Speeds / Config

So after assembling a CoreXY kit, I'm in the process of trying to dial in the speeds and some of my numbers don't seem to make complete sense so I'm curious to know what configuration for slic3r other people are using for speeds for the CoreXY designs.

Right now, I'm still trying to get it to travel without the decel skipping steps and going "clunk" at the end of the travel, but currently I have the following in my Marlin config:

#define DEFAULT_AXIS_STEPS_PER_UNIT   {160,160,160,290}  // GT2 Belts with 1/32 step count, MK8 extruder
#define DEFAULT_MAX_FEEDRATE          {500, 500, 70, 50}    // (mm/sec)
#define DEFAULT_MAX_ACCELERATION      {7000,7000,2000,10000}    // X, Y, Z, E maximum start speed for accelerated moves.

#define DEFAULT_ACCELERATION          900    // X, Y, Z and E max acceleration in mm/s^2 for printing moves
#define DEFAULT_RETRACT_ACCELERATION  3000   // X, Y, Z and E max acceleration in mm/s^2 for retracts

// The speed change that does not require acceleration (i.e. the software might assume it can be done instantaneously)
#define DEFAULT_XYJERK                20.0    // (mm/sec)
#define DEFAULT_ZJERK                 10.0     // (mm/sec)
#define DEFAULT_EJERK                 5.0    // (mm/sec)

The DEFAULT_MAX_ACCELERATION for 7000 was established with trial and error moving with G1 X10 Y180 F7000 commands before it stopped going clunk on those commands. But every now and again it will go clunk during a print on a travel move a lot smaller of distance. And DEFAULT_ACCELERATION was established during a print until it stopped going "clunk" using the LCD to manipulate this on the fly.

I've been trying to use the default speeds in a slic3r for the moment, and it works (sort of) but with my bowden setup I would think unless I'm into a processing limit in the Arduino Mega it should be capable of going much faster still. And it doesn't seem to make a difference on the "clunk" when I mess with XY jerk.

The kit had 17HS3001-20B for motors, but I have a few 17HS16-2004S1 motors on hand that makes me wonder if it'll will increase speeds or make much of a difference.

Hi,

check the nexts videos:
[www.youtube.com]
[www.youtube.com]

I do not know if is the same "clunk" problem you are trying to describe.

Its close when your first video is around 0:38. It only seems to happen when it goes to slow down from a travel move on mine, and it seems ok for the full distance travels like your showing, mine seems to clunk for the smaller travel moves and only occasionally.

Edited 1 time(s). Last edit at 05/31/2016 03:37PM by PDBeal.

there is big probability is the same problem.

the problem should be the board you are using is a 8bit and simply can not process fast enough at the speed you try to move the carriage, to solve this you can do:

- reduce the max speed
- print without the lcd or with a 20x4
- forget marlin and use something more recent, like repetier
- upgrade to a 32 bit board

what type lcd you are using? from my experience this happens more if you are using the called full lcd, the one with 20x4 line need less computation power to display the info.

try to make the same test without lcd and using pronterfase

Edited 1 time(s). Last edit at 05/31/2016 07:10PM by filipeCampos.

The Arduino Mega has the Reprap Discount LCD attached to it, but the actual print is coming from Octoprint on the Raspberry Pi2 over USB. The LCD is attached, but only really used it to manipulate the odd parameter to see if it made a difference.

I was curious if I was reaching some processing limit with the Arduino Mega and have been looking at the Duet, but what bugs me about the Duet is the Arduino Due does not seem to be available anymore which could mean the Duet might be harder to find in the future.

I did try the Marlin RC4, but for whatever reason it had issues trying to home the Z axis so I gave that up and went back to the 1.0.2-1 version. I'll take a look at repetier too and see if that's any different.

After watching the previous videos, I'm going to try the same sample test.gcode and see how it looks and start there for speed manipulations.

Of course most of the speed issues started when I attempted to print thingiverse.com of which they say it should take approximately 50minutes which took closer to 3 hours with my speed setups which seems abnormally long assuming 50min was a true accurate time.

the octoprint over usb will not be cause of any problems, in the past i have used a similar solution with a raspberry pi 1 (512) and never have any trouble with speeds.
The lcd consume a lot of computer power to only update the info, this is a well know problem and one of the main reason that most deltas use 32 bit board.
In a Cartesian printer like prusa for some reason never have this type problem, only happens first time using a ramps in a corexy. Maybe because i was always print slow on the prusa or maybe the corexy need more computation power to move.

