Makerbot Replicator 2 extrusion troubleshooting (the steps I took, for the sake of others)

[James Rowlands]

I recently got my second Replicator 2, along with a large amount of True White PLA, and straight out of the box on the sample SD card files I appeared to be having some troubles with extrusion. I am getting much better results after trawling through this group and other forums for solutions.

My problems, as far as I can remember:

1. Extrusion was weak on the sample prints, I ignored this and went on to print a larger object for my Quadrotor.
   
2. During the initial laying of rafting I got the familiar clicking noise of the filament pushing motor and intermittent, pearly extrusion, often completely separate from each other.
1. To rectify this I tried the following
1. Changing temperature from the default 230c to 225c & 235c.
2. Manually clearing the Thermal Barrier tube
2. This appeared to work. I set about printing at the higher temperature
3. During a dramatic shift in width and therefore speed of the layers on the same part as no#2 I experienced a change to even weaker extrusion (I wasn't at the printer so I didn't hear clicks), which eventually rectified itself, failed again and rectified
1. Instead of continuing on this part I began printing a smaller one, not realising at the time that the change in layer width was a potential problem.
4. The new, smaller part highlighted the problem in changes in layer width even better by failing as soon as the layers shrunk.
1. At this stage I'd poured over the group for solutions and I attempted the following:
1. Changing and clearing the Thermal Barrier tube (restarted good extrusion, still failed at the same place)
2. A light dab of spray on Canola Oil on the tip of the filament (caused some curling on extrusion, corrected with blob method)
3. Using a 60cm box fan next to the build plate
2. The last step rectified the change in layer width, allowing me to get a complete print
3. This apparently happens because the amount of energy been used to heat the PLA as the extruder is operating does not change rapidly. Going from a fast flow to a weak flow results in over heating, causing a build up of retracted, semi-melted plastic, causing the jam
5. Assuming I'd fixed my problem I set about doing a larger print, but I was back to rafting extrusion failures!
1. I took a break and had some drinks because I didn't know what to do anymore.
6. Today, I decided to approach the problem afresh and went about printing a basic cube, following some further problems I'd read about
1. I adjusted feedstockmultiplier and feedDiameter, achieving different results:
1. Print 1
1. 1.73mm
2. 0.97x
3. 230c
4. Result:
1. Support; clicking, rough
2. Cube; clean sides, can only just see through bottom layer
2. Print 2
1. 1.82mm
2. 0.97x
3. 230c
4. Result:
1. Support; rough
2. Cube; clean sides, can see through bottom layer more
3. Print 3
1. 1.82mm
2. 1.05x
3. 235c
4. Result:
1. Support; major gaps
2. Cube; same as print 2
4. Print 4
1. 1.65mm
2. 1.05x
3. 235c
4. Result:
1. Support; clicking, intermittent gaps
2. Cube; clean sides, least transparent bottom layer

So, yet again I'm out of ideas and Makerbot are well and truly overdue on their ticket that I sent in nearly 2 days ago. Anyone know what direction I should be headed in? I'm used to filament that just works ... the previous printer I operated on was much more reliable than this, albeit not without it's issues. Unfortunately I don't have calipers at the moment.

[Enginwiz]

Makerbots default temperature setting of 230°C for PLA is wrong.

230°C is too hot for PLA. PLA will degrade to black soot

and clog your hotend  if you bake it too hot.

Reduce the nozzle temperature to 215°C or even lower.

 

[Bryon Miller]

When you clear your barrier tube, do you get it to the point that you can shine a flashlight up from the bottom of the nozzle and you can see the light shine through the barrier tube if you look down the hearter block hole from the top?  If so, I suspect you have some garbage filament on your hands.

[Ryan Carlyle]

1) Don't bother submitting tickets, they take forever to answer them. I've submitted tickets twice and never received any response at all. Call tech support on the phone and keep calling until you talk to a person. THEN tech support is quite good.

2) You need to MEASURE the filament diameter, not just input various guesses. Your packing density / feedstockMultiplier calibration is wrong if you don't have the actual diameter inputted when you calibrate. Once you properly calibrate packing density once, you only have to measure diameter after that (except repeat for each extruder hardware and filament type combo.)

3) Drop your extrusion temp to 210C for PLA. Some people go lower. 230+ is way too high.

4) Re-purge your nozzle at the right temperature to make sure no crap is on there. Filament should extrude straight down during a load cycle. If it doesn't, you probably have a nozzle clog (possibly from printing too hot).

5) Be careful with spray canola. It may have other ingredients in it to reduce the viscosity for the spray mechanism. No way of knowing what that'll do. I would stick with regular non-spray oil. The optimal way to deliver canola seems to be a dampened sponge in a printed filament wiper (check Thingiverse).

[James Rowlands]

I've now switched back to a non-Makerbot PLA and I've gotten a few successful prints without the big, active fan, oil or custom profile changes.

The best print I've gotten so far was at 235c, and 80mm/s ... I'm currently printing at 220c and 80mm/s but it's not extruding enough.

The support structures simply don't print as well with either PLA as they did on the last Replicator I used, with the exact same roll of non-Makerbot PLA. I get the feeling that despite cleaning the thermal barrier tube thoroughly, there is something wrong with it.

[Ryan Carlyle]

Try printing slower and colder. 235 is seriously too hot for non-Makerbot PLA and somewhat too hot for Makerbot PLA. There's a high chance you have carbonized debris in your nozzle now.

I'm guessing you have crap in your nozzle and the high temp is simply reducing the viscosity enough to let you squeeze out some plastic for a while. But in the long run that's going to get worse, not better.

[James Rowlands]

Is it possible to clear out carbonised debris? I've now done ~400g of prints with the after market stuff, that are satisfactory. The rafts still aren't as perfect as they were on the old machine, and I've got a problem with the filament tangling and stopping prints occassionally, but extrusion hasn't gotten any weaker!

Also, a lot of the extrusion failures have occurred at lower speeds ... this is due to the factor I explained in the first comment; considerable extrusion counter-acts the temperature as the flow cools the hot end. Switching from fast to slow in the same print can cause the machine to not immediately catch up, and overheat the hot end, so much so that when retraction occurs it jams the colder top portion.