Checking extruder

[Craftgizmos]

Well, I'm almost there with the Rostock MAX. Heat bed works, hot end heats, motors and belts seem OK. After trying a few times and watching that plastic plate move while it is heating I'm going to get a piece of glass.

The question I have - what code can I use in the manual Repetier window to get the extruder motor to turn on and off to test it just to make sure that is working before I try it with filament?


Richard

[barnett]

I would home the machine first, then heat up the hot end past about 180, then try the extrude button in the print panel of Repetier. You'll get an error if the hot end isn't past a min value (set in the firmware I think). Over 180 works for me.

I would think for testing, extruding 5mm at a speed of 60mm/min is fine. I routinely use that button (20mm at a speed of 240mm/min) to get the extruder primed right before starting a job.

[Craftgizmos]

Thanks,

I went out and got the glass plate. So when I set the Z axis, do I do it with the blue tape on the plate, and with the bed heated?

How much force should I use to burnish the tape down onto the glass surface? I tried that on the plastic plate and it seemed OK, but when it cooled the blue tape bubbled and ridged.

[tom10122]

Most people use Kapton tape for heatedbeds, Blue painters tape is usually used for non-heated beds ( i could be wrong)

[Polygonhell]

The adhesive on Blue Painters tape will melt at about 60C, so most people don't use it as a surface on a heated bed.
If you are using glass and printing ABS, then you can dissolve some ABS in some acetone and apply that to the surface of the glass.
You can also use Kapton or PET tape, but they are often difficult to source locally.
But yes when you set the actual Z Height at the end of calibration you should do it with as close to the final conditions as possible, and the bed and hotend heated for at least 20s after they reach temperature.

[geneb]

Window tinting works well for ABS. Your local auto parts store should have it.

g.

[Craftgizmos]

g. - in the manual for the red cube print there's blue tape on the bed and from what I read you were heating the bed to 55. Right? I'm sure I'll understanding more once it starts printing. I just want to see the thing squirt.

Thanks.

[geneb]

Yep.

g.

[Craftgizmos]

IT SQUIRTS!!

I had some trouble getting it to extrude, turns out I hadn't tightened the big bolts through the bearings on the extruder so things were slipping and I wasn't getting good traction on the filament and consequently ineffective control.

Moving onto the final steps and test printing. I have to check the bed calibration again since I took the hotend apart to figure out the problem.

And, the middle of my heated bed is a little bit low. I think I saw something somewhere that this can be addressed in the firmware, but I can't find that again. Can I compensate for a slightly low middle in the configuration files?

Thanks to everyone for all the help!

[Craftgizmos]

I have been practicing the nozzle cleaning process, acetone, a big pin and a single strand of wire. Has anyone tried the blowtorch method?

Now, using the window tint, which was pretty easy to handle, I got something.

[img]http://www.craftgizmos.com/rostock/cube1.jpg[/img]

The first portion looks pretty good, and it is quite square, but partly up the towers is started going bad. I followed the settings in the manual, but for the hotend temp which I had at 255. My first trials were at 235, but that didn't seem enough, and I've had trouble getting it to stick. What's happening? To me it looks like the ABS is getting too cold, but at this point that's a guess.

I have the original deeper nozzle, is that an issue? I also had a lot of trouble with the PTFE tube, so I spent some time fitting it like another and I used two tiny washer up at the top to make it a little more snug.

Do the laser pointer spot temperature readers work for getting a good idea of what the hotend temp at the nozzle is?

And, just now, I got up this morning, turned it on, and tried extruding only. It seemed OK. Writing this post I left it aside, on. Now, trying to extrude again, it doesn't want to feed. I've tried making the feed tension even tighter, but that doesn't help. I'm not sure just what I'm doing wrong.

[mhackney]

I always (when I need to) clean my nozzles with a torch. The trick is to get as much material out of the nozzle before charing. I heat it up until the plastic melts and then pull out the material with tweezers. The, heat up until the material burns off.

I've printed with the original nozzles on H-1 for a long time and it works fine. I think you should step back and work on calibrating with a simper item to print like the single wall calibration thing. It looks like you have filament starving - not getting enough filament. Some things to check:

1) extrusion calibration - when you tell it to extrude 10mm does it? You can draw a mark on the filament and watch it move through the Bowden tube. The filament should move 10mm when told!

