New Tevo Tarantula with Chimera head, "issues"

First, the details:
Newly build Tevo Tarantula (boatloads up upgrades installed).
Chimera clone (gift from son)
Using stock MKS board.
Marlin 1.1.8 with suggested two-headed configuration.h settings
Simplify3D 4.0

Built and tested using Pronterface and the S3D connection page.
So, I know both extruders work, both E0 and E1 heaters and thermistors work (maybe, see later)
All the mechanical stuff works.
I have been able to print with E0.

Now the main problem.
Sometimes when I am heating the second "head", the first one suddenly says it is 358C! It doesn't just go high, it goes right to 358, every time.
When this happens it appears like commands that were supposed to be controlling the E1 now control E0.
There may be other weird things too, but these are the key ones that I see.
I don't seem to have any connection issues, when I disconnect the E0 thermistor, the temperature goes to -6, not 358, so that doesn't seem to be it. And besides, I have checked E0 when it was saying that it is 358, it is not heated up, so this is clearly a bogus measurement, from somewhere...

Is this a Marlin bug? Did I set something wrong? I have attached my config.h file should anyone be inclined to look at it. I think that I have it all just fine, but something is truly running amok.

All ideas welcome, I am head-scratching...
DLC

On my 3D Printer when I get a reading of -14 the thermister is open
when I get a reading of 358 the thermister is shorted

Quote
Roberts_Clif
On my 3D Printer when I get a reading of -14 the thermister is open
when I get a reading of 358 the thermister is shorted

I have never had that happened. It looks like I need to replace that thermistor.
Onward.

Now if I can figure out why the gcode from S3D chooses the wrong extruder.

Thanks,
DLC

It could be a bad thermister or the wires on the thermister are shorting.

Quote
Roberts_Clif
It could be a bad thermister or the wires on the thermister are shorting.

Either one is bad, and worse when intermittant. Usually the problem is a press-down screw being too tight and crushing the insulation. I have a LOT of these type thermistors, so I cut wires, connectorized that thermistor and replaced it. As things fail I tend to put connectors close to the head because it is a task to remove a wire from the head all the way back to the board through zip ties and spiral wrap wire dressing!

After this I got through some of a print before discovering that they cheap knock-off Chimera has one nozzle that is lower than the other. No print will work with that setup!

Back to the wrenches...

DLC

I have many times done this, cut the wires about 2-3inches from the thermister and splice in a replacement.
Using shrink tubing to cover the splice.

I have changed my spiral wrap wire dressing, with a 3D Printed chain made it easier to replace the thermister although it is still not an easy task..

Edited 2 time(s). Last edit at 06/11/2018 07:20AM by Roberts_Clif.

Quote
Roberts_Clif
I have many times done this, cut the wires about 2-3inches from the thermister and splice in a replacement.
Using shrink tubing to cover the splice.

I have changed my spiral wrap wire dressing, with a 3D Printed chain made it easier to replace the thermister although it is still not an easy task..

I am using the Thingirob modular X-car for my X carriage. I'll have to re-mix a chain drag to fit that one, and while it is aesthetically pleasing, I doubt its value, it increases the amount of wire needed for my build and . Regardless, a new thermistor and all is running fine.

Now if I can just get the Chimera clone head to make a decent print...

thanks,
DLC

I have finally gotten this thing dialed in about as well as I think that it is possible with my current setup. My nozzles would jam frequently, and I did some investigation and found that the fan on the heat sink is LAUGHABLE. Far too weak and puny for the job. The heat sink gets HOT, not warm, not a little hot, but HOT. I tried lots of different things and some are not possible because the the "Fang" part cooler that I am using. The one upgrade that does appear to work is to double up 30mm fans. This shot:

Shows How I did it. I now get pretty decent prints. I STILL cannot get the nozzle exactly the same height, the left one is always a little bit lower. But, still not bad, here are a few of my recent prints. The dinosaur is a jointed print-in-place and came off the bed articulating just fine.


I am feeling better about the work that I have into this.
DLC

I see you got your Tevo Tarantula Printing. Good Show!

Now the hard part learning all the little secrets of how to get that perfect print. Just kidding you will have lots of fun learning the rest.

---

Computer Programmer / Electronics Technician

Quote
Roberts_Clif
I see you got your Tevo Tarantula Printing. Good Show!

Now the hard part learning all the little secrets of how to get that perfect print. Just kidding you will have lots of fun learning the rest.

I am thrilled because I am getting two color prints to come out. I would never be happy with the print quality that I am getting on a single Head printer. I have to tune each head to give a good print now.

Oh yeah, good times...
DLC

I think they look good for your first color print..

What filament are you using?
Post your slicer settings, It appears that you could some help fine tuning the settings..

It appears you already have a good Slicer ("Simplify3D 4.0")

---

Computer Programmer / Electronics Technician

Quote
Roberts_Clif
I think they look good for your first color print..

What filament are you using?
Post your slicer settings, It appears that you could some help fine tuning the settings..

It appears you already have a good Slicer ("Simplify3D 4.0")

I have Chimera clone mounted to a Tarantula X-carriage carrier for this X-carr (https://www.thingiverse.com/thing:1438795)
I spent a couple of hours fiddling to level the heads by putting standoffs on the Chimera so I had access to the grub screws on the back of the heat sink while the head is attached to the printer. That was "kind of" successful and I think that I can improve on that. I wish that I could find a heat sink that puts the grub screws on the SIDE of the heat sink. This one is an idiotic design. The X carriage is remarkably consistent and the height on the left and right are dead-on with each other. I have a custom Z-min setup that is easy to adjust as well. The Tarantula is very smooth and quiet when moving - Not at all like the racket that Delta's make when printing.

Yes, I use Simplify3D. Merging two two stl files for dual printing is stupid simple with S3D. Here are my slicer specifics:

eSun PLA+
Temperatures
Bed temperature 60C or 0C on blue tape. Sticks a little better when 60C.
Filament temperature 225C

Speeds
Base: 60mm/s
Infill: 60% speed
Walls: 60% speed
Reduce speed for layers <20 seconds

Cooling I use a Thingiverse: [www.thingiverse.com] dual fang part cooler with 40mm fan.
Layer 1: 0
Layer 2+: 60%
Increase speed for layers <20 seconds

Ooze shield with both extruders, one wall thick that is 3mm away from the part. I put a 6 wall brim on it to keep it in place
3mm retraction
0.3mm Z-hop with retraction
40mm/s retraction rate
12mm retraction on tool change
.5mm coast at end of layer

I still have smearing on the faces, probably because I cannot get perfect head alignment. It is close right now, but no biscuit! I think that the walls are pretty rough, I wonder if this is a function of positional repeatability between part changes.
I am going to increase my Z-hop to see if that helps avoid smearing the left head over the surface that the right head is printing. I seem to get more nozzle "drool" from the left extruder than the right one, I wonder if the thermistor is not accurate on that one and I should reduce the temperature even though it is the same PLA+ manufacturer.

I knew this would be a long learning curve to perfect a two head setup.. And the first one is always the most "interesting".

Thanks!
DLC

Edited 2 time(s). Last edit at 07/09/2018 04:32PM by dlc60.