Is there any low warp ABS available in U.K.

As above. I have managed to get ABS prints as flat and as dimensionally accurate as I need, but once I get excelent bed adhesion the shrinkage is relieved by delamination. Although this delamination is slight, it is in areas where there will be stress so is not acceptable. I believe that just a small improvement in warpage of the material will fix this, but am unable to find any suppliers in the U.K. of SmartABS or other ABS materials with reduced warpage.

For info, Printing on a Prusa 1 with hotbed at 112 degrees, extruder at 236 degrees, no fan and enclosure (bag) at 45 degrees - can't go hotter as there are too many PLA parts in the printer.

Have you tried lowering your bed temp to 90C for layers subsequent to the first? Decent filament should remain attached to the bed at that temp and maybe relieve some of the stresses.
Are your printing tall objects?

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Waitaki 3D Printer

I am having no problems with attachment to the bed (although it has taken me a long time to learn how to do that for most models) It is failure in the model, typically above 20 mm above the first layer. The only ways that I can think of to cure this are higher chamber temperature or ABS (or other high temperature material) with better anti-warp characteristics. The main types of this, SmartABS and ABS+ do not seem to be availabel in the U.K.

Mike

Have you shielded your printer against draughts? This is very important when printing ABS models with much depth.

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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].

Protected against drafts by enclosing the whole thing in a box made of large cell double wall bubble film. The temperature self limits to about 40 degrees. I know that geting the temperature up to 60 degrees on my Rostock makes for briliant prints but the Rostock does not achieve the accuracy of my Prusa 1 and the Prusa has PLA parts so even 40 degrees is a bit of a stretch. The best bet remains finding a source of ABS with lower warpage.

Mike

236 is low for ABS. You will get better layer adhesion at higher temperatures. I use 250C for natural ABS and 240C for coloured.

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[www.hydraraptor.blogspot.com]

Too high of bed temperature will cause what you are describing. When I started out my first printer had the bed wired on all the time (around 100c) and it caused problems. Below is a photo of my comparison. Lulzbot recommends 230c print and 80c bed though they do say you can use 100c for first layer if you have an adhesion problem. I have not had the issue since I started just using 85c on the bed.

Quote
leadinglights
I am having no problems with attachment to the bed (although it has taken me a long time to learn how to do that for most models) It is failure in the model, typically above 20 mm above the first layer. The only ways that I can think of to cure this are higher chamber temperature or ABS (or other high temperature material) with better anti-warp characteristics. The main types of this, SmartABS and ABS+ do not seem to be availabel in the U.K.
Mike

Yes, I know that - what I was getting at was that the filament should stay attached with a lower temp - hence suggesting trying it at 90C to lower the delamination stresses.

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Waitaki 3D Printer

I have managed to take a picture of this problem to better explain. The photo is the worst of 8 prints, others wouldn't have photographed so well, but will still be too weak



The print in question is an extruder. The smallest hole is the 2mm filament hole, mid size are for 3mm screws and largest hold is for a 6mm brass bar that the screws screw into. I think you will instantly see why this particular delamination is bad juju.

Over the years I have tried many techniques - including reducing the bed temperature, switching off the bed after the first few layers and many others. The only consistant cure for the problem shown is to keep the whole print good and warm and this is what I am doing here; but on the printer in use the highest I am willling to go is 40 to maybe 50 degrees.

I will try Nopheads suggestion of a higher extruder temperature - the 236 degrees I haven't budged from for a very long time now as it just worked.

In the end though, I hope that there will be filaments at the TCT show in Birmingham next week

I think E3D are floging SmartABS. Have never used it so can't say how good it is... Looks pricy.

I've found that prepping my material helps with layer adhesion and warping, along with preventing drafts. I dry out everything. I'm continuously drying out my desiccant and my filament. I also go crazy cleaning my build plate with acetone before I use glue or hairspray.

I spoke to a number of knowledgable people at the TCT exhibition at the NEC yesterday and showed them the sample (photo in earlier mailing) and there seems to be a bit of a consensus as to the cause of this delamination when all normal causes had been eliminated:

1. The ABS that I used was possibly substandard
2. Black is not a good choice for mechanically stressed parts as undispersed carbon black can act as a point of disslocation. Also, poorly coloured other plastics can be "recovered" by adding carbon black.
3. ABS can be hygroscopic (JerseyGirls point)

So I have ordered several spools of natural Abs

Edited 1 time(s). Last edit at 10/01/2014 05:02AM by leadinglights.

Yesterday I tried printing another batch of the same part, but using a freshly opened white ABS from 3D Filaprint. While greatly improved, there was still delamination.

Today I went back to the TCT exhibitiobn at the Birmingham NEC to see if I could get any further input from filament suppliers there and had several useful suggestions. While I was at the Reprap stand, somebody that I was talking to said "I bet you are using hexagonal infill". His thought is that the layers of the hexagon are substantially solid in the Z direction while rectilinear infill would be much more compliant, having only thin pillars of solid material where the two directions meet. Looking at the G-code, there are large areas of solid infill between each of the main areas of cracking - I think that this is where the different stresses on the uncompressible infill and the cooling outer perimeters are acting.

The new tack is:

1. In the old, crappy black material, print off just one with a rectilinear infill at the same 25% which I previously had in hexagon.
2. If this has worked, print a batch in the white material that I used yesterday.
3. If this did not work, use some samples of ABS+ that I got at the show from ICE.
4. If neither of the above work then redesign the lower end where the cracking is occuring. Possible ideas are to use a different slicer to jigger about with the solidly infilled areas.

With the first try I will use the existing temperatures but with all of the others I will increas the temperature orf the hot end to 250 degrees. This is so that I can get rid of the stresses instead of just hiding them with better perimeter layer adhesion.

Mike