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

snoozer

Hi,

I got a bunch more done now. I have moved the z end stop to the z max end and installed an inductive probe for now till I have a piezo probe to go. Had to modify my bed mount as well, I was to worried about losing height on the extruder and it was higher than the bed can reach without losing a few turns on the lead screws. Had to raise the springs a little. The bed for now is the original that came with the printer. Its OK actually. The heater is a adhesive silicone mat with a pretty good wiring harness in a thick silicone tubing. I have made some strain relieve to prevent pulling on the heater when the bed moves. Its a 24V supposedly 300W but in reality more 280 looking at the current it draws. I was surprised how long it take to heat up. I guess I am spoiled with the Prusa. I had it going for a couple hours at 60 degree to start and went to 120 in the end which took for ever. That's all acceptable for the moment but definitely not a solution in the long run. I was super disappointed with the spring steel sheet that I got from Amazon I think it was. Once I had applied the PEI sticker it would no longer lay flat. I guess I should have pre bend it slightly cause it looks as if the PEI is pulling the edges up. Its also very thin, not anything like the Prusa one. Its basically unusable. The last observation I made was the difference is probing distance for my inductive probe between the aluminium, bed and spring steel. Without the steel and only aluminium the probe barely triggers before digging the nozzle in. The probe is then so low that I worry about proximity to a print. With the spring steel that approx 1.5mm better. That surprised me a little, did not expect just big difference.

I had no go on macros yet or making use of the z max switch, that's on the agenda for next week. Also trying to find better spring steel with PEI and a piezo probe cause I want to be able to print on glass as well.

Here a few pics of today.

snoozer

Just a quick add on, an impression of the fast non print move speeds I get so far.

https://youtu.be/PBN2l-wafVY

dc42

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

Just a quick add on, an impression of the fast non print move speeds I get so far.

https://youtu.be/PBN2l-wafVY

That's noisier than I expect from a Duet. What stepper motors are you using, and at what current and microstep setting (M906 and M350 commands in config.g) ?

snoozer

@dc42 Hi,

My settings are here:

M350 X16 Y16 Z16 E16 I1
M906 X900.00 Y900.00 Z1500.00 E800.00 I1

I have not yet done anything with the extruder cause I don't yet have a good bed solution. The motors I have on X,Y and Z are 0.9 degree rated at 1.7A.

0_1557734771912_MT-1704HSM168A-RevA-100cm-wires.pdf

Regards
Jan

PS: The noise in the Z axis is MUCH more intense in the video than in reality, I believe I had the bed resonating with the bolts holding it as well.

Veti

why are you running X and Y at 900mA if the steppers are 1.7A?

also you are moving your Z axis at a very high speed. what is the sound at a more reasonable speed of 6-10mm/sec?

snoozer

I have not fully fine tuned the stepper settings yet cause I am not yet at a stage where I actually print. Getting to grips with mechanical issues and macros, end stops, probes etc...... From what I have read and what makes logical sense to me is that there is no need to drive the steppers with the highest rated current but rather find a sweet spot between desired torque and needed current, I could probably reduce that even further but I just did not yet get around giving it a good test. If I move everything at slow speeds like the Prusa does by default I hardly hear anything little background wine. The Prusa would be louder. One of my main concerns was the time it takes to move Z from 0 to max. On this particular build because its not as freely accessible like most Cartesian printers I like to have the bed move quick to Z max for ease of access. That's also the reason for playing around with z probe for z 0 and end stop for z max so I can do quick moves but yet have the ability to home to 0 for the last 5mm at slow speed since I know the dimensions. In general I think its my mindset to move all axis as fast as possible without losing steps or causing mechanical damage on non print moves. Power consumption and noise are not really issues for me. Having that said, I obviously don't have the experience yet to know what is the limit but I am not losing steps with my set up as it is for now and I have no rubber dust from the belts.

Thanks
Jan

snoozer

I have ran the bed leveling a few times now to see where I am re bed adjustments. Its the 1st time that I did that now after having the Z probe working. Once its done the probing I get the overemphasized graphical representation of the bed. The bed and the probed view are on a different plain level. The probed bed is approx 5mm below the ideal bed. Is that an issue with some offset that I have not taken care of or is that the difference due to position from homing to z0 and then probing at a much slower speed.

Thanks
Jan

Veti

thats the difference between your height and your actual height as measured by your z probe.

if you have a fixed probe having a z max endstop does not make much sense in my opinion.

snoozer

@veti The end goal is to be able to turn on the printer, move quick to Z max without the need to home to z 0 because I may still have a print on the bed or what ever. This way I can have a macro to move fast to z max, do what ever is needed and then move to z 0 +5mm and go slow from there to probe for z 0. That's the idea behind it but as I said, I am still in the process of learning and finding good ways to mount end stops, probes etc..... Piezo probe on the top of my list now..... redesign extruder mount etc..... plenty of playing around to do I don't even know if I leave it at micro switches or rather change to optical or other ways for homing. The smaller and lighter the better, contactless probably ideal.

