Tagged: heated bed mosfet
- March 15, 2017 at 9:04 pm #29622
So I decided I should give ABS a try. I fired up Repetier-Host and set the extruder temperature to 230°C and the bed to 110°C. It didn’t take too long to get the extruder up, but the bed was taking a long time. I left it alone for a while and checked back and my display was showing an error that it wasn’t able to get up to temp quickly enough so it shut everything down and wanted me to reset. I tried it again just using the display and the same parameters with the same result. It looks like my bed temperature is pretty much maxed out at 96°C. Do I have a bum bed or will I have to build an enclosure before I can get the bed hot enough for ABS? Parts for this one are all from here IIRC.March 15, 2017 at 9:09 pm #29623
What people find is the need for a mosfet ancillary power supply for the heated bed… the out of box from the RAMPS may not be adequate enough to power the extruder hot end and the bed… here are some examples of these devices:
you can pick these up for roughly 10-20 perMarch 15, 2017 at 9:10 pm #29624
The link appears to break on the mosfet guide…
The correct URL which may need to be cut and paste is: https://3dprint.wiki/reprap/electronics/heatbed_mosfetMarch 16, 2017 at 8:35 am #29640
I have one of those mosfet boards earmarked for my next printer (MP3DP XL maybe). I’ll give it a try to see if the RAMPS is the limiting factor.March 16, 2017 at 8:47 am #29642
I have two of them on my desk, my vendor is very adamant about me carrying them. I’ll send you one Bill. I have not had the ramps be my limiting factor yet. I had one heat bed that must have been designed wrong, it would fry the mosfets in less than a week even with a fan and a heatsink on them, and the old robos used to have the same issue.March 16, 2017 at 12:02 pm #29651
I’m running a small test print right now at 90°C on a sheet of PEI. After it’s done I’m going to install the board and try the same print at 110°C. First glance says the print is going to curl at 90°C…March 16, 2017 at 12:21 pm #29652
Don’t feel too bad. I have a Da Vinci XYZ Pro enclosed printer and it struggles to lay down ABS without curling. I know 100% of my issues are due to temp conditions in which I am printing (keep the house at 71, geothermal system with fan pushing air all the time). I need to wait for spring/summer temps here in Illinois before I give it another go. I had decent luck printing when I threw a comforter over top the entire enclosure while printing. The wife told me I had to move my ‘toys’ to the basement and out of our living space as she was tired of plastic bits all over the wood floor and stepper motor noises coming from all corners of the house (had 4, 3D printers running at once at one point in time). So now I have them all tucked away waiting for decent temps before printing again…
NeilMarch 16, 2017 at 12:29 pm #29654
I have never had ABS print very well for me. Then I tried PET, I will never use ABS again.March 16, 2017 at 6:01 pm #29667
OK, here’s what I’ve tried so far… I manually stepped the bed temperature up a degree at a time to see where it maxed out. 105°C seems to be the absolute max, and 100°C is much more doable. I added the higher amperage mosfet board in using the stock supply and tested again. Essentially the same results as before. I next posited the power supply itself might be having issues, I connected a voltage meter in to verify voltage, 12.3V with no load, 12.1V while heating. Next was to try a new supply, I grabbed a server supply I had on the shelf (19A of 12VDC) and jury rigged it to the mosfet board. It reads 12.1V idle and 11.9V under full load. Same results. My next step is to try a different hot bed, I have one of the PCB type and a piece of glass to test with tomorrow… If all else fails I’ll look into an enclosure (maybe if I remixed Jeff’s base to be rectangular I could attach) or maybe giving up on ABS for this printer. The XL has a 600W heater, so might able to handle this better even if the area is nearly triple the stock MP3DP. IIRC the heater on the MP3DP is rated at 11A, or 132W…March 16, 2017 at 6:07 pm #29669
Well I read that wrong, I didn’t think you had one, well now you have a spare on the way.
Do you have the bottom of the beds insulated in any way? I use stick on cork shelf liner.March 16, 2017 at 9:36 pm #29684
I don’t have any insulation under the bed, though that sound like it might be worthwhile. I’ve got some thin cork sheets, but they don’t have any adhesive. I’ll investigate tomorrow, that might be better to test before swapping the heat bed.March 19, 2017 at 8:41 pm #29799
Well, the attempt at sticking a cork sheet to the heat bed didn’t turn out quite as envisioned. My contact cement is only rated to 120°C, too low to stay stuck. I found some spray on gasket designed for engines that is rated at 250°C so I gave a coat to the cork and a coat to the bottom of the bed. Slapped them together and clamped overnight. When I pulled the clamps off today it seemed stuck, so I assembled. A couple of minutes into the first print it fell back off. 🙁
I was looking into insulation to put around the boiler in my espresso machine, which is more of a thick blanket that I may be able to fill the full volume between base plate and heat bed. If that works I’ll continue trying to get ABS working, if not I’ll plan on using ABS on the MP3DP XL, which should have more than enough heat.March 20, 2017 at 7:19 am #29821
Mine usually stay on with the edges taped. My oldest pinter has the cork saggin like an old car headliner but I have never bothered to replace it. Here is what I have used most recently. Although, I don’t ever go above 60C, maybe that is the problem. Before the cork the thing to use was cardboard, probably much more of a fire hazard but a lot of people used it. Maybe you could just get a bit of the small round insulation and put it in the gap between the bad and the carrier. That would make a nice air gap. Sorry I just totally realized a super hot bed is something I have not tried since torture testing the robos, and my lack of information might not be helping.
Attachments:March 20, 2017 at 2:45 pm #29865
And of course [slaps forehead] I never thought of just taping the cork on. I’ll give that a try when I get back home the end of the week. I figure the heater bed is pretty common, used on a lot of printers, so there should be some reasonably easy way to get it hot enough for ABS…
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