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Why does my print have tiny zebra stripes?

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Posted · Why does my print have tiny zebra stripes?
Here is my print (#27 btw)
:D Thats a long time printing, lol.

Just curious, for those who have printed that boat, how long were the print times usually?

I have Cura set at 50mm/s Main Print speed, all else left calculated, .25mm Layer Height, 5% line infill, and Cura is calculating an Hour to print this thing.

Does that sound normal? Im just getting into printing, and I have yet to grasp the size of the object/ print time relation ship. Some of the items I put on the bed, Cura calculates 12Hours to print. I never print it because it takes to long.

What are some print times you guys get with this boat?

Also this discussion was very informative, and I also suffer from this Automatic Mixed decay issue.

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Posted · Why does my print have tiny zebra stripes?

Print times can be discussed in a different topic. But it depends on your printer. Some can print faster then others. You will quickly learn printing is not a fast process. Just start your long print before bed then when you get up it will nearly be done and it won't feel like it took so long :p

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Posted · Why does my print have tiny zebra stripes?

An hour is kind of fast. 50mm/sec at .25mm layer height with a .4mm nozzle - multiply those 3 numbers and you get 5mm^3/sec. That's pushing it a bit. I don't like to go that fast. Try 30mm/sec with .2mm layers if you want it to look better. If you are really in a rush use a .6mm nozzle and .3mm layers at 30mm/sec.

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Posted (edited) · Why does my print have tiny zebra stripes?

Found this while searching other stuff

Seems it plugs between the motors and interpolates the steps removing the zebra.

Will order 4 and test!

https://m.imgur.com/gallery/uRF3s

In theory if it interpolates the steppers might have less torque... Will take a month to arrive so.. More soon-ish

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Posted · Why does my print have tiny zebra stripes?

Here is the link to the guy who came up with this.

hwttp://www.engineerination.com/2015/02/drv8825-missing-steps.html?m=1

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Posted · Why does my print have tiny zebra stripes?

That looks like it gives the same results as shorting out that resistor to ground.

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Posted (edited) · Why does my print have tiny zebra stripes?

It does work indeed!

Poated the whole before/after on my twitter account.

Clearly this needs more tests, some thermal photos on the steppers after a few hours use (because they seem to get hotter). So if you plan to use this, buy also some stepper chips heat sinks (hyper cheap and easy to install).

So yeah, a nice 8€ fix. Ofc there's an almost invisible remaining zebra on some angles, but to remove that most probably one would need to move to a better stepper chip like duet3d, replicape or wait a few years until UM makes a new board (because boards don't pop out of thin airs and that needs time to be developed I suppose).

Warning

I take zero responsibility if anyone gets his board damaged, or if their version doesn't work. I don't sell nor promote this stuff. I just found it, bought it and share my results.

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Posted · Why does my print have tiny zebra stripes?

can you add the details and photos of the installation and fitting including the chip heatsinks etc. :-)

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Posted · Why does my print have tiny zebra stripes?

can you add the details and photos of the installation and fitting including the chip heatsinks etc. :-)

I would love to but very very little time lately.

Heat sinks are just very easy and they should have a ready sticker. You just place it over the stepper chip and done. I bought them year+ ago on a shop in spain.

The TL-Smooth are easy to install they come with a cable that also fits the um2 board, so you only need to watch that the cables are in the correct order (they warn that on their aliexpress) and plug the P2 to the extender they sent and plug the motor to the P1 side (this is on the diagram they have on the aliexpress that probably was ripoff from the creator of the idea).

So. Complex? Not at all. They even include a plastic to hold the thigy so they don't touch an conductive part. I think they are heat sinking plastics for what I seen on their photos.

I will try my best to do a very short video of the install this weekend. But it's really straightforward (except the part to unclip the cables if they are wrong, and twist the pairs).

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Posted · Why does my print have tiny zebra stripes?

Nice, if this saves me any risk compared to bricking my board with solder, then ill give it a go!

A little list of all the things I need would be great. But again, if and when you have time, I know things can get busy in life!

M

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Posted (edited) · Why does my print have tiny zebra stripes?

Basic and most important step before plugging the TL-Smooth things

The rest is just very easy, remove the motor cable, plug it on the P1 and plug the extended cable from the P2 to the board. Also a very visual guide for anyone that ever wondered how to reverse the motor cable pairs :D

Enjoy the music :p It's 02.00 of the night and I was really tired to find a music XD

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Posted · Why does my print have tiny zebra stripes?

