50mm Tower Calibration

Hello,

I've recently built a prusa mendel v2 and am in the calibration stage. Over all, I'm really happy with the results, however, I could use some expert advice.

I'm using PLA and printing the calibration set I found here: [www.thingiverse.com]

My 50mm Tower prints aren't blobs, but they are shriveled looking. The creator of the calibration set suggests reducing the hot-end temp by 5 degree increments. I started at 185 and lowered it to 180 with no perceptable change in print quality. Since he also mentions that lowering your temp too much may burn out your extruder motor, I stopped there.

Does anyone have any advice for how to improve my tower print? Should I lower my temps further? Add a fan?

I'd appreciate any help I can get.

Thanks.

Use a fan, print slower, or print multiple copies at the same time.

I agree with polygonhell, but would emphasize one thing. If you re printing a small tower then slowing down can actually be counterproductive because the hot extruder remains too close to the tower. Your only recourse here is, as he says, print multiple copies so that the head moves away for a bit, and/or more agressive cooling.

Interestingly, skeinforge has two alternatives in the cool plugin to battle this. Each has its own set of problems. Slowdown seems to be the most commonly used choice, but it has the issue I mention above where the head remains too close to small towers. The other choice, orbit, has an issue with oozing.

Thanks for the replies. I'll try adding a fan as you both suggest.

As a follow-up comment, I would like to be able to print single copies of tall, narrow structures if needed. Is that an unreasonable expectation with PLA? Does the author's (of the calibration set) advice seem sound? Is reducing the temp. of the hot-end a good idea? Any thoughts on that?

You have to give the plastic a chance to get down to temperature low enough that the following layer will sit nicely on top of it and it's temperature gradient doesn't melt the layer underneath.
Dropping the extruded temperature will help with this and the author is right, most people print much hotter than they need to, as long as you abort the print when the stepper starts to slip, you won't damage it, You'll probably end up having to clean out the hobbed bolt after it shreds the plastic. IME there isn't much point going below about 170 and I think Marlins default safety for running the extruder is 175.
Whether slowing down will work depends on layer height among other issues.
You're going to have to experiment, if you need to just print one and the fan and slowing down aren't enough, then you should try the Orbit plugin on Skeinforge.

If you are currently not using a fan I think you'll be surprised how much difference it makes on it's own.

Ok, thanks again for your reply. I'll definetly add a fan.

Hey guys,

I wanted to stop back in to say thanks again. I added a 40mm fan and slowed down the print speed a bit. These changes allowed me to keep my hot-end temp at 185. I'm attaching an image of the before and after prints.

It's looking much better.

I think saying the tower looks better is an understatement

Glad to have been of help

I finally printed the tower, I had to put my flow rate on the code to 0.8, bit slow, and also the inflil on 20% ale there is still a lot of plastic. I am printing ABS on 205 celcuis, i also had to lower the temperature from the previous calibration tests, box and thin wall. But my most important concern is the blob that makes on the corner where the hot end goes up a layer each time, i tried with Jitter on 3, and nothing happened i cant get rid of the blob in this one or in the skin calibration"¡¡!!!! thanks.