Front Intake Heatsink MK2.5 WIP - help requested
I wanted to explore a front intake heatsink cooling setup to see what would happen. Some of the traits I've come to depend on with my modified MK2S are:
Images below are screenshots of Rhinoceros modifying MK3 SCAD files to have the same features but with a dual part cooling arrangement as well as aforementioned front intake.
I would like help sourcing or designing a board that converts voltage fan control to PWM to use a pair of Noctua NF-A40x10 PWM without any modification to mini-RAMBo or firmware. A straight bolt in solution.
As always, constructive criticism is welcome!
I am leaning toward just plugging in one of these in.
Information below from Amazon description.
KNACRO Voltage - to - PWM module / 0-5V / 0-10V voltage converted to 0 -100% PWM
Product description
Module Working voltage: DC5V - 12V; (Power Requirements: greater than 100mA). PWM signal receiving frequency range: 1KHz ~ 3KHz.
4.5V to 10V peak to peak level, jumper inserted at 5V. Class level signal mainly for general industrial control card (such as MACH3 board), 5V CPU
interface
Interface Description:
Instructions:
When the frequency is changed, the corresponding relationship may be offset needs to be recalibrated.
By adjusting the iutput voltage to regulate the duty cycle.
Accuracy can be controlled by adjusting potentiometer.
MK2S kit owner since 8/15/2017
Re: Front Intake Heatsink MK2.5 WIP - help requested
Why so complicated ?
You can control the fans directly with the PWM from die Atmel :
https://shop.prusa3d.com/forum/improvements-f14/alternative-nozzle-cooling-t4395-s30.html#p36090
Nice design ! I'm very interrested because I'm just updating my MK2 to a version between MK2.5 and MK3 :
- MK52 heatbed
- modified MK3 Extruder, a hybrid between MK2 and MK3, or maybe your design 😉
- strenghten the y-frame with 20x40 alu-extrusion (modified BEAR mod)
Thomas
Re: Front Intake Heatsink MK2.5 WIP - help requested
Hey Thomas, good to speak to you again!
Yeah, I forgot about your mod, I think my brain said to me "you are not skilled enough to do this" in the voice of Alec Guinness and removed the memory as a safety precaution. Damn brain. But, turned out an astute member on another thread found a low-kick-over 40x20 pressure fan that exceeds performance of Noctua's 40x20 while being able to go from 10% to 100% without an issue. It is unfortunately a Sunon so I may very well do your mod someday...brave pills are on order (different from brave sauce which causes slurring and poor coordination) so we shall see, we shall see.
I'll do a search on your posts to see what I might be able to incorporate but as our design goals seem slight different, perhaps only the head module is compatible between us. I will not be getting MK3 until Prusa Research fully matures the firmware/hardware as my hero Thomas Sanladerer found out live, it ain't ready for prime-time. Hopefully, the MK2.5 firmware changes will not suffer but I fear it will.
MK2S kit owner since 8/15/2017
Re: Front Intake Heatsink MK2.5 WIP - help requested
Hi !
I read your posts about the comparison of the Noctua fans, very interesting !!! So, the 20mm fan is not really better than the 10mm. I've not tested my Sunion, but it makes a lot of pressure (and sound 😮 )
Maybe 2 smaller Noctua will be much better than one big fan. Thats the reason for a another design of the head. And your head is excellent for better viewing under the nozzle. The PRUSA design covers the whole nozze, it's hard to see what's going on under the nozzle. My design is better, but not oprimal. My new modified hybrid will use the old 30mm hotend fan, this is the crux.
Thomas
Re: Front Intake Heatsink MK2.5 WIP - help requested
@Thomas
I tested that Sunon 40x20 2 pin fan today. Performs quite comparably to Noctua NF-A4x20 FLX being a little more powerful and louder but vibrates and looses performance when there is back-pressure...which is everywhere we want to use it. But it obviates need for PWM as it has near same range as stock centripetal blower fan.
I purchased as DigiKey but more importantly, you can get legible details there.
@All
As I am still very interested in pursuing flanking 10mm PWM fan arrangement, I will attempt my way of using Voltage-to-PWM adapter so no firmware or hardware modification to MK2S is required. But, as "far-east" bulk electronics are not the most trustworthy, I intend make sure it is compatible first.
What I know.
I don't know a circuit diagram from genealogy map so wish me luck!
