Dodgy wiring because I knew I had to bring it all out of the enclosure on the first one. Bed crash got it. Was at the computer and heard the crash, looked over and saw a bic lighter sized flame
This one I had the board and everything out of the enclosure and had to reset Z for some reason. Keep forgetting that any time you save config in klipper it’s going to reset which means bed is coming down. Was standing right there looking at it when it smoked.
Quick amazon search shows several in the $45-80 range. Of course being the first time I will ever attempt to do a repair like this I would prefer to stay cheap. If I find its something I use quite often and want a better one I can always upgrade later and use the cheapo to melt heat shrink lol. But at the same time I don’t want to get the cheapest out there and fail the repair because of that.
Makes sense. Hoping someone chimes in with recommendation(s)…
IIRC you have two 1/4 Alu plates, the heated bed, and the bed support plate that mounts on the Z posts? Another fellow board killer on the forum (where’s my badge?) was happy with “constant force spring” steel (?) coils they added to each Z post, it helped balance the weight more so the bed is less guillotine during reset? I forget who.
I was thinking about it today and wondered what I could do. I do think most of my problem is its just so heavy. I’ve been thinking about ditching the lower aluminum plate for something else. I’ve got a piece of 1/4" MDF that is big enough but idk if that would be good or not. I see some go with extrusions and I guess that would be a good route too. I just don’t know which way I want to go yet.
As far as fixing the boards I don’t have a whole lot of confidence I can get it handled lol. I’ve seen plenty of YouTube videos of guys fixing circuit boards and such. I’ve always just thought there’s no way I can manage that. But when the second one went up in smoke today I thought why not try. If one of these $45 range hot air stations will work and I get one repair made then I broke even just about. If I don’t get either repaired then it wasn’t a huge learning expense, well not much more than it already is with 2 dead boards.
I’m honestly amazed the skr doesn’t have that built in. Or does it and you all are simply generating enough force to overload the safety features
Some kind of equalizer would work, maybe goofy but springs attached to the top of the frame and hooked on the bottom of the build plate? Just enough to make the bed fall slower.
Hydraulic shocks would be the “end all” way but to costly and have to be tailored to each build because of various build factors.
My bed is SUPER heavy. Mostly because this is my first ever 3d printer build and I didn’t have a clue of what I was doing. Bed and bed support plate are both out of 1/4" thick aluminum. plus add a glass bed on top of that. at 300mmx300mm its quite heavy and when its at the top it has 375mm of free fall before it crashes at the bottom. How it hasn’t broken any of the lower belt holders i truly don’t know lol. I’m looking at the cad now and thinking about cutting a new bed support out of 1/4" MDF I have laying around. Hoping that will cut at least a little of the weight off of things. One other thing I can do is stop forgetting that save_config in klipper is going to cause a restart and crash. Since the first burn out I had been much better about lowering it down. I have it end my PRINT_END Macro to lower it all the way down. Problem is it doesn’t always happen at the end of the print lol.
Okay but also an all aluminum bed is awesome. Why don’t you just chip away at the aluminum with your lr3? Think frame/exoskeleton for the glass. No reason it has to be all one piece.
The LR3 cut the bed and the bed support for this printer.
Hmm. that’s something I hadn’t thought of yet. I wonder how much I can get rid of without effecting anything. Seems like a 1" runner all the way around would be more than enough and cut the entire center out basically? Its not a part you can really see so no sense making some cool design in it.
This thread is terrific! You do amazing work!! And, BTW your LR3 is sweet. I’m in the infant stages of building an LR3 and I want to try mill the XZ plates on my newly finished MPCNC.
I have so many questions if you would have the inclination to provide guidance to a novice.
That’s .250 aluminum plate, right?
What endmill did you use?
What was your z-step?
Did you use the same endmill for the holes and the perimeter? It appears that the was no tool change.
Thinking about this bed deal more. Ive had problems in the past with it not always wanting to finish a bed level. I only have 3 points that the bed attaches…
Bed is 300mm square and the support plate cut like what you see in the pic. I didn’t know it was able to go to 4 points with the bed support or how to accomplish that. I see it now but I still cant quite get the DXF to come out right
and have 4 mounting points for the bed. I really think that might support the back corners of the bed better and might keep my bed more level when it heats up but I really don’t know. In this sketch the screw holes aren’t in the right place because the bed is moved back for some reason. If I can figure out how to get the bed to move correctly then I think it will put the 4 holes like it should and give me the correct DXF. Then I could just set in a 25mm offset to the inside and have a better supported bed with a lighter bed support. I have more aluminum that I can cut a new one out of. But honestly I’m really thinking about going to MDF to get it even lighter if that will be enough to support it. I know @vicious1 is super busy but if you have 2 seconds to chime in I would love to hear your thoughts as well
I’m liking the first option. Those I could get for $20 a piece ($60 total) and I can configure klipper to keep the bed up. I have plenty of heater pins open to control the 24v. The second option being open source is great but at $50 a pop that pushes it more than I want to spend.
1/4" Ply Bed Support Plate, was initially cut based on the sketched outline (faint blue and purple). 2 thick coats of primer paint.
However, Bed Support ended up much smaller (Brown outline), trimmed off bunch of material (Red scribbles) so the Filament Spool and drag chains (bed power, and Z Stepper wiring) could fit internally.
1/4" Alu Bed, measured and cut 4 holes for mounting Alu Bed (Blue outline) to Support Bed based on where holes were located in the Mains voltage heater pad.
Used 4 bed leveling springs to mount, something like. I use this adjustment option to try and get bed level by hand during initial assembly.
This reduces how much time Klipper/automated bed Z tilt leveling needs to do each print.
Well after recent developments I think I am going to back up and punt on this for now. My current plan is to fix my wiring to get it out of the enclosure better/cleaner. Also I am going to rig up something to limit the Z. A lot of times when I am working on something and need the bed up and out of the way for a short time I will take one of my filament dry boxes and put it underneath it. I’m going to take a similar approach and put something in there that will allow enough Z travel for the things I need to get printed but not enough to let this heavy ass bed fall 375mm. I think with the weight its picking up enough speed before the sudden stop and that’s what’s causing the problem. So limiting the fall to a much shorter distance should mitigate the burning boards. I want to leave it heavy for any testing that needs to be done. That way we will know that whatever new thing Ryan and Mike are cooking up will handle the heavy beds lol.
Man… Its always something LOL. So I took yet another spare SKR and got it hooked up this evening. Only one spare left so hopefully things don’t keep burning up LOL. Well this one is off of my full sheet LR3, Never been hooked to a printer. Never even had power hooked to the heated bed ports. Flashed the firmware and came back to the computer to get the serial ID all set up so klipper could talk to it. Got that changed in printer.cfg and did a restart. It connected to it and immediately shut down due to temp out of range. So I figured I must have missed one of my thermistors ( I have 2 extras reading “chamber temp”. Walked over to the printer and I could smell something heating up. Reached in and touched the bed and WOW was it hot. Looked over at the SSR and its just lit up solid. Hurried up and cut power. Grabbed my Fluke IR thermometer and it was at 305°F. Disconnected the wires from the board to the SSR and turned it back on. On startup the mosfets for the bed and another for one of the 3 heater ports on the side are just pegged. IDK why but glad I didn’t leave the room for a while. No telling how hot that 750w mains heater would have gotten that bed up to. I’m going to switch the bed over to one of the other heater ports that’s NOT messed up and keep a very close eye on it for any more problems. I wish I knew what was causing that.
Yes sir. Usually run a 5-10% stepover at full DOC. around 20mm/s 50% Trochoidal width. And I run an air mist with just a hint of 99% Isopropyl Alcohol to keep the aluminum real cool.
I have a few videos cutting different things from aluminum…