2) make sure the filament can come off the spool easily. Mine starts to wind up and bind. I need to make a better axel with bearings so the spool turns freely.

3) make sure the filament is not slipping in the extruder. You can test and set this by removing the Bowden tube at the extruder. Then you can test extruding and retracting and be able to watch the filament. First, make sure the rollers are not so tight that they are distorting the filament. They can actually smash it into an oval if over-tightened. I like to start with them loose and while the the extruder is turning, I grab the filament going into the extruder and try to stop it from moving. If I can, I tighten the 2 pressure adjustment screws an 1/8 turn and try again. I keep doing this until I can't stop the filament from moving without a lot of force.

4) make sure retraction is working. I put a mark on one of my extruder gears with a Sharpie. I leave it there always. That way it is a glance and I can see which direction and how fast the extruder is moving. I had a situation where retraction was being over-driven causing the extruder to stall. It sounded like it was moving but the mark verified it was not. Makes for nasty looking prints!

5) Hook everything up. Then extrude through the hot nozzle into air for 100mm or more to make sure everything is working properly. Retract and extrude manually. Watch that gear mark. If the extruder is turning but nothing is coming out the nozzle, you have a blockage or too much friction somewhere. Many times its the inner teflon tube if you are printing with 1.75mm filament. Push filament through the tube by hand and see if it is hanging up. I had this problem and the tube had probably gotten too hot and constricted. You are running at a high temp and 255°C could have affected this tube. Replace it if it is damaged. Make sure those washers you added are not constricting the tube.

6) Push filament through the Bowden tube though the hot nozzle to see how much pressure is required. It will take some but you should be able to push it through. You need to disconnect the Bowden from the extruder to do this.

I'll add more if I remember. The other thing is, watch that first layer. If your nozzle is pressed against your build surface it blocks the flow of plastic. This can create all sorts of havoc that might not show up until later. Your "raft" on the pink part looks very thin.

Once your extruder and temps are set and working. Make sure you have good layer heights. I use .3mm with .5mm nozzle. Also make sure your nozzle is moving in a plane co-planar with the build surface. If it is moving in an arch, that can cause interlayer sticking issues too.

I have a spot temp probe and it is not useful to measure the nozzle temp. It's fine for the hot plate. The nozzle is too small and it gives much cooler readings than my thermocouple probe.

On your last remark, were you extruding into air and it stopped feeding?

[Craftgizmos]

Thanks, I'm sure there are multiple factors.

With the blowtorch cleaning. I saw a youtube video that has the guy heating it and then dipping the nozzle into alcohol to cool it. Do you do that? If so, what do you dip it in.

I took the bowden tube off at the extruder and tried pushing filament by hand. That worked. It was better when it was set at 255 than at around 240. Then, then I tried to take that cut piece of filament I was using and pulled out, fed a new piece of filament from the spool into the extruder [and yes I've checked the spool etc.] It seemed to get hung up when it met what was remaining in the PTFE near the nozzle, or at least that what it seems to me. And, yes, I think I'm making the tension nuts on the extruder too tight, but I'm trying to figure out the factors. Or, is somehow the nozzle really blocked up. I don't see and filament oozing out around the bottom of the PTFE. When I take the nozzle off there just a small plug at the bottom, at the bottom when there is the bevel that is clean, not goopy with melt ABS.

Yes. I'm just squirting in the air now.

[mhackney]

OMG - NO!!! Don't do that. That is really dangerous and a good way to start a fire and/or spray yourself with flaming alcohol. Alcohol burns with an almost invisible flame so it can be very dangerous, by the time you see it, you are on fire.

I let it air cool then clean it with cotton swabs and acetone.

[Craftgizmos]

That's why I asked. And I guess it is rubbing alcohol, but...

http://www.youtube.com/watch?v=6bTfl35zlHE

This looks like nozzle flambe. I'll try it with the torch sometime.

How do I tell if I have totally FU the PTFE?

[mhackney]

For one thing, the filament won't slide through it. If it does and it looks OK, its good to go.