MK2S kit owner since 8/15/2017
Re: Front Intake Heatsink MK2.5 WIP - help requested
Be careful !
The stock fan-output is NOT voltage driven, it's also PWM. Look at the shematic of the RAMBo, the fan will be pulsed, not more not less. There is no capacitor to make a voltage. Your voltage to PWM converter will not work.
I think, they use the bulid in capacitor in the fan to make a voltage driven singal.
By the way, I use a much more powerfull SUNON : https://www.tme.eu/de/details/psd1204phb1a/dc-luefter-12v/sunon/psd1204phb1-a2zgn/
Thomas
Re: Front Intake Heatsink MK2.5 WIP - help requested
Thanks Thomas, Ultimachine warned of this too. I'm learning EM slowly. Mental glitch refuses to accept Ben Franklin's error on electron direction, will get over it.
On your Sunon, wow, you're running a 12,000 RPM 2.9W fan? Considering the 44.2 dB is lower than stock, you're getting nearly 3X flow, 7X pressure and 2/3 cost of the Noctua 40x20! Are you printing at max nozzle temp? Definitely, you'll have no problems with heat soak at MK2's max stock nozzle temps. Apparently mini-RAMBo can output quarter amp just fine, WOW again! Could I use this as low as 10-15%? Aw, I feel inadequate.
MK2S kit owner since 8/15/2017
Re: Front Intake Heatsink MK2.5 WIP - help requested
Mostly the fan is running with 50 to 70%, cooling is wonderful. Brigdeing looks good. But fan is a little bit noisy at full speed.
Yes, fan can run at about 10%, but not lower bcause it has an autostart function. If fan accidently stops, it restarts itself after a few seconds. 10% is minimum to keep fan alive.
The best thing, you can easily fully modify the fan for PWM with tacho-signal too.
The transistor can drive up 2amps, but this is not recommended. And it's not necessary if you using the PWM input. Connect fan between +12V and GNG permanent and control it with the PWM from the Atmel, as described above.
https://www.onsemi.com/pub/Collateral/NCV8402D-D.PDF
Thomas
Re: Front Intake Heatsink MK2.5 WIP - help requested
Ordered a cheap Japanese Oscilloscope kit to test stuff so I'll know for sure what is going on. On the NCV8402D PDF, is this the one on the RAMBo managing power for Fan 2 terminal? Does your PCB insulation scrape method bypass this chip?
When looking for a place to tap the signal to test, I thought why not solder in signal lead here...
My MK2.5 is on backorder so I might make a hybrid like the other post just to test my flow design in ABS before final one in PC. 😀
MK2S kit owner since 8/15/2017
Re: Front Intake Heatsink MK2.5 WIP - help requested
Yes, it's the same wire.
Yellow circles are vias, so it's easily accessable. Yust remove the solder stop and connect a thin flexible cable. Voila - You have a PWM signal.
It's was not so easy acessable to solder a wire on these solder-pad of the transister/IC, so I use the vias.
Yes, fan1 and fan2 is controlled with this dual MOSFETFET/IC.
My mod dosn't bypass anything, it "steals" the PWM signal directly from the ATMEL. The signal can be connected directly to the PWM-input (not the tacho-signal, yelow wire) of the fan. But, in general, yes you are bypassing (or better pass over) the IC.
Thomas
Re: Front Intake Heatsink MK2.5 WIP - help requested
Finished my cheap ocilliscope kit. Testing Fan 2 (part fan) for fun for now. It was set at oct 112 I think.
This little guy is not the most accurate so take any of these readings with a huge choking grain of salt. But, it was interesting to see what the Mini-Rambo throws at fans connected to fan port 2. Conclusion, definately not PC fan PWM standard, guessing the hard tap will also NOT be 25 kHz.
MK2S kit owner since 8/15/2017
Re: Front Intake Heatsink MK2.5 WIP - help requested
Abandoned PWM conversion. Will source a pair of Sunon 10mm and hope they have low kickover. Ordered a bunch of parts to be similar to Thomas' build such as DC to DC constant current LED driver and Osram 4K 200mA LED but with addition of a bimetal thermal 40°C auto switch to be placed near block. If all goes well, I'll share my US shopping list, if not, look forward to a shakey cam horror video of a printer on fire.
MK2S kit owner since 8/15/2017
Re: Front Intake Heatsink MK2.5 WIP - help requested
look forward to a shakey cam horror video of a printer on fire
😮 😆
Thomas