Anet A6 3D printer

Flushed with my success at using Black and the new White I decided to print a Fidget Widget, all went well until I decided to use Red for one of the gears, a new roll, it just won't stick! After changing a variety of settings, including going back to tape on the bed I decided to do a comparison with the filaments that work, I also opened the other 2 rolls of filament that I have, Wood colour and Silver. I changed the heating slightly, took the oven up to 200^oC, then put the test in and waited for the oven heat light to go out. Then opened the door and took the test piece out to cool at room temperature.

All filaments deformed and stuck well, except the Red, which just laid there and looked at me!
Final thickness from the original 1.75mm.
Red, 1.7mm
White, 1.2mm
Black, 1.1mm
Wood, 1.05mm
Silver 1.05mm
I have no doubt that the newly opened filaments will work perfectly, why the Red should deteriorate so badly in it's sealed bag I have no idea, it grieves me to have to throw away another 1kg roll of filament!

Klippy
Are you sure the red is PLA?
For instance ABS only fully melts at a higher temperature, as much as 240C, hence the shrinkage problems when using it on physically larger prints.

How did I get so old and still be so dumb!

You're absolutely right Simon. And the white I had so much trouble with?

Also ABS, a dunces hat for me I think.

I haven't as yet tried the White again, the Red extrudes nicely but doesn't stick.
Being an inveterate fiddler I decided to upgrade things.

This is the new Titan extruder, I'm going to try for a Bowden setup which will take the weight of the steeper motor and feed away from its position on the X carriage. I understand the dead weight affects the print quality.
The Titan extruder allows temperatures of up to 285^oC
This is the old setup.

A lot of this will be moved up to the bridge with a snake to feed the filament down to the Extruder.
The toothed belt in the first picture is glass fibre with a steel core reinforcement to replace the original rubber belts.

I noticed that there was a considerable wait time to heat the bed and the extruder so I'm fitting Mosfet drivers.

I was very worried when I saw the JST socket on the board but, not to worry, everything you need is in the pack.

Mosfets mounted, I had to move the righthand up a little when I realised it was going to interfere with access to the SD card. Since heat will be involved I've used stand offs to keep them away from the support bracket.

Not very tidy at the moment, the supplied wires for power (12volts) are not fit for purpose, the Extruder side is fine, but there is a 1 volt drop in the wiring (all 9" of it) to the bed heater Mosfet, and the wires are warm to touch!

Klippy
Where is the 12V coming from? Is it up to the load?
On my A8 it is the power supply board that is the limiting factor. The extruder cooling fan noticeably slows down when the bed heater cuts in.

It's the drop between where the power goes into the main control board to where it's connected to the Mosfet. Measured at the power pack I get 12.4volts on standby and 12.3volts when both heaters are on. One of the recommended upgrades is to fit a 30amp supply as opposed to the standard 20amp.

I've wired the power from the power pack direct to the bed Mosfet in 2.4mm² multistrand, then from the bed Mosfet to the Extruder Mosfet leaving the other wiring in place to create a 'ring' of power. There's still a drop but what leaves the power pack at 12.3volts arrives everywhere else at 12.15volts, I haven't done any testing but the extruder seems to heat up very quickly The plus side is I no longer have more than 2 spade lugs under each connector screw, 3 or more is never a good idea, they seem to squeeze out.

Well, a test indicates that I have 11.95volts everywhere when heating, except at the power supply which is 12.3volts. The major factor is the Bed, until it kicks in the voltage is 12.35.
The new drive belts are now fitted, they're almost impossible to cut, I eventually had to use a Dremel with a cut off disc! I wonder if it's worth the change, the original belts only stretch by 2mm over their entire length.
I now have to print the goodies to do the Bowden conversion, wish me luck, I'm going to try the Red ABS again since some of the bits are structural.

Klippy
Never had much success with ABS as there is too much shrinkage. It really requires a totally enclosed hot box to keep everything at about 60C until the print is complete so it can then cool down as a complete structure.

I am still on my original belts after 897 hrs printing. I have only tightened them once after about 650 hrs and then only by one tooth.
I can't be sure but from the noise it makes when travelling under power I fear one of the table linear bearings is on the way out.
In addition I have a suspicion one of the Z stepper motors (or its driver) is playing up. It makes a different noise when moving compared to the others but so far it keeps going.
If I ever get a new one a self levelling bed is a must.

Well, after several days of, helping Mary with the ceiling and intermittently fiddling with the Red and White ABS, I've given up trying to use ABS at the moment, I can get it to extrude just fine, what I can't get it to do is stick to the build plate, I've tried temperatures from 40^oC to 100^oC. And now to add insult to injury I find the build plate is now slightly concave! By about 0.2mm. I can only assume that the aluminium heater plate expands slightly more with temperature than the magnetic mat of the PEI plate.
On the power side, the control board draws almost no current but when both heaters are on the current soars to 13.5amps, but there's no sag in the fan speed.

I believe the problem is that although it does stick to the bed well enough for say the first 10 layers where the bed temperature keeps the ABS warm to reduce the cooling contraction but once above that height the filament cools and shrinks much more. This causes the part to bend which is about the most effective way of breaking the bed adhesion as it will tend to 'lift away' from the furthest edge.

If you have a large area in contact with the bed that will resist it lifting off the contraction can be so great after about 25 layers that the head ends up too far from the previous layer so any subsequent printing is not even attached.

That same print worked perfectly in PLA.

Anyway PLA is a much 'greener' being made from plant material rather oil based ABS.

Being a 'greenie' I'm with you, it's just that ABS is stronger and I wanted to use it for the Bowden feed fittings.
Having gone back to the PLA I'm printing just fine, except that I'm concerned about the bend in the bed, luckily it's from corner to corner, NW to SE is flat, NE to SW is quite visible with a straight edge, I estimate 0.2 or0.3mm so I decided to fix it. I've cut one side off a piece of square section aluminium tube.

The irregularly shaped hole in the centre is to miss the thermistor.
And this is what it looks like installed.

Now a 0.05mm shim will not pass anywhere under a straight edge.
I also noticed what could have been a contributing factor, the compression springs hadn't been finished properly.

The wire hasn't been finished off properly

A small modification with a grinder, now the spring will push evenly.

Interesting that they had gone to the trouble to 'close' the end coil of each spring. Its almost as if the final operation had been omitted.

The springs on my A8 are exactly the same (closed but not ground flat) so next time I disassemble the bed I will do exactly the same thing.

Moving on, I had enormous trouble leveling the bed, in the end I had to add washers under the springs to even the pressure applied to the underside of the bed. It's now working nicely and I now have the luxury of printing first time every time.

I probably downloaded the wrong Bowden motor fitting, and I had to fit a 6mm thread into the block.