Thanks dude Hope its all good for the UM2 as thats all I got!

You make me want to do more vids!! I have some time soon! it will be my turn ;)

M

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Posted · Why does my print have tiny zebra stripes?

I got mine also some time ago and was able to test them yesterday, they work pretty well.

Even when only used for X and Y, so i have two spare for one of my other printers as well :D

tlsmoother.thumb.jpg.a06009fda8c0d32847d9d97f800098d5.jpg

Probably UM should add them to their store for upgrading all their UM`s one to three :D

sincerly Chri

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Posted · Why does my print have tiny zebra stripes?

Just installed the TL-Smoothers on my UM2go+ on all 4 steppers it seems it halves the effect of zebra stripes. A nice improvement and I think it's worth it.

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Posted (edited) · Why does my print have tiny zebra stripes?

I finally decided to figure out why my UMO Z stepper has often stuttered when homing for a new print, requiring a power-off reset (an annoyance that I've lived with for over five years now). The short of my investigation (swapping drivers around) is my Z "Ultisputter" has always been defective! Looking on the bright side (an excuse to upgrade), I just ordered a new set of five Pololu DRV8825-based drivers. I figured they would be an improvement over my 4983-based drivers, but now I'm not so sure.

After much online study, the zebra stripes seem to be most common with 8825 drivers and the diodes might be the only way to mitigate the problem. Also looking at the datasheets for the 4983, 4988, and 8225 chips, only the 4988 offers a 100% mixed decay mode (mixed decay is active for both rising and falling currents), which is what you're getting when you tie ROSC to ground. This configuration is reported here as a good one for the UMO/2/2+.

I can't find a schematic for my old 4883-based Ultistepper and I'd like to know to know what value of ROSC was used. I'm not too keen on trying to probe the tiny board to find out (and I can't read the old and faded values on the old components either). Regardless, if the chosen ROSC is the usual 10k, my Ultisteppers are running the typically too short Toff timing.

At least the 8225 offers a mixed decay mode, but it lacks the 100% (rising AND falling current) mixed decay mode that only the 4988 offers with a grounded ROSC configuration.

You can download all the datasheets from Pololu. I'm an electrical engineer but have never bothered to study stopper motor control. Now I realize it's quite a critical but sometimes demanding design task!

From the 4988 data sheet:

For some applications where microstepping at very low speeds is necessary, the lack of back EMF in the winding causes the current to increase in the load quickly, resulting in missed steps. This is shown in Figure 2. By pulling the ROSC pin to ground, mixed decay is set to be active 100% of the time, for both rising and falling currents, and prevents missed steps as shown in Figure 3.

So maybe I'd better order a set of 4988-based StepSticks too. They're cheap!

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Posted · Why does my print have tiny zebra stripes?

Im gonna get me some! which ones would I need for the um2?

Could you possibly post a link?

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Posted · Why does my print have tiny zebra stripes?

Im gonna get me some! which ones would I need for the um2?

Could you possibly post a link?

You can't change the stepper driver on UM2. Only the old UM0.

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Posted · Why does my print have tiny zebra stripes?

Can you not purchase the TL-smoothers for the UM2? if not thats my hopes and dreams dashed!

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Posted (edited) · Why does my print have tiny zebra stripes?

Can you not purchase the TL-smoothers for the UM2? if not thats my hopes and dreams dashed!

 

The tl-smooth plugs between the motor and the already installed old chips of um2/um2+/um3 boards. So yea you can install that man. They are cheap as chips. Just buy them on the seller at aliexpress.

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Posted · Why does my print have tiny zebra stripes?

Im gonna get me some! which ones would I need for the um2?

Could you possibly post a link?

 

 

Can you not purchase the TL-smoothers for the UM2? if not thats my hopes and dreams dashed!

 

Yes. They may be your best bet, if you don't wish to modify your existing stepper motor cables with diodes yourself. You can also buy them here:

https://thegr5store.com/store/index.php/umo/tl-smoother-removes-zebra-stripes.html

On the other hand, different diodes or trying multiple diodes in series (depending on the diode's forward voltage drop) might yield different results, if you choose to modify your cables yourself.

