Rambo and/or EZstruder stepper overheating?

[Captain Starfish]

All set up nice, get an hour into a print today and I get a skipping extruder. Damn. So I crank up the extruder temp but no go, still jumping all over the place. And WOW that motor is warm. Kill the build, let everything settle down a bit but leave the PEEK fan and extruder heater going, try to retract and THAT's skipping too! Hmm. Release the red knob and pull manually and it's free and easy.

Then I find a note in a similar skipping extruder thread mentioning that it could be the RAMBO tripping out and slacking off the extruder motor when the board overheats.

This makes plenty of sense.

Anyway, two parts to this question:

1. Is it normal for the stepper on the ez-struder to get quite warm to the touch? Not hot enough that I can't hold onto it for a while, but hot enough that this becomes quite uncomfortable.

2. Is there a convenient method or optimal location for throwing a fan over the board?

[Eaglezsoar]

All set up nice, get an hour into a print today and I get a skipping extruder. Damn. So I crank up the extruder temp but no go, still jumping all over the place. And WOW that motor is warm. Kill the build, let everything settle down a bit but leave the PEEK fan and extruder heater going, try to retract and THAT's skipping too! Hmm. Release the red knob and pull manually and it's free and easy.

Then I find a note in a similar skipping extruder thread mentioning that it could be the RAMBO tripping out and slacking off the extruder motor when the board overheats.

This makes plenty of sense.

Anyway, two parts to this question:

1. Is it normal for the stepper on the ez-struder to get quite warm to the touch? Not hot enough that I can't hold onto it for a while, but hot enough that this becomes quite uncomfortable.

2. Is there a convenient method or optimal location for throwing a fan over the board?

It is normal for the stepper to become quite warm.
Some place a 50mm fan in the door behind the LCD and let the air blow over the Rambo, some place a larger fan like a 60 or 80 in front of the Rambo using varying mounting techniques such as double sided tape on it's base or hot melt glue.
I have a small squirrel cage fan that works perfectly for cooling the Rambo but the place I bought them from no longer sell them. You can find a 5 or 12V Squirrel cage on Ebay. They tend to run loud so I put a speed control on it to slow it down.

[Captain Starfish]

Thanks - good to know it isn't just me with the warm stepper.

I've got a little 40mm 12V fan which will hotmelt into the LCD slot nicely, hopefully that will be enough. Or would I be better off hanging it under the USB plug and facing the side of the board, maybe even with a little ducting to force the flow over the driver chips?

[Eaglezsoar]

Thanks - good to know it isn't just me with the warm stepper.

I've got a little 40mm 12V fan which will hotmelt into the LCD slot nicely, hopefully that will be enough. Or would I be better off hanging it under the USB plug and facing the side of the board, maybe even with a little ducting to force the flow over the driver chips?

I think your second option with the ducting would be your best choice.

[geneb]

Captain Starfish - do you have a meter with a thermocouple? If so, please run the same job, same settings and as soon as you hear the extruder start to skip, touch the thermocouple probe to the PEEK barrel on the opposite side of the fan. Check at the bottom of the PEEK closest to the nozzle and again at the top of the PEEK barrel. I'm curious to see what you're getting for temps.

g.

[Captain Starfish]

Sorry, Gene - I don't any more, gave it back to my brother after I calibrated the thermistors.

[Captain Starfish]

Excellent.

Hotmelted the 40mm fan side-on to the board so it flows across the drivers.

Twice as far into the print as I was yesterday and she's going great guns.

Happy days, thanks for the help as always.

[Eaglezsoar]

Great Captain. Glad to hear she is sailing the mighty seas again!
If that stepper still feels too hot you might want to reduce the current going to it. Take it down maybe in increments of 10 but don't take it down too far.

[Eaglezsoar]

Captain Starfish - do you have a meter with a thermocouple? If so, please run the same job, same settings and as soon as you hear the extruder start to skip, touch the thermocouple probe to the PEEK barrel on the opposite side of the fan. Check at the bottom of the PEEK closest to the nozzle and again at the top of the PEEK barrel. I'm curious to see what you're getting for temps.

g.

Since he doesn't have the meter maybe the good old finger test would give a crude indication of temperature on the peek.
And Captain, the meters can be had for $20 or so and you really should have one now that you are a 3DER.
Amazon.com have several that are inexpensive.

[Eric]

Or a temperature-only meter from ebay, if you can wait for shipping. About $5 total after you buy a 9V battery for it. The display is C only, no F option, but not a problem in this hobby, is it? I have two of these myself, in addition to a multimeter with a temperature probe.
http://www.ebay.com/sch/i.html?_sacat=0 ... 2c&_sop=15

[Captain Starfish]

I did think of dropping the stepper current - I guess it can drop until it starts jumping on fast retracts or other jerky movements, plus a bit of a safety margin, yes?

