Started printing with the A5, problems with new firmware and stepper drivers.

Prokktor

Hello,

I got my first printer a few days ago and I hope you can help me with a few problems:

- the bed was assembled with blue tape and metal clamps (maybe instead of glue?) so I left the clamps and tape in place, as I saw in some youtube video was that correct?
- I wanted to calibrate the polulu stepper drivers, but they did not even have potentiometers (attached a picture) I want to upgrade them to tmc2130 anyways but what are those things? nerver saw stepper drivers without a poti

So far I printed with PLA (JGaurora) with 215 C, PLA (Jandex) with 230 C and PETG with 260 C, PLA worked fine, with PETG I only got a nice brim but everything else was simply to cold to stick... (cooling was off)

I read about the community firmware and installed it today, both for the printer and the LCD board. That presented me with new problems instead of solutions:

- the description said that hotend temperatures would be recalibrated, but I still need to print jandex PLA at 230 C thats somewhat strange
- the 4 bed leveling points are much closer to the corners now right on the blue tape and next to the metal clamps thats highly impractical, those new points also move the leveling screws behind the frame so they are next to impossible th reach now... I dont really understand the reasons for that
- the hotend temperatures are are constantly shifting while printing now between +2 C  and -2 C of what they should be. I understand I need to do a pid tuning but why is that necessary since the (mis) calibration of the temperature is exactly the same as before

I hope you can help me a little,

regards

Martin

Samuel Pinches

Hi Martin, welcome to the forum. Thanks for all of that feedback, there are some good points you raise in there. I don’t know that you’ll find any of my answers sufficient, but hopefully they get you in the right direction.


1. The tape is probably good to leave on. The risk is the metal clips cutting through the solder mask on the PCB heater, and causing a short circuit. That is why there are specific marked out places where to put the clips on the heater.

2. Yes. No poteniometer is bizzare. No idea why JGAurora thought that was a good idea. Same chip, they have just hardcoded the vref with a fixed resistor rather than a variable one. Just another of the changes JGAurora have made to the A5 over time.

3. Your nozzle temps sound way too hot. Above 260C is dangerous as PTFE insulation breaks down to release toxic vapours. I recommend buying a thermocouple and measuring your actual nozzle temps. Check the thermistor at the head is making good contact with the heater block.

If the measured temps are still way off, I can guide you through doing a recalibration of the thermistor, once you have a thermocouple meter handy.

4. Yes, I’m sorry, the positioning of the levelling points is far from ideal. You can change this in the mks_config.txt file, the coordinates are set in there. You will then need to reflash the Lcd firmware. If you have some good coordinates that work, let me know and I’ll add it to the next version of the community lcd firmware release.

5. PID variables are different in the community firmware to the original firmware. Doing a PID tuning should help. I would recommend looking into #3 first.

kind regards,
Sam

Prokktor

Thanks a lot for the answers!

I am absolutely sure my Temp readings are at least 10 C off, I know I am not supposed to go beyond 250 C in with the current hot end. (I already ordered some stuff to change that)
I also ordered the thermocouple yesterday, so it should arrive tomorrow, my infrared t. has 200 C max :-(

I saw most of the important videos on youtube, pid tuning and thermocouple calibration where among them. (Yes I can be really crazy when learning new stuff^^)

One last question:
The guides on how to install the tmc2130s seem to deactivate the endswitches for the axes, maybe they use the stall detection of the tcm i dont know. Can I just leave the switches in working order and not use the tcms for that?
(Had really bad experiences with my laser engraver and stall detection, no not ever again^^

regards

Martin

Samuel Pinches

Hi Martin, yes I recommend to keep using the physical end stops. I don’t know that it’s worth bothering with the SPI control just for current adjustment, main advantages of the TMC are just the silent stepping.  The TMC 2208 is also a good option.

Prokktor

Oh thank you I will look into them.
 And I still have another question:
What parts of the hotend are actually temperature sensitive (my goal is nylon so I need to reach 270 C max)?
I already ordered 1m Capricorn high temperature bowden tubing.
(https://www.captubes.com/shop/#!/1-Meter-Low-Friction-Bowden-Tubing/p/82190682/category=23214267)
May that already be enough?

My final step will be a Titan/E3D hotend, but for now I ordered a cheap chinese clone to see if I even get it assembled^^

kind regards,
Martin

Samuel Pinches

For any printing above 255C, you cannot have PTFE in the hot end. Capricorn is still PTFE. They make NO claims that their product is any safer than regular PTFE, please don't be misled!!

You need an all metal hotend, that does not have any PTFE in the heat break. Please see the E3D website for an example of this.

Heater, thermistory, nozzle, etc are all good up to ~280C, it is the PTFE that is the first and most important part to eliminate from the hot zone.

Prokktor

Oh ok I read in some Forum that this can be used for higher temps and they claim it can withstand higher temps than "other tubing"^^ (Here: https://www.captubes.com/specs.html)
If I simply monitor the temperature at the bowden connector and make sure it is below 250C would that be enough? 