From

https://www.reddit.com/r/3Dprinting/comments/5kful2/so_ive_recently_discovered_that_missing_steps/

The whole point of this board is to introduce a slight voltage drop into the wires, to compensate for using low-voltage steppers with a too high supply voltage. The S3G diodes have a slightly higher voltage drop, so if you were to use 1N5404's you'd need to replace each S3G diode with 2 1N5404's in series. They ripped this board/idea/concept off from Schrodinger Z who went with the 2 1N5404's route.

In the end and for his DRV8825 controllers, Schrodinger Z used two 1N5404 in series for each direction, but he did try a single diode for each direction first:

http://www.engineerination.com/2015/02/drv8825-missing-steps.html?m=1

1N5404 to 1N5408 diodes should all work about the same.

I've studied the 4983, 4988, and 8825 datasheets and they all work slightly differently WRT mixed decay mode so your mileage may vary with various corrective actions. I don't know which controller the UM2 uses but, if it's a 4988, it would certainly be worth trying to ground the ROSC pin (either with a jumper to ground or by just bypassing an existing pull down resistor, if present, with a small "blue wire"), if you can handle the fine soldering job required. Unfortunately, if the controller is integrated onto the UM2 board, a lot more is at risk during such a mod than when hacking a cheap and replaceable "StepStick" or other Chinese controller board! If you're uncomfortable with it, then go with the diodes or commercial TL- Smoother diode modules.

I have a set of Pololu 8825 drivers and a set of StepStick 4988 drivers ordered for my UM0. I plan to try diodes on both controllers and also a grounded ROSC configuration on the 4988s.

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Posted · Why does my print have tiny zebra stripes?

It all sounds too complex for me I think. Ive even ditched the Olson block and gone back to OEM. So ill just stick to what I know for now I think cheers for all the information. I am still interested but only when i get a new printer will I risk bricking this one! And it really should have been integrated by now!!! this stepper issue has been known for a long time!

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Posted (edited) · Why does my print have tiny zebra stripes?

My StepStick 4988 drivers arrived from RepRap Champion today and they arrived with a big surprise, which might provide another option for those who would rather not rework their PCB in order to ground the 4988 ROSC pin to enable mixed decay mode on both rising and falling portions of the current waveform. The big surpise was the PBs are green instead of red! No--just kidding (though the boards ARE green instead of "StepStick Red," as pictured on the RepRap Champion website but the layout is obviously still a StepStick).

No--the big surprise was that ROSC is already grounded, because the R4 component on the board is populated with a zero ohm resistor. Yippee! My aging eyes are spared from the board rework!

Before I installed the new drivers, I measured my driver boards' Vrefs, as set by the Ultimaking, Ltd. Ultistepper manufacturer, and found them to be set from around 0.66 V to 0.68 V, which translates to 1.65 A to 1.70 A. According to the Pololu website, 1.7 A is the limit for the SY42STH38-1684A stepper motors so my UMO was set to run the steppers right up at maximum current.

Even though the RepRap Champion website says their StepSticks can be adjusted for up to 2 A, I found that the highest I could set the Vref to be around 1.2 V to 1.3  V, depending on the board, before the wiper adjuster on the pot would max out (full clockwise) and drop Vref to zero volts, requiring me to back off the pot a touch. Given that my StepSticks use 0.1 ohm sense resistors (rather than the Ultistepper's 0.05 ohms), the maximum current setting for the RepRap Champion StepSticks is (in theory) 1.5 A to 1.625 A. I set them as high as possible and the slightly lower current (again, in theory) doesn't appear to affect the operation of my machine. I haven't printed anything yet but my stuttering Z stage is still gone too, which is what motivated this upgrade in the first place.

RepRap Champion shipped the SpeedSticks incredibly fast (I ordered them Friday night and received them Monday from clear across the U.S.) so I still have a set of Pololu 8825 boards coming from elsewhere to try too. I'll let everyone here know if my occasional light zebra stripes change (hopefully for the better).

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Posted · Why does my print have tiny zebra stripes?

It all sounds too complex for me I think. Ive even ditched the Olson block and gone back to OEM. So ill just stick to what I know for now I think cheers for all the information. I am still interested but only when i get a new printer will I risk bricking this one! And it really should have been integrated by now!!! this stepper issue has been known for a long time!

@gr5 sells the TL-Smoothers in his webshop. If you asked him nicely he could make sure all the cables are wired up correctly so all you need to do is plug them in which is very simple.

But agree this should have been fixed by now.

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