Welcome to the SeeMeCNC Community

mhackney wrote:Interesting Gene, I've never seen this reversing behavior on skipping extruders. The Steve's extruder and Greg's extruder just skipped without reversing. Maybe its related to geared vs direct drive? At 200 steps per revolution and 16 micro steps, a skipped step would be very little movement.

I'm wondering, now that I am paying close attention, if the grooves the extruder leaves on the surface of the filament might not snag somewhere - maybe a transition from PTFE to PTC or hot end, and that can be fairly random based on geometry. I have been continuously measuring the input diameter of my filament and it is very consistent and when you look in the Bowden, there is lots of free space (which in itself is a problem with hysteresis). With the E3D, this tube goes right down to the hot end so there is nothing in the path except the PTC at the extruder end and the hot end itself. The hot end ID is right at 2mm I believe (from a visual inspection) so maybe the fuzz raised on the filament can snag the edge randomly.

The PTFE tubing provided with the Kraken and E3D have a much smaller ID, plenty of room for the filament but not the kind of excess the stock PTFE has. I haven't switched over to this material yet.

Filastruder.com has the tubing with the 2mm ID and I think that it is the same as what you are speaking of. $7.50 for 750mm doesn't sound bad.

This might be hard to see but you should get the idea:

[img]http://mhackney.zenfolio.com/img/s5/v11 ... 6297-4.jpg[/img]

I used masking tape for a quick & dirty experiment. In addition to suspending the Bowden in the printer, I also "braced" the Bowden where it exits the extruder with tape. Since doing this, I have yet to have a "tat, tat, tat". I am printing with a filament now that I have noticed this problem with more in the past. Before adding the supporting tape, sure enough, at what I thought were reasonable temps, I was hearing the skips, I straightened out the Bowden and taped it as shown (after manually pushing the filament to get past the digit the extruder left) and now 85 layers later, no "tat, tat, tat". Not conclusive but maybe something to investigate.

mhackney wrote:aerouta, out of curiosity do you have a part cooling fan mounted on your effector and if so, can you show a photo please.

I just had a problem and though "crap, now I'm jinxed!" that turned out to be related to my fan. It blows sort of pointed down towards the nozzle. As I was printing a long piece with lots of fill that caused the fan to deflect even more up to the nozzle I started getting the "tat, tat, tat" of skipped extruder steps. I turned up the heat and it went away (+5°) then I started investigating and realized the fan position so I turned the fan down to 25% and started dropping the temp again in 3° increments a full 15°! I think the nozzle is pretty isolated from the heater block (and thermistor) that maybe at the very tip it can "freeze" momentarily and lead to a blockage. More work to investigate but turning the fan down solved the problem and salvaged the part.

Here are some pics of the cooling fan.

aerouta wrote:Are the some pics of the cooling fan.

He meant a fan cooling the part being printed.

MSURunner wrote:

aerouta wrote:Are the some pics of the cooling fan.

He meant a fan cooling the part being printed.

Oh, I missed that. I do not have any fans cooling the part.

Ok, I might be on too something. I suspect the driver chip is overheating and hiccuping. I just did a test with making a "print" but with NO filament in the extruder. So there is no resistance at all. Guess what, I get the same odd behavior on this particular (large) part. I did a little research and it might be the driver on the RAMBo overheating. I have a heat sink to put on it and an extra fan to blow over it. I'll hook that up and see how it goes.

I usually print with the RAMBo door open but lately I've kept it closed and that's when I started seeing the occasional "tat, tat, tat". More experiments to do but this seems logical.

How's that old line go "if it weren't for bad luck I'd have no luck at all!"?

I carefully disconnected all power to my RAMBo in order to put the heat sink on the extruder driver (I did learn this much!). I carefully applied the special nonconductive heatsink adhesive to the sink and carefully attached it to the driver. Then I powered up and now my machine is mis-behavin'. When I try to home, all axis go DOWN about 5cm and stop. The extruder does not work at all. I pulled things apart and discovered that I probably shorted across those microscopic diodes (I think) near the stepper driver. The drivers on this board are so small and don't stick up much. I disconnected all 4 steppers and hooked each up one at a time and each of the X, Y and Z indeed go down when home and act odd on other moves and E does nothing

Bummer. My Azteeg X3 Pro did not show today (snow storm delay most likely) and my second RAMBo has not been returned after I blew the fan output. So, I am all wound up with no place to go.

