Draught shields for Mini Kossel

I have recently started printing larger ABS parts. My prints are mostly sticking to the bed OK, however they are delaminating to some extent about 35mm above the bed. I am printing with the extruder at 240C and the bed at 110C.

In an attempt to avoid the delamination, I propose to make a screen to put around my Mini Kossel, in the hope that this will be enough to keep the print warmer higher up. I will try a cardboard screen initially, but if it works I would like something more permanent. So I have two questions:

1. Is a screen around the Mini Kossel likely to solve the delamination problem?

2. What I have in mind it to print some plastic plates about 200mm tall and 50mm wide to fit on the backs of the towers, stood off slightly so as not to interfere with the carriage rollers. They will have blind angled slots near the edges so that I can drop pieces of hardboard or Perspex into them. Is there an existing design for something like this? I did a search on Thingyverse, but didn't find anything.

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Large delta printer [miscsolutions.wordpress.com], E3D tool changer, Robotdigg SCARA printer, Crane Quad and Ormerod

Disclosure: I design Duet electronics and work on RepRapFirmware, [duet3d.com].

This setup keeps the chamber temperature little over 30C. It raises the aluminium bed temperature upto 40C which helps adhesion of PLA filament.
The heating device is a 60W light bulb, and a 12V fan on 5V.



I think full enclosure with an adjustable ventilation window is right solution for ABS filament.

One popular technique being used by some people is a plastic oven bag sized for a turkey. They put the open end over the bed, and I guess poke a hole through the bag for the effector. I have personally never tried it, but it supposedly does work for preventing ABS warping.....

Quote
dc42
I have recently started printing larger ABS parts. My prints are mostly sticking to the bed OK, however they are delaminating to some extent about 35mm above the bed. I am printing with the extruder at 240C and the bed at 110C.

In an attempt to avoid the delamination, I propose to make a screen to put around my Mini Kossel, in the hope that this will be enough to keep the print warmer higher up. I will try a cardboard screen initially, but if it works I would like something more permanent. So I have two questions:

1. Is a screen around the Mini Kossel likely to solve the delamination problem?

2. What I have in mind it to print some plastic plates about 200mm tall and 50mm wide to fit on the backs of the towers, stood off slightly so as not to interfere with the carriage rollers. They will have blind angled slots near the edges so that I can drop pieces of hardboard or Perspex into them. Is there an existing design for something like this? I did a search on Thingyverse, but didn't find anything.

I wish Zavashier would chime in, he recently posted a lengthy, very detailed guide on that very same issue in the French forum. The best and clearest howto I have read on the subject. Send him a PM, he might write a translation in English. The short of it is that just a screen to avoid cold air from reaching the ABS part is not enough.

Edited 1 time(s). Last edit at 04/08/2015 03:22PM by AndrewBCN.

Well I found that the cardboard draught shield made only a little difference, it just shifted the delamination up a few layers. So I just tried this:



The bottom part is the original cardboard draught shield. I have put a plastic bag on top, loosely taped to the cardboard. Then another plastic bag on top of that, in the hope of getting at least some air space between the bags to slow down the heat loss. The only heating inside is from the heated bed and the hot end.

This is the result (left is with just the cardboard, right is with the bags as well):



Still not perfect, but a big improvement.

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Large delta printer [miscsolutions.wordpress.com], E3D tool changer, Robotdigg SCARA printer, Crane Quad and Ormerod

Disclosure: I design Duet electronics and work on RepRapFirmware, [duet3d.com].

David,
i made full enclosure for my ormerod wooden and polycarbonate (Marlon SFX 3mm) and I'm building one for my delta too (Polycarbonate only).
On my ormerod it made a difference between unusbale and usable part. I was experimenting exactly just as you do - i was printing kossel vertexes and it delaminated heavilly, but not as much as yours - which i thing is due to my bed having 250mm diameter - so there is more heat around. I have made lasercut bottom and top plates which owerlaps the casing as to provide support fot the PC.

Pavel, that looks good! It's time for me to start designing an enclosure for the Midi-Kossel conversion I am building (same height as the Mini Kossel I am starting from, but 300mm diameter printable area).

Do you have a separate enclosure heater, or do you just rely on the heat from the heated bed and hot end?

My Kossel motor mounts are 54mm tall - more than usual tor 15mm extrusion because I want to fit an IEC mains connector between the horizontal extrusions. Maybe that is why the delamination is so bad? Or maybe I need to try another ABS filament. Anyway, as soon as I have finished another 2 vertices, I will be able to start on the conversion.

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Large delta printer [miscsolutions.wordpress.com], E3D tool changer, Robotdigg SCARA printer, Crane Quad and Ormerod

Disclosure: I design Duet electronics and work on RepRapFirmware, [duet3d.com].

I rely on heatbedand hot only so far, i mesured temperature around X-Arm rib and it is around 45°c when the heatbed is heated at 105°c this seem enough for ormerod.
But i don't know what about the delta - i haven't finished the enclosure yet. The delta is more tall i hope it'll be ok.
I also use longer vertexes actualy 60mm as i put the duet board under the hood and possibly even the power source later.
The underside of my kossel will be open and i'm going to put some active ventilation over the duet board. The heatbed is insulated from the bottom aluminium plate as well as the duet is from the bottom plate.
Insulating the heatbed from bottom made it to heat faster from cold to 110°C from aprox 15 minutes to about 12 minutes.
Also look at this video, it is something i was also considering doing: [www.youtube.com]
Maybe it can help you to print the vertexes at least.

Pavel