*is printing a multi part file...
One of the parts as apparently on a blob of oil or some nonsense, is going to fail and probably ruin the whole print.
Pause print. Sigh.
Remember that the g-code viewer has a cancel part function.
upload version 3.2 of DWC.
enable Gcode Viewer plugin.
cancel the failing part.
RESUME PRINT!
ALL. OF. THE. WINNING.
Like seriously, epic epic feature to have.
Identical g-code run on machines with significantly different accleration settings can have quite dramatic differences in print time, for the reasons already described. There are lots of machines out there that claim huge print speeds but can't actually deliver. And even if your printer really can hit 600mm/s within its own travel, printing huge thick layers at low feed rates will always be faster than thin layers at high speeds.
The deep details of print speeds and slicer settings are not widely understood, that often even includes the people writing the software.
I'm fairly certain that both Cura and S3D still don't actually calculate extrusion volumes correctly...
@Phaedrux said in 3D GCode Viewer integrated with DWC:
@theruttmeister said in 3D GCode Viewer integrated with DWC:
upload version 3.2 of DWC.
Mid Print?! Without skipping a beat? Nice.
Yep.
Just paused, uploaded the zip of the right version of DWC.
Took longer to load the gcode for visualization!
Killer feature!
What @thwe said.
Aligning two rails on the same plane (assuming you align the frame well), is much much easier.
Oddly one of the very interesting bits of design feedback I've heard, is put the rails under the extrusions, not on top. That way they don't collect dust.
Seems silly, but its actually really nice.
Not using coreXY would be more rigid. Don't get me wrong, H-bot (or a weird monstrosity I designed) would be less stiff.
Basically, with the type of bearings, mounts (I'm assuming metal) and frame you've selected, all of your lack of rigidity will be from belt stretch. Two ways to minimize that stretch are to reduce the length of belt and increase its width. CoreXY uses a longer belt than you would have on a conventional cartesian/flying X motor. The flying X motor adds more weight and wiring complexity, so it might outweigh any advantage...
TLDR:
Wider belts is the easiest way to get more stiffness.
Its also really important to design in a way to adjust the belt tension!
2
I wouldn't.
Having the bed be structural and heated is a big challenge. If you are going to heat that bed (which will take lots of power, look at an SSR) then you want to both mechanically and thermally isolate it from a separate frame that is the actual Z stage. I've had great results just using nylon foam as a structural spacer. It can be glued, is a great insulator and rigid enough to work well mechanically. Its still a foam though and will happily absorb any expansion of the bed.
Screws and rails in-axis, its theoretically better, I think your bigger issue is that you seem to be relying on the motors own bearings to carry all the vertical load. They are not designed to do that, you should think about including a thrust washer.
3
How much does that gantry weigh? I'm guessing 450g for the extrusion. Plus the weight of the rail, rotational mass of the motors etc, if you are worried about the weight of the pulleys, don't be. If you mean the extruder? Its more significant, but the difference is going to be small compared to the mass of everything else, at least for acceleration not involving X.
If you really want to get higher speeds use bigger motors. NEMA23's are not much more expensive and produce vastly more torque. I don't know why everyone is so fixated on NEMA17's...
4
How fast do you need to go? 24V, 32 tooth GT2 pulleys and NEMA23's get me up over 500mm/s... Which given the huge mass of my extruder, is quite scary.
More voltage is better for speed... And you can always just use the Duet3's heated bed circuit to drive your extruder and only supply 24V to it.
You shouldn't need to actively cool the steppers if they are big enough. People tend to have to when they undersize the motors, overdrive them to get enough torque, then discover they get crazy hot (although good steppers will run hot enough to burn you without being damaged themselves).
You could also get an external relay or SSR to drive an extruder heater, although I'd try and avoid that myself. There is also the Toolboard 1LC if you can get one.
I'd suggest trying 24V at first.
5
How are you actually connecting your uprights to the crossbars? I don't see anything for that. But there are lots of easy ways to do that. If you haven't already go look through Misumi's website and see the millions of options. Including getting them to machine stuff into the ends of the extrusions.
The rest seems fine, although I wouldn't use u-channel for the gantry. If you change it the way @thwe suggests you can use flat brackets, which is way easier.
And to echo what @whopping-pochard said, if you move (in fact you can probably just remove completely) the 'front' crossmember, you get a much better view of the printhead/nozzle.
Similar theme, with the extruder mounted on top of the gantry, you have very little space around it for things like fans for cooling prints. Or fans to cool the extruder itself.
Don't forget to plan for filament mounting, and electronics!
