Anyone on the FB page will probably know me as Jeremy Snyder…recently finished a Y-Axis mod to make the front and rear edges of the bed more stable and stronger, now since I mainly print ABS I’m constantly having issues with the print bed not getting hot enough to get ABS to stick well to my glass bed.
Actually I should say, I can get the bed hot enough, just needs 30min to get to that temp…so it got me thinking, has anyone thought of an external power supply just for the heat bed and using a Mosfett device like
Basically, cut the cable to the bed, wire the snapmaker to the mosfet device to control that and put the second power supply into the mosfet allowing that device to handle the extra power and heat up the bed faster/hotter.
Anyone thought of this as well? has anyone tried it yet?
This would be nice @Edwin: would the bed be OK with higher temperature? And would you need to chenge the temperature sensor? In my understanding the limiting factor for the temperature on A350 is only the power of the power supply.
Temperature sensor wouldn’t be an issue, its the same kind of unit that is on my FLSUN and homemade printer…heck I’ve gotten the bed to 100 before, just takes a LONG time to get there.
I should state also that I’ve done this mod to my FLSUN cause the controller had a history of burning out the heatbed wiring, its super easy to do.
Edwin got information from there electrical engineer. He said the limiting factor is the controller itself (not the power supply like mentioned in kickstarter updates…)
I asked this about 4weeks ago, thinking about printing on hotter bed.
so if its the controller then (like the FLSUN and the weak heatbed power supply control board) putting in a secondary larger mosfet to take the power would be a valid way to do it.
Reviving a dead topic since I’ve finally got around to finishing/fixing my A350…I did the mod, installed a new second power supply for the bed and a separate MOSFET heat bed controller and I can say I don’t see much improvement in the time it takes to heat up…
I’m beginning to think the heat bed limitations are completely in the bed itself…my FLSUN Cube heats up to 90 degrees in 2-3 min, the A350 still takes 4-5 min to get to 70 degrees.
Might search online for 350x350 heatbeds to replace this one with.
I suppose you’re on the wrong road here. A stronger power supply would be able to source more power, but the bed itself will not demand more power. Power = Voltage x Current, and Current = Voltage / Resistance. So resitance is fixed for the bed, voltage is nothing you should go beyond specification, so current will stay the same regardless how much juice is available, and thus power will stay the same. I’d strongly discourage increasing voltage, since the bed will be rated for I assume 24V, and will eventually fail/burn if you raise voltage.
The road to go is a mains powered heat bed like e.g. this kind: https://e3d-online.com/products/high-temperature-heated-beds
But using them requires a) knowledge of handling mains voltage safely, and b) a circuit that switches mains based on the Snapmaker “signal”, while not exposing Snapmaker to mains. On a spontaneous search I found this: https://3dprinting.stackexchange.com/questions/5765/mains-powered-heatbed-safety - but make sure that you are really well informed before you try this! Your health is at danger, and if this catches fire, the health of other potentially also…
If I am right and Snapmaker heated bed runs at 24V, you may have a safer chance with an 48V bed like these: https://de.aliexpress.com/item/32761863867.html - still a lot can go wrong, but at least the voltage is not hazardous on touch.
That’s just my thoughts, no proper research done.
I didn’t go over the 24V, early on it was speculated (and mentioned by SM team) that the limit of the heat bed on the A350 was that the controller couldn’t support the extra current thus it was limited internally by the controller. I just added a second heatbed controller that removed the limitation (supposed) from the SM controller and a second power supply to ensure the limits weren’t from the power supply as well (also always a good idea to run heatbeds on second power supplies IMO, done it with my other custom printer), as for safety I’ve taken all precautions my wiring is over rated for the loads and in my day job I wire more complicated and safety related items than a 3D printer.
I’ll be looking into higher voltage and temps beds in time, I gotta do a test to see how long it takes to get my unit to 90 or 100 degrees so I can properly print ABS, got a job I need to print and it would be nice to be able to run both printers full time.