Samuel Pinches

Nowhere does the manufacturer make the claim about higher temperatures being safe to print with their product. At the top of that page it says:

WARNING: PRINTING AT HIGH TEMPERATURES MAY CREATE HARMFUL OFF-GASSING

Prokktor

Oh you dont need to scream at me, I am just asking noob questions :-)

I will probably go your way and use mesh bed leveling with a fixed bed which I am going to insulate from below with elastomer tape. (I hope thats a good idea) Util them I will use the 40/270 on the y axis and the custom 20/285 on the Y axis for leveling, so its at least a symetrical cross even if it has no right angles.

Ok back to the temps (no i am really not evil I just want to learn):
There is an Aluminum Rod which has attached to it (from bottom up)
1. A metal object with nozzle, thermistor and heating element, all of them are at nozzle temp
2. some Space
3. A heatsink with an active fan
4. A connecter to a bowden tube

Ah ok I just found the Information myself:
The rod is called throat, it contains a teflon tube, and teflon is just another name for PTFE... so measuring the throat temps at the top does me no good.

So an all metall hotend ist just a hotend without the tube in the throat, which needs more force when the filament is pushed through where the titan (3:1 direct drive) comes into play.

Did I get that right now?

regards and thanks for your patience

Martin

Another change made by JGAurora: My printer is labeled 300W instead of the 350W mentioned in all the reviews, I start to think I got a much cheaper model for the same money than all my predecessors...

Samuel Pinches

haha - sorry! 

You can also buy sheets of cork insulation fairly cheap, I'm not sure what kind of elastomer tape you're thinking of, but as long as it can tolerate 100C it should be fine.

Samuel Pinches

Also, the term "throat" and "heat break" may be used interchangeably in some places.

The problem is the teflon is nice and low-friction. So an all metal heat break will have more friction. For this reason, it requires very high quality machining to make a low friction all metal heat break - and that is why they are so hard to find. I also don't yet know of a source for an all metal heat break for the A5 that matches all the same dimensions.

So yes, a direct drive is a good upgrade to go with an all metal hot end.
Cheers,
Sam

Prokktor

Thank a lot for all your answers, but I just encoutered another problem:

I rewatched Da Hai´s Mesh Bed Leveling Video and the S1 point seems to be on the blue tape and probably even on the metal clamp, that would destroy my nozzle :-(. Is there a way to adjust the mesh bed leveling positions?

Samuel Pinches

Yes, in the firmware configuration.h file, you can set 

#elif ENABLED(MESH_BED_LEVELING)

  //===========================================================================

  //=================================== Mesh ==================================

  //===========================================================================

  #define MESH_INSET 10          // Set Mesh bounds as an inset region of the bed

  #define GRID_MAX_POINTS_X 3    // Don't use more than 7 points per axis, implementation limited.

  #define GRID_MAX_POINTS_Y GRID_MAX_POINTS_X

You can change the mesh inset (unit is mm) to change the border margin on the bed.

Prokktor

Oh great thank you!

Prokktor

@Samuel Pinches

You said you did not know of any throat of the right dimentions.

I just bought:

BIQU Titan Extruder + Nema 17 Stepper Motor + V6 Bowden Extruder Fully Kits For 3D Printer

to check if an E3D Titan will fit.

It came with this throat:


its 26mm and M6

:-)

Samuel Pinches

Oh wow!! the original e3d V6 is actually an M6 + M7 design.


 I think this  BIQU one is a V5 design. Is this all metal, or does this heatbreak have a PTFE liner? Also, how precisely machined is this heatbreak, if it is all metal, is the quality high enough to avoid high friction? If so, it should work.

Prokktor

Ok I will try after the current print job. 
My plan is:
Assemble the Titan with the old heavy JGAurora motor and simply replace the extruder assembly.
Next comes the Capricorn Bowden, cut a little shorter than the original and definitivly more precise.
Then the original hotent, just with the replaced throat.

Yes its all metal.

Erm one more question:
Since I do not have the Meanwell power supply, can I simply use a mosfet with a 12V powersupply (I know i have to exchange the heating element)
They use an optocuppler right?
(I have a large box of 60A + 12V power supplies and rather use them instead of buying new 24V ones.

PS:
Fair warning: This Titan does not seem to be of the highest quality, should you only want the throat dont buy the set and probably get the e3d original^^

Prokktor

Ok. Test ist completed:
Positive:
I got it assembled, everything fits.

Negative:
It does not work^^

The cheap plastic titan slips too much, and even after I increased its strength th JGAurora extruder is also to weak.
The Motor never had problems didnt even get warm, but the grip on the filament is just not strong enough.

No full metal extruder with a bowden^^ (ok maybe a higher quality titan does the trick...)

Prokktor

@Samuel Pinches

This here is the throat alone I think:
https://www.banggood.com/de/1Pc-2-Type-M6X25-Extruder-Accessory-1_75mm-Thread-Nozzle-Throat-For-3D-Printer-p-1031128.html?rmmds=myorder&ID=42257&cur_warehouse=CN

If you want to link it in the wiki.

Strange findings:
I measured the Stepper driver heat sinks while printing.
From Display to Powersupply:
1 50C
2 50C
3 70C
4 60C

Thats strange: The z axis driver that does next to nothing with a 800 stepps/mm translation is hotter than the extruder that pushes filament through the tigher bowden tube I installed...