Regards,
Michael

mhackney wrote:How's that old line go "if it weren't for bad luck I'd have no luck at all!"?

I carefully disconnected all power to my RAMBo in order to put the heat sink on the extruder driver (I did learn this much!). I carefully applied the special nonconductive heatsink adhesive to the sink and carefully attached it to the driver. Then I powered up and now my machine is mis-behavin'. When I try to home, all axis go DOWN about 5cm and stop. The extruder does not work at all. I pulled things apart and discovered that I probably shorted across those microscopic diodes (I think) near the stepper driver. The drivers on this board are so small and don't stick up much. I disconnected all 4 steppers and hooked each up one at a time and each of the X, Y and Z indeed go down when home and act odd on other moves and E does nothing

Bummer. My Azteeg X3 Pro did not show today (snow storm delay most likely) and my second RAMBo has not been returned after I blew the fan output. So, I am all wound up with no place to go.

Regards,
Michael

That's a bummer . Can you use the 2nd extruder connection and rewire the pins in configuration.h/pins.h?

Unfortunately no, even disconnecting the extruder the axis drivers are not working properly. They move erratically. I test each axis individually and each misbehaves. Homing causes them to move down. Odd but busted.

mhackney wrote:Unfortunately no, even disconnecting the extruder the axis drivers are not working properly. They move erratically. I test each axis individually and each misbehaves. Homing causes them to move down. Odd but busted.

DOH, I misread what you had written -- I thought you said the main axes worked when you had the extruder disconnected . Sorry man, that's really disappointing. I'm glad it didn't happen to me when I added the heatsinks -- it never occurred to me that stick the little heatsinks on could damage the board .

True story...

If you read my posts from yesterday in this thread you'll see that I screwed the extruder driver on my RAMBo - I thought I shorted it.

Well, last night "I had a dream". I have no idea why I was dreaming about the RAMBo but there it was. I saw the RAMBo floating in the air and when I saw it the first thing that popped into my head was "check the EEPROM". Odd huh? Well, I woke up this morning and actually remembered this little "dreamette" and checked my EEPROM from RH. Sure enough, it was crap. Some stuff was correct but other parameters had been reset to 0 or were garbage.

So, I did a clear_eeprom and uploaded the firmware after changing the EEPROM_MODE to a new value. Guess what, everything works fine now! Unbelievably lucky today. Should buy a lottery ticket!

Just goes to show, sometimes its just better off to sleep on it LOL

mhackney wrote:True story...

If you read my posts from yesterday in this thread you'll see that I screwed the extruder driver on my RAMBo - I thought I shorted it.

Well, last night "I had a dream". I have no idea why I was dreaming about the RAMBo but there it was. I saw the RAMBo floating in the air and when I saw it the first thing that popped into my head was "check the EEPROM". Odd huh? Well, I woke up this morning and actually remembered this little "dreamette" and checked my EEPROM from RH. Sure enough, it was crap. Some stuff was correct but other parameters had been reset to 0 or were garbage.

So, I did a clear_eeprom and uploaded the firmware after changing the EEPROM_MODE to a new value. Guess what, everything works fine now! Unbelievably lucky today. Should buy a lottery ticket!

That is spooky!

I have lots of odd dreams but never about RAMBo boards!

mhackney wrote:Hey guys, you seriously tapped this small hole with a M3-.5 tap without pre-drilling to 2.5mm? It doesn't even seem deep enough to get enough threads on a regular taper tap. I do have bottoming and plug taps too but none of them will start in that little blind hole. Are you sure you are not tapping the larger hole in the bottom left corner?

[img]http://mhackney.zenfolio.com/img/s11/v3 ... 5006-3.jpg[/img]

What did you end up doing for this? I bought an E3D V5 bowden from Filastruder and my block looks the same as the one in the picture. The drawing files on E3D's website do not match it but I think those are V4 drawings(or maybe V3? Not sure what ISS means in the corner). I bought the threaded stud thermistor as well but it seems like there could be some issues with putting it in that hole on the left.

The hole runs all the way through the block and the thermistor is nowhere near long enough to get as close to the nozzle as it should. With one open end, it seems like breezes from fans and such would also affect temperature dramatically. I've thought about filling one end with muffler putty to prevent that. I'm still concerned, even doing that, that my temps wouldn't be as accurate as just using the thermistor that it came with.

