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SoliForum - 3D Printing Community → Help/Repair/Maintenance → Park, home, and Y axis skip problems after E3D install
Or is the aluminum bed platform the best way to go?
Platform doesn't matter. Its the plate that matters. Don't bother upgrading anything but the bed plate. I still think it might be the rails, but you can check the bed for flatness with a straightedge.
Go to the hardware store and get a piece of glazed tile (the really smooth glossy white kind, usually can get a bunch of different shapes and sizes for bathroom detail). That is as flat a surface as glass, without it bowing when clipped. If you using ABS, then you will need to let the ceramic soak the heat up a bit before running your print.
At the very least, you will be able to verify whether the bow is actually in the bed or in the rails.
Platform doesn't matter. Its the plate that matters. Don't bother upgrading anything but the bed plate. I still think it might be the rails, but you can check the bed for flatness with a straightedge.
As it happens I have a spare -- when my original heating element died and Solidoodle took more than a month to ship out a replacement, I bought one and stashed it. I thought part of the point of the aluminum over the original wood was to avoid this kind of thing, but I expect I misunderstood.
I'm not sure that I have a straightedge I can trust to be more precise than the less-than-a-millimeter bowing I'm seeing here, but tomorrow I'll take a look through the workshop to see if anything I have seems reliable. I'll also look at whether I want to try the spare bed.
Go to the hardware store and get a piece of glazed tile (the really smooth glossy white kind, usually can get a bunch of different shapes and sizes for bathroom detail). That is as flat a surface as glass, without it bowing when clipped. If you using ABS, then you will need to let the ceramic soak the heat up a bit before running your print.
I've been curious about the advantages of ceramic over glass anyway. Last time I was up in Burlington I almost bought a few at Home Depot but I didn't have the details with me. Will have to next time, though that's a few weeks off.
I thought part of the point of the aluminum over the original wood was to avoid this kind of thing, but I expect I misunderstood.
The bed platform won't cause warping like you're describing.
Ceramic:
Advantages: THICK HEAVY FLAT. It will not bend when it is clipped to something like 1/8" glass will. It has such a high density, it takes awhile to cool down when the print is done, this helps eliminate curling on the edges.
Disadvantages: THICK HEAVY. It takes awhile to heat up. I personally dont have the patience. I need a more powerful heater before I switch to ceramic. It is also much thicker and can cause problems with Z axis setscrew.
You could print a raft over the whole bed and then measure its thickness at different points to get a picture of how it is warped. .
You probably already know this, but be sure to set your nozzle to bed gap and bed warping with everything hot.
Okay, so I got a carpentry framing square across the print bed (no glass) front to back, and am able to slide about two sheets of post-it note underneath it at the center without it catching. When I set the same square across the bed left to right, there's no room to slip a post-it note under it at any point. So I assume that even if my square isn't perfectly rigid and straight-edged, that still shows that there's a difference between the two.
When I do the same test with glass in place with two clips, the bowing is much less pronounced, but still present. I can only just get a single sheet of post-it to slide freely under the center, but none when I set it left to right. Three clips makes no noticeable change.
Think I will try the straightedge test on the spare print bed I have and if it seems to pass better, I'll try installing it. But I also think I'm going to get some of that tile next time I'm in town, either way.
I moved the print head all the way to the back and held the straightedge against the right side rail, and I do see a small amount of bowing there too. There's just a bit more than one sheet of post-it-note thickness I can slip between one end of the straightedge and the rail, if it's snug at the other end of the straightedge (8" long). I see no such bowing on the left rail. So... maybe it's not as simple to fix as I hoped. 
The spare print bed I have does not have any noticeable bowing, according to the same straightedge-and-post-it test, on either the X or Y axis. Still, I hate to use it up if a ceramic tile, which is an upgrade worth considering in its own right, would also resolve the bowing on the print bed. Plus I don't know if that bowing in the rail is more or less important, or how hard it is to replace or repair, so I'm going to hold off on the bed swap for now until I can try the ceramic tile, and/or until I find out more about the rail issue.
(Solidoodle only sells the complete carriage assembly, and at $100 plus shipping, but I'm not sure if that would all have to be replaced or just the rail -- or if there's a way to repair it or work around it -- or whether I'd even be able to manage the replacement and subsequent recalibrations in the first place. Plus, would lawsy's carriage replacements help, if the rail is the problem, even if only to reduce the difficulty or cost of the replacement?)
Looks like one can buy the rail separately here (thanks to 2n2r5 for the pointer) and it seems like it might be within my reach to replace it -- the rail seems much easier to replace than the entire carriage.
Y-rails are a piece of cake to replace. Like 5 minutes.
While you are waiting for a new rod try twisting the bent one 180 degrees and see if it makes a difference. Just Loosen the house clamps and give it a turn. You could also try pulling it out and turning it around. While it is out maybe you could roll it on a piece of glass to spot where the bend is and mark it with a sharpie so you can keep track of it
Ordered that new rail. I wonder if it would be better to rotate the bent one so that it bends up, to cancel out the downward bend in the bed? Or would it be better to face it left or right?
It's good to have an idea what's wrong, and what I can do to fix it. But it's another "just happened to go wrong" thing in the story of this printer, unconnected (so far as I can see) to all the others. In fact, it's two of them at once. Maybe I should fix it, then sell while it's working, as Hazer suggested... (but I suppose this should go into that other thread, though I think that other thread may be beyond its usefulness).
Take it out, and roll it on something super straight. A kitchen counter works well for that. Even if its not perfect, what your looking for becomes obvious when you roll it fast. A wobble. Once you see where the wobble is worst, you roll it slow to mark the high point.
If this is your right side Y rod, this is perfect. You put that mark to face left or right (not up or down). The right side Y carriage has the delrin follower so it does not care if the rod zig-zags left to right. It will have problems when it goes up/down. That is one if the pros of the follower design. Only the left side rail needs to be super straight.
I decided not to fiddle about with rotating the bent rail, and just waited until I could replace it, which I've done.
I also have a sheet of glazed ceramic tile on the platform and heating up now:
Couldn't find anyone who has a wet saw I could use, and couldn't even find the straight-line tile cutters, and it wasn't worth buying either just to do three or four tiles that don't have to be perfect or pretty; so I settled for a hand-held tile cutter:
hence the ragged cuts.
In the past I either had no curl, or a lot, usually on one corner. This time, I had a slight amount of curl, but everywhere. Do I need to run the bed heater on higher or lower when using ceramic? Or I just need to let it sit a while after reaching temperature before printing, but otherwise use the same temperature (I usually use 90)?
Same temp, but ceramic will take alot longer to get hot enough on top before printing. 10 minutes at least.
The good news is that the skipping seems to be gone.
The bad news is that the curling is not solved even by letting the heat soak in for 20 minutes at 90C before starting to print. And it's so bad that the resulting prints are unusable unless small:
Not sure what else to try. This had plenty of hairspray, enclosure in place, nothing else changed other than the ceramic.
Maybe I should go back to glass and see if the rail change is enough with just that.
I briefly tried ceramic, and my distinct impression was that the glaze isn't really all that flat. I have some 220 grit on order, and am going to try grinding 3 tiles against each other (same technique used to make optical flats) to see if I can make the surface really flat and if that will make tile work better (as long as I don't go too far and grind off all the glaze).
What sort of contact does the tile have with the heater? Every tile I looked at had a very rough surface, totally useless for heat transfer. You either need to heat the tile better or test it's temperature another way.
As for 90C ... that seems very low anyway. I set my heater at 115C and give my glass a good amount of time to warm up, and if I'm printing I wont turn off the heater at all for hours, so I can get things as stable as possible in my enclosure.
As for 90C ... that seems very low anyway. I set my heater at 115C and give my glass a good amount of time to warm up, and if I'm printing I wont turn off the heater at all for hours, so I can get things as stable as possible in my enclosure.
Thats actually the recommended temperature for the SD bed by SD themselves, and there is valid arguments to it. Its been gone through before, but basically, you don't need it that hot, and in fact, cranking it hotter, whilst it does outwardly appear to 'fix it' to some extent, is really only plastering over the problem.
You can succesfully print with full adhesion on the SD bed at a mere 90°, and actually get LESS warping, as at the lower tempreatures, as your heater isn't driving as hard on as short a duty cycle, the bed temp *over the surface of the whole bed* is more equal, there is less delta between the thermistor and the bed edges.
At >90°, you will begin developing large 10-25° delta's across the bed surface... at 115, you will certainly be getting 115 at the thermistor, but the bed edges will be down around 90 anyway... meaning that on a LARGE print you will actually get *worse* warping and lifting, as parts of the model cool at vastly different rates to the rest of the model.
Anyway - yes its counter intuitive, but its to do with temp consitency.... have a look at the thermal images I posted months ago to get a better understanding...
Lower Temp == More Even Temp.... More Even Temp == less propensity to warp regardless of model size ...
The much higher temps thrown around for the likes of RepRaps is due to their need to combat 'drafts' that will rapidly cool the bed - so they over compensate. On a Solidoodle - you just stick cardboard on the sides of the frame, problem solved...
Thanks Adrian, thats interesting, and certainly something I will experiment with.
With no actionable ideas or directions on how to address the curl problem with the ceramic, I tried going back to glass, but while the rail has been replaced, the bed still has the warping that makes it impossible to level and calibrate. When I get it leveled so it's the right height at the outer edges, the middle is too low and the plastic won't stick; if I adjust up at that point, anywhere off the middle ends up having layer 2 rub on layer 1, making a mess.
So the next step is switching out the bed with the spare. That'll have to wait for another night, though.
You can try setting a thicker first layer in slic3r to make it more tolerant. I would suggest both the first layer height and the first layer extrusion multiplier.
SoliForum - 3D Printing Community → Help/Repair/Maintenance → Park, home, and Y axis skip problems after E3D install
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