a dead 3d printer i found on gumtree. Rebrain buildlog

Some progress.
In testing I've only wired up the z stepper. Both on pronterface and the control screen the stepper moves but very erratically. It will move in the direction I want but then will move back, or sometimes even go the wrong way and stutter.
Ive tried changing the sensorless homing sensitivity and the changing the stepper motor 4 pin wirings (the 6 to 4 pin wires are swapped on some printers).

I cant deactivate sensorless homing unless I cut a pin off the tmc2209 which I dont want to do (yet).

This is the pinout I used - I also tried reversing the outside pins

Reading thru the config files on marlin to see if there is another setting causing this. Hopefully this weekend I can get this sussed

 

yea ok ok - so heres the deal with motors

no.1 u can actually find each pair of cables by shorting out the 2 pins and if the motor doesnt spin freely and has some resistance- youve found a coil pair-,
(dont move it too fast , because if you do the sparks can actually damage the internals, this is how you generate electricity )
doesnt matter if u swap coil pairs the only thing that happens is the motor direciton changes- u can change it back in firmware or just sawp the cables again
- or literally flip the connector

no.2
also- for Z- what ive found is good instead of having (if u have dual Z) going in series instead of parallel is wayyyyy smoother for motion less interference,
microstepping doesnt get skipped so you get that nice nice z-moves ur stepper controller might run marginally hotter though

 

That's really a driver level issue, have you got access to jumpers to change the microstepping?

Also check your wiring is physically intact - maybe swap the stepper cable / stepper motor if you can to rule out an issue

 

nah the vibrating motor that changes random direction is 100% incorrect coil pairs wired up to 1a1b2a2b

by default u should be running 1/16 microstepping- and make sure ur connectors are good-, as shadowburger said it cant hurt double checking

 

Thanks guys.
I did try using the cable on x stepper and it did the same stuttering, so that rules out the motors.
I will try making up another cable and retesting- because ive only got jst connectors(not dupont) i cant just flip them.
Do you think the motor cable pinout in my post above is correct?

Maybe one of the contacts isnt crimped correctly, so one coil is doing nothing- I will test tonight.

 

did u try finding the coils using my technique described where you short out two of the pins and turn the motor- and find the pair by finding the ones that cause the motor to brake or "harder to turn"

because im 99.9% sure you just need to swap around the wires on the connector

 

says here 2b2a1a1b that means its phase2 and phase 1

1 and 2 are the phases, and A and B are the (+) and (-)

mate the pairs using the shorting technique, and if the directions wrong or not working, flip the wire on one of the pairs. or flip the whole connector/plug

if this isnt the issue- IT might be too little or toomuch power from the potenteometer/firmware- Or maybe a UART issue- But i doubt that- Out of the box usually even the chineese arn't sadistic enough to over/under amp your motors

however i highly sugest you fine tune them for your application- meaning strong enough to move things but weak enough not to overheat the stepsticks or the motors

you can get weak vibration or weird noises occurring when you under power- and u can get loud violent juddering if u over power chances of you actually breaking the motor are slim- the stepstick on the otherhand...

i suggest you experiment with this just so you understand the characteristics of motors/powering them with steppsticks

 

Thankyou! I have x and y working smooth and quietly now. I must have the pins wrong and when I flipped them the were wrong again but in a different way(my above internet pinout diag is wrong). Your explanation helped
atm Z is smooth but weirdly seems to move far too much---ie 1mm on pronterface is about 10mm. I'll hopefully have some time tomorrow to play with the settings and re-connector the rest of the wires(and test the heaters!)

 

steps-per-mm value in firmware?

 

Yeah, i changed 1 setting but missed another(or 10 settings ).
X, y and z smooth now.

Just got the bed hooked up and it heated up perfectly, the mosfet only got warm and the pc psu handled it well.

Tomorrow will be the cables for the fans, hotend temp, hotend to mosfet.
Im not sure if sensorless homing is working, and i think i need to wire and setup the endstop for z(x and y hopefully will use sensorless)


Then to understand marlins bedlevelling and a few now nondiscovered mystery software/firmware issues.

Then hopefully a small print.. much excite

 

It lives!


Not pretty with its guts all over the table, but first test print very quite

 

that is properly amazing man congrats!!!
now u need to print a nice enclosure for it all!

very nice benchy* indeed!


if u can mount everything to the printer itl make it way easier to transport- i hate having two boxes for one printer

 

Thanks so much for your help - it was very cool to see that first print work perfectly.
The prints look very good, considering its still a work in progress(and i was using the wrong nozzle settings 0.6 and it was 0.4).

I would like the psu and box mounted on the printer or even give the printer sturdy legs and put the electronics underneath, as i think it would look neater and use much less bench space.

3d is new to me, i'm finding the tech very cool ie slicer settings with infill calcs etc
So much to learn.

Thinking the next print will be a box i found that fits the skr board, 2 mosfets and has a 120mm fan blowing down. Simple but functional. If i stay with the atx psu, i may keep it external

 

atx psu is nice n quiet n safe
no mains exposed.. size sucks tho

 

So... Printer working well but the magnetic print bed had damage in the middle. So not wanting to wait for a replacement to arrive for china i bought a glass cutting board from a discount shop. Then traced around it, then used the angle grinder with diamond wheel to cut it:

Shattered into a million pieces. On the first touch of the grinder.

Then i found bunnings selling large magnetic sheet for signs. I thought 'it gets hot in the sun so the print bed will be fine'.


And yes the heat made it go wriggley and completely useless.

So.. I did these retarded things because im impatient.

 

If you want some basic things to happen in short order using something from a local store then just get some blue tape.

Otherwise recommend steel sheet.

 

i had the same issue with glass- youre supposed to use proper glass cutters but even then if u dont score it right it shatters

 

All you have to is go to your local glazer and get them to cut 3 mm glass to the size of your Printer bed. I just ring up put my order in and pickup same day and it’s cheap, no need to order OS.

 

Probably tempered glass, can't cut that.
Your local glazier will have 3mm glass which they will cut to size and bevel the edges for a reasonable price.

 

I hope your all safe and using 'world virus condition' as an excuse to tinker at home.

Thanks for the bed advice.. currently im using glass from a $4 picture frame.
Adhesion is tricker now, glue stick works too well and hairspray does not work well enough.

I did have a issue, the tmc2209 driver running Y started doing very strange things ie grinding the stepper and only moving in 1 direction. Lucky i had a spare.

Printed the box in 9.5hrs using a .8mm nozzle, it came out great!

Cable management was difficult, but got there in the end (except the multi psu cables)


The lid didnt print perfect but good enough. RGB because its the only spare fan i have.


Future ideas are:
printing a mount for the screen
Dual z upgrade
Threaded rod brace
All metal hot end
Mounting the whole printer on chunky ali channel and hiding the new box and psu underneath.