It's like it's been made for those old Honeywell axial thermistors(not what it came with) but that would seem like a downgrade since those are out of fashion.

I ended up just using the larger 2.5mm through hole. It works fine, no issues with temps. I used thermal grease to seal the end of the thermistor in the hole.

BTW, the Kraken comes with four of these heat blocks. I'm going to be mounting these threaded thermistors on them. The Kraken blocks do not have this through hole though so I need to drill and tap the holes.

I posted photos and tips on installing the screw in terminators on the E3D (and Kraken) hot ends over in the Kraken topic. Take a look, it was actually a lot less problematic than I anticipated. AND, it turns out that the thermistor is cemented into a blind hole in the brass nipple, so on the E3D through hole, there shouldn't be any problem with air currents affecting temp reading.

Screw in terminators? What model, the T-1000?

dpmacri wrote:

mhackney wrote:Have you ever tried to move a stepper that is powered up? You have to overcome the holding force which is quite high on these little buggers. The "retract" that I observe is a lot more than the spring effect of compressed PLA could provide. It's an odd thing!

Yeah, they're tough little buggers . But perhaps the skipping is due to an overheated mosfet and so the motor loses all of it's holding power momentarily while the mosfet shuts itself down for a split second .

Well, I've been running 100% reliably now and feel confident (after some confirming tests) that I know the root cause of my and probably other's EZStruders skipping steps. The culprit? heat! My attempt to install a heatsink on the extruder driver was almost a disaster but luckily I did not do damage to my RAMBo. But, I did remove it. I then installed a 40mm fan in the cutout LCD opening in the door in the chamber when're the RAMBo resides:

[img]http://mhackney.zenfolio.com/img/s10/v9 ... 8937-4.jpg[/img]

This fan is wired to my E3D barrel fan on a switch so I turn it on when I start up and leave it on all the time. The fan is simply glued into the slot, it is almost a perfect friction fit. Now with the fan directed at my RAMBo, the board stays cool and I've printed for 100s of hours with many looooong 16+ hour prints with no "tat, tat, tat"! And, just to verify my hypothesis, I switched off the fan part way through a print and in about 10 minutes I started hearing the "tat, tat, tats" again. I flipped on the fan, manually assisted the extruder until the RAMBo cooled and I was back into flawless operation.

Now I think the symptoms make sense, I was seeing the stepper/extruder reverse during these skipped steps. Probably the thermal shutdown shuts off power from the stepper coils allowing the compressed filament to push back, thus reversing the rotation a few degrees.

Great place to mount the fan. Not sure I would have thought of that, I have the small squirrel cage fan mounted to the floor.
Many places or ways to mount, what's important is to get a fan in there.

Agreed, I assumed convection cooling would be sufficient but it is not!

Great, I will give this a try also.

Well after much hullabaloo and messing up of my stepper motor wiring, I got the e3d v5 installed and running.

What an awesome difference!

I really haven't done my usual tweaking yet, nor have I added my layer cooling fans for PLA, but so far this prints wonderfully! I recommend this wholeheartedly for anyone on the fence! You wont regret it!

The two things I didn't like (nothing functional, just aesthetic)
- Thermistor installation (and this goes for any hot-end I've seen). Especially for an schmick and well-machined head like this, it seems like a crime to go and muck it up visually by installing a thermistor with silicone goop and kapton tape. It bugged me so much that I went and got a 3mm threaded stud thermistor (from ebay) and tapped out the hole on the side of the heater block (you can read about this in detail elsewhere on the forum, it's worth it ). I didn't end up threading it all the way in (I was worried about breaching the other side) but it seems to have no ill effect, and is more responsive than the stock hot end in temp readings.
- The fan shroud. Again for an awesome looking hot-end, with such attention to detail... It seems bizarre that it comes shipped with a shroud that looked like it was printed with a horribly uncalibrated head and machine. It was wobbly, blobby and what I would expect from a first print, not from the manufacturer of an industry-leading hot-end. I understand that they probably have a machine running all day with these things, and while functional, it's ugly as hell and does not seem to match the rest of the 'package and presentation' of their sleek product.

Maybe I'm fussy... Though if the hot-end didn't look as awesome as it did, I probably wouldn't have cared

Anyway, here are some pics.

Ignore the last one, it's a repeat :/
http://imgur.com/a/Ffh2h#4

You did a nice looking and a neat job with the wires.
Great job!