For my experience i could only printing well with a ramps 1.4 with the lcd disconnected and printing from the sd card or raspberry. With the lcd i always have a not fluid movement with micro stops that make the "clunk" sound you describe. This stops happens in random place and sometimes in slow movement. The repetier firmware display the number of move the board was in memory and allow me to understand better the cause of the problem. The firmware will have a buffer of movement that is consume when is printing, when there a lots of little movements that buffer will go empty and the board do not fulfill in time the buffer. The stop is caused because the buffer is empty, the printer stop and resume when the firmware fullfill again the buffer.

lots of person goes with the duet, is a pretty solid and cheap board, one of the best value for the money.
But there are other very good ones, you can buy on ebay a smoothieboard clone or original if you have the $. The smoothie firmware is pretty good and like the duet is was a little web server, this way there is no need of the raspberry.
You can go with a radds 1.5, i use one on my printer and already made many, many hours of prints with it without any type o problems, is rock solid. This solution is a little more expensive and do not have the web server, but is a good solution for you if you already have octoprint. Was the big advantage you can use 1/128 steppers, there are very silent and reduce a lot the motor vibrations. And you can use repetier, marlin or the duet firmware.

Edited 1 time(s). Last edit at 06/01/2016 04:58AM by filipeCampos.

Your XY max feed rates are far too high for an 8-bit controller with 160 steps/mm. Try reducing them to 200mm/sec. Also I suggest reducing acceleration from 7000 to 3000. The acceleration algorithms used in most (possibly all) 8-bit firmwares are crude and don't generate the steps accurately at the proper times.

As filipe says, dumb graphical LCDs such as the RRD one take a lot of extra CPU power, and this may be impacting the ability of the processor to do accurate motion control.

Regarding the Duet, although the design was loosely based on the Arduino Due, it is a completely different beast, and it does not depend on the availability of or support for the Arduino Due

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Large delta printer [miscsolutions.wordpress.com], E3D tool changer, Robotdigg SCARA printer, Crane Quad and Ormerod

Disclosure: I design Duet electronics and work on RepRapFirmware, [duet3d.com].

I did try repetier firmware, and it taught me a thing or two about the speed settings and such, but one odd thing was the travel. I had to add the STEP delay of 2 for the DRV8825 drivers, but on marlin my X, and Y use 160 STEPS for full travel yet repetier took 320 for the same travel. I even tried a few different settings disabling quadstepping and babystepping but didnt see any change as to why it took 320 before it did the full 200 mm travel.

I think I'm going to try swap out my motors and see if there's any change, but with repetier it wouldnt go any faster even when I set my max speed to 10000 and acceleration to 10000 and jerk to 100, but with marlin it was trying to go faster but obviously was missing steps and creating the "chunk" sound. And this was only using the first test.gcode so I am wondering if there's a correlation to the 320 STEPS requirement and my speeds.

Since lower speeds seem like a workaround, I've pulled the trigger and ordered a 0.8.5 Duet and the Panel Due 7" LCD from Filastruder. It'll be interesting to see the difference and to find out if higher speeds are possible.

In my head, I can't see a bowden corexy not going faster than 200mm/s, but it'll be an interesting trial for the 2 very different controllers.

With a 32 board you can achieve speed much high that most printer supports mechanically.

I pretty sure that most printer do not print at 200mm/s, this speed are normally used only for the travel speed. Printing fast is something everyone do at least once and them them conclude the print quality you get is sh*** and lower the speed to something between 60 to 120mm/s max. Bowden setup and fast print speed is a very bad combination to get quality. If you go with a direct extruder is more easy to achieve qualiy at higher speed that using bowdem.

Edited 1 time(s). Last edit at 06/02/2016 04:33AM by filipeCampos.

At this point, if I can achieve higher travel speeds that would be sufficient, I know it can't print that fast, but it just seems so slow to move around sometimes and would be nice to remove some of the dead time.

I'm really not too interested in the whole direct drive, especially if I'm looking ahead to a future build I'm planning to try the kraken extruder head which 4 direct drives would be a ton of weight to move around.

