Mistake?

[onthuhlist]

Beginning to think it was a mistake to pick up a used Cube 3. The auto level works, but not the auto gap. To get the auto level to work, I had to do a fair amount of sanding on the bed. Still has divots which I think may be messing with the auto z-height procedure, but if I sand more the bed won’t be flat. So I had to do manual z height. I read elsewhere on this forum that the z height gauge is .23mm, which is slightly over 2 sheets of paper thick. I think that is too much. So I am using 1 sheet of paper like the Ender 3.

I tried to print the test print with the ABS cartridge that came with the printer. Extrudes fine. Am using Elmers Xtreme glue stick, and after a few layers the cumulative tension in the cooled layers causes the edges to curl like french fries. Then I realized - augh! No heated bed! In my desire to get dual color printing, I got a printer with no heated bed. Even though I plan to print mostly PLA, the heated bed on my Ender 3 is a lifesaver.

So maybe it’s not worth it to mod the printer, if I am gonna have a non-heated bed.

So I guess my immediate question is what “glue” do you need to get ABS to stick? MIG welding the part to the darn bed? (Yeah, I’m frustrated. Sorry. Bad day.)

[TommyDee]

20190414_131630.jpg

This is ABS on Cube3

Your surface needs help. They wear because the magnet holes have air and that expands with heat bubbling the white plastic until it cracks.
Solution: LokBuild. ...and CubeGlue. There are many reasons I do this but the most important one is that it works!
I've used less than 1/2 an ounce of CubeGlue in the last year. I mix it with water and recharge the surface with water. LokBuild is unique in that it retains the glue, unlike the original build surface which gives up the glue too easily.

No heated bed is serious oversight for ABS. PLA doesn't have issues and PETG is a dream to work with.

Gap; too much 'squish' causes adhesion issues. 0.23mm is a very soft touch that I can get away with using the LokBuild and glue. This makes sure the first layer isn't proud of the periphery. The ABS build in the image uses such a method.

20210220_155726.jpg

A recent PETG print. The only adhesion is 4 traces on the bottom lip.

I am not a shill for LokBuild, I just know it works. Not perfectly as advertised but the CubeGlue made up for that in droves.

I am also using this setup in my CubePro. Big sheet of LokBuild and a slathering of glue on the build plate. I never remove the glue. A little wetting of the glue recharges the glue. I've printed ABS parts that crack half way up the part because the base is so well adhered to the build plate. I once made a square ABS fixture about 2-1/2" square on the build plate and it stuck all around. Once I removed it from the build plate, the edges curled right up a little. Less than it would have had it lost adhesion, but it deformed after removal. ABS is just a pain in the drain to work with. However, you can print ABS on supports and remove the bed from the equation.

[onthuhlist]

Thabks TommyDee. If folks like you are passionate about this, it may be worthwhile to persevere. I need to redo my Ender 3 bed also so maybe I can kill 2 birds with 1 stone.

[dougk12]

As a rule, I never trust the auto z-gap. It only aligns from the print head assembly to the plate and the issue is that the print tip lengths vary enough to make a difference. .05mm is enough of a difference between just right and too little/much z-gap.

I confirm it manually with the OEM z-gap "gauge" or a piece of paper that is also .1 mm thick. I track the z-gap on a sticky note so I can make slight adjustments easily. It's also handy if I fire off the occasional calibration function and forget to cancel when it gets to the z-gap part. I own more than one of these and it is quite handy on the rare occasion that I need to investigate a string of print failures. A few test print files and adjustments later, I am back to perfect z-gap again.

I was kind of excited to do a DIY heated bed based off of the instructions linked here but the above solution is starting to sound better and better.

[onthuhlist]

Thanks guys. I just had an idea; I tend to use 3D-Fuel Pro PLA most of the time anyway. It has some ABS-like properties without the fumes, and I often extrude it at 220-230 deg C. Does anyone know the Cube 3’s print temp for ABS? If comparable I might be able to print Pro PLA using the ABS filament chip as is, without having to find another PLA chip. Although the Pro PLA also does better with a heated bed.

[TommyDee]

As a tip, the auto-Z is based on your maintenance gap setting. The closer the default setting is, the more accurate auto-gap works. I don't use auto-gap as I have the default gap set very wide for glass beds. This avoids driving the glass plate into the nozzle accidentally. Menu:Setup|Calibrate|Auto Gap

[dougk12]

That is very interesting to me because I’ve never understood what that setting did. Do I understand correctly? The higher the setting, the wider the actual checks during z gap function? Smallest setting would only check center of plate and highest would go to edges?

[TommyDee]

Try this Doug... Set a wide gap in the maintenance panel and then auto-gap. This should maintain the gap set in maintenance.

Considering I always manually gap in the end, where auto-gap lands doesn't matter. Probably saved a glass plate at least once.

[onthuhlist]

As a tip, the auto-Z is based on your maintenance gap setting. The closer the default setting is, the more accurate auto-gap works. I don't use auto-gap as I have the default gap set very wide for glass beds. This avoids driving the glass plate into the nozzle accidentally. Menu:Setup|Calibrate|Auto Gap

So now I have a slough of questions for you.
1. Do I understand correctly that you have the default gap so wide that you cannot auto-level your plate? Or is it close enough to auto level? 2. To manually set the gap do you use the manual z height calibrate function with a sheet of paper? 3. Where did you get a glass bed for the Cube 3? 4. I though you were using Lokbuild surface? Are you using this on top of a glass plate?

[TommyDee]

LOL thanks for all the great questions onthuhlist.

Gap and level are independent from what I can tell. I do not use AutoLevel. I actually went through a long process to dial it out. See this - http://www.print3dforum.com/showthread.php/1165-Z-ticks

I do manually set the gap. I only have to do this when I change tips. Very rare thing to do with the bowden tube upgrades over the stock setup.
I use a very light touch gap.

eBay for the glass - glue magnets underneath - I used ShoeGoo so you could remove the magnets if desired.
https://www.ebay.com/itm/170mm-x-170...D/332155620354

PETG will pit b-glass. I have LokBuild on one of my glass plates. I don't have much use for these glass plates but they are good solid spares, probably flatter than the stock plates.