Switching to PLA

[jesse]

I would like to try printing in PLA again. Last time I didn't use a fan and the PLA jammed all the way into brass PTC connector.

I plan to print this 40 mm fan mount to cool the top part of the extruder. http://www.thingiverse.com/thing:40845

I ordered this 40 mm fan: http://www.ebay.com/itm/120991697424

Is it necessary to also have a fan blowing down on the layer of PLA that prints: http://www.thingiverse.com/thing:28412

Is there an issue with momentum from adding weight and gyroscopic movement of the fan to the hot end? There's room for me to add 3 fans.

Should the bottom part of the hot end be insulated to keep it at the right temperature? kapton tape or silicone tape?

If anyone has a guide to printing PLA on the rostock max please post the link.

[Polygonhell]

Anything that blows air on the thermal break is fine.
The fans weigh very little, I used a 40mm fan for a while currently using a 25mm fan.
You can add a fan for cooling the material, it's not required, but for any print with a significant overhang or small part you'll want as much cooling as you can get.
If you try and cool the plastic excessively you'll want to insulate your Hotend, I use silicon tape, but it just needs something to stop the air cooling the Al block too much.

[mhackney]

A 25mm /1" fan fits perfectly between the head space, is directed at the cooling fins and is all the air you need. Low mass, not so much air that it causes cooling of the hot end.

Cooling the part independent on geometry. I find that small prints and pillar like features require a cooling fan or 2 or 3 on the part. PLA stays plastic longer than ABS and if not cooled the part can bend/warp while printing.

[jesse]

Where did you buy the 25x25 mm fan?

[Polygonhell]

Where did you buy the 25x25 mm fan?

http://www.ebay.com/itm/170998575504?ss ... 1497.l2649

[MorbidSlowBurn]

Newegg has similar ones under case cooling.

[dbarrans]

Jameco has it also: p/n 2131881.

- dan

[jesse]

Thanks.

Any reason for selecting a thickness?

Seems like it goes from 5 mm up to about 10 mm.

[jesse]

I added the 25x25x10 mm fan.

http://www.ebay.com/sch/i.html?_sacat=0 ... an&_sop=15

http://www.ebay.com/sch/i.html?_odkw=25 ... n&_sacat=0

The fan fits perfectly in the gap. I hot glued it in place just to make sure it stays there. It's a 5 volt fan, so I'm running it at 40% from the Fan 0 port. Not sure it would make it long at 12 volts. I recommend getting the 12 volt fan instead.

[img]http://i.imgur.com/ag5t17K.jpg[/img]

The printer is now able to print PLA. I made some stretchlets.

[img]http://i.imgur.com/sPg9zeA.jpg[/img]

One challenge has been getting the PLA to stick to the glass heated print bed. The material stays gooey for a few seconds unless it's cooled.

[MorbidSlowBurn]

You may still burn out the fan using the fan port on the Rambo. I believe the port is PWM which means that when you run at 40% you are still hitting it with 12V but only 40% of the time. With the PEEK fan there is little need to control it from the Rambo. If you have a regular computer supply you could run a lead straight from the 5V to the fan. If you want control you can always add a simple switch in line to turn it off.

[jesse]

You may still burn out the fan using the fan port on the Rambo. I believe the port is PWM which means that when you run at 40% you are still hitting it with 12V but only 40% of the time. With the PEEK fan there is little need to control it from the Rambo. If you have a regular computer supply you could run a lead straight from the 5V to the fan. If you want control you can always add a simple switch in line to turn it off.

Good idea. Do you know if the RAMBo supports a limit of 5 volts for the fan port in the firmware?

That little fan sounds like a jet turbine at 12 volts, which I tried for testing.

[Eaglezsoar]

If you need to run a 5 volt fan on 12 volts, there are several ways to do it.
One way is with a potentiometer that introduces a variable resistance that controls the speed of the fan.
You can also use a voltage divider using a 10K and a 15K resistor in series. One end of the 10K resistor connects to
+12 the other end connects to the 15K resistor and the positive connection to the fan. The other end of the 15K resistor
would connect to ground. The voltage between the two resistors would be approximately 5 volts.