When I had such luck with the borrowed thermocouple and meter, I bought one on fleaBay - combination clamp meter for high current stuff plus the thermocouple, AUD$30 delivered, just got to wait for it to turn up

[Eaglezsoar]

Or a temperature-only meter from ebay, if you can wait for shipping. About $5 total after you buy a 9V battery for it. The display is C only, no F option, but not a problem in this hobby, is it? I have two of these myself, in addition to a multimeter with a temperature probe.
http://www.ebay.com/sch/i.html?_sacat=0 ... 2c&_sop=15

Good find, Eric. Probably a 2 to 3 week delivery time but at that price I can wait.

[Eaglezsoar]

I did think of dropping the stepper current - I guess it can drop until it starts jumping on fast retracts or other jerky movements, plus a bit of a safety margin, yes?

When I had such luck with the borrowed thermocouple and meter, I bought one on fleaBay - combination clamp meter for high current stuff plus the thermocouple, AUD$30 delivered, just got to wait for it to turn up

What number do you have in there now for the extruder current?
And I'm glad you bought a meter.

[Captain Starfish]

Whatever the defaults were for the latest Repetier source:

Code: Select all

// Motor Current setting (Only functional when motor driver current ref pins are connected to a digital trimpot on supported boards)
#define MOTOR_CURRENT {175,175,175,225,0} // Values 0-255 (RAMBO 135 = ~0.75A, 185 = ~1A)

[Eaglezsoar]

Whatever the defaults were for the latest Repetier source:

Code: Select all

// Motor Current setting (Only functional when motor driver current ref pins are connected to a digital trimpot on supported boards)
#define MOTOR_CURRENT {175,175,175,225,0} // Values 0-255 (RAMBO 135 = ~0.75A, 185 = ~1A)

So 225 is the default. I think SeeMeCNC defaulted to that for a reason so unless you feel that it is really running too hot, I would not change it.
If you feel you should change it do not go below 200 or 210.

[Captain Starfish]

No dramas - it's not getting any worse. If anything I might clip a heatsink onto the back of the stepper and leave the current as is.

[Lochemage]

Are you sure it has anything to do with the temperature, and not because you have a jam in your nozzle? Sometimes dirt can get into the nozzle (usually because it was on the filament and not properly brushed off), this can jam if the dirt builds up and is unable to pass through the nozzle.

EDIT: Also, 255 current seems quite high, I'm only running at 185 and it's perfect. When I tried experimenting with higher currents, my motor would sometimes buzz really loud and the strength of it would dig holes right through the filament.

[Eaglezsoar]

I think he is running his current setting at 225, not 255.

[Captain Starfish]

^^ this. 225.

The fan on the rambo has completely fixed this issue.

I also got sick and tired of PLA jamming during the pre-heat because I was forgetting to manually kick off the PEEK fan as well, and moved the fan to HEAT 1. When I eventually go dual head I'll sort something else out.

Got home last night (missus was there with instructions of where to find the power switch and fire extinguisher) to find my printer still printing a job about 3" above the job, bloody hotend jammed again and the extruder had stripped the filament to the point where it snapped at the drive hob gear. D'OH!

I'm getting a little sick of PLA, I'll admit. Might be chucking my ABS spool back in there and forgetting PLA if this kind of crap continues much further.

[ccavanaugh]

If you are doing heavy retraction, try reducing your extruder acceleration. I had to drop to 2000 with similar issues.

The PLA is more brittle and seems to tear easier than the ABS.

[Eaglezsoar]

Perhaps you should increase your hotend temperature a little so it doesn't take so much force to push the PLA through.

[Captain Starfish]

Running at (calibrated) 195 now, 200 seems a little excessive but I might give it a go - and play with the accel too.

I probably shouldn't have it running at 130% speed on 30mm/s either

[Eaglezsoar]

200c is not necessarily excessive, depends on Color, Manufacturer, etc. Users have reported higher temperatures then 200c to get the PLA to print properly.
I definitely would watch those speeds until you get it to extrude properly.

[Captain Starfish]

Thing is it prints just fine at 195, so I cranked up the speed a bit and watched it for half an hour, flawless performance. Went away and it must have been another hour and a half before it ballsed up.

Hmmm, will pull out the nozzle tonight and have a look see whether it's crept again.

Might be time to buy a couple of larger nozzles from SeeMeCNC - the 0.35 is good for fine stuff but damn it's slow.

[Eaglezsoar]

Thing is it prints just fine at 195, so I cranked up the speed a bit and watched it for half an hour, flawless performance. Went away and it must have been another hour and a half before it ballsed up.

Hmmm, will pull out the nozzle tonight and have a look see whether it's crept again.

Might be time to buy a couple of larger nozzles from SeeMeCNC - the 0.35 is good for fine stuff but damn it's slow.

Some use nozzles of .2 or .25 also but for the reason you mention, better detail. If you don't need that level of detail then something like a .4 or .5 would be fine and there are
more users running those sizes instead of .25 or .35 The detail I see from a .5 is fine for what I print and I don't have to print like a snail crawls.