[mhackney]

Ok, I watched this guy's video. He is out of his mind. Firstly, if you want to cool the brass, use water. I anneal brass all the time for my reelmaking. Once soft, you can not harden it again unless you work harden it. This is NOT what you want to do. You do not want the brass so hot that it gets red. That will anneal the brass - a one way street on the nozzle. His torch is way hotter than it should be. You want a nice big and gentle flame to head the part evenly.

Please do not have flammable solvents like alcohols and acetone anywhere near your torch. Have a fire extinguisher handy too and work outside if you can. The fumes are toxic. I basically melt and physically get as much plastic out as possible. Then I heat and char the remaining plastic. When it has charred, let the nozzle cool completely and use cotton swaps, wires and acetone to clean it up.

[Craftgizmos]

I have not grabbed my torch and a dish of flammable liquid.

The tube seems OK, I'm extruding again at 234 now without the little washer. I tried another print and got much of the same mess after awhile.

Any thoughts? Do I try it with faster feedrate or slower print speed? Or...? I think someone else had something similar.

[Polygonhell]

It's really hard to block a hotend with ABS, PLA behaves differently, so it's very easy to do it, but ABS doesn't really suffer from blocking hotends unless it's got crap in it.
General rule on debugging prints is start sloooowwwww, then worry about increasing speed later.
When it stops extruding, if you take the bowden tube out of the quick disconnect on the nozzle, can you push filament through by hand?
With the original Nozzle the coldest I could print ABS reliably was 235, and I would commonly run at 245, but a lot depends on the plastic, have you tried other plastic, or just the one roll?

[mhackney]

Yes, sllllooooowwwww down. 10mm/s is a good slow starting point. You can watch carefully what's happening at that speed too.

Interesting that everyone is printing so high temp with ABS. I am running 210 to 220°C depending on filament measured with both a thermocouple and my thermistor. WIth my H-1 this right where I was printing these materials too.

cheers,
Michael

[Craftgizmos]

And, I did change the first layer to .4 and the following to .3, but that didn't do much. I'll slow it down. Could backlash have anything to do with the shattered appearance when it starts to make the towers on the hollow cube? I think I'll snug up my belts and look over the cheapskates for wobble.

When I finally get to it I think I want to try the LED lights on the carriage. I'm forever grabbing my flashlight.

Thanks.

[JakeCShake]

I agree with the high temps. I believe we usually ran ABS at around 230C and it was fine. As for the LED I'm not sure I like the idea of drilling through the carriage......Have you tried the LED ring print???? Barnett and others have printed it out on their machines and installed. Looks great and less physical trauma to the carriage. Maybe it doesn't matter...just commenting how cool it did work.

[mhackney]

No issues with drilling, they are small holes. The new nozzle is too short and anything hanging below the carriage will likely interfere. That's one reason I'm considering shortening the 3 aluminum spacers that hold the hot end. If I got an extra 1/2" clearance I can make a ring for more LEDs and an integrated duct for cooling the print.

[JakeCShake]

Got it....just worried about the carriage as a complete noob to this amazing technology. Was even worried about sanding the U-joints too much, luckily that worked out alright. Enjoying your inputs....thank you......

[Craftgizmos]

Hey,

I haven't given much thought yet to just how to add some lights, it's just that it is sometimes hard for me to see.

I've also thought about shorter spacers so there was a little more room below the carriage.

I tried a slow print and it was worse, more like spaced beads rather than a continuous flow. I keep thinking it should be a little more like frosting coming out of a pastry bag, but that doesn't seem to be the case. It seems a little constipated.

[mhackney]

@JakeCShake - if worse came to worse you could get replacement parts from Steve! But really, there is no issue with a couple of small holes. In fact, there are already 3 holes molded in that are a little closer to the center. I tried using them first but they cast a shadow off the nozzle.

@Craftgizmos - that is very strange indeed. How has your filament been handled? It almost sounds like silicone or other contaminant. Do you have a different filament to try?

If you can extrude into air a nice long continuous filament but yet you are seeing it bead up at slow speed when printing it could also be you have way too high temperatures. Try turning down your hot end 5°C at a time and extrude into air. See how low you can go to get a continuous bead. Then add 5°C and try a print. That's how I typically "calibrate" for new filament when I get it.

It should look more like frosting coming out of a pastry bag!