Just to close the loop on this one, I have upgraded the Arduino Mega / Ramps / 4x20 LCD boards to the Duet 0.8.5 / PanelDue 7". With that being the only change, the system was able to achieve much higher speeds on all axis through the First test.gcode.

And on a positive side, the PanelDue for the Duet is miles beyond the 4x20 LCD screen for the Arduino Mega. I can't say I'd buy another Duet yet, as I'm really not liking the whole integrated stepper drivers that are part of the board that are not replaceable and do not have any sort of heatsink attached or included, but that will soon change on my new setup.

Quote
PDBeal
And on a positive side, the PanelDue for the Duet is miles beyond the 4x20 LCD screen for the Arduino Mega.

Thanks!

Quote
PDBeal
I can't say I'd buy another Duet yet, as I'm really not liking the whole integrated stepper drivers that are part of the board that are not replaceable and do not have any sort of heatsink attached or included, but that will soon change on my new setup.

Some things you need to know about stepper driver chips used in repraps. Apart from one type (the THB6128), they are designed to be cooled from the bottom of the chip, through the printed circuit board. They have a metal tab on the underside that is soldered to the PCB for this purpose. So the whole PCB acts as a heatsink. The chip manufacturers generally specify a minimum area of attached PCB required to meet the current rating of the chip. So the Duet (and Smoothieboard etc) is using the driver chips exactly as the manufacturer intends.

Plug in Pololu or stepstick drivers have tiny PCBs, much smaller than the manufacturer recommends. Sticking a heatsink on the top may make you feel better, but it doesn't cool the chip significantly, because the plastic top of the chip doesn't conduct heat well (unlike the metal pad on the bottom). The only sensible way to cool those modules is to use a fan to blow air over the PCB, and not to stick heatsinks on the top (because they obstruct the air flow to the PCB ).

On-board drivers are far more reliable than plug-in ones. I can think of three reasons that may explain this. First, the driver chips are much better cooled because of the large PCB. Second, you know what current you are setting, because it is done in firmware. Whereas setting the current by turning a pot on a stepstick is rather hit and miss unless you do it properly with a multimeter and ceramic screwdriver, and you know what value the current sense resistors are. Third, when motors decelerate they generate power, and this needs to be absorbed by the capacitors on the motherboard. On plug-in drivers, this path goes has significantly more resistance and inductance because of the plug and socket. This makes it more likely thast you will get voltage transients that damage the driver.

Your on-board drivers on the Duet will continue to serve you well, as long as you don't connect or disconnect motors with power applied, or short the outputs. Blown stepsticks are very common; blown drivers on Duets are rare.

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Large delta printer [miscsolutions.wordpress.com], E3D tool changer, Robotdigg SCARA printer, Crane Quad and Ormerod

Disclosure: I design Duet electronics and work on RepRapFirmware, [duet3d.com].

Quote
dc42
The only sensible way to cool those modules is to use a fan to blow air over the PCB, and not to stick heatsinks on the top (because they obstruct the air flow to the PCB ).

So would you recommend a fan on top blowing down, a fan on the bottom blowing up, or a fan on the side blowing across (on this one I'm presuming the fan would be near the SD card and blow towards the power connector or vice-versa)?

Quote
PDBeal

Quote
dc42
The only sensible way to cool those modules is to use a fan to blow air over the PCB, and not to stick heatsinks on the top (because they obstruct the air flow to the PCB ).

So would you recommend a fan on top blowing down, a fan on the bottom blowing up, or a fan on the side blowing across (on this one I'm presuming the fan would be near the SD card and blow towards the power connector or vice-versa)?

The ideal is to have a fan blowing air from the side so that it flows over both sided of the PCB. For the Duet, you can do this by positioning a fan so as to blow air along the line of driver chips. For stepsticks, it depends on whether they are sufficiently unobstructed to allow airflow along the underside of the board as well as the top.

There is a one stepstick board you can get that mounts the chip on the underside of the board and the heatsink on the other, see [www.panucatt.com]. I haven't used them, but in this configuration the heatsink should work, especially if used with a fan.

Edited 1 time(s). Last edit at 06/06/2016 05:43PM by dc42.

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Large delta printer [miscsolutions.wordpress.com], E3D tool changer, Robotdigg SCARA printer, Crane Quad and Ormerod

Disclosure: I design Duet electronics and work on RepRapFirmware, [duet3d.com].