@Nxt-1 said in To rigidify or not to rigidify? - vibration issues:
@H2B
I wonder how applicable that technique is to the size of machine I have.@mrehorstdmd said in To rigidify or not to rigidify? - vibration issues:
How about a couple strap clamps?
I tried with the only strap clamp I could find and did not really notice a significant difference sadly, worth the try though.
I suspect that right now, adding more rigidity is not going to do anything. In fact its probably just going to add things that can resonate.
@theruttmeister
I got myself four bag of ready to concrete mix and will play with it, hopefully in the coming days. Most likely I will go with the M5 bolt+t-slot nut approach as drilling holes trough the extrusions is just asking for troubles with all the interrupted cuts, at least with the tool I have at my disposal. I'll report my findings once I have something to report.
That seems the most sensible path. You can use the same 3D printed mold technique you used for the base, and mold the through holes for bolts right into the concrete. Don't forget a draft angle!
Other people have covered it but...
220VAC is not the issue, all of Europe uses that voltage without everyone suddenly bursting into flames 
But I'm guessing that your heater is not just a couple of hundred watts.
The rule of thumb is, either design your heated bed to be able to withstand the max temp it will reach if just set to 100% for an indefinite period of time.
Or add a fail-safe device like a thermal fuse.
And make sure the fuse is either inside the heater (if you can get it made that way) or mounted somewhere that its going to be the first thing that overheats.
Grounding the bed is excessive, a silicone heater should be double insulated, if its shorted to the bed its because you have drilled through the bed, or some other nonsense.
@dgrat said in To rigidify or not to rigidify? - vibration issues:
Have you enabled interpolation on your machine? I have the feel, that dampening 800 Hz vibrations is also not that easy. There are too many Alu parts which can resonate, even if you add endless weight.
Its not about adding endless weight. Its about adding the right kind of weight.
Metals like aluminum are essentially great big crystals, that propagate vibration really well.
CNC machines traditionally use cast iron, not steel, because its actually much more of a granular structure. Because the vibrations are having to cross lots of boundaries between the grains, the materials soak up a lot of the energy. Epoxy granite is used a lot because it has this property, its a mix of aggregate, with epoxy as a binder. Its almost all boundaries between rocks and epoxy, so its really good at absorbing vibration (plus you don't have to wait weeks for it to fully harden like cast iron, and you don't need a foundry).
Regular concrete isn't quite as good as cast iron or epoxy granite, but its still much better than aluminum, and its so cheap and easy compared to those others...
There are lots of people out there building cnc machines using steel or aluminum bonded into concrete or epoxy granite, its a very effective.
Will there still be bits that vibrate or resonate? Probably, but this is a test that will cost tens of dollars and is fun. And based on what the machining world has been doing for over a century, its probably going to work.
What you have designed, because its floating on 3 points (which is elegant), runs the risk of not running true to ANY of the linear constraints... you could end up with a bed that translates and rotates relative to all three axies as it moves in Z.
To prevent that, you would need to precisely align 3 rails on three separate planes, which themselves need to be precisely aligned to be at least parallel.
Possible, but a lot of work.
You also now have the issue of CPE in the screws compounding (only an issue if you buy cheap leadscrews though).
The advantage of reducing the number of rails, is that you greatly reduce the challenge of aligning those rails relative to each other.
Lots of commercial printers use just 2 linear constraints and a single screw because of the need for a simple (hence cheap) assembly process. They then rely on the bed/frame stiffness to compensate for the cantilever.
The big advantage of rails on extrusions is that they can handle very high side-loads which means you can have just 2 rails and a large cantilever. Do that right and you only have to align 2 rails on the same piece of extrusion.
And given that good quality rails are expensive... fewer is generally better.
All of which is probably academic, in an FDM printer, especially a home built one.
And for custom leadscrews. Misumi. Not cheap, but very high quality.
The number 1 issue I normally see is beds that are not tightly enough constrained in the x/y plane, so things move about and cause vertical ripples.
It can also be motor resonance. Stepper motors will move more smoothly at certain speeds. You can try just changing the speed to see if that helps.
Printing a tower that changes speed by ~5mm/s every 5mm is a nice way to see if that is what is causing the artifact.
@TF_Sinthoras said in First Benchy printed - Issues:
Thank you all for the advices, the thing with the Speed is interesting, I will try that on the weekend.
I use 245°C for printing of the PETG Filament. Is this already High for PETG?
Speed at the moment is 60mm/s
Retraction at 6mm
Retract speed at 50mm/sExtruder is a Bondtech BMG
Hotend E3D V6 Full MetalSeems that to be okay?
I agree with the @Blacksheep99, the retraction distance seems very long, its been a decade since I used a bowden, but it seems high even for that. The time to retract that far is probably causing the blobs.
And 245°C might be fine... but it varies based on exact material, extruder, individual thermistor etc. Best thing to do is print some test parts at 5 or 10 degree intervals.
PET can tend to be a bit more stringy than PLA. It doesn't have quite a big a thermal window, so it needs a little more work to get a temp high enough for your speed needs without getting stringing.
@TF_Sinthoras said in First Benchy printed - Issues:
Hello Community,
I have build up my BLV MGN Cube (XY-Core) with a Duet2 Wifi and now I get everything to Work. I did the PID Calibration of Heatbed and Hotend, Calibration via 20mm Cube and now I have printed my first Benchy. I get some Issues and have no Idea how to go on, can you help me with your experience? Material is PETG from "DasFilament". I run this Material on my Ender 3 already and have quite good results.
Here the Pictures:
Ripple
Looks like classic motor instability. Steppers have a speed range where they provide smooth motion as well as speeds where they do not. If you print a tower that increases in speed with height you can identify the optimum speed for your motors.
Then use that speed for the outer wall.
For example, I print everything but the outer wall at 80mm/s, but the outer wall at 25mm/s.
sudden little Overextrusion
Its oozing when it reaches the end of a line, slicers have multiple different ways of dealing with that. Look at retraction (retracting too slowly can give the hotend enough time to ooze, for example). Could also be too high a temp.
fine Stringing
Either not retracting enough, or more likely too high a temp.
You have any ideas? Thanks a lot for everything.
Tobias
@alankilian
Yeah, I'm going to guess you have a minimum layer time set, so its slowing the 'without' down to get that layer time up.
I'm going to guess the speed difference is the issue, regardless of what's actually being affected by the speed.
Without knowing how rigid your machine is its hard to guess... but it might be that your jerk/acceleration settings are too aggressive.
Normally you would expect the faster print to look worse (due to layers pulling the prior layer about when it hasn't cooled enough).
What order are you putting down walls and infill? Cura wants to default to infill first, which causes very noticeable artefacts in the surface finish.
Do you have a minimum layer time set? One thing I could imagine is the one on the left being printed with a higher feed rate and we are seeing flex in the machine.
What benefit are you looking for?
Its possible to build a hotend with a many thermal zones as you want. Gets a bit complicated to assemble, plus it gets very expensive fast.
But what benefit do you think you'll get from that cooler nozzle?
Because having wildly different temps in the zones just increases the risk of boiling the polymer when the dwell time is too long.
Plus when extruding at a high rate, that polymer flow is going to equalise the temps quite quickly.
@zapta said in Lead screw nut - brass vs POM and radial clearance/backlash:
Just stumbled upon this video. Informative beginning and proposes an interesting magnetic Z lead screw to bed DIY coupler design.
Yikes.
That's a very complicated way to add backlash to a ballscrew!
There have been a number of printed compliant joint designs kicking around for ages, constraining things so that the motion is only planar is not that hard.
If you have trouble getting the PID dialed in, you can always change how sensitive the thermal error check is.
(If saw, you have a really low mass hot-end and you keep meaning to do the auto-tune propperly but squirrel........)
Sorry, where was I?
Oh yes.
M570
If you know that your fan on tool 0 causes a 15 degree drop that only lasts 20 seconds (and isn't causing printing issues) you might put in:
M570 H0 P30 S20
IMHO the default error parameters are quite strict... but I can't say that's bad, I know people will shoot video of the burning printer before they try and put out the fire
@zapta said in [3D Printer Connectors - What's best for in-line connections?](/post
Apropos connectors, WhamBam came recently with an interesting 3D printer gantry connector system https://whambamsystems.com/mutant
Shame they can't design a belt drive correctly... 
I have to ask...
Is your design requirement that your printer fits into the boot (trunk) of an NB MX-5 (Miata)?
(I wish a scissor kinematic was available 10 years ago, would have helped).
POM should be just fine. They came with the motors, never had an issue.
People often over or under constrain the z-axis rails, that coupled with things like failing to control movement in the build surface makes the Z axis more complicated than people expect
(Seriously, I saw a real retail printer that had at least 1mm of lateral play in the build surface... all prints had Z banding due to that fundamental design flaw).
The key thing is to have the rails be square/true/parallel and able to control the bed, the leadscrew should almost be floating.
If you are getting consistent z banding after the changes you describe, I would look closely at all the other things that could be moving (assuming that it's not the classic red herring of a dodgy PID tune).
If you want to have the bed stay in position, an 8mm lead isn't going to help. Its good for speed, but a 4mm lead might be a better compromise.
I've never seen a difference with anti-backlash on Z. Either the axis is well enough designed that it doesn't matter (due to gravity) or the axis is not well designed and has other issues.