I have done a mod and have tested it for some weeks.- I mounted the cnc plate with a few screws to the machine, carved out the place of the thermistor of the heat bed and placed it on it.- Sure you have to mount the heatbed to the cnc plate…
I have not done a research how uneven it is in this position.- I had to add some screws because of leveling but at the moment i am happy,- but i still have this in the head, if there are leveling problems again.
Now i am able to heat till 114°C on the display, meassured hottest spot in the middle is about 98°C (with a voltcraft IR 260-8S IR-Thermometer), the coldest spot is about 65°C, heatup takes half the time, i guess…
I didn´t run a abs print yet but i guess in the enclosure it would be no problem to get it stick.
Heat-Isolation from the bottom of the heat bed is a great way to improve temperature.
(If i am doing cnc i will post a pic of the rest.)
nice, I used a 1/8" piece of acrylic to separate the heatbed from my 1/4" plate that attaches my modified Y axis, fortunately the 1/8" doesn’t cause any issues with leveling due to height.
I’ll say it does seem to warm up a quicker, just not as fast as I’d like or as fast as my Makerbot or FLSUN cube warm up, granted I did the same heatbed mod to my FLSUN cause they are prone to damaging the controller since the heatbed draws too much.
I think an independently powered 120v heat bead would be the most efficient way to handle this problem. It would not be difficult for me, however I do not want to lose print space in the X or Y axis and the closest 120v bed I have found is only 300mm^2. As far as isolation has anyone considered or tried a ceramic sheet?
I am curious to know if anyone has anymore updates on these mods? Has anyone looked into modifying the controller programing to bypass the controller limiting the heated bed temp?
I am curious I am trying to see what extents I can print with my SM. Trying to print fused/filled filament that needs bed temps over 110 c.
@TrippieHippie as mentioned in the discussion above, the limitation has more to do with the bed itself than the limits of the controller/power supply. If you would like to print at a bed temp of 110+C, I would recommend looking into external beds like those linked above as reaching those temps takes a long time, even with thermally isolating the bed.
Snapmaker has said that the bed is rated up to 120°C, so it is simply an electronic issue. You can use a different power supply, or an additional power supply, but you need to ensure that nothing overheats. I haven’t looked into the specs of the MOSFET that is on the board, but you might need to obtain one with a higher current/heat rating.
i do think snapmaker company could do much $$$ if they add a heatbed which could increase heat temperature for the A350 models, but there must be a reason (which i don‘t know) that they didn’t offer such a solution. Unfortunately they don’t read in here which sucks like there customer support. Without the community out there which help each other the company just don’t exist anymore, just my opinion.
The reason is the power supply would either need to be different for the A350 due to the large power draw, making manufacturing more expensive, or making every model other than the A350 significantly oversized, making manufacturing more expensive. This was addressed in the kickstarter.
The issue is not so much the ratings of the MOSFETs but the entire power supply is wattage limited, from the transformer all the way downstream. However, the resistance of the bed is set to draw a given wattage at the 24V source. Either the resistance would need to be decreased by designing a new PCB bed, which would overdraw the power supply requiring a more powerful power supply, or the voltage would need to be raised, which would of course require a different power supply.
I went the 120V silicone heater way with a solid state relay but this absolutely requires custom firmware to implement PID control of the temperature as the default bang-bang without modification causes the bed to reach about 200C in about 15 seconds with the 750W heater, overshooting more than 200% of the target temp. Thanks @MooseJuice for your contributions in the AC heater project.
That was the first part of my statement, either use a different power supply, or use an additional power supply (just for the bed). When I spoke with Edwin on this 2 years ago, he also stated that they had overload and overheating concerns, which is part of the second portion, where I talked about the MOSFET. Their concern also included the overheating of the Linear Modules, and the Controller. All of this needs to be taken into account when working on a solution.
P.S. A 120V solution with a solid state relay is also a VERY NICE option, but we still need to be wary of overheating the other components, which was Snapmaker’s greatest concern.