Jan

PS: I have just read this and flew over the write up:
https://forum.duet3d.com/topic/7948/external-triggers

I love the idea of actual buttons. That would be even better if I get that to work without the need of interacting on DWC for certain things such as "Go to Z max fast" or load and unload filament.

snoozer

While I was playing around this WE I figured out that my cable management leaves a lot to desire. The Duet mount IS temporary, that will go on a metal sheet which will also be the rear wall of my printer in the final set-up. My worry is the harness from the frame to the head. I was hoping the PTFE tube for the filament guide would provide enough strength to support the harness in a nice arch from frame to head but it does not. I dislike cable chains when used hinge side up, it is not meant to be used that way in my opinion. So I am thinking of sliding contacts or a compressions coil spring long enough to form an arch from the frame to the head to use in the same way people use the normal plastic wire wrap stuff. I am ofc not finding such a spring. Has anybody solved this issue somehow nice and neat without support from the top (hanger for harness) ? Any other good solutions that people use ? Just trying to gather ideas that people have for this issue.

Jan

deckingman

@snooze Flexible conduit might be what you need - like the picture in this link https://www.toolstation.com/conduit-ducting/p92502?store=JC&utm_source=googleshopping&utm_medium=feed&utm_campaign=googleshoppingfeed&mkwid=sgsL3oOy9_dc&pcrid=142003768299&pkw=&pmt=&product=92502&gclid=CjwKCAjwq-TmBRBdEiwAaO1en8lu35EdHtSVejabt_2pdkSxZ_-XAWPJxwIb8iPoU_FfJddLwLAyjRoCwSEQAvD_BwE

Fix the ends securely to the frame and print carriage.

snoozer

@deckingman I was looking at conduit like that. I am not confident it will stay up and its a lot of drama to add wires etc. after initial installation. I have seen these kind of kitchen water taps with the coil to hold them.

https://www.google.ie/search?q=küchenarmatur+spiralfeder&source=lnms&tbm=isch&sa=X&ved=0ahUKEwj6_NWWyJjiAhU7TxUIHcjSCcIQ_AUIDigB&biw=1379&bih=804

I have to check what length they are and inside diameter. Weight might be an issue here. I am probably thinking way to fancy..... maybe a simple spring steel rod bundled together with the plastic wrap or inside a PTFE tube and wrapped in with that would be simpler and just as effective.

deckingman

@snoozer Something like that might work too. I use cable chain on it's side which isn't ideal but it's OK. The type I use can be opened up which makes it easier to add another conductor should that be necessary (I have about 40 conductors going to my carriages from the frame because I have 5 extruders that move, plus heaters, lights, end stops, a probe, fans etc.

You can buy split flexible conduit too, that can be opened up.

If I used conduit or a spring such as you describe, I'd find some way to support the end some distance above the centre of the bed, rather than a loop from the frame. So the carriage just has to "drag" the end around but it doesn't have to take the weight.

Just a tip if you do go that route with conduit or a spring type thing (spiwrap might work too but it's a bit stiff), work out how many conductors you need including heaters, fans, lights, ends stop switches and anything else you can think of, then add a couple more "just in case". It's a lot easier to feed them all in as a bundle taped together here and there, than it is to add another conductor at a later date.

snoozer

@deckingman I try to avoid the need of support from above if I can. The idea is that I can have a full acrylic made hood on top without any further obstructions to keep the heat in but easy access if needed. Sure If I find no other way I can also make a support frame on top. Re wiring, I am nowhere near to a final setup yet but I have added a spare 4 core cable with Dupont connectors just in case, so I don't have to rip it apart for everything I like to test.

Are you actually using shielded cable on your machine ? Just wondering if you had issues with noise from the stepper motors and probes etc ? The cables that came with the motors are non shielded which I actually don't like so much.

Jan

deckingman

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

Are you actually using shielded cable on your machine ? Just wondering if you had issues with noise from the stepper motors and probes etc ?

No and No - (with a couple of caveats). I twist the motor wires but they are unshielded. I'm not sure of the source but I used to get a noisy signal when I used a PT100 on my bed. Not much but enough that the temperature reading had about +_ 0.5 degree "oscillation" in the signal. However, this happened regardless of whether the motors were moving or not so I doubt that the motors were the cause. Changing the PT100 to a simple thermistor fixed the problem.

snoozer

On my ToDo list I now have:

This WE

Macro for Z-Max
Part cooling
PSU Mount
Temporary fix bad spring steel surface

Following Weeks

Piezo Probe
Wiring harness support
Tooling Plate Alu Bed
230V AC Heater with Solid State Relay
Bed heater insulation (thermal)
Push buttons to call macros (Fast to Z-Max, Home XY, Home Z, Load and unload filament, E-Stop

Scachi

@snoozer I am currently building a rat rig V-Core too , did you flip your belts somewhere to run on the smooth belt side on the idlers ? Looks like there isn't enough space to twist them anywhere.

snoozer

@scachi

Hi,

no I have not flipped them over anywhere, the smooth side is not running on the idlers everywhere, just on the inner idlers on the X gantry.

Regards
Jan

snoozer

Here a couple more links to Thingiverse with my bed spring mount and the strain relieve for the bed heater wires (Fusion 360 links included).

https://www.thingiverse.com/thing:3636671
https://www.thingiverse.com/thing:3636679

Also a box for the PSU I use till I have my mains AC bed heater.
https://a360.co/2VL0WOC

Consider these quick and dirty designs, I am all about functional, not "nice looking".

Have FuN!
Jan

snoozer

@scachi I have read that people dislike running the teeth on plain idler. I can imagine on a very small diameter idler that could be an issue but the idlers in the V-Core are pretty big actually. Once I get printing I shall be on the lookout for issues I guess.

Jan