Easy peeling raft

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Robin
Posts: 113
Joined: Sat Dec 29, 2012 6:59 pm

Easy peeling raft

Post by Robin » Sun Dec 30, 2012 6:20 pm

While demolishing a part trying to chew off an unpeelable raft with a Stanley knife I noticed my next print was just finishing layer 10, the top of the raft.

I waited until layer 11 appeared, paused the print and looked around for something that might weaken the bond. When nothing obvious came to hand I simply licked my finger, wiped it on the top of the raft and resumed the print.

You will not believe how well it works unless you try it. Very often I can pop the part off the perf board and leave the raft behind.

As release agents go, it has a lot to recommend it. It's free, in limitless supply and no bottle to lose.

Hope I didn't put you off your coffee :mrgreen:

Marcus
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Location: Germany

Re: Easy peeling raft

Post by Marcus » Tue Jan 01, 2013 3:28 pm

I've got to try that when I'm back ! :-)

Robin
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Re: Easy peeling raft

Post by Robin » Tue Jan 01, 2013 8:46 pm

I can show you it works... :mrgreen:

Here's a part printed in Octave red which sticks like ..er.. anything using the new ROM.

No room to get a blade in underneath it, but the support structure is still intact thanks to the magic fluid.
release.jpg
release.jpg (152.57 KiB) Viewed 12893 times

Blown454
Posts: 49
Joined: Fri Oct 12, 2012 6:13 pm

Re: Easy peeling raft

Post by Blown454 » Sat Jan 05, 2013 7:32 am

Hey there Robin et al,

I buy lots of Octave filament as well (as well as OEM), and while you have a pretty cool trick there ;), Octave came out with a great new accessory that makes the raft/support issues go away completely. I used to fight anything raft and support related when printing the Octave stuff, not anymore, and no more Xacto slices on my fingers (or bandaids :) ). Check out this video and it will show you how to print at lower temp for Octave filament. If you are technical, you can make it yourself. http://www.youtube.com/watch?v=VghB1NlEnQ0

Robin
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Joined: Sat Dec 29, 2012 6:59 pm

Re: Easy peeling raft

Post by Robin » Sat Jan 05, 2013 5:28 pm

Interesting because I had already seen a youtube of someone fitting a potentiometer to get control over the nozzle temp.

I found it curious because it meant the printer was either being very simplistic with a thermocouple (no cold junction) or using a thermistor. I didn't think thermistors were good for 270degC but I am usually behind the times so no big surprises there.

The obvious question is... If you weaken it at the raft interface by lowering the nozzle temperature, do you not weaken it everywhere else?

What we need is someone who has this Octave switch gizmo to try snapping identical parts made on the two settings :mrgreen:

In the switch installation video he warns against throwing the switch mid print and there is a reason for that. I accidentally clicked "Stop All" when aiming for "Resume Print" today, it seemed to resume okay but the nozzle heater stayed off. It got some way before stopping with a "Nozzle too cold" error so flicking the switch mid print could stop it dead in it's tracks.

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DrewPetitclerc
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Re: Easy peeling raft

Post by DrewPetitclerc » Sun Jan 06, 2013 7:45 am

Robin wrote:
As release agents go, it has a lot to recommend it. It's free, in limitless supply and no bottle to lose.
You realize that it is not the "magic" fluid that is helping, what is happening is you are cooling the top layer of raft/support before the next layer of "part" is put down thus keeping them from "bonding" as well. :lol:

If you nozzle temp was calibrated for the plastic as well as it is for the OEM plastic you will notice that the same "cooling period" is accomplished as the extruder is done with the last "support" layer in an area it will move to another print area and this will allow time for the "cooling" of the layer before the next "part" layer is laid down thus the ease of removal. :geek:

I would recommend adding one of the 2 temp control devices mentioned around here, my choice has been the fully adjustable from 300c to 200c in 5c increments (pricey for some, but worth it to me) or the switch method that drops it about 30c (cheap but useable). :D

Regards
Drew
Drew Petitclerc
Petitclerc Designs
Owner/Senior Principal Designer, prototype, tooling and test equipment design and 3D printing
http://flash-graphics.deviantart.com/
http://www.thingiverse.com/DrewPetitclerc

roller
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Location: Brisbane, Australia

Re: Easy peeling raft

Post by roller » Sun Jan 06, 2013 2:26 pm

I found it curious because it meant the printer was either being very simplistic with a thermocouple (no cold junction) or using a thermistor. I didn't think thermistors were good for 270degC but I am usually behind the times so no big surprises there.
I believe (based upon the research and reporting of others on the forum) it's a platinum RTD so is capable of high temps and quite accurate. The resistance table that has been supplied with that info certainly seems to be correct.

Robin
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Re: Easy peeling raft

Post by Robin » Sun Jan 06, 2013 5:08 pm

That sounds likely. If you look at the circuit board it has a pair of LM2596 chips which I suspect power the heaters.

These are 5 pin switching regulators. The pins are power in, ground, power out, a convenient ON/OFF input from the microcontroller and a feedback pin which will switch the output OFF when the Volts rise above 1.235V or switch it ON when they drop below that number. It can handle up to 3 Amps

I presume the temperture sensors connect to the feedback pins, after a bit of jiggery pokery with resistors to set the temperatures.

There is no adjustment available and we presume the sensor is replaceable, so it must be calibrated from new.

You might expect the micro would simply read the temperature on a fairly slow interrupt and switch the heaters on/off accordingly, but what if it stopped working? This micro independant temperature control is a nice feature. I assume the sensor is pulling the line down, so the heater goes off should the sensor wire at the top break, Do try not to short it out :mrgreen:

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