Aero was THE main reason why I got it. The BMG./Mosquito design could be placed mostly above the gantry to maintain build height. I think that I have to accept the limitations at this point. What annoys me the most is that the belt fastening/tensioning is part of the hotend/extruder mount. In any future design I would make sure mechanics are independent of hotend and other components.

    Have FuN!

  • Right, I am back to my 1st design (Orange PLA further up in a pic), all I am gaining on the Y axis would be 7mm with the new design or so, cant be bothered. The underslung mount and some others similar lose significant Z height, I prefer not to follow down that road. On top of those issues I have not yet received my machined cast Aluminium plate. The supplier in the UK did not want to send to IRL so I used Parcel Wizard in NI with a UK Address. The supplier had all the details correct as confirmed by mail BUT left some details out on the shipment so now DPD can not associate the delivery to my Parcel Wizard Account....... emails back and forth now for a week...... I nothing happens I order a new plate from IRL this time.

    I have been looking a lot more into the Mosquito Magnum and the BMG M, I see a lot of advantages mechanically with that entire idea, The heat-break no longer has to deal with any mechanical load and no more frustration on nozzle changes with spinning heatblock. The nozzle change drama is what stops me from using bigger nozzles on big prints, I hardly ever need fine detail, just strong and fast is what I need most times. The downside is the price, the lot with extruder, hotend, heater etc comes to approx 380 Euro. Have to sleep a few nights over that.

    So all in all a bunch of delays by choice and inflicted from outside.

  • I hope snoozer and mods don't mind, RatRig has a sale for this kit ATM

  • Hello after a long time,

    summer is over and social life is returning to a lower level of intensity. I have not touched the printer all summer, was just to much RL stuff going on. Back at it now since a few days.

    So the state of play right now:

    • Precision Piezo is set up and working
    • Still original print bed
    • Optical end stops in progress as we speak.

    The piezo probe took me some time to get working. The issue I had mostly was it would not trigger at low speed but super sensitive on acceleration and even walk by. For now I ended up wedging the piezo between the V-Core metal carrier and the printed hotend mount. My attempts with a "pocket" for the piezo failed every time and location. I have a bit faster moves now for probing on the Z axis but slowed the X and Y right down between probe points for mesh levelling. Probing the entire bed now can take approx 10 min but thats OK cause it works SUPER good and I don't need to do it every time anyway. The microswitch based end stops for X and Y click, even that click sets off the piezo, so I finally have to get on with my optical end stops. Printing holders now and wipers to pass through.

    A more serious mechanical issue with the RatRig design is the fact that I have 2 independent yet from the same driver driven steppers. During my probing fails that caused the entire bed to go out of level alignment. For now to quick fix that issue I print sleeves that go over the Z lead screws to have a fixed level point at the bottom to align this. For a permanent solution I will upgrade to the 3x lead screws and also join the motors with a drive belt, the 3rd lead screw having the belt drive only from the other 2 motors. I may have issued with weight in the end. the aluminium plate with the glass print surface is over 5kg (weighing scales max), so I might have to upgrade the motors or use one big motor to drive the 3 lead screws, not sure yet.

    Anyway, I am back on track and I see a linear rail version of this on the horizon. RatRig have that in the pipe.

    Have FuN!
    Jan P.

  • I just finished my upgrade to the V2 hardware and three Z motors. I drive them separately so that I can use the Duet firmware's auto levelling. Of course, I needed to get a Duex expansion board so that I had enough stepper drivers.
    Before, when I had two Z motors, I could also drive them separately and keep the bed level on the X axis.

    Any reason why you don't use this feature?

    Fitting the Orion to my V-Core was simple. I created a custom hot end mount which was designed to fit with the parts that Idris has made available on Thingiverse: Precision Piezo Orion Parts

    Basically, I used the E3D groove clamp for the hot end and incorporated the essential elements of the corresponding top into the design of my hot end mount. The essential elements are simply four 3mm holes arranged on 26mm centres for the screws which go into the clamp and a 15mm wide conical depression above the Orion board which allows it to flex when the clamp transmits pressure on the nozzle to the board.

    I'm currently working on a new design for the mount so that the clamp for the hot end can be screwed on from below. As it is now, I need to use 50mm long M3 screws which go all the way through the mount from the top and that's not exactly ideal.

  • @grizewald , thanks for the suggestion. The reason I don't use independent motor drives is that I am convinced once the belts are in place on the lead screws like in @deckingman's printer there is simply no need to drive them separate. I am using a (or will be once I have it machined) 10mm aluminium plate as heated bed and 5mm float glass. I think it will be very rigid. The maximum height difference would come from the pitch of the lead screw over one notch of the belt. I am very confident that can be dealt with with the mesh bed levelling. Also now that I have seen they will have a linear rail version of the RatRig soon (November / December apparently) I don't want to spend any money on the extension board, I rather build the new version once I have this one done.

    Re piezos, I am not using a E3D V6, I have a Titan Aero, my mount would be very different. The reasons behind that choice have been mainly the gain in build height and less leverage on the nozzle due to the shorter compacter design. My next build will NOT have a Titan Aero again, in fact I probably go away from E3D and look at the BMG-M with the Mosquito hotend. I had issues with clogging (had the fan speed to low) and the extruder is often missing steps at higher speeds (not a pancake motor). So for now I am OK with the piezo cowboy style mount cause it works. I will revisit that once I have the print bed finished. I am not happy with my hotend mount anyway, its very hard to service. I would love a modular (possibly magnetic) mount.

    Anyway, optical end stops 1st, proper bed next.

    Jan P.

  • @snoozer said in Core-XY based on Rat Rig V-Core and Duet 2 Ethernet:

    The maximum height difference would come from the pitch of the lead screw over one notch of the belt.

    Not even that. To get the bed level, simply slacken the grub screws on the pulleys and turn each individual screw. Once level, tighten the grub screws and that's it until you take the printer apart. Built correctly (and it's not difficult or expensive to do) there is no need for any flatness or level compensation - ever.

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