Test strength of ABS print

So I have been concerned a bit about the strength of ABS prints, specifically for some GoPro mounts I make.

The fingers on these prints can be squeezed together and they will break but so can the originals from GoPro but it takes a bit more strength on the originals.

So I fashioned the test rig in the photo with a bolt running through the mount and a bit of wire looped under that so I could hook my fish scale to it.

To my surprise I was able to max out my fish case (past the 50lb mark) over and over with no damage to the mount at all. I did some quick calculations and that means the mount should be safe (with the 6oz. camera) for over 133G's

I will probably test each individual finger on the mount separately later. But I am rather happy with the outcome and I will feel safer about producing these mounts for others. ** Always use a leash with a GoPro camera if you value it **

** Always use a leash with a GoPro camera if you value it ** I have heard on other forums of many of the manufacturers mounts breaking and people losing their cameras.

Just thought I would share. I know this is not very scientific testing but I feel more secure now.

its worth a thought none the less, but i think there are a lot of other things that come into account too, like infill and temps during print, but these are good results to see.

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[mike-mack.blogspot.com]

Absolutely there are a ton of variables. Too many to think everybody would have the same results but I should be able to replicate these and not worry that they will break easily.

If you get the printing parameters right, ABS parts is quite strong.

I have been running some tests with a load cell, to test the layer bonding of the parts I print.
The test piece I use is 10x10mm where it is supposed to break apart, I print it with 0.25mm layers 0.5mm width, 2 perimeters and 10% infill.

When printed at 245 degrees, the parts come apart at around 40 to 50Kg in a straight pull, if I reduce the temperature to 230 degrees, I get failure as early as 25-30Kg.

It's rather time consuming to systematically test parts, so I haven't yet got around to test other parameters, such as infill, slight over/under extrusion, speed and perimeters.

My setup can be seen here:
[ralfsfablab.blogspot.dk]

Glad to hear about your testing. I too learned that temperature is important and I now print all my ABS at 245 when I use to print at 240. Even this small 5 degree jump has a made a difference.

So I will also try a higher temp now, last time I lowered the temp and it seemed the strength got better, but maybe with the new filament I'm using now it might be the other way around..

I have just finished testing some red abs I bought off eBay, the label says "ReprapZone", I printed 4 test pieces at 4 different temperatures, 235, 240, 245 and 250 degrees, this was the results, numbers represent breaking load in Kg:

235 degrees:
25.3, 28.3, 29.7, 33.9

240 degrees:
37, 37.8, 39.6, 47.5

245 degrees:
42.6, 44.7, 49.4, 50.6

250 degrees:
45.4, 47, 48, 53

At 250 degrees the test piece started to break apart other places than it was supposed to break.

I was suprised by the rather large difference between 235 and 240 degrees, but nophead says it quite well in this old post: [forums.reprap.org]
Maybe the wiki on ABS should be updated?

Yes I think 245 is the sweet spot, I have printed at 250 but I occasionally got tiny chunks of burnt ABS in the print, I think they were small amounts stuck on the nozzle that burned then fell into the print.

it be intresting to see a pla test too

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Check my rubbish blog for my prusa i3

up and running
[3dimetech.blogspot.co.uk]

I'm waiting fom some PLA to arrive in the mail, when I get this I'll do a similar test.

I got my PLA and have made some preliminary tests.

The parts is printed with 0.25mm layers, and 0.7mm perimeter width, and 2 perimeters. The cross section where the part is supposed to break is 10x10mm square.

The control print was printed in ABS at 240 degrees:
45, 56.4, 59.5, 60.3

PLA at 205 degrees:
53.3, 54.9, 55.8, 68.3

PLA at 210 degrees
54.9, 57.1, 60.5, 61.1

So PLA layer bonding seems to be a tiny bit better than ABS, but more testing is needed.

Cool interesting to know.

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[mike-mack.blogspot.com]

Keep the part orientation in mind too. Based on that pic, your mount is going to be weaker than it otherwise could be since upward force could cause the layers to delaminate; they're only held together by the bond between them and the adjoining layers. By contrast, if you printed the part rotated 90 degrees, then any forces exerted will have to actually rip the individual strands of plastic, which is a much harder task.

For a very good layer adhesion you should give Nylon a try.

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Most of my technical comments should be correct, but is THIS one ?
Anyway, as a rule of thumb, always double check what people write.