i3 Suddenly OverExtruding: ideas?

[clough42]

The test with the bed screws out Gave the same results.

I ran a test with the indicator on the metal rods, and they showed no movement at all, so it's probably the wood warping.

I'll run one more test with the indicator on the wood itself to confirm.

[abuharsky]

I have the same problem with wooden Y carriage warping, but after 20mins of heating - all ok. I think,this is due to the use of insulator made of cardboard.

I want to try aluminium Y carriage .

So, calculated linear expansion for aluminium carriage with 210mm width and 100C temp:

ΔL = a * L * Δt = 22 * 10 ^ -6 * 210mm * (100C - 20C) = 0,36mm - which is almost 0.1% of the original length.

[clough42]

I ran another test with the dial indicator on the wood itself, the heat bed attached with only one screw. I get the same results, so it's definitely the wood warping as it heats--first downward as the top surface heats, and later upward as the heat soaks through.

An aluminum bed mount is probably the right solution. It will expand slightly along the long axes, but it should stay flat, since it will heat evenly, being a conductor. With sufficient insulation, I expect it won't heat that much anyway, since it should dump most of the heat to the air.

Note that this doesn't seem to affect the i3v very much at all--just the i3. The left side of the bed has only one bearing, and it's way back in the center of the bed. This amplifies any warping significantly. With the i3v, the wheels are way out at the edges, and this seems to help significantly--at least in the 8" version. I don't see any of the compression effects at all in my 8" i3v. My 12" is still in pieces.

[clough42]

One more note: I spoke with Colin briefly about this, and he told me that the warping cases he has seen are due to lack of insulation or painting the bed mount. All of mine are lacquered, so I can't say what it would be like otherwise.

[TopJimmyCooks]

My 8" bed is unpainted except for about 3/4" around the edges, and insulated with 1/4" cork tile, with the heater board on the original bolts and springs ( one nylon spacer at the home corner). I have noticed a very similar problem recently at the front edges of the bed, with ABS/110deg bed setting. I haven't done any precise measurement although I could. My main indication is that an abs print of the same stl and otherwise same slice besides the different material profile, shows the issue and pla does not.

Looks to be aluminum bed frame time. Anybody selling a good one?

[clough42]

Yeah...I went back and looked at a bunch of parts in my scrap bin and many old ABS parts show these effects. PLA prints are completely smooth top to bottom.

[TopJimmyCooks]

anybody tried the 8" aluminum plate Colin is selling?

http://www.makerfarm.com/index.php/build-plate.html

[sniffle]

you arent the only one... 12" beds have had this problem since day 1... its gotten a bit ridiculous honestly. I have an aluminium sheet to replace the carriage, jsut haven;t gotten around to fixing it yet.

[clough42]

anybody tried the 8" aluminum plate Colin is selling?

http://www.makerfarm.com/index.php/build-plate.html

Huh. I knew that was coming, but it's not at all what I was expecting. I was thinking skeletonized 1/4" plate. I guess I'm not sure how this works. It won't fit the i3, and the hills aren't in the right place fur the i3v wheels, are they?

In any case, I'm transplanting my 8" i3 electronics into a 12" i3v frame, so I'll get to experience all the fun issues with that.

[WatsonGravy]

Interesting.. I'm currently having similar "over extruding" issues with my 12" i3v. I have been losing my mind trying to get this thing dialed in the last few days, back and forth with e-steps, z calibration, extrusion multiplier... on and on.

You now have me convinced my bed is warping as well... i will be watching this to see the outcome.

5 hour prints failing because of the extruder hitting filament build up is testing